Design a Plant to Manufacturing of Ferrous Sulfate Monohydrat

DESIGN THE MANUFACTURE OF (20 TONES/DAY) FERROUS SULFATE MONOHYDRATE

THE PROJECT REPORT ON THE DESIGN THE MANUFACTURE OF (20 TONES/DAY) FERROUS SULFATE MONOHYDRATE FROM WASTE PICKLE LIQUOR

SUBMITTED BY: SURESH KUMAR ROLL NO: 08/S8/33 REGISTRATION NO: S/III/13/40

INDIAN INSTITUTE OF CHEMICAL ENGINEERS SEPTEMBER -2013

1


(A)

STATEMENT OF THE PROBLE

2


Design the manufacture of (20 Tones/day) Ferrous Sulfate monohydrate from waste pickle liquor. Pickling is generally associated with the removal of scale with mineral acid. Sulfuric acid is the most commonly used pickling acid. The spent pickle liquor generally contains about 15 to 20% ferrous sulfate and about 2 to 5% sulfuric acid. This spent liquor is first neutralized with excess iron in a neutralization tank and then filter of excess iron. The solubility of ferrous sulfate increases up to 65 0C and then decreases where ferrous sulfate exists as monohydrate. At ordinary low temperatures, it exists as ferrous sulfate heptahydrate. An evaporative crystallizer is used to produce ferrous sulfate monohydrate which operates at 650C. After separation of crystals, the mother liquor is recycled back to neutralization tank. Prepare a design report consisting of the following.

Full Marks

3


Literature

1.

Survey

15 Detailed

2.

flow

sheet

15 Material

3.

and

Energy

balance

20 Design

4.

of

neutralizer

unit

including

mechanical

design

30 Design of Evaporative crystallizer unit including mechanical design

5.

40 Instrumentation

6.

and

process

control

in

the

process

15 Plant

7.

layout

10 Safety

8.

and

pollution

abetment

aspects

10 Cost

9.

Estimation

15 10.

Detailed engineering drawing of the neutralizer and evaporative

30 crystallizer ----------Total 200 -----------

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CONTENTS TOPICS

PAGES

A. Major performance & Equipment data

6

1. Literature survey

12

2. Detailed flow sheet

29 [Docket]

3. Material and Energy Balance of the plant

33

4. Design of neutralizer unit

46

5. Design of Evaporative crystallizer

69

6. 83

Instrumentation

and

process

control

in

7. Plant Layout

the

process [Docket] 88 [Docket]

8. Safety and pollution abatement aspects

99

9. Cost estimation

116

10. Detaited engineering drawing of the reactor and centrifuge

11. Nomenclature

126 [ Docket] 129 5


12. Bibliography

137

CHAPTER-I MAJOR PERFORMANCE & EQUIPMENT DATA

6


I. MAJOR PERFORMANCE & EQUIPMENT DATA OVERALL MATERIAL BALANCE AROUND THE PROCESS COMPONENT

BASIS 100KG PRODUCTION INLET( KG) OUTLET( KG)

AS PER PRODUCTION RATE INLET(KG) OUTLET(KG)

Ferrous sulfate through Pickle

89.4

0

795.66

0

22.35

0

198.92

0

335.25 88.71

335.25 26.613

2983.73 789.52

2983.73 236.86

10.6

25.31

94.34

225.26

57.72

0

513.71

0

0

100

0

889

liquor Sulfuric acid Through pickle liquor Water through pickle liquor Lime solution Water Sulfuric acid required Ferrous sulfate monohydrate formed Impurity Calcium Sulfate TOTAL

1.18 0 605.21

6.90 111.12 605.19

10.5 0 5386.38

61.41 988.97 5385.23

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PROCESS DESIGN OF THE NEUTRALIZER Type of Neutralizer No of Neutralizer Volume of Neutralizer Height of Neutralizer Diameter of Neutralizer Inlet nozzle diameter of the Neutralizer for

CONICAL 1 12.72 m3 3.038 m 4.000 m 48 mm

Pickle liquor Inlet nozzle diameter of the Neutralizer for

30 mm

Lime solution Outlet nozzle diameter of the Neutralizer

60 mm

MECHANICAL DESIGN OF THE NEUTRALIZER Shell material Shell thickness Effective gasket seating width Nozzle Thickness Agitator type Power taken to agitator Agitator diameter Permissible stress of Shaft Max. Torque Actual Shaft Speed Critical Shaft Speed Flange Thickness Max. Stud diameter Force per bolt Bolt Size Coupling diameter Height of bracket from foundation Maximum compressive load Base plate thickness of Bracket Web plate thickness of Bracket Base plate thickness for column

LOW CARBON STEEL 20 mm 7.9 mm 20 mm Turbine 450 Kw 1200 mm 25488 N/mm2 32406 Nm 200 rpm 320 rpm 35 mm 20 mm 9421 N 24 M 130 mm 2.25m 15830 kg/cm2 25mm 20mm 20mm

PROCESS DESIGN OF THE CALENDRIA EVAPORATIVE CRYSTALLIZER Type of Crystallizer

CALENDRIA

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No of Crystallizer Crystallizer Area Crystallizer feed nozzle diameter

01 64.97 m2 60 mm

Crystallizer Product nozzle diameter.

60 mm

Steam Inlet nozzle diameter

40 mm

MECHANICAL DESIGN OF CALENDRIA EVAPORATIVE CRYSTALLIZER Evaporator material Number of tubes Pitch of the tube (triangular) Evaporator Area Tube Material Area of central down take Diameter of tube sheet Calendria Sheet Thickness Tube Sheet Thickness Thickness of Flange Number of bolts Pitch circle diameter Size of bolts Outside diameter

LOW Carbon Steel 605 125 mm 9860 mm Brass 1880 mm 3710 mm 12 mm 36 mm 40 mm 112 3825 mm 20 M 3894 mm

Drum height

3000 mm

Drum Thickness

10 mm

Critical External Pressure

0.058 N/mm2

Permissible stress

15.9 N/mm2

Head thickness is based on an external pressure Conical head angle

0.1 N/mm2 1200

COST ESTIMATION OF THE PLANT SL.No ACCOUNT HEAD

EXPENDITURE IN RUPEES

9


1

PURCHASE EQUIPMENT COST (E1)

148115711

2

PURCHASE EQUIPMENT INSTALLATION ( 39% of E1 )

57765127

3

INSTRUMENTATION (INSTALLATION) ( 28% of E1)

41472399

4

PIPING (INSTALLED ) (45% of E1 )

66652069

5

ELECTRICAL (INSTALLED ) (10% of E1 )

14811571

6

BUILIDING ( INCLUDING SERVICE) (22% of E1)

32585456

7

SERVICE FACILITIES (55% of E1 )

81463641

8

LAND ( 6% of E1 )

8886942

1 2

TOTAL DIRECT COST (D)

451752916

INDIRECT COST ( I) ENGINEERING AND SUPERVISION (15% OF E1 )

22217356

CONSTRUCTION EXPENSES (12% OF E1 )

17773885

3

LEGAL EXPENCES (2% OF E1 )

2962314

4

CONTRACTOR’S FEE (4% OF E1 )

5924628

5

CONTINGENCY ( 10% OF E1 )

14811571

TOTAL INDIRECT COST (I)

63689754

TOTAL DIRECT + INDIRECT COST (D+I)

515442670

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CHAPTER-1 LITERATURE SURVEY

L ITERATURE SURVEY INTRODUCTION

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One billion gallons of waste pickle liquor are discharged from American steel mills every year. This waste, which results from cleaning steel in various stages of its manufacture, contains enough iron to built more than 200000 automobiles and contains about one million tons of sulfuric acid. During the last seventy years, many processes have been proposed both for the recovery of the iron or acid values of waste pickle liquor and for the elimination of the waste. From 1888 when Kirk man received a British patent on waste -acid treatment to the present day, increasingly intensive research effort has been devoted to finding a practical answer to this problem. The desirable characteristics of a satisfactory solution to the pickle liquor disposal problem may be summarized as follows: 1. Elimination of Pollution 2. Attractive economics 3. Simple and compact operation with demonstrated reliability 4. Products that can be readily disposed of. No one process, certainly, will meet these criteria for all pickling operations, and therefore Koppers offers to built a variety of plants covering both the by -product recovery and simple disposal techniques.

THE INDUSTRIAL REVOLUTION The huge increase in demand for strip steel for automobiles and cans eventually led to the development of continuous strip picklers, in which the uncoiled strip was drawn continuously through tubs of hot sulfuric acid. Early lines processed several narrow strips

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at speeds of 30 to 100 fpm, with the successive coils being held together with mechanical clips, but, in time, speeds of up to 400 fpm were obtained with welding of each coil to the next - take-up systems or looping pits were added to keep the pickler on stream while the welding was taking place. A NEW ACID ON THE SCENE Some specialty batch picklers had used hydrochloric acid previously, especially if a high quality surface was needed, but the expense, corrosiveness and fuming problems made this acid unattractive. However, from 1960 to 1965, three things took place to change this: - the development of light-weight, strong and cheap plastics materials, such as FRP and polypropylene, which made corrosion and fume control easier - the development of processes to regenerate (or reclaim) the spent acid not just the free acid, but also the acid that had reacted with the scale - the increasing public awareness of the damage to the environment that results from dumping spent sulfuric pickle acid into streams and rivers Strip picklers then realise that hydrochloric acid could be an attractive alternative to sulphuric acid not only because it could be regenerated (so eliminating the pollution problem) but also because pickling speeds were higher, scale breakers were not needed, and product quality was better. PHYSICAL AND CHEMICAL PROPERTIES: Synonyms :

Ferrous Sulfate Monohydrate, Mono

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Trade Name:

Iron Sulphate Monohydrate

Molecular Weight:

169.91

Product Use:

Fertiliser

Chemical formula :

FeSO4. H2O

Form :

Powder

Color :

Greyish - yellow

Odor :

Odourless

pH Value (20 oC) at 50 g/l H2O :

1.5-3.8

Melting point : ( approx )

~ 300 oC ( release of crystal water ),

Boiling point :

Not available

Ignition temperature :

Not combustible

Flash point :

Not flammable

Explosion limits Lower :

Not applicable

Upper :

Not applicable

Vapour pressure :

not applicable

Density (20oC) :

~ 2.97 g/cm3

Bulk density :

~ 850 kg/m3

Solubility in water (20oC) :

256 g/L

Thermal decomposition :

> ~ 300 oC

CHEMICAL STABILITY & REACTIVITY INFORMATION

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CHEMICAL STABILITY Under normal conditions of temperature and pressure, Ferrous Sulfate Monohydrate is stable. Ferrous Sulfate Monohydrate reacts in moist air to form ferric sulfate. Ferrous Sulfate Monohydrate looses water in dry air and may discolour upon exposure to moist air, forming a brown coating of extremely corrosive, basic ferric sulfate. CHEMICAL STABILITY: CONDITIONS TO AVOID Water of crystallization will be released when exposed to temperatures over 300 deg. C. INCOMPATIBILITY Avoid strong alkalis, soluble carbonates, gold and silver salts, lead acetate, lime water, potassium iodide, potassium, sodium tartrate, sodium borate, and tannin. HAZARDOUS DECOMPOSITION Sulfur oxides and dioxides are normal decomposition products. May liberate toxic metal fumes and acrid smoke. HAZARDOUS POLYMERIZATION WILL NOT OCCUR.

THE THEORY Quite often the pickling process is wrongly referred to as a "cleaning" process. As we discuss the technology involved in pickling, we will discover just how wrong that reference really is.

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The pickling process is in fact a chemical process and has very little to do with "cleaning" the steel. In other words, pickling does not remove anything but mill scale; to remove grease or soot or whatever from the steel, don't look to the pickle tank to do it. In order to appreciate the following discussion on the theory of pickling, it is helpful to be familiar with some basic chemistry. The action which creates the bubbles under the scale is caused by the acid reacting with iron. This is called a "chemical reaction". Chemical reactions are expressed in equations, showing all components needed to create the reaction on the left side and all components being created on the right side of the equation. Thus the chemical reactions at work in the pickling process are expressed as follows: Iron Oxide + Sulfuric Acid = Iron Sulfate + Water (FeO)

(H2SO4)

(FeSO4)

(H2O)

Iron + Sulfuric Acid = Iron Sulfate + Hydrogen (Fe)

(H2SO4)

(FeSO4)

(H2)

Sulphuric acid in its pure molecular state will not react with either iron or iron oxide, it must be dissolved in water in order to become reactive. It follows therefore, that these reactions only take place in aqueous solutions (in the presence of water). Both reactions create iron sulfate as a by product and both reactions are exothermic, meaning heat is created during the reaction. However, there is a distinct difference between the two in that iron dissolves quite rapidly, even violently at higher temperatures, while iron oxide dissolves very slowly or hardly at all under certain conditions. THE PICKLING EXPERIMENT

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If we now immerse a piece of steel covered with mill-scale in a sulphuric acid solution, we will observe the following: ● bubbles form at every crack in the mill-scale ● little flakes of mill-scale float off the steel ●bubbles form on the newly exposed surfaces of the steel

●the solution temperature rises slightly ●the acid concentration is decreasing ●the solution is turning slightly green ●more and more mill-scale flakes are floating dispersed in the ● solution and are slowly settling to the bottom ●finally, the surface of the steel is free of mill-scale and instead is covered in furiously dancing bubbles which are rising rapidly to the surface of the solution

●an acrid odour rises from the surface of the solution ●the colour of the steel changes from a bright silvery gray to a dull blackish gray

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●the steel is removed, the action in the solution stops,microscopically tiny particles suspended in the solution slowly settle to the bottom. ●A layer of precipitate is visible on the bottom of the vessel.

The above observations accurately describe all the events taking place when steel is being pickled. THROWING CURVES Looking at the solubility curve, we can see, that three separate conditions determine the state of solubility: solution temperature, acid concentration and ferrous sulfate concentration (expressed as iron). Also we can see that the curves come to a definite peak; the line connecting these peaks is the phase change line. At this point, let us observe another experiment using the same pickling solution from the previous experiment just prior to dumping it. Assuming that the solution is at 180°F, 10.8% iron

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and 10% acid. To find out how this solution relates to the solubility curve, follow this procedure: - - draw a vertical line at 180°F - - note where this line intersects with the curve representing 10% acid - - draw a horizontal line from this intersection to the left - - note where this line intersects with the iron scale: 10.8% To find out, what significance this has on our experiment, we must know more about how to interpret the solubility curve:

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PICKLING LIQUOR REGENERATION The pickling acid bath contains mainly ferrous chloride (FeCl2) produced on account of the following reaction and the unused hydrochloric acid (HCl). Fe0 + 2 HCl = FeCl2 + H20 The regeneration of spent pickling liquor is carried out by oxidizing its dissolved iron chloride (FeCl2) in a fluidized bed reactor at about 800°C. The valuable ferric oxide (Fe203) is also produced as a by-product. For this, the reaction is reverse of pickling reaction, producing gaseous hydrochloric acid. 4 FeCl2 + 02 + 4 H20 = 2 Fe203 + 8 HCl The hot reactor gases are first passed through the cyclone separator to recover the Fe 203 granules and then passed through the pre-evaporator to concentrate the incoming spent pickling liquor. The hydrochloric acid is recovered by the absorption of gaseous HCl in water in the absorber. OTHER PROCESSES: A process for producing ferrous sulfate monohydrate directly from iron in the absence of the production of the intermediate ferrous sulfate heptahydrate, the steps of said process comprising: Generally speaking, this invention relates to a process for the production of ferrous sulfate from scrap iron. More particularly, this invention relates to the production of ferrous sulfate monohydrate from scrap iron in the absence of the intermediate formation of ferrous sulfate heptahydrate . As is well known, ferrous sulfate is particularly useful as a starting material in the manufacture of pure iron oxide which, in turn, is useful in the

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manufacture of ferrites. When it is realized that only slightly more than 61 lbs. of ferrous sulfate monohydrate yields the same quantity of ferrous sulfate as 100 lbs. of ferrous sulfate heptahydrate, the economic advantages of using the monohydrate form for the production of iron oxide become obvious, even if one is only considering the difference in handling weight involved. The difference, of course, as well known, is in the water content of the heptahydrate form of ferrous sulfate which must be driven off so as to provide a satisfactory economical ingredient for the production of pure iron oxide. Other advantages of the monohydrate form of ferrous sulfate over the heptahydrate form include the fact that it is more readily calcined to form iron oxide and it does not fuse nearly as readily when heated as does the heptahydrate. In addition, when stored, it is much more stable and does not rapidly oxidize in air or absorb moisture as does the heptahydrate form. In the past, attempts have been made to produce ferrous sulfate from iron by dissolving the iron in sulfuric acid. However, such a reaction produces the more undesirable heptahydrate form of ferrous sulfate, as well known. Attempts have been made to overcome this problem, particularly in processes for recovering iron salts from waste pickle liquors. However, such processes are directed to different problems than those related to the production of the monohydrate from scrap iron in that such processes involve solutions which must be handled in a manner so as to remove the iron salts therefore and include the application of elevated temperatures or pressures or a combination of the two for producing an intermediate monohydrate product from such pickle liquor solutions. Thus, the problem arises where in order to produce ferrous sulfate directly from iron, such as steel scrap, one obtains the undesirable ferrous sulfate heptahydrate which from an economic standpoint creates certain problems in its use in

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the production of further products therefore, and conversely, if it is attempted to produce the more desirable final product of the ferrous sulfate monohydrate, uneconomical processes such as utilization of expensive evaporation and/or high pressure techniques must be used in order to control the reaction for the recovery thereof from spent pickle liquors. By contrast, and quite unexpectedly, it has now been found in accordance with this invention that by combining iron, such as steel scrap, with a sulfuric acid solution at a concentration of between about 10-90 percent for a period of time to reduce the acid concentration to a particular level, separating any precipitate and/or impurities contained therein from the acid solution of reduced concentration, and thereafter adding concentrated sulfuric acid in an amount sufficient to increase the frre acid concentration to within a particular range, a ferrous sulfate monohydrate precipitate is formed which is readily separated from the reacting environment and under conditions requiring no pressure and very little temperature. The reaction takes place with little or no control necessary and the end product is separated after a period of time with the only requirement being that the reaction be allowed to go to completion at a particular level of free acid concentration. The resulting precipitate is readily separated from the reacting solution by filtration and if a batch-type procedure is used, as described in more detail below, any unreacted iron in the filter cake is easily separated therefore magnetically. As is obvious with such an arrangement, little attention must be given to the reactants during the reaction period thus reducing substantially the cost simply because no temperature and/or pressure controls must be utilized to any appreciable extent for maintaining control during the reaction period. It has been found, in accordance herewith, that a substantially pure form of ferrous sulfate monohydrate is achieved. In addition, the

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process in accordance herewith, is readily applicable to a continuous procedure in which sulfuric acid and iron are reacted, with the sulfuric acid being at a particular range of concentration and with the sulfuric acid being continuously circulated through a container of scrap iron. This continuous procedure continues until the free acid concentration is reduced to a particular level at which time the acid solution is drawn off and filtered to separate out any impurities and/or precipitate. To the filtrate is added concentrated sulfuric acid to bring the free sulfuric acid concentration up to a particular range of concentration at which point the pure ferrous sulfate monohydrate is precipitated. The product is thereafter filtered off and the filtrate is recalculated back through the scrap iron container where additional amounts of iron scrap are added continuously to maintain the initial reacting conditions. Accordingly, it is one object of this invention to produce ferrous sulfate monohydrate from iron, such as iron scrap, In addition, it is another object of this invention to produce such ferrous sulfate monohydrate in substantially pure form and in the absence of the production of the intermediate ferrous sulfate heptahydrate. It is a further object of this invention to produce such ferrous sulfate monohydrate by the reaction of the iron with sulfuric acid which reaction requires little or no control during the reaction period. A further object of this invention is a process for the production of ferrous sulfate monohydrate directly from scrap iron in the absence of any pressure requirements and at only slightly elevated temperatures and requiring no expensive evaporative and/or calcining procedures. In addition, it is an object of this invention to produce substantially pure ferrous sulfate monohydrate which is readily separable from the reaction environment, and which product in turn is readily separable from any unreacted iron from the reaction of the process. Before describing this invention in more

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detail, it may be well to note that this invention has been found applicable to a wide variety of iron sources, such as, for example, scrap iron left over from detaining operations, which operations are usually applicable to discarded tin scrap in which the relatively valuable tin plate has been separated from the steel thereof, as well known. For example, satisfactory results have been achieved in accordance herewith, and under satisfactorily and economically attractive conditions in commercial scale operations with ferrous scrap resulting from detaining operations with the ferrous scrap being added to the reaction zone along with a sulfuric acid solution in a concentration of between about 10-90 percent, and maintaining the admixture at a temperature between about ambient to 100°C. for a period of time sufficient to reduce the free acid concentration down to between about 2-35 percent, separating the resulting solution from the unreacted iron, filtering the solution to remove any precipitation and impurities contained therein, adding concentrated sulfuric acid to the solution to bring the free acid concentration up to between about 35-45 percent for precipitating pure ferrous sulfate monohydrate, and separating the pure ferrous sulfate monohydrate from the filtrate. The reaction environment requires no application of pressure and/or vacuum procedures in order to provide satisfactory results, in accordance herewith. The reaction produces a ferrous sulfate monohydrate substantially with no control thereof and the precipitated ferrous sulfate monohydrate is readily separated from the reaction zone, and in certain instances the resulting separated precipitate may be separated from any unreacted ferrous scrap merely by application of magnetic means. In considering generally the conditions for achieving the enhanced results in connection herewith, which conditions are more specifically set forth below, one may note that satisfactory ferrous sulfate monohydrate

24


product may be produced in accordance herewith in cyclic operations in which after the precipitate product has been separated from the acid solution, and any unreacted iron separated from the precipitate product if a batch-type procedure is used, additional quantities of iron and sulfuric acid may be introduced into the reaction zone for the production of additional amounts of ferrous sulfate monohydrate, with care being taken only to maintaining the free sulfuric acid concentrations in the reaction zones within the ranges noted above. A preferred cycle of operation in accordance herewith for producing the ferrous sulfate monohydrate product includes admixing iron, such as scrap produced by detaining operations, and sulfuric acid in a reaction zone having between about 10-90 percent free sulfuric acid concentration, and preferably 40% H2 SO4. The temperature of the admixture is maintained between ambient and 100°C., and preferably 50°C. The reaction zone is maintained as above for the period of time necessary to reduce the free acid concentration down to the range of between about 2-35 percent for the reaction to come to completion, and preferably about 20-30 percent, and thereafter, any precipitates and impurities are separated from the solution. Then concentrated sulfuric acid is added to the solution to bring the free acid concentration up to between about 35-45 percent, preferably 40 percent, to precipitate out the pure ferrous sulfate monohydrate product. The precipitate is separated from the acid solution, preferably by centrifuge, to obtain a substantially pure ferrous sulfate monohydrate product and the remaining filtrate is recycled to the first reaction zone for further reaction with additional quantities of iron. The process in accordance herewith achieves the desired pure ferrous sulfate monohydrate directly from a reaction of iron and sulfuric acid in the absence of the production of any of the undesirable intermediate ferrous sulfate heptahydrate, and with

25


little or no control being necessary for the reaction environment, thus eliminating expensive evaporative, pressure and/or vacuum application procedures. Further, the ferrous sulfate monohydrate has a much larger quantity of the desired ferrous sulfate on a weight for weight basis and is readily stored for long periods of time without requiring provisions for preventing oxidation and water absorption. The results achieved by the process, in accordance herewith, examples were prepared using the preferred ratio of reactants, in accordance herewith, and under the preferred control conditions for the reaction zone. It is to be understood, however, that these examples are being presented with the understanding that they are to have no limiting character on the broad disclosure of the invention as generally set forth herein and as directed to men skilled in the art. STORAGE AND HANDLING: STORAGE: Store in cool, dry, well ventilated area removed from combustible materials, herbicides, fungicides and foodstuffs. Ensure containers are labeled, protected from physical damage and sealed when not in use. Keep from extreme heat and open flames and make sure that the product does not come into contact with substances listed under "Materials to avoid" in Section 10. Bagged fertilizers should be stored under cover and out of direct sunlight. If stacking is necessary, bulk bags should be stored in a stable manner, preferably in a pyramidal style. Bulk bags should not be stacked more than two high for bags containing 1000 kg or more, or more than four high for bags containing up to 500kg. The pallet Capacity Rating (Design Weight) should not be exceeded on the bottom tier for other packs

26


HANDLING: Before use carefully read the product label. Use of safe work practices are recommended to avoid eye or skin contact and inhalation. Observe good personal hygiene, including washing hands before eating. Prohibit eating, drinking and smoking in contaminated areas. DISPOSAL CONSIDERATIONS DISPOSAL: There are many pieces of legislation covering waste disposal and they differ in each state and territory, so each user must refer to laws operating in their area. In some areas, certain wastes must be tracked. The Hierarchy of Controls seems to be common the user should investigate: Reduce, Reuse, and Recycle and only if all else fails should disposal be considered. Special help is available for the disposal of Agricultural Chemicals. The product label will give general advice regarding disposal of small quantities, and how to cleanse containers. ECOLOGICAL INFORMATION: ENVIRONMENT: Avoid contamination of waterways. ECOTOXICITY EFFECTS: Dissolves slowly in water. Harmful to aquatic life at low concentrations. ENVIRONMENTAL EFFECTS: Can be dangerous if allowed to enter drinking water intakes. Do not contaminate domestic or irrigation water supplies, lakes, streams, ponds, or rivers. MOBILITY IN ENVIRONMENTAL MEDIA: Dissolves slowly in water Persistence/degradation: Will persist for weeks in soil, but is a plant nutrient.

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CHAPTER-2 DETAILED FLOW SHEET

28


2. DETAILED FLOW SHEET BRIEF OUTLINE OF THE

FERROUS SULFATE MONOHYDRATE FROM

PICKLE LIQUOR: Spent pickle liquor is a waste material of the pickling operation of steel mills. Pickling is a treatment of iron and steel plant with aqueous sulfuric acid solutions to remove the scale from their surfaces. The sulfuric acid interacts with the iron oxide during the pickling, and forms water soluble ferrous sulfate with it. The effectiveness of the sulfuric acid solution gradually diminishes as its acid content decreases and its FeSO 4, content increases. The disposal of large amounts of pickle liquor not only represents a serious loss in unreacted sulfuric acid, but causes an objectionable pollution problem, even after neutralization. The pickle liquor is received at the steel plant at a temperature of about 87.80C

and normally with contain 5% H2SO4 and 20% FeSO4. This solution is

neutralized with excess iron in a neutralization tank. The pickle liquor can be neutralized with lime [Ca(OH)2] to precipitate out the metals as hydroxides. Most of the sulphate will also precipitate out as calcium sulphate (gypsum) so that a mixed filter cake is produced. The neutralization of pickle liquor with calcium hydroxide or oxide, with the precipitation of iron as ferrous` hydroxide and the formation of calcium sulfate, generally requires a quantity of lime considerably in excess of the stoichiometric amount. When the lime slurry is combined with the pickle liquor, the surfaces of the lime particles are coated with-a nearly impervious layer of ferrous hydroxide and sometimes calcium sulfate, thereby decreasing the availability of the lime, necessitating the use of. a considerable excess for neutralization.

29


After filtration the solubility of ferrous sulfate increases up to 650C and then decreases where ferrous sulfate exists as monohydrate. At ordinary low temperatures, it exists as ferrous sulfate heptahydrate. The calendria type evaporative crystallizer is used to produce ferrous sulfate monohydrate. The crystallizer is operated at 650C and pressure at 0.1N/mm2 . d combine with it to form ferrous sulfate heptahydrate and simultaneously with the concentrating of the sulfuric acid in the pickle liquor as a result of the extraction of water therefore, solubility of ferrous sulfate in the pickle liquor decreases with the result that the ferrous sulfate heptahydrate precipitate in the slurry is greater in quantity based on the ferrous sulfate than the amount of ferrous sulfate monohydrate added to the spent pickle liquor. The ferrous sulfate heptahydrate crystals are separated from the liquid leaving a more concentrated pickle liquor, The recovered heptahydrate may be reconverted to monohydrate by dehydration and recycled to the water extraction step for the regeneration of a new amount of pickle liquor. Thus, the process is self-sustaining, as after the initial start up, it furnishes its own water extracting agent, and no ferrous sulfate monohydrate is required from external sources to maintain the operation. Moreover, an excess of ferrous sulfate monohydrate is produced, equivalent to the amount which precipitates out of the pickle liquor or concentration. This material may be withdrawn from the process and utilized in the sulfuric acid manufacture. The concentration of the sulfuric acid in the pickle liquor may be increased to by water extraction with ferrous sulfate monohydrate. REACTION: REACTION: (NEUTRALIZATION UNIT)

30


FeSO4+ Ca(OH)2----→ FeO + CaSO4+ H2O------------------(i) H2SO4 + Ca(OH)2 --→ CaSO4 +H2O---------------------------(ii) FORTIFIER FeO +2 H2SO4 ----→FeSO4 + H2O---------------------------------------(iii) CRYSTALLIZER FeSO4 + H2O----→ FeSO4.H2O---------------------------------------------(iv) PROCESS FLOW SHEET:

DETAILED FLOW SHEET OF FERROUS SULFATE MONOHYDRATE FROM PICKLE LIQUOR

31


CHAPTER-3 MATERIAL AND ENERGY BALANCE

32


MATERIAL BALANCE INTRODUCTION: Material and energy balances are very important in an industry. Material balances are fundamental to the control of processing, particularly in the control of yields of the products. The first material balances are determined in the exploratory stages of a new process, improved during pilot plant experiments when the process is being planned and tested, checked out when the plant is commissioned and then refined and maintained as a control instrument as production continues. When any changes occur in the process, the material balances need to be determined again. MATERIAL BALANCE: Desire rate of production of Ferrous Sulfate Monohydrate = 20 Tones/Day =7300 Tones/Year Note; [In a continuous plant the on steam time varies from 93% to 96%,here operating factor is 93% of steam time , In the present case 1 year will be 365*0.93 =339.5 working days i.e. 340workig days.]

So. Desire rate of production = (7300X1000 )/ (24X340) Kg/hr = 894.60 Kg/hr Material balance of the entire plant will be calculated on the basis of 100kg of Product.

33


REACTION: (Neutralization Unit): FeSO4+ Ca(OH)2----→ FeO + CaSO4+ H2O..................(i) H2SO4 + Ca(OH)2 --→ CaSO4 +H2O..............................(ii) Main reaction: FeO +2 H2SO4 ----→FeSO4 + H2O................................(iii) Crystallizer: FeSO4 + H2O----→ FeSO4.H2O......................................(iv)

3.a.IV. MATERIAL BALANCE OVERALL PROCESS AT A GALANCE DATA AND ASSUMPTION i)

Sulfuric acid inlet through Pickle liquor as 5%.

ii)

Ferrous sulfate 20% based on feed.

iii)

Rest material is water = 75% of feed.

iv)

Lime [Ca(OH)2]as a neutralizing agent.

v)

Ca(OH)2 solution is 70% pure. Rest is water.

vi)

After neutralizer solution react with 98% pure sulfuric acid.

vii)

Rest 2% of sulfuric acid is impurity.

CALCULATION Basis : 100 kg of Ferrous sulfate monohydrate production

34


Time : 1hour operation We get from reaction, 100 kg of Ferrous sulfate monohydrate Crystal production. So, from equation (iv),we get Ferrous sulfate required= (151.8/169.8)*100= 89.40 kg Water required = (18/169.8) *100=10.6 kg From equation (iii), Ferrous oxide required =( 71.8/151.8)* 89.40 =42.29 Kg Sulfuric acid required( (98% ) ={(98/151.8)* 89.40}/0.98 = 58.90 kg Impurity = 58.9*0.02= 1.18 kg Pure Sulfuric acid = 58.90-1.18 = 57.72 Kg Water produced = (18/151.8)* 89.40 kg = 10.60 kg From equation (i), Ferrous sulfate required = (151.8/71.8)* 42.29 =89.41 kg Lime solution required (70% )[ Equation. i] = { (76/151.8)*89.41}/0.70 kg = 63.95 kg Calcium Sulfate formed Water formed

= ( 136/151.8)*89.41 =80.10 Kg = (18/151.8) * 89.41 = 10.60 Kg

Pickle liquor required = 89.41/0,2 =447.05 Kg Sulfuric acid enter through feed = 447.05* 0.05 = 22.35 kg From equation (ii), Lime solution required(70%) [Equation ii] ={(76/98)* 22.35} /0.70 =24.76 Kg Calcium Sulfate formed

= (136/98)* 22.35 = 31.02 Kg

Water formed (equ.ii) = (18/98)* 22.35 = 4.11 Kg

35


Total Calcium Sulfate (equation i +equation ii) = 111.12 Kg Total Lime solution = 63,95+24.76 =88.71 Kg Total water formed (equation i + equation. ii+ equation. iii) = 4.11+10.60+10.60 =25.31 Kg Desire rate of production =

889.71 Kg/hr

Conversion factor = (889.71/100) =8.897≡ 8.90 SO. total pickle liquor= 447.00* 8.9=3978.30 Kg Ferrous sulfate inlet through pickle liquor= 89.4*8.9= 795.66Kg Sulfuric acid inlet through pickle liquor = 22.35* 8.9 = 198.92 kg Water enter through pickle liquor

= 335.25* 8.9 = 2983.73 Kg

Impurity at outlet = 1.18/0.171 =6.90 Kg OVERALL Material BALANCE AROUND the process COMPONENT

BASIS 100KG PRODUCTION INLET( KG) OUTLET( KG)

AS PER PRODUCTION RATE INLET(KG) OUTLET(KG)

Ferrous sulfate through Pickle

89.4

0

795.66

0

liquor Lime solution

88.71

26.613

789.52

236.86

10.6

25.31

94.34

225.26

0

100

0

889

22.35

0

198.92

0

Water Ferrous sulfate monohydrate Sulfuric acid Through pickle

36


liquor Water through pickle liquor Sulfuric acid

335.25

required Impurity Calcium Sulfate Total

57.72 1.18 0 605.21

335.25 0 6.90 111.12 605.19

2983.73

2983.73

513.71 10.5 0

0 61.41 988.97

5386.38

5385.23

3.a.V. MATERIAL BALANCE AROUND NEUTRALIZER AT A GLANCE DATA AND ASSUMPTION i)

Sulfuric acid inlet through Pickle liquor as 5%.

ii)

Ferrous sulfate 20% based on feed.

iii)

Lime [Ca(OH)2]as a neutralizing agent.

iv)

Rest material is water = 75% of feed.

MATERIAL BALANCE AROUND NEUTRALIZER AT A GLANCE

Component

Input Kg

Out put Kg

Pickle liquor Lime solution Sulfuric acid Through

795.66 789.52

0 236.86

pickle liquor Water through pickle

198.92

0

liquor Calcium Sulfate Water produce

2983.73 0 0

Ferrous sulfate through

2983.73 988.97 130.92

37


Ferrous oxide Impurity Total

0 0 4767.83

376.38 49.80 4766.66

3.a.VI. MATERIAL BALANCE AROUND FORTIFIER AT A GLANCE DATA AND ASSUMPTION i)

98% pure Sulfuric acid is feed

MATERIAL BALANCE AROUND FORTIFIER AT A GLANCE

Component

Input Kg 0

Ferrous sulfate Sulfuric acid Water produce Ferrous oxide Impurity Total

513.71 0 376.381 40.30 930.39

Out put Kg 795.75 0 94.34 0 40.30 930.39

3.a. VII. MATERIAL BALANCE AROUND EVAPORATIVE CRYSTALIZER AT A GLANCE DATA AND ASSUMPTION i)

Temperature maintained at 650C

ii)

Pressure at 0.1 N/ mm2

III)

MATERIAL BALANCE AROUND EVAPORATIVE CRYSTALIZER AT A GLANCE

Component

Input Kg

Out put Kg

38


Ferrous sulfate Water Ferrous monohydrate Impurity Total

795.66 3078.065 20.10 3893.83

0 2983.72 890 20.10 3893.82

3 b. ENERGY BALANCE: 3.b.i .ENERGY BALANCE OF THE PLANT. Process stream at high pressure or temperature, and those containing combustible material, contain energy that can be usefully recovered. Whether it is economic to recover the energy content of a particular stream will depend on the value of the energy that can be usefully extracted and the cost of recovery. The value of the energy will depend on the primary cost of energy at the site. It may be worth while recovering energy from a process stream at a site where energy costs are high but where the primary energy cost are low. The cost of recovery will be the capital and operating cost of any additional equipment required. If the savings exceed the operating cost, including capital charges, then the energy recovery will usually be worthwhile. Maintenance cost should be included in the operating cost. 3.b.ii. ENERGY BALANCE Energy balances can be calculated on the basis of external energy used per kilogram of product, or raw material processed, or on dry solids or some key component. The energy consumed in food production includes direct energy which is fuel and electricity used on the farm, and in transport and in factories, and in storage, selling, etc.; and indirect energy which is used to actually build the machines, to make the packaging, to produce the

39


electricity and the oil and so on. Food itself is a major energy source, and energy balances can be determined for animal or human feeding; food energy input can be balanced against outputs in heat and mechanical energy and chemical synthesis. III.(b) iii. ENERGY BALANCE AROUND THE EVAPORATIVE CRYSTALIZER Here we used a Calendria low carbon steel. REACTIONS ARE AS BELLOW FeSO4 + Ferrous Sulfate

H20--------------→ Water

FeSO4●H2O Ferrous sulfate monohydrate

DATA & ASSUMPTIONS: i)

Temperature 65 °C

CALCULATION: The basic equation for solving for the capacity of the evaporator, which is written as, q= UA ΔT..................................(ii) where ΔT K is the difference in temperature between the condensing steam and the boiling liquid in the evaporator. The feed to the evaporator is F kg/hr having the solid content of x F mass fraction, temperature TF, and enthalpy hF J/kg. Coming out as a liquid is the concentrated liquid L kg/h having solid content of x L, temperature T1, and enthalpy hL. the vapour V kg/h is given off as pure solvent having a solid content of y V = 0, temperature T1, and enthalpy of HV. Saturated steam entering is S kg/ hr and has a temperature of T S and enthalpy of HS. The condensed steam leaving of S kg/hr is assumed usually to be at T S, the

40


saturation temperature, with an enthalpy of h S. This means that the steam gives off only is latent heat, which is λ = HS - hS------------------------------(ii) The vapour V is in equilibrium with the liquid L, the temperature of vapour and liquid are the same. Also the pressure P1 is the saturation vapour pressure of the liquid of composition xL at its boiling point T1. For the material balance since we are at steady state, the rate of mass in = rate of mass out. Then for a total balance, F= V +L For a balance on the solute alone, F xF = LxL For the heat balance, since the total heat entering = total heat leaving So, Heat in feed + Heat in steam = Heat of concentrated liquid + Heat in vapour + Heat in condensed steam The assumes no heat lost by radiation or convection, Substituting and we get, F hF+

SHS

= L hL + VHV + ShS------------------------(I)

Substituting into, FhF + S λ

=

L hL + VHV -------------------------------(ii)

The heat q transferred in the evaporator is then, q = S( HS - hS) = S x λ The latent heat λ of steam at the saturation temperature T S can be obtained from the steam tubes. However, the enthalpies of the feed and products are often not available. These

41


enthalpy- concentration data are available for only a few substances in solution. Hence, some approximation are made in order to make a heat balance. Here, we get, xF = 0.2, F = 3893.83 Kg, L = 1393.72 Kg & V = 2500 Kg as per material balance. Specific Heat of Ferrous sulfate = 0.167 cal/ gm 0C = 0.699 kJ/ Kg K hF = 1* 0.699 * (65-25) = 27.97 kJ We assume the steam supplied at saturated at 143.3 kPa, from steam table we get the steam temperature is 383.2 K, at this temperature the latent heat 2230 kJ/kg From equation, we get, 3893.83 x 27.97 + S x 2230 = 2500 x 0 + 1393.72 x 2618 or, 108.91 + 2230S = 3648.75 or, S = 1636.17 Kg Steam required 1637 kg /h 3.b.iv. ENERGY BALANCE AROUND THE COOLER DATA & ASSUMPTIONS: (a) Pickle liquor enter the cooler at 87.8 0C & out let temperature at 25 0 C (b) Cooling water enters at 250C and leaves at 400C i.e. rise in temperature is 150C (c) Saturated steam of pressure 3 kg/cm2 absolute is supplied as heating media. CALCULATIONS: COOLING WATER REQUIREMENT FOR CONDENSER Cooling water requirement for condenser is given by the equation; WC x CP water x (T2 – T1)

= Wm x CP pickle liquor x (T3 – T4) -------(iv)

Where,

42


WC

= Weight of the cooling water ,kg

CP water

= Specific heat of the water, Kcal/kg 0C

T2 – T1

= Rise of Cooling water temperature, 0C

V

= Vapor from the column top to overhead condenser, kg mole /hr

Wm

= Weight of the pickle liquor ,kg

CP pickle liquor

= Specific heat of the water, Kcal/kg 0C

T3 – T4

= difference of pickle liquor temperature , 0C

we get WC x4.18 x 15 = 3978.745 x 4.18 x 62.8--------------(v) or, WC = 16657.69 kg Therefore, we use specific heat of pickle liquor is based on water specific heat because pickle liquor consist of 75 % water. So, Cooling water required = 16658 kg/ h OTHER FORMS OF ENERGY Motor power is usually derived, in factories, from electrical energy but it can be produced from steam engines or waterpower. The electrical energy input can be measured by a suitable wattmeter, and the power used in the drive estimated. There are always losses from the motors due to heating, friction and windage; the motor efficiency, which can normally be obtained from the motor manufacturer, expresses the proportion (usually as a percentage) of the electrical input energy, which emerges usefully at the motor shaft and so is available.

43


When considering movement, whether of fluids in pumping, of solids in solids handling, or of foodstuffs in mixers. the energy input is largely mechanical. The flow situations can be analysed by recognising the conservation of total energy whether as energy of motion, or potential energy such as pressure energy, or energy lost in friction. Similarly, chemical energy released in combustion can be calculated from the heats of combustion of the fuels and their rates of consumption. Eventually energy emerges in the form of heat and its quantity can be estimated by summing the various sources.

44


CHAPTER-4 DESIGN OF NEUTRALIZER UNIT

PROCESS DESIGN OF THE NEUTRALIZER . Neutralization is the process of adjusting the pH of solution through the addition of an acid or a base, depending on the target pH and process requirements. Spent pickle liquors are

45


neutralized with an alkali such as sodium hydroxide (caustic soda) or calcium hydroxide (lime). In the case of stainless steel pickle liquors containing fluoride, lime is usually utilized. Calcium fluoride is only slightly soluble, so that fluoride ions are precipitated simultaneously with the metal ions. Unfortunately, neither lime nor caustic are effective in removing nitrate ions which are tightly regulated in many jurisdictions. The cost of these neutralizing chemicals and disposal of the resulting sludge is considerable and can contribute appreciably to the overall cost of pickling the metal. The engineering design of a successful neutralization system involves several steps. Engineering design should be based on several factors such as optimum process parameter, laboratory-scale tests and their results, and finally, cost analysis. Practical aspects such as availability of neutralizing agent in the near vicinity and thus reduced transportation costs play an important role in process design. The important steps involved in neutralization process design are outlined below. All neutralization process, irrespective of type of waste, share several basic features and operate on the principle of acid- base reaction. Successful design of a neutralization process should consider the following: ● Influent wastewater parameters ● Type of neutralizing agent used ● Availability of land ● Laboratory scale experimental results The overall

design of neutralization process involves the design of the following

features: i. Neutralization basin ii. Neutralization agent requirements based on theoretical and treat ability studies

46


iii. Neutralization agent storage (e.g., silo, silo side valve, dust collector, and foundation design) iv. Neutralization agent feeding system v. Flash mixer design. CALCULATION OF NEUTRALIZATION SIZE Assume solution depth = 1.5 m and detention time period= 40 min. Total Flow rate per hour = Pickle Liquor + Lime solution = 3978.745 + 789.52= 4768.265 Kg Flow rate per hour = {4768.265 Kg /(1000 Kg/m3)} = 4.768 m3/h Required Volume = 4.768( m3/h) x (1/60 ) (h/min) x 40 min =3. 18 m3 Total volume = 3.18/ 0.25 = 12.72 m3 So, Required Volume = (1/3 ) * A* h here, A= area of the top of the tank h= height of the tank (1/3)* (π/4)d2 * h = 12.72 Assume diameter = d= 4 m or, (1/3)* (3.14/4) (4)2* h =12.72 or, h = 3.038 m INLET AND OUTLET NOZZLE DIAMETER CALCULATION : Nozzle Diameter is given by

D = (8.4 W0.45)/ ρ0.35

47


Where, D = Diameter, mm W = Mass flow of fluid, Kg/ hr. ρ = Density of fluid, kg/m3 CALCULATION OF INLET NOZZLE Mass flow rate of Pickle liquor inlet = W = 3978.745 kg 960 Kg/m3

Average Density of Inlet liquid= So, inside diameter of inlet nozzle

D inlet = 0.84 x (3978.745)0.45 / ( 960) 0.31 = 4.165 Cm = 41.65 mm

Use 48 mm diameter including corrosion allowance. Mass flow rate of Lime solution inlet = W = 789.52 kg Average Density of Inlet liquid=

960 Kg/m3

Lime

inlet nozzle diameter D inlet = 0.84 x (789.265)0.45 / ( 960) 0.31 = 2.012 Cm = 20.12 mm Use 30 mm diameter including corrosion allowance. CALCULATION OF OUTLET NOZZLE Mass flow rate of outlet nozzle D outlet = ( 8.4 x W0.45)/ ρ0.35

48


Where, W = Mass flow rate of outlet = 4766.66 kg ρ=Average density kg/m3 =

1000

We get, D outlet = 0.84 x (4766.66)0.45 / (1000) 0.31 = 4.46 Cm = 44.6mm So use 60 mm diameter including corrosion allowance.

PROCESS DESIGN OF THE NEUTRALIZER Type of Neutralizer No of Neutralizer Volume of Neutralizer Height of Neutralizer Diameter of Neutralizer Inlet nozzle diameter of the Neutralizer for

Conical 01 12.72 m3 3.038 m 4.000 m 48 mm

Pickle liquor Inlet nozzle diameter of the Neutralizer for

30 mm

Lime solution Outlet nozzle diameter of the Neutralizer

60 mm

MECHANICAL DESIGN OF THE NEUTRALIZER DATA AND ASSUMPTION: ●SHELL SIDE i) Internal diameter ii)Material

= 4000 mm = LOW CARBON STEEL

iii) Permissible Stress = 13.00 Kg / mm2

49


iv) Working pressure

= 1.033 Kg / Cm2

● FLANGED AND SHALLOW DISHED i) Internal diameter ii) Crown radius

= 4000 mm = 4000 mm

iii) Knuckle radius

= 6% of shell I.D. = 240 mm

iv) Material

= Same as Shell

i) Material

= Hot soled carbon steel

ii) Permissible Stress

= 5.87 Kg / mm2

● BOLTS

iii) Permissible Stress (Operating condition) = 5.45 Kg / mm2 ●FLANGES i) Material

= Carbon steel

ii) Permissible Stress iii) Gasket

= 9.5 Kg / mm2 = Asbestos

CALCULATION; DESIGN OF SHELL We know the equation of thickness of shell, t = (PD1)/ (2fj-P)----------------------------------(vi) Where, P = Design pressure J = joint efficiency f = design on permissible stress at design temperature = 13.00kg/mm2 D1 = Internal diameter = 4000 mm

50


Hence design pressure

= 10% excess of internal pressure

We know internal pressure

=1atm=1.033 kg/cm2

So design pressure

= P=(1.1*1.033) =1.136 kg/cm2

t = (1.136x 4000)/{2x13.00x100x(0.85-1.136)} = 5.84mm Use minimum thickness 20 mm.

4. b.iii. DESIGN OF GASKET The flange is made of cast iron with a glass lining (raised face) in the form of a ring. A flat Teflon gasket of 4000 mm internal diameter and 4040 mm external diameter and 3mm thickness is used to cover the raised face. Gasket factor = (m) = 2.00 Minimum design seating stress = 112 kg / mm2 Basic gasket seating width (b0) = 0.5 X ( 4000 -4040)/2 =10mm Effective gasket seating width (b)

= 2.5x b0

= 7.9mm NOZZLE THICKNESS We get, tn = [(PD) / ( 2fj – P )]---------------------------------------(vii) Where, tn = Nozzle thickness,

P = Design pressure

f = Permissible stress,

D = Inside diameter

51


J = Joint efficiency =1 (For Seamless pipe)

We get, tn = (1.136x 4000)/(2 x1300 x1 x 1.136)-----------------------(viii) = 1.54 mm use 20 mm thickness DESIGN OF AGITATOR DATA & ASSUMPTION:

Liquid in vessel

Diameter of the vessel

= 4000 mm

Internal pressure of the vessel

= 0.5 N/ mm2

Diameter of the agitator

= 1200 mm

Maximum Speed

= 200 rpm

● sp gravity

= 1.2

● viscosity

= 600 cp

Overhang of agitator shaft between bearing and agitator = 2200 mm Agitator blades (flat) nos.

=6

With of the blade

= 75 mm

Thickness of blade

= 10 mm

Baffles at tank wall nos.

=4

Shaft material - commercial cold rolled steel Permissible stress for key (carbon steel) shear crushing

= 65 N/ mm2 = 130 N/mm2

52


Carbon steel stuffing box = 95 N/mm 2

permissible stress Studs and bolts (hot rolled carbon steel) permissible stress

= 58.7 N/mm2

Assumed that the vessel geometry conforms to the standard tank configuration. From the equation, NRC=(ρNda2)/ μ------------------------------(ix) where, NRC

= Reynolds Number

ρ

= density of the liquid in Kg/ m3

da

= agitator diameter in m.

μ

= viscosity in kg/m sec

N

= speed of agitator in revolution per second

We get, NRC= [1.2 x 1000 x (200/60) x ( 1200/1000)2]/ 600 x 10-3 = 9600 From the power curve, NP = 2.8 From the equation, P= [(NP x ρ x N3 x Da5)/gc x 75 ]------------------(x) where, N gc

= Power in Kg m. = gravitational acceleration in m/sec.

53


P = {2.8 x 1.2 x 103 x (200/60)3 x (1200/1000)5 }/9.81 x 75 = 420.90 hp Gland losses =10% = 42.09 hp Power input = 420.90 + 42.09 = 462.99 hp = 462 .99 x 0.7457 =345 Kw Transmission system losses = 20% = 462.99 x 0.2 =92.60 hp Total hp = 462.99 + 92.60 = 555.59 hp = 555.59 x 0.7457 = 414 .30 Kw This will be taken as 425 kw to allow for fitting losses. Use 450 Kw ( 603 hp) motor SHAFT DESIGN For shaft design assume power required as 603 hp. Use solid shaft of diameter d. From the equation, we get, Average Torque = TC = (hp x 750x 60)/ (2π x N)-----------------------(xi) = (603 x 750 x 60)/ 2π x 200 = 21604 Nm Max. Torque = Tm = 1.5 x 21604 = 32406 Nm From the equation, we get, ZP = (1.5 x TC ) / fS --------------------------------(xii) =32406 /55 = 589.2 cm3 or,

(π d3)/16 = 589.2

54


or,

d3 = 3002 = 14.4cm≡ 15 cm

From the equation, Fm = Tm/ (0.75 x Rb)---------------------------(xiii) Where, Rb = radius of the blade The torque Tm is resisted by a force Fm acting at a radius of 0.75Rb from the axis of the agitator shaft. Fm = (32406 x 1000)/ (0.75 x 600) = 72013 N The maximum bending moment M occurs at a point near the bearing, from which the shaft overhangs M = Fm x l = 72013 x 2.2 [ where,

l = shaft length between agitator and bearing] = 158428.6Nm

From the equation, Me = (1/2) [ M + √ M2+ (Tm)2] --------------------------------(xiv) where, M = bending moment. Me = (1/2) [ 158428.6 + √(158428.42 + 324062)] = 160068 Nm From the equation, we get, f = Me/ Z ------------------------------------(xv) where, Z= modulus of section of the shaft cross section.

55


f = 160068 x 1000 / {(π x 43 x 1000)/32} = 25488 N/mm2 Stress f is higher than the permissible elastic limit ( 246 N/mm2). Therefore, use a 6 cm diameter shaft for which the stress will be f =221 N/mm2 DEFLECTION OF SHAFT From the equation, δ = Wl3/ 3 EI------------------------------------------(xvi) Where, l

= appropriate length

W

= Concentrated load

E

= modulus of elasticity

I

= moment of inertia of the cross section of shaft

We get, δ = Fm x (220)3 /3 x 19.5 x{ (π x 64)/4} x 104 x 1000 = {72013 x (220)3 x 4 }/ {3 x 19.5 x π x 64 x 104 x 1000} = 1.29cm From the equation, NC= (60 x 4.987 )/ [δ1+δ2+δ3+( δS/1.27)]2 -----------------------(xvii) Where δ1,δ2,δ3 & δS are the deflections in cm due to each load. Nc = (60 x 4.987)/ √ 1.29 = 263.45 rpm

56


Since the actual shaft speeds is 200 rpm which is 76% of the critical speed, it is necessary to increase the value of critical speed, by decreasing the deflection. So, we chose 6.5 cm diameter shaft. therefore,

δ = 0.94 cm Nc = (60X 4.987) / 0.94 = 320 rpm

Actual speed of 200 rpm is satisfactory, which is 62.5 % of the critical speed. BLADE DESIGN From the equation, f = Max. BM/Z = F {0.75 x (Rb - Rh)}/ (b1 x bw2/6)--------------(xviii) Where,

F

= force on each blade

Rb

= radius of blade

Rh

= radius of hub

We get, f = ( 673 x 1000) / {10 x (75)2/6} = 71.78 N/ mm2 The value of the stress is well within the endurance limit for carbon steel. HUB AND KEY DESIGN Hub diameter of agitator

= 2 x Shaft diameter = 2 x 6.5 = 13 cm

Length of hub Length of key (ll )

= 2.5 x 6.5 = 16.25 cm = 1.5 x Shaft diameter = 1.5 x 6.5 = 9.75 cm

From the equation,

57


Tmax/(d/2)= ll b fs = (it/2) fc ---------------------------(xix) = (673x 100)/ {(6.5 x 10) /2} = 9.75 X b x 65 = 9.75 x (t/ 2) x 1300 x 10 b = 3.27 mm t = 3.27 mm Use 4 mm x 4 mm x 10 cm key. STUFFING BOX AND GLAND Internal design pressure = 0.55 N/mm2 From the equation, b= d + √d = 6.5 + √ 6.5 = 9.05 cm----------------------(xx) Load on gland t =( Pb/2f )+ c--------------------------------(xxi) = (0.55 x 9.05 x 10)/ (2x 95) = 0.262 + c = 4 mm And we get, a = b+ 2t = 9.05 + 0.8 = 9.85 cm ≡ 10.00 cm Load on the gland F

= [(π / 4) x 0.55 ( 9.052 - 6.52) x 100]------------------(XXII) =1712 N

Size of stud 1712 = (π x do2/4)x n x f1 = (π x do2/4) x 4 x 58.7

58


do2 = 9.29 cm = 92.9 mm do = 9,63 mm Minimum stud diameter = 20 mm Flange thickness

= 1.75 x 20 = 35 mm

COUPLING A clamp coupling is taken. It is made of cast iron . We get from the equation, Force per bolt = (2x Tmax)/[ πμd x (n/2)] --------------------------------------(xxiii) = (2x 673 x 1000) / {π x 0.35 x 65 x (4/2)} = 9421 N Area of the bolt

= 9421/ 5870 = 1.605 cm2

Diameter of the bolt

= (1.605 x 4) /π = 2.044 cm = 20.44 mm

Use 24 M size bolts Overall diameter of coupling = 6.5 x 2 = 13 cm BRACKET OR LUG SUPPORT FOR A VERTICAL CONICAL VESSEL

These can be easily fabricated from plates and attached to the vessel wall with minimum welding length. They are made to rest on short columns or on beams of a structure depending on the elevation required. They can be easily leveled. Due to the eccentricity of these support and the resulting bending moment, compressive, tensile and shear stresses are induced in the vessel wall. These stresses must be combined with circumferential and

59


longitudinal stresses produced in the vessel wall due to operating pressure. The shear stresses being of a smaller magnitude can be ignored. DATA AND ASSUMPTION Diameter of the vessel

=

4000 mm

Height of the vessel

=

3.038 mm

Clearance of the vessel with contents

=

1 meter

Weight of the vessel bottom to foundation No. of brackets

= =

Diameter of anchor bolt circle

4

=

Wind pressure (P)

2755 mm 128.5 kg/ cm2

=

Height of the bracket from foundation

60000 kg

=

2.25 meter

Permissible stresses for structural steel:=

14000kg/ cm2

Compression

=

1233kg/ cm2

Bending

=

1573 kg/ cm2

Tension

Permissible bearing pressure for concrete

= 35 kg/ cm2

MAXMUM COMPRESSIVE LOAD Wind pressure from the equation, Pw = K p h D0-------------------------(xxiv) Where, K = Coefficient depending on the slop factor [0.7 for cylindrical surface] H= Height of the vessel D0 = Outside diameter of the vessel

60


= (4000+2 X10) = 4020 mm = 4.020meter We get, Pw = (0.7 x 128.5 x 3.038 x4.020) = 1098 Kg Then we get from the equation, P = [{4 x Pw x ( H – F )}/ n Db + ( w / n)]------------------------(xxv) Where, P= Total force due to wind load action acting on the vessel. E = Vessel clearance from foundation to vessel bottom H= Height of the vessel above the equation Db = Diameter of the bolt circle  w = Maximum Weight of the vessel with attachments and contents n = No. of brackets We get, P = {(4 x 1098 x 3.038)/ (4 x 4.020)}+ (60000 /4 ) = 15830 Kg

[ Where, h = H - F ]

BRACKET ● BASE PLATE Suitable base plate size:a = 140 mm =14 cm; b = 150 mm=15 cm

61


We get from the equation, Paw= ( P/ab) -------------------------(xxvi) = ( 15830)/(14 x15) =75.39 kg/ cm2 We get, f = [0.7 Paw x ( b2 / T12) { a4/ ( b4+a4)}]--------------(xxvii) The thickness t1 should be so chosen that the stress (f) should be within permissible limits. f =[ 0.7 x 75.39x (152/T2) { 144/ (154+144)}]

i.e.

=( 5122/ T2) Now we know that, f = 1575 kg / cm2 Then we get, T2 = [(5122/1575)X 100] = 18.03 mm We use 25 mm thickness. WEB PLATE We get from the equation, Stress at the edge, f = (3PC/ T2 h2)---------------------------(xxviii) The edge is at an angle  from the horizontal. The maximum compressive stress parallel to the edge of the web plate = (3PC/ T2 h2) x (1/cos)-----------------------------(xxix) Where,

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C =[ (A –D)/2]----------------------------------------------(xxx) And C, T2, h,  are the stress shall not exceed the permissible value. Bending moment of each plate = (15830/2) x {(4.020 – 4.000)/2} x 100 =7915 Kg cm Stress at the edge of f = [{7915/( T2 x 14x14)} x (1/0.707) x (1/100)] = (0.57/ T2) We know that, f = 1575 kg/cm2 We get, T2 = 0. 00036 cm =0.004 mm Use 20 mm thickness. COLUMB SUPPORT FOR BRACKET It is proposed to use a channel section as column.[6]. Size

= 150 x75

Area of cross section (A)

= 20.88 cm2

Modulus of section (ZYY)

= 19.4 cm2

Radius of section (YY)

= 2.21 cm

Weight

= 16.4kg/m

Height of the foundation

= 2.25 m

Equivalent length for fixed ends (le)

= (L/2) = (2.25/2)

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=1.125m Slenderness ratio

= ( le/) = [(1.125 x100)/ 2.21] = 51.0

Then we get from the equation, f= [(w/A x n) +{ ( w x e )/ n x z}]-----------------(xxxi) Where, w = Load an column,

A= Area of cross section,

z = Modulus of section of the cross section, n = Number of column,

e = Eccentricity,

We get, f = (15830/20.88) + {(15830 x 0.75)/27.2} = 1194.6 kg/cm2 We get, fc = [(w/A x n) [ 1+ a (le/)2] + {( w x e ) / n x z }] Where, le = Effective length of the column a = Constant r = Radius We know, le = 0.5 ( for fixed ends of the column) We get, fc = [(15830/2x20.88){ 1+ (1/7500) (51.0)2}]+{(15830x 0.75)/27.2} = 947 kg/cm2

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The calculated values are less than the permissible compressive stress and hence the channel selected is satisfactory. BASE PLATE FOR THE NEUTRALIZER The size of the column is

= 150 x 75

The base plate extends 20 mm on either side of the channel Side B = 0.8 x 75 + 2 x 20 = 100 mm Side C = 0.95 x 150 + 2 x 20 = 182.5 mm Now we get from the equation, Pb = P x (1/ B x C) Here B and C are the two sides Bearing pressure, Pb = (15830/4 ) x { 1/ (10 x 18.25)} =21.68 kg/cm2 Than the permissible bearing pressure for concrete stress in the plate f = [{(21.68/2) x (20)2}/100] / (t2/6)

= 260.22/ t2 Where, f = 1575kg/cm2 Therefore, t2 = 260.22/1575 Or, t

= 0.41 Cm = 4.1mm

Use 20 mm thickness MECHANICAL DESIGN OF THE NEUTRALIZER A GLANCE

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Shell material Shell thickness Effective gasket seating width Nozzle Thickness Agitator type Power taken to agitator Agitator diameter Permissible stress of Shaft Max. Torque Actual Shaft Speed Critical Shaft Speed Flange Thickness Max. Stud diameter Force per bolt Bolt Size Coupling diameter Height of bracket from foundation Maximum compressive load Base plate thickness of Bracket Web plate thickness of Bracket Base plate thickness for column

Low carbon steel 20 mm 7.9 mm 20 mm Turbine 450 Kw 1200 mm 25488 N/mm2 32406 Nm 200 rpm 320 rpm 35 mm 20 mm 9421 N 24 M 130 mm 2.25m 15830 kg/cm2 25mm 20mm 20mm

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CHAPTER- 5 DESIGN OF EVAPORATIVE CRYSTALLIZER

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PROCESS DESIGN OF EVAPORATIVE CRYSTALLIZER Crystallization is a process in which solid crystalline phases separate from liquids. The object of the process is usually the recovery of the solute from the solvent. The performance of the process is evaluated by the size, shape, structure and purity of the solute. Crystalline products have an attractive appearance, are free flowing, and easily handled and packaged. EVAPORATIVE CRYSTALLIZATION The calendria type evaporator preferably with short wide tubes and large central down take, with the bottom in the form of a conical head can be used as a crystalliser. AREA CALCULATION CALCULATION: The basic equation for solving for the capacity of the evaporator, which is written as, q

= UA ΔT------------------------------(i)

where ΔT K is the difference in temperature between the condensing steam and the boiling liquid in the evaporator. The feed to the evaporator is F kg/hr having the solid content of x F mass fraction, temperature TF, and enthalpy hF J/kg. Coming out as a liquid is the concentrated liquid L kg/h having solid content of x L, temperature T1, and enthalpy hL. the vapour V kg/h is given off as pure solvent having a solid content of y V = 0, temperature T1, and enthalpy of HV. Saturated steam entering is S kg/ hr and has a temperature of T S and enthalpy of HS. The condensed steam leaving of S kg/hr is assumed usually to be at T S, the

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saturation temperature, with an enthalpy of h S. This means that the steam gives off only is latent heat, which is λ = HS - hS----------------------------------(ii) The vapour V is in equilibrium with the liquid L, the temperature of vapour and liquid are the same. Also the pressure P1 is the saturation vapour pressure of the liquid of composition xL at its boiling point T1. For the material balance since we are at steady state, the rate of mass in = rate of mass out. Then for a total balance, F= V +L-------------------------------------(iii) For a balance on the solute alone, F xF = LxL ----------------------------------(iv) For the heat balance, since the total heat entering = total heat leaving So, Heat in feed + Heat in steam = Heat of concentrated liquid + Heat in vapour + Heat in condensed steam The assumes no heat lost by radiation or convection, Substituting and we get, F hF +

SHS

= L hL + VHV + ShS------------------(v)

Substituting into, FhF + s λ

=

L hL + VHV -------------------------------(vi)

The heat q transferred in the evaporator is then, q = S( HS - hS) = Sλ--------------------------------(vii) The latent heat λ of steam at the saturation temperature T S can be obtained from the steam tubes. However, the enthalpies of the feed and products are often not available. These

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enthalpy- concentration data are available for only a few substances in solution. Hence, some approximation are made in order to make a heat balance. Here, we get, xF = 0.2,

F = 3893.83 Kg, L = 1393.72 Kg & V = 2500 Kg as per

From material balance. Specific Heat of Ferrous sulfate = 0.167 cal/ gm 0C = 0.699 kJ/ Kg K hF = 1* 0.699 * (65-25) = 27.97 kJ We assume the steam supplied at saturated at 143.3 kPa, from steam table we get the steam temperature is 383.2 K, at this temperature the latent heat 2230 kJ/kg From equation no (i), we get 3893.83 x 27.97 + S x 2230 = 2500 x 0 + 1393.72 x 2618 or, 108.91 + 2230S = 3648.75 or, S = 1636.17 Kg Steam required 1637 kg /h The heat required q transferred through the heating surface area A q= S x λ or,

q = 1636.17 x 2230 x (1000/3600) = 1013516 W

And we get , then,

ΔT= Ts-T1 = (383.2- 373.2) =10

q = 1013516 = U x A x ΔT = 1560 x (A) x 10 [ U = overall heat transfer coefficient) A = 64.97 m2

FEED, PRODUCT AND STEAM INLET NOZZLE DIAMETER CALCULATION:

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Nozzle Diameter is given by

D = (8.4 W0.45)/ ρ0.35-----------------------------(viii)

Where, D = Diameter, mm W = Mass flow of fluid, Kg/ hr. ρ = Density of fluid, kg/m3 CALCULATION OF FEED NOZZLE Mass flow rate of Feed = W = 3893.83 kg Density of the fed liquid = 990 kg/m3 So, inside diameter of inlet nozzle D inlet = 0.84 x (3893.83)0.45 / ( 990) 0.31 = 4.08 Cm = 40.80 mm Use 60 mm diameter including corrosion allowance. CALCULATION OF PRODUCT NOZZLE Mass flow rate of overflow nozzle D overflow = (8.4 x W0.45)/ ρ0.35-----------------------------------(ix) Where, W = Mass flow rate of outlet = 3892.82 kg ρ= Average density kg/m3 = 1270 Kg/m3 We get D Product = 0.84 x (3892.82)0.45 / (1270) 0.31 = 3.78 Cm = 37.8mm

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Use 60 mm diameter including corrosion allowance. CALCULATION OF STEAM INLET NOZZLE D mother liquor = (8.4 x W0.45)/ ρ0.35-------------------------------------(x) Where, W = Mass flow rate of Steam = 1636.17kg ρ= Average density kg/m3 = 1000 Kg/m3 We get, D outlet = 0.84 x (1636.7)0.45 / (1000) 0.31 = 2.76Cm = 27.6 mm Use 40 mm diameter including corrosion allowance PROCESS DESIGN OF THE EVAPORATIVE CRYSTALLIZER Type of Crystallizer No of Crystallizer Crystallizer Area Crystallizer feed nozzle diameter

CALEMDRIA 01 64.97 m2 60 mm

Crystallizer Product nozzle diameter.

60 mm

Steam Inlet nozzle diameter

40 mm

MECHANICAL DESIGN OF THE EVAPORATIVE CRYSTALLIZER DATA AND ASSUMPTION: ● DATA: i) Evaporator drum under vacuum =external pressure 0.1 N/mm2 ii)Amount of water to be evaporated = 25000 N/hr iii) Heating Surface required = 220mm2

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iv) Steam pressure

= 0.13 N/mm2

v) Density of liquid = 9900N/m3 vi) Density of Vapour= 0.83 N/m3 ●

M ATERIAL i) Evaporator

= Low carbon steel

ii) Tube

= brass

iii) Permissible Stress for low carbon steel = 98 N/ mm2 iv) Modulus of elasticity for low carbon steel = 19.0 X 104 N/mm2 v) Modulus of elasticity for brass = 9.4 X 104 N/mm2 ●. FLANGES i) Material ii) Permissible Stress iii) Gasket

= Carbon steel = 9.5 Kg / mm2 = Asbestos

4. HEAD i) Conical head at bottom = Cone angle - 1200 ii) Conical head at top = Cone angle - 1200

CALCULATION CALENDRIA WITH VERTICAL TUBES: Use 100 mm outside diameter 1.5mm thick tubes. The length of the each tube is taken as 1220 mm, the effective length being 1165 mm. Number of tube = {(Heat transfer area)/(πx0.1x1.165)} = 220/(πx0.1x1.165)

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= 605 Pitch of tube (triangular) = 125mm Area occupied by tubes from the equation an = n x 0.866 ST2 ..................................(i) Where, ST

= pitch of tube.

n

= number of tubes

an

= Total area

From equation (i), an = 605x0.806x(0.125)2 = 8.16 m2 Let the proportionality factor β be 0.9. Then we get from the equation AS = π x (D2/4) = (n x0.866ST2)/β Where, AS = area of the shell D= inside diameter of the shell Area required = 8.16/0.9 = 9.86 m2 Required area for central down take = 40% x cross-section area of tubes = [0.4x 605x{(πx0.01)/4}] = 1.88 m2 Use a 1500 mm inside diameter and 1520 mm outside diameter pipe as a central down take.

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Actual area of down take = (π x 1.522)/4 = 1.81 m2 Total area of the tube= 9.06 +1.81 = 10.87 m2 Diameter of tube sheet= (10.87 x 4)/π = 3.71 m2= 3700 mm CALENDRIA SHEET THICKNESS From the equation, ts = PDi /(2fJ-P)-------------------------------(ii) Where,

Design Pressure = P Diameter of tube sheet = Di Permissible stress = f Joint Efficiency = J

So, we get. ts = (0.165 x 3710)/( 2 x 98 x 0.85 - 0.165) = 3.67 mm use 12 mm thickness sheet .

CALENDRIA TUBE SHEET THICKNESS: From the equation, k= {EStS (Do- tS)}/{EtNTi (do-tt)}....................................(iii) Where, ES =elastic modulus of shell Et = elastic modulus of tube Do= outside diameter of shell do=outside diameter of tube

75


tS = shell thickness tt = tube wall thickness N = number of tubes in shell Then we get from equation (ii), k= {19.0x 104x 10( 3710 -10)}/ {9.5 x 104 x 605 x 1.5 x (100 -1.5)} =0.832 From the equation Shell side pressure = F =√{k/ (2+3k)} = {0.832/ (2x3x0.832)}0.5 = 0.43 And from the equation, we calculate tube sheet thickness t= FG √ (0.25p/f)---------------------------------------(iv) Where, t= effective thickness of the tube p= design pressure f= allowable stress at appropriate temperature G= mean diameter of gasket So, we get, t= (0.43 x 3710) √{(0.25x 0.165x 100)/98} =32.8 mm With corrosion allowance the thickness may be taken as 36 mm. BOTTOM FLANGE OF CALENDRIA A flange is provided at the bottom of calendria for fixing the conical head. The size of flange selected is as follows:

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Thickness of the flange

= 40 mm

Number of bolts

= 112

Pitch circle diameter

= 3825 mm

Size of bolts

= 20 M

Outside diameter

= 3894 mm

EVAPORATOR DUM The entrainment separator is to be used in the form of baffles, placed at the top of the drum. The diameter of the drum may be same as that for the calendria. However, it is necessary to check the size from the point of satisfactory entrainment separation. From the equation, we get Rd = (V/A) / 0.0172X { (ρL - ρV)/ρV}0.5--------------------------(v) Assuming Rd = 0.8 for the baffle system A = {(25000/3600) x (1/0.83)}/(0.8 x 0.0172) {( 9900- 0.83)/0.83}0.5 = 5.7 m2 Drum Diameter = (D= 5.7x 4)/π = 2.69m Use drum length = 3 m DRUM THICKNESS: Drum is under vacuum. Design is, therefore, based on an external pressure of 0.1 N/mm2. Assume a thickness of 10 mm. The critical external pressure is calculated by the equitation as follows: pc= { 2.42E(1/Do)5/2}/ (1- μ2)3/4[(L/Do)- 0.45(1/Do)1/2]-------------------(vi) ={ (2.42x 19x104)/(1- 0.32)3/4}x [ (10/3730)5/2/{(30/3730)- 0.45(10/3730)1/2}]

77


= 0.235 N/mm2 Pall =Pc/ 4 =0.058 N/mm2----------------------------------------(vii) According to IS-2825 Unfired fusion welded pressure vessels, excluding: a = Pressure exceeding 20 N/mm2, b= Ratio of outside to inside diameter grater than 1.5, c = Internal operating pressure less than 0.1 N/mm2, d = Intern diameter less than 150 mm, e = Nominal water capacity of 500 litres or less. we get, L/Do = 3000/(3710+20) = 0.806 Do/t = (3710+20)/ 10 = 373 Factor,

B=350 Pall = B/(14.22x 373) = 350/ (14.22 x 373) = 0.0662 N/mm2

The thickness of 10 mm is not satisfactory. Assume a thickness of 12 mm. ps= {(2.42 x 19.104)/ (1-0.32)3/4} x (12/3734)5/2/[ (3000/3743) - 0.45 (12/3734)1/2] = 0.371 N/mm2 Pall = 3.71/4 = 0.093 N/mm2 According to IS-2825, we get, L/Do = 3000/ (3710 +24) = 0.806 Do/t = (3710+24)/12 = 310

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Factor,

B=350 Pall = 450/(14.22x 310) = 0.102 N/mm2

The thickness may be taken as 13 mm inclusive of corrosion allowance. The compressive stress from the equitation, fc = pD/2t = (0.102x 3734)/(2 x12 ) = 15.9 N/mm2 which is well within the permissible stress value. CONICAL HEADS AT TOP AND BOTTOM: The head thickness is based on an external pressure of 0.1 N/mm 2 Assume a thickness of 14 mm. The conical head with an angle of 1200 is taken as equivalent to the shell, with the length of shell as equal to the diameter of shell. According to IS-2825, L/Do = 3710/(3710+28) = 0.996 ≡ 1 Do/t = (3710+28) / 14 = 267 Factor, B = 450.6 Pall = 450/(14.22 x 267) = 0.118 N/ mm2 The thickness may be taken same as the drum thickness.

MECHANICAL DESIGN OF EVAPORATIVE CRYSTALLIZER Evaporator material Number of tubes Pitch of the tube (triangular) Evaporator Area Tube Material Area of central down take Diameter of tube sheet Calendria Sheet Thickness

LOW Carbon Steel 605 125 mm 9860 mm Brass 1880 mm 3710 mm 12 mm

Tube Sheet Thickness

36 mm

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Thickness of Flange Number of bolts Pitch circle diameter Size of bolts Outside diameter

40 mm 112 3825 mm 20 M 3894 mm

Drum height

3000 mm

Drum Thickness

10 mm

Critical External Pressure

0.058 N/mm2

Permissible stress

15.9 N/mm2

Head thickness is based on an external pressure Conical head angle

0.1 N/mm2 1200

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CHAPTER- 6 INSTRUMENTATION AND PROCESS CONTROL IN THE PROCESS

81


INSTRUMENTATION AND PROCESS CONTROL IN THE PROCESS PROCESS A process is broadly defined as an operation that uses resources to transform inputs into outputs. It is the resource that provides the energy into the process for the transformation to occur.

PROCESS CONTROL Process control is the act of controlling a final control element to change the manipulated variable to maintain the process variable at a desired Set Point.

82


A corollary to the definition of process control is a controllable process must behave in a predictable manner. For a given change in the manipulated variable the process variable must respond in a predictable and consistent manner. Following are definitions of some terms we will Nbe using in out discussion of process control: The manipulated variable (MV) is a measure of resource being fed into the process, for instance how much thermal energy. �A final control element (FCE) is the device that changes the value of the manipulated variable. �The controller output (CO) is the signal from the controller to the final control element. �The process variable (PV) is a measure of the process output that changes in response to changes in the manipulated variable. �The Set Point (SP) is the value at which we whish to maintain the process variable. Figure shows a block diagram of a process with a final control element and sensors to measure the manipulated variable and process variable. In single loop control systems the actual value of the manipulated variable is often not measured, the value of the process variable is the only concern.

83


BASICS OF PROCESS CONTROL OPEN LOOP & CLOSE LOOP CONTROL  In open loop control the controller output is not a function of the process variable. In open loop control we are not concerned that a particular Set Point be maintained, the controller output is fixed at a value until it is changed by an operator. Many processes are stable in an open loop control mode and will maintain the process variable at a value in the absence of a disturbance

 Disturbances are uncontrolled changes in the process inputs or resources. However, all processes experience disturbances and with open loop control this will always result in deviations in the process variable; and there are certain processes that are only stable at a given set of conditions and disturbances will cause these processes to become unstable. But for some processes open loop control is sufficient. Cooking on a stove top

84


is an obvious example. The cooking element is fixed at high, medium or low without regard to the actual temperature of what we are cooking. In these processes, an example of open loop control would be the slide gate position on the discharge of a continuous mixer or ingredient bin.  In closed loop control the controller output is determined by difference between the process variable and the Set Point. Closed loop control is also called feedback or regulatory control. The output of a closed loop controller is a function of the error.  Error is the deviation of the process variable from the Set Point and is defined as E = SP PV. A block diagram of a process under closed loop control is shown in figure

PROCESS CONTROL Operations are automated to reduce variability, to minimize the time required, to increase productivity, and so on. Remaining competitive in the world market demands that the plant be operated in the best manner possible, and microprocessor-based process controls provide numerous functions that make this possible. Safety is never compromised in the effort to increase competitiveness, but enhanced safety is a by-product of the processcontrol function and is not a primary objective. By attempting to maintain process

85


conditions at or near their design values, the process controls also attempt to prevent abnormal conditions from developing within the process. Although process controls can be viewed as a protective layer, this is really a by-product and not the primary function. Where the objective of a function is specifically to reduce risk, the implementation is normally not within the process controls. Instead, the implementation is within a separate system specifically provided to reduce risk. This system is generally referred to as the safety interlock system. As safety begins with the process design, an inherently safe process is the objective of modern plant designs. When this cannot be achieved, process hazards of varying severity will exist. Where these hazards put plant workers and/or the general public at risk, some form of protective system is required. Process safety management addresses the various issues, ranging from assessment of the process hazard to assuring the integrity of the protective equipment installed to cope with the hazard. When the protective system is an automatic action, it is incorporated into the safety interlock system, not within the process controls.

86


CHAPTER- 7 PLANT LAYOUT

87


PLANT LAYOUT INTRODUCTION The efficiency of production depends on how well the various machines; production facilities and employee’s amenities are located in a plant. Only the properly laid out plant can ensure the smooth and rapid movement of material, from the raw material stage to the end product stage. Plant layout encompasses new layout as well as improvement in the existing layout. It may be defined as a technique of locating machines, processes and plant services within the factory so as to achieve the right quantity and quality of output at the lowest possible cost of manufacturing. It involves a judicious arrangement of production facilities so that workflow is direct. DEFINITION A plant layout can be defined as follows: Plant layout refers to the arrangement of physical facilities such as machinery, equipment, furniture etc. with in the factory building in such a manner so as to have quickest flow of

88


material at the lowest cost and with the least amount of handling in processing the product from the receipt of material to the shipment of the finished product. According to Riggs, “the overall objective of plant layout is to design a physical arrangement that most economically meets the required output – quantity and quality.”According to J. L. Zundi, “Plant layout ideally involves allocation of space and arrangement of equipment in such a manner that overall operating costs are minimized. IMPORTANCE Plant layout is an important decision as it represents long-term commitment. An ideal plant layout should provide the optimum relationship among output, floor area and manufacturing process. It facilitates the production process, minimizes material handling, time and cost, and allows flexibility of operations, easy production flow, makes economic use of the building, promotes effective utilization of manpower, and provides for employee’s convenience, safety, comfort at work, maximum exposure to natural light and ventilation. It is also important because it affects the flow of material and processes, labour efficiency, supervision and control, use of space and expansion possibilities etc. ESSENTIALS An efficient plant layout is one that can be instrumental in achieving the following objectives: ●Proper and efficient utilization of available floor space ●To ensure that work proceeds from one point to another point without any delay ●Provide enough production capacity.

89


●Reduce material handling costs ●Reduce hazards to personnel ●Utilise labour efficiently ● Increase employee morale ●Reduce accidents ●Provide for volume and product flexibility ● Provide ease of supervision and control ● Provide for employee safety and health ● Allow ease of maintenance ● Allow high machine or equipment utilization ● Improve productivity TYPES OF LAYOUT As discussed so far the plant layout facilitates the arrangement of machines, equipment and other physical facilities in a planned manner within the factory premises. An entrepreneur must possess an expertise to lay down a proper layout for new or existing plants. It differs from plant to plant, from location to location and from industry to industry. But the basic principles governing plant layout are more or less same. As far as small business is concerned, it requires a smaller area or space and can be located in any kind of building as long as the space is available and it is convenient. Plant layout for Small Scale business is closely linked with the factory building and built up area. From the point of view of plant layout, we can classify small business or unit into three categories: 1. Manufacturing units

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2. Traders 3. Service Establishments ●Manufacturing units In case of manufacturing unit, plant layout may be of four types: (a) Product or line layout (b) Process or functional layout (c) Fixed position or location layout (d) Combined or group layout (a) Product or line layout: Under this, machines and equipments are arranged in one line depending upon the sequence of operations required for the product. The materials move form one workstation to another sequentially without any backtracking or deviation. Under this, machines are grouped in one sequence. Therefore materials are fed into the first machine and finished goods travel automatically from machine to machine, the output of one machine becoming input of the next, e.g. in a paper mill, bamboos are fed into the machine at one end and paper comes out at the other end. The raw material moves very fast from one workstation to other stations with a minimum work in progress storage and material handling. The grouping of machines should be done keeping in mind the following general principles. a) All the machine tools or other items of equipments must be placed at the point demanded by the sequence of operations b) There should no points where one line crossed another line. c) Materials may be fed where they are required for assembly but not necessarily

91


at one point. d) All the operations including assembly, testing packing must be included in the line Advantages: Product layout provides the following benefits: a) Low cost of material handling, due to straight and short route and absence of backtracking b) Smooth and uninterrupted operations c) Continuous flow of work d) Lesser investment in inventory and work in progress e) Optimum use of floor space f) Shorter processing time or quicker output g) Less congestion of work in the process h) Simple and effective inspection of work and simplified production control i) Lower cost of manufacturing per unit Disadvantages: Product layout suffers from following drawbacks: a. High initial capital investment in special purpose machine b. Heavy overhead charges c. Breakdown of one machine will hamper the whole production process d. Lesser flexibility as specially laid out for particular product. Suitability: Product layout is useful under following conditions: 1) Mass production of standardized products 2) Simple and repetitive manufacturing process 3) Operation time for different process is more or less equal

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4) Reasonably stable demand for the product 5) Continuous supply of materials Therefore, the manufacturing units involving continuous manufacturing process, producing few standardized products continuously on the firm’s own specifications and in anticipation of sales would prefer product layout e.g. chemicals, sugar, paper, rubber, refineries, cement, automobiles, food processing and electronics etc. ● Traders When two outlets carry almost same merchandise, customers usually buy in the one that is more appealing to them. Thus, customers are attracted and kept by good layout i.e. good lighting, attractive colours, good ventilation, air conditioning, modern design and arrangement and even music. All of these things mean customer convenience, customer appeal and greater business volume. The customer is always impressed by service, efficiency and quality. Hence, the layout is essential for handling merchandise, which is arranged as per the space available and the type and magnitude of goods to be sold keeping in mind the convenience of customers. There are three kinds of layouts in retail operations today. 1. Self service or modified self service layout 2. Full service layout 3. Special layouts The self-service layouts, cuts down on sales clerk’s time and allow customers to select merchandise for themselves. Customers should be led through the store in a way that will expose them to as much display area as possible, e.g. Grocery Stores or

93


department stores. In those stores, necessities or convenience goods should be placed at the rear of the store. The use of colour and lighting is very important to direct attention to interior displays and to make the most of the stores layout. ●Services centres and establishment Services establishments such as motels, hotels, restaurants, must give due attention to client convenience, quality of service, efficiency in delivering services and pleasing office ambience. In today’s environment, the clients look for ease in approaching different departments of a service organization and hence the layout should be designed in a fashion, which allows clients quick and convenient access to the facilities offered by a service establishment. FACTORS INFLUENCING LAYOUT While deciding his factory or unit or establishment or store, a small-scale businessman should keep the following factors in mind: a) Factory building: The nature and size of the building determines the floor space available for layout. While designing the special requirements, e.g. air conditioning, dust control, humidity control etc. must be kept in mind. b) Nature of product: product layout is suitable for uniform products whereas process layout is more appropriate for custom-made products. c) Production process: In assembly line industries, product layout is better. In job order or intermittent manufacturing on the other hand, process layout is desirable. d) Type of machinery: General purpose machines are often arranged as per process layout while special purpose machines are arranged according to product layout

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e) Repairs and maintenance: machines should be so arranged that adequate space is available between them for movement of equipment and people required for repairing the machines. f) Human needs: Adequate arrangement should be made for cloakroom, washroom, lockers, drinking water, toilets and other employee facilities, proper provision should be made for disposal of effluents, if any. g) Plant environment: Heat, light, noise, ventilation and other aspects should be duly considered, e.g. paint shops and plating section should be located in another hall so that dangerous fumes can be removed through proper ventilation etc. Adequate safety arrangement should also be made. Thus, the layout should be conducive to health and safety of employees. It should ensure free and efficient flow of men and materials. Future expansion and diversification may also be considered while planning factory layout. DYNAMICS OF PLANT LAYOUT Plant layout is a dynamic rather than a static concept meaning thereby if once done it is not permanent in nature rather improvement or revision in the existing plant layout must be made by keeping a track with development of new machines or equipment, improvements in manufacturing process, changes in materials handling devices etc. But, any revision in layout must be made only when the savings resulting from revision exceed the costs involved in such revision. Revision in plant layout may become necessary on account of the following reasons: a) Increase in the output of the existing product

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b) Introduction of a new product and diversification c) Technological advancements in machinery, material, processes, product design, fuel etc. d) Deficiencies in the layout unnoticed by the layout engineer in the beginning. APPLICABILITY OF PLANT LAYOUT Plant layout is applicable to all types of industries or plants. Certain plants require special arrangements which, when incorporated make the layout look distinct form the types already discussed above. Applicability of plant layout in manufacturing and service industries is discussed below. In case of the manufacturing of detergent powder, a multi-storey building is specially constructed to house the boiler. Materials are stored and poured into the boiler at different stages on different floors. Other facilities are also provided around the boiler at different stations. Another applicability of this layout is the manufacture of talcum powder. Here machinery is arranged vertically i.e. from top to bottom. Thus, material is poured into the first machine at the top and powder comes out at the bottom of the

machinery

located on the ground floor. Yet another applicability of this layout is the newspaper plant, where the time element is of supreme importance, the accomplishment being gapped in seconds. Here plant layout must be simple and direct so as to eliminate distance, delay and confusion. There must be a perfect coordination of all departments and machinery or equipments, as materials must never fail.Plant layout is also applicable to five star hotels as well. Here lodging, bar, restaurant, kitchen, stores, swimming pool,

96


laundry, shaving saloons, shopping arcades, conference hall, parking areas etc. should all find an appropriate place in the layout. Here importance must be given to cleanliness, elegant appearance, convenience and compact looks, which attract customers. Similarly plant layout is applicable to a cinema hall, where emphasis is on comfort, and convenience of the cinemagoers. The projector, screen, sound box, fire fighting equipment, ambience etc. should be of utmost importance. A plant layout applies besides the grouping of machinery, to an arrangement for other facilities as well. Such facilities include receiving and dispatching points, inspection facilities, employee facilities, storage etc. Generally, the receiving and the dispatching departments should be at either end

of

the plant. The storeroom should be located close to the production, receiving and dispatching centres in order to minimize handling costs. The inspection should be right next to other dispatch department as inspections are done finally, before dispatch. The maintenance department consisting of lighting, safety devices, fire protection, collection and disposal of garbage, scrap etc. should be located in a place which is easily accessible to all the other departments in the plant. The other employee facilities like toilet facilities, drinking water facilities, first aid room, cafeteria etc. can be a little away from other departments but should be within easy reach of the employees. Hence, there are the other industries or plants to which plant layout is applicable.

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CHAPTER- 8 SAFETY POLLUTION AND ABATEMENT ASPECT

SAFETY POLLUTION AND ABAT EMENT ASPECTS INTRODUCTION

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Safety is a very important aspect to be kept in mind during our day to day

life.

Especially safety plays a very significant role during the operation of a plant like ours and its importance has to be understood by one and all. Prevention of any accidents is the duty of the plant personnel especially the operators, who undoubtedly can play a major role. They can meet this challenge only when they are well versed with all aspects of operations, physical & chemical properties of chemicals being handled, hazards in handling the chemicals and the first and the foremost thing is to know how to do a job safety. The most important thing in safety is the attitude of the personnel towards safety which would be a decisive factor in the safe operation of the plant. So all the personnel should have a positive attitude towards safety. Safety and loss prevention in process design can be consider under the following board headings: a.

Identification and assessment of the hazards.

b. Control of the hazards: for example, by containment of flammable and toxic materials c. Control the process, Prevention of hazardous deviations in process

variables

(pressure, temperature, flow) by containment of flammable and toxic materials. d. Limitation of the loss. The damage and injury caused if an incident occurs: pressure relief, plant layout, provision of fire-fighting equipment.

SAFETY INDEX The safety and loss prevention guide development by Dow Chemical Company provides a method for evaluating the potential hazards of a process and assessing the safety and

99


loss prevention measures needed. In this procedure, a numerical fire and explosion index is calculated, based on the nature of the process and the properties of the materials. The index can be used in two different ways. In the preliminary design, the Dow index will indicate whether alternative, less hazardous processes should be considered in the manufacture of the specific chemical product. In the final design, after the piping and instrumentation diagrams and equipment layout have been prepared, the calculated index is used as a guide to the selection and design of the preventive and protective equipment needed for the safe plant operation. Safety is a very important aspect to be kept in mind during our day to day life. Especially safety plays a very significant role during the operation of a plant like ours and its importance has to be understood by one and all. Prevention of any accidents is the duty of the plant personnel especially the operators, who undoubtedly can play a major role. The most important thing in safety is the attitude of the personnel towards safety which would be a decisive factor in the safe operation of the plant. HAZARDS IDENTIFICATION EMERGENCY OVERVIEW: Product exists as a greyish/brown granular powder. Loses water at about 300 deg. Decomposes at higher temperatures. Soluble in water. The primary health hazard associated with exposure to this compound is the potential for irritation of the eyes, skin, nose and other tissues which come in contact with dusts or particulates of Ferrous Sulfate monohydrate. Ferrous Sulfate Monohydrate is not flammable or reactive. Thermal decomposition of Ferrous Sulfate Monohydrate produces irritating vapors and toxic

100


gases. Emergency responders should wear proper personal protective equipment for the releases to which they are responding. HAZARD STATEMENTS CAUTION: May cause irritation to eyes, skin, respiratory tract and gastrointestinal system. Harmful if swallowed. Chronic Exposure may cause adverse liver effects. Target organs affected from poisoning may include the liver, kidneys, digestive, circulatory, cardiovascular, and central nervous systems. Avoid contact with eyes and skin. Avoid breathing dusts. Wash thoroughly after handling. Keep container closed. Use with adequate ventilation. POTENTIAL HEALTH EFFECTS: EYES Exposure to particulates or solution of Ferrous Sulfate Monohydrate may cause moderate to severe irritation of the eyes with symptoms such as stinging, tearing and redness. Prolonged exposure of the eyes may cause discoloration to the sclera. Prolonged, low level contact with corrosives may result in conjunctivitis. POTENTIAL HEALTH EFFECTS: SKIN Ferrous Sulfate Monohydrate can cause irritation of the skin, especially after prolonged exposures. Repeated skin contact may lead to dermatitis (red, cracked skin). POTENTIAL HEALTH EFFECTS: INGESTION This product is harmful if swallowed. Ingestion of concentrated solutions or powder may cause nausea, vomiting, diarrhea, and black stools. Pink to red-brown discoloration of the urine is an indication of iron poisoning. Severe hemorrhagic gastritis with abdominal pain, retching, and violent diarrhea may occur. Circulatory system may be affected with

101


symptoms of shock, rapid, weak or no pulse, and severe hypotension may occur. Chronic Exposure may cause adverse liver effects. Severe or chronic Ferrous Sulfate poisonings may damage blood vessels. Large chronic doses cause rickets in infants. POTENTIAL HEALTH EFFECTS: INHALATION Dusts and mists from solutions may cause mild to moderate irritation of the nose and throat. May cause irritation of the respiratory tract. 8.IV. FIRST AID MEASURES FIRST AID: EYES Immediately flush the contaminated eye with plenty of water for 15 minutes. Seek medical attention immediately. FIRST AID: SKIN If irritation occurs, wash gently and thoroughly with water and non-abrasive soap. If irritation persists, seek medical advice. Completely decontaminate clothing, shoes, and leather goods before reuse. FIRST AID: INGESTION Immediately give 8 ounces of water. If vomiting occurs naturally, rinse mouth and repeat administration of water. Never give anything by mouth to an unconscious or convulsing person. Obtain medical advice immediately. FIRST AID: INHALATION Remove source of contamination or move victim to fresh air. Apply artificial respiration if victim is not breathing. Do not use mouth-to-mouth method if victim ingested or inhaled the substance; induce artificial respiration with the aid of a pocket mask equipped

102


with a one-way valve or other proper respiratory medical device. Administer oxygen if breathing is difficult. Get immediate medical attention. FIRST AID: NOTES TO PHYSICIAN Provide general supportive measures. Consult nearest Poison Control Centre for all exposures except minor instances of inhalation or skin contact. 8.V. FIRE FIGHTING MEASURES Fire and Explosion Hazards: Irritating and highly toxic gases may be produced by thermal decomposition Extinguishing Media: Copious quantities of water Fire Fighting: If a significant quantity of this product is involved in a fire, call the fire brigade. Firemen should wear self contained breathing apparatus and full protective clothing. HANDLING AND STORAGE HANDLING PROCEDURES All employees who handle this material should be trained to handle it safely. Do not breathe dust. Avoid all contact with skin and eyes. Use Ferrous Sulfate Monohydrate only with adequate ventilation. Wash thoroughly after handling. STORAGE PROCEDURES Keep container tightly closed when not in use. Store containers in a cool, dry location, away from direct sunlight, sources of intense heat, or where freezing is possible. Material should be stored in secondary containers or in a dyked area, as appropriate. Store containers away from incompatible chemicals. Storage areas should be made of fire-

103


resistant materials. Post warning and “NO SMOKING” signs in storage and use areas, as appropriate. Use corrosion-resistant structural materials, lighting, and ventilation systems in the storage area. Floors should be sealed to prevent absorption of this material. Inspect all incoming containers before storage, to ensure containers are properly labelled and not damaged. Have appropriate extinguishing equipment in the storage area (i.e., sprinkler system, portable fire extinguishers). Empty containers may contain residual particulates; therefore, empty containers should be handled with care. Do not cut, grind, weld, or drill near this container. Never store food, feed, or drinking water in containers that held Ferrous Sulfate Heptahydrate. Keep this material away from food, drink and animal feed. Do not store this material in open or unlabeled containers. Limit quantity of material stored. ACCIDENTAL RELEASE MEASURES Spillage: Minor spills do not normally need any special cleanup measures. In the event of a major spill, prevent spillage from entering drains or water courses. As a minimum, wear overalls, goggles and gloves. Stop leak if safe to do so, and contain spill. Sweep up and shovel or collect recovered product into labelled containers for recycling or salvage, and dispose of promptly. After spills, wash area preventing runoff from entering drains. If a significant quantity of material enters drains, advise emergency services. This material may be suitable for approved landfill. Ensure legality of disposal by consulting regulations prior to disposal. Thoroughly launder protective clothing before storage or reuse. Advise laundry of nature of contamination when sending contaminated clothing to laundry. PERSONAL PROTECTION:

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The following information on appropriate Personal Protective Equipment is provided to assist employers. Personal Protective Equipment: Eyes/Face Wear chemical goggles Personal Protective Equipment: Skin Where contact is likely, wear chemical resistant gloves, rubber boots, and coveralls. Nitrile gloves are recommended. Gloves should be tested to determine their suitability for prolonged contact with this material. Personal Protective Equipment: Respiratory None required where adequate ventilation conditions exist. If airborne concentrations are above the applicable exposure limits, use NIOSH-approved respiratory protection. Oxygen levels below 19.5% use of a full-face piece pressure/demand SCBA or a full face piece, supplied air respirator with auxiliary self contained air supply. Personal Protective Equipment: General Have an eyewash fountain and safety shower available in the work area. Use good hygiene practices when handling this material including changing and laundering work clothing after use. Wash hands thoroughly after handling material. Do not eat, drink, or smoke in work areas. CHEMICAL STABILITY & REACTIVITY INFORMATION Chemical Stability Under normal conditions of temperature and pressure, Ferrous Sulfate Monohydrate is stable. Ferrous Sulfate Monohydrate reacts in moist air to form ferric sulfate. Ferrous

105


Sulfate Monohydrate looses water in dry air and may discolor upon exposure to moist air, forming a brown coating of extremely corrosive, basic ferric sulfate. Chemical Stability: Conditions to Avoid Water of crystallization will be released when exposed to temperatures over 300 deg. C. Incompatibility Avoid strong alkalis, soluble carbonates, gold and silver salts, lead acetate, lime water, potassium iodide, potassium, sodium tartrate, sodium borate, and tannin. Hazardous Decomposition Sulfur oxides and dioxides are normal decomposition products. May liberate toxic metal fumes and acrid smoke. Hazardous Polymerization Will not occur. TOXICOLOGICAL INFORMATION Acute Toxicity A: General Product Information Pink urine discoloration is a strong indication of iron poisoning. Symptoms of severe poisoning may occur within 30 minutes or may be delayed for several hours. Poisoning may affect the liver, kidneys, digestive, circulatory, cardiovascular and central nervous system. Systemic effects may include shock, rapid or weak pulse, severe hypotension, dyspnea, and emphysema. Additional Data: Interactions with medicines may cause adverse effects. B: Component LD50/LC50 Ferrous Sulfate Heptahydrate

106


Oral LD50 Mouse: 1520 mg/kg Carcinogenicity A: General Product Information No information available. B: Component Carcinogenicity None of this product's components are listed by ACGIH, IARC, NIOSH, NTP, or OSHA. Epidemiology There is a large body of data on the clinical toxicology of ingested iron salts. There are little data on the health effects from occupational (inhalation or dermal contact) exposures. The recommended exposure limit reduces risk of skin and mucous membrane irritation. Neurotoxicity Has not been identified. Mutagenicity Has not been identified. Teratogenicity No information available. Other Toxicological Information None. STABILITY AND REACTIVITY Reactivity: This product is unlikely to react or decompose under normal storage conditions. Conditions to Avoid: Moisture

107


Incompatibilities: Alkalis, soluble carbonates and oxidising materials Fire Decomposition Products: Sulphur oxides Polymerisation: This product is unlikely to undergo polymerisation processes. EXPLOSIONS: As explosion is the sudden, catastrophic, release of energy, causing a pressure wave (blast wave). An explosion can occur without fire, such as the failure through over-pressure of a steam boiler of an air receiver. When discussing the explosion of a flammable mixture it is necessary to distinguish between detonation and deflagration. If a mixture detonates the reaction zone propagates at supersonic velocity (approximately 300 m/s) and the principal heating mechanism in the mixture is shock compression. Closed system, ventilation, explosion proof electrical equipment and lighting are the prevention. In case of fire, keep drums, etc., cool by spraying with water is fire fighting. STATIC ELECTRICITY: The movement of any non-conducting material, powder, liquid or gas, can generate static electricity, producing sparks. Precautions must be taken to ensure that all piping is properly earthed (grounded) and that electrical continuity is maintained around flanges. Escaping steam, or other vapors and gases, can generate a static charge. RISKS FACTOR: The main hazards encountered in the plant process are: a)

Mechanical break-down risks

b)

Electricity risks

c)

Chemical exposure risks

108


d)

Fire and explosion risks

e)

Corrosive material contact risks

f)

Safety interlocks by-passing

Likely to be handled are given in the hazard chart. Action to be taken to skin contact. Suffocation, asphyxiation and poisoning risks are occurs. SPILLAGE DISPOSAL: Personal protection: filter respirator for organic gases and vapors. Collect leaking and spilled liquid in sealable containers as far as possible. Absorb remaining liquid in sand or inert absorbent and remove to safe place. GENERAL PROCESS HAZARDS The general process hazards are factors that play a primary role in determining the magnitude of the loss following an incident. A.

Exothermic chemical reactions: the penalty varies from 0.3 for a mild

exothermic, such as hydrogenation, to 1.25 for a particularly sensitive exothermic, such as nitration. B. Endothermic process: a penalty of 0.2 is applied to reactors, only. It is increased to 0.4 if the reactor is heated by combustion of a fuel. C. Materials handling and transfer: this penalty takes account of the hazard involved in the handling, transfer and warehousing of the material. D. Enclosed of indoor process unit: accounts for the additional hazard where ventilation is restricted. E. Access of emergency equipment: areas not having adequate access are penalized. Minimum requirement is access from two sides. F. Drainage and spill control: penalizes design conditions that would cause large spills of flammable material adjacent to process equipment; such as inadequate design of drainage.

109


SAFETY CHECK LISTS Check lists are useful aids to memory. A check list that has been drawn up by experienced engineers can be a useful guide for the less experienced. However, too great a reliance should never be put on the use of check lists, to the exclusion of all the factors to be considered for any particular process or operation. A short safety check lists are given by Carson and Mumford (1988) and Wells (1980). Balemans (1974) gives a comprehensive list of guidelines for the safe design of chemical plant, drawn up in the form of a check list. A loss of prevention check list is included in the Dow Fire and Explosion Index Hazard Classification Guide, Dow (1987). ●MATERIALS (i) Flash point (ii) Flammability range (iii) Auto ignition temperature (iv) Composition (v) Stability (vi) Toxicity (vii) Corrosion (viii) Physical properties (ix) Heat of combustion/reaction

●PROCESS 1. REACTORS (a) Exothermic-heat of reaction (b) Temperature control –emergency systems (c) Side reactions-dangerous? (d) Effect of contamination (e) Effect of unusual concentrations(including catalyst) (f) Corrosion 2. PRESSURE SYSTEMS (a) Need (b) Design of current codes (c) Materials of construction-adequate? (d) Pressure relief-adequate?

110


(e) Safe venting systems (f) Flame arresters ●CONTROL SYSTEMS (a) (b) (c) (1) (2) (3) (4) (5) (d) (e) (f) (g) (h) (i)

Fail safe Back-up power supplies High / low alarms and trips on electrical variables Temperature Pressure Flow Level Composition Back up/duplicate systems on critical variables Remote operation of valves Block valves on critical lines Excess-flow valves Interlock systems to prevent mis –operation Automatic shut-down systems

●STORAGES (a) Limit quantity (b) Inert purging/blanketing (c) Floating roof tanks (d) Dykeing (e) Loading /unloading facility-safety (f) Earthling (g) Ignition sources-vehicles ●GENERAL (a) (b) (c) (d) (e) (f) (g) (h)

Inert purging system needed Compliance with electrical code Adequate lighting Lighting protection Sewers and drains adequate, flame traps Dust-explosion hazards Build-up of dangerous impurities-purges Plant layout (1) Separation of units (2) Access (3) Sitting of control rooms and offices (4) Services

111


(i)

Safety showers, eye baths

●FIRE PROTECTION (a) (b) (c) (d) (e) (f) (g)

Emergency water supplies Fire mains and hydrants Foam systems Sprinklers and deluge systems Insulation and protection of structures Access to buildings Fire-fighting equipment

EFFLUENT TREATMENT PLANT (ETP): The water is polluted by the plant effluent. Here in the Ferrous sulfate plant, the bottom draw is chiefly water with traces of heavier products and. A part of this water is removed from the system along with the chlorine compound. Rest of the water is re-used in the scrubber. A critical factor in this effluent water is the Biological Oxygen Demand (BOD). It refers to the oxygen requirement by the metabolizing organisms. As the number of organisms increases, the demand for O2 increases proportionally. Depletion of O2 in water may lead to death of fish and other aquatic animals, a flat taste of water, and eventual death of aerobes. The BOD is therefore an important indication of the levels of pollution in the water.

112


113


CHAPTER-9 COST ESTIMATION

COST ESTIMATION OF THE PLANT INTRODUCTION The cost estimation is a specialised subject and a profession in its own right. the design engineer, however, needs to be able to make quick, rough, cost estimates to decide between alternative designs and for project evaluation. Chemical plants are built to make

114


a profit, and an estimate of the investment required and the cost of production needed before the profitability of the project can be assessed. COST INDICES Most cost data that are available for making a preliminary or predesign estimate are only valid at the time they were developed. Because prices may have changed considerably with time due to changes in economic conditions, some method must be used for updating cost data applicable at a past date to costs that are representative of conditions at a later time. Cost Indices the value of money will change because of inflation and deflation. Hence cost data can be accurate only at the time when they are obtained and soon go out of date. Data from cost records of equipment and projects purchased in the past may be converted to present-day values by means of a cost index. The present cost of the item is found by multiplying the historical cost by the ratio of the present cost index divided by the index applicable at the previous date. Ideally each cost item affected by inflation should be forecast separately. Labor costs, construction costs, raw-materials and energy prices, and product prices all change at different rates. Composite indices are derived by adding weighted fractions of the component indices. Most cost indices represent national averages, and local values may differ considerably. TOTAL CAPITAL COST Total Capital Cost The installed cost of the fixed-capital investment CFC is obviously an essential item which must be forecast before an investment decision can be made. It forms part of the total capital investment CTC. The fixed-capital investment is usually regarded as the capital needed to provide all the depreciable facilities. It is sometimes divided into two classes by defining battery limits and auxiliary facilities for the project.

115


The boundary for battery limits includes all manufacturing equipment but excludes administrative offices, storage areas, utilities, and other essential and nonessential auxiliary facilities. METHODS FOR ESTIMATING CAPITAL INVESTMENT Various methods can be employed for estimating capital investment. The choice of any one method depends upon the amount of detailed information available and the accuracy desired. Seven methods are requiring progressive less detailed information and less preparation time. Consequently, the degree of accuracy decrease with each succeeding method. I)

Method A: Detailed item estimate

II)

Method B: Unit cost estimate

III)

Method C: Percentage of delivered-equipment cost

IV)

Method D: Long factors for approximation of capital investment

V)

Method E:Power factor applied to plant/capacity ratio

VI)

Method F: Investment cost per unit capacity

VII)

Method G: Turnover ratio..

COST ESTIMATION OF THE NEUTRALIZER COST OF VESSEL BODY Cost of Low carbon steel is Rs. 1260 per kg, Weight of shell Material content of the Vessel body Ws = (/4) ( D02- Di2) x H x---------------------------------------(i) Where,

116


Di = Inside diameter of the Vessel = 4.00 meter D0 = outside diameter of the shell side = Di + 2 x Shell thickness = (4 + 2 x 0.020) = 4.04 meter H = Height of reactor = 3.038 meter  = Density of material of shell body = 9000 kg/m3 There fore, Weight of Vessel body = (/4)[ (4.04)2 – (4)2] x 3.038x 9000 = 6902 kg Cost of Vessel body

= 6902 x 1260 = Rs. 8697341 /-

OTHERS ACCESSORIES OF NEUTRALIZER Others Accessories Costing= 120 % of Vessel body cost = 8697341 x 1.2 = Rs. 10436809 FARRICATION COST Fabrication cost

= =

40% of the Vessel material cost 8697341 x 0.4

= Rs.

3478936

/-

117


Hence the total cost of the Neutralizer (T) = Cost of Vessel material + Others Accessories Cost +Fabrication cost = Rs. (8697341 +10436809+3478936) = Rs. 22613086

/-

COST OF HEPTAHYDRATE FILTER Heptahydrate Filter Cost

= 60% of cost of Neutralizer (T) = Rs.

13567851

/-

COST OF FORTIFER Fortifer cost

= 70% cost of Neutralizer (T) = 0.7 x 22613086 = Rs. 15829160

/-

COST OF MONOHYDRATE FILTER ( 1st) Cost of filter

= 40 % cost of the Neutralizer (T) = 0.4 x 22613086 = Rs. 9045234 /-

COST OF EVAPORATIVE CRYSTALLIZER Cost of Crystallizer

=

150% cost of Neutralizer (T)

= 1.5 x 22613086 = Rs. 33919629 /COST OF MONOHYDRATE FILTER ( 2st) Cost of filter

= 40 % cost of the Neutralizer (T) = 0.4 x 22613086 = Rs. 9045234 /-

118


COST OF EFFLUENT TREATMENT PLANT WASTE TREATMENT COSTS 

Methods and costs of treating waste water and gas.



Waste gas: Take a credit for a combustible (fuel) waste gas that is at a concentration above the upper flammability limit as the cost of an equivalent amount of natural gas based on its lower heating value (LHV). (Tabulations of data.) The same can be done if the combustible components are present below the lower flammability limit, but sufficient oxygen is present for catalytic combustion to recover the LHV. HYSYS gives the LHV for a stream under the Properties tab. If the gas is below the lower flammability limit and consists of components that can be burned to CO2 and H2O, assume that these components are eliminated in a flame at a cost of 2.50/kg. Any products not permitted to be exhausted (such as SO2 in many places) must be removed before the gas is released. Charge 10.00 per kg of materials that must be removed. Assume these are 2001 prices; update the burning cost using the price of natural gas and the waste treatment cost by the price of electricity.



Waste water: Charge Rs. 12.50 per kg of components that must be removed before discharge of the water. This cost is for 2001, so update using the cost of electricity.

Cost of ETP

= 150% cost of Neutralizer (T) = 1.5 x 22613086 = Rs. 33919629 /-

COST OF OTHER ACCESSORIES

119


Cost of other accessories =

45% Cost of the Neutralizer(T)

=0.45 x 22613086 = Rs.

10175888

/-

TOTAL COST OF EQUIPMENT (E1) = 22613086+ 13567851+ 15829160+ 9045234+ 33919629+ 9045234+ 33919629 + 10175888 = Rs. 148115711 /-

Sl. No. 1

ACCOUNT HEAD

2

PURCHASE EQUIPMENT INSTALLATION ( 39% of E1 )

57765127

3

INSTRUMENTATION (INSTALLATION) ( 28% of E1)

41472399

4

PIPING (INSTALLED ) (45% of E1 )

66652069

5

ELECTRICAL (INSTALLED ) (10% of E1 )

14811571

6

BUILIDING ( INCLUDING SERVICE) (22% of E1)

32585456

7

SERVICE FACILITIES (55% of E1 )

81463641

8

LAND ( 6% of E1 )

8886942

1 2 3

PURCHASE EQUIPMENT COST (E1)

EXPENDITURE IN RUPEES 148115711

TOTAL DIRECT COST (D)

451752916

INDIRECT COST ( I) ENGINEERING AND SUPERVISION (15% OF E1 )

22217356

CONSTRUCTION EXPENSES (12% OF E1 ) LEGAL EXPENCES (2% OF E1 )

17773885 2962314

120


4

CONTRACTOR’S FEE (4% OF E1 )

5924628

5

CONTINGENCY ( 10% OF E1 )

14811571

TOTAL INDIRECT COST (I)

63689754

TOTAL DIRECT + INDIRECT COST (D+I)

515442670

ESTIMATE COMPONENTS ARE IN TABLE

121


CHAPTER-10 DETAILED ENGINEERING DRAWING OF THE NEUTRALIZER AND EVAPORATIVE CRYSTALIZER

DETAILED ENGINEERING DRAWING OF NEUTRALIZER AN EVAPORATIVE CRYSTALLIZER

122


NEUTRALIZER The engineering design of a successful neutralization system involves several steps. Engineering design should be based on several factors such as optimum process parameters, laboratory- scale tests and their results, and finally, cost analysis. Practical aspects such as availability of neutralizing agent in the near vicinity and thus reduced transportation cost play an important role in process design.

NEUTRALIZER [Original drawing are kept inside the Docket. ]

EVAPORATIVE CRYSTALLIZER:

123


This is the simplest type of industrial crystallizing equipment. Crystallization is induced by cooling the mother liquor in tanks; which may be agitated and equipped with cooling coils or jackets.

CALENDRIA EVAPORATIVE CRYSTALLIZER [Original drawing are kept inside the Docket]

124


CHAPTER-11 NOMENCLATURE ARE USED

125


NOMENCLATURE Nomenclature is a term that applies to either a list of names or terms, or to refer to something that is a term or to the system of principles, procedures and terms related to naming—which is the assigning of a word or phrase to a particular object, event, or property. The principles of naming vary from the relatively informal conventions of everyday speech to the internationally-agreed principles, rules and recommendations that govern the formation and use of the specialist terms used in scientific and other disciplines. Naming "things" is a part of our general communication using words and language: it is an aspect of everyday taxonomy as we distinguish the objects of our experience, together with their similarities and differences, which we identify, name and classify. The use of names, as the many different kinds of nouns embedded in different languages, connects nomenclature to theoretical linguistics, while the way we mentally structure the world in relation to word meanings and experience relates to the philosophy of language MATERIAL AND ENERGY BALANCE OF FERROUS SULFATE MONOHYDRATE PLANT R

= Reflux Ratio

m

= Mass flow rate

L

= Amount of reflux, Kg mole/ hr



= Molar Latent heat, Kcal/ Kg mole

D

= Total Kg moles of overhead product drawn

126


Wc

= weight of cooling water required, Kg/hr

∆HP

= Enthalpy of the product

∆HR

= Enthalpy of the reactants.

∆HT

= Enthalpy at the temperature

∆H25

= Standard heat of the reaction

VR

= Vapor leaving the reboiler, Kg mole/hr

T2 –T1

= Rise of cooling water temperature, °C

V

= Vapors entering the condenser from top of the column, Kgmole/hr

Cp

= Specific heat

Ws 11.a.ii.

= Steam requirement of reboiler. Kg/hr PROCESS DESIGN OF NEUTRALIZER AND EVAPORATIVE

CRYSTALLIZER M

= Average molecular weight of gas.

L

= Length of Reactor, Meter

D

= Diameter, mm

W

= Mass flow rate of fluid, Kg/hr



= Density of the fluid, Kg/M3

R

= Gas constant

T

= Temperature in,

U0

= Linear gas velocity, m/ sec.

NRe

= Reynolds’s Number

L

= Length of Reactor, Meter

127


P

= Pressure in atm.

11.a.iii. MECHANICAL DESIGN OF NEUTRALIZER AND EVAPORATIVE CRYSTALLIZER P

= Design Pressure Kg/ cm2

f

= Design on permissible stress at

t

= Design temperature, Kg/mm2

D1

= Internal Diameter of shell, mm

J

= Joint Efficiency

T

= Shell thickness

W

= Stress intensification factor, mm.

R1

= Knuckle radius, mm.

Rc

= Crown Radius, mm

th

= Head thickness, mm.

b

= Effective gasket or joint contact surface width under pressure.

b0

= Basic gasket seating width

G

= Diameter of gasket load reaction

Ya

= Minimum design seating stress, Kg / cm2

fb

=

Permissible stress in bolts under operating condition.

Wm1

= Bolt load at atmospheric condition, Kg.

Wm2

= Bolt load under operating condition, Kg.

Am2

= Total bolting area, cm2

m

= Gasket factor.

B

= Bolt circle diameter, mm.

128


C

= corrosion allowance.

Wm

= Total bolt load, Kg.

hG

= Radial distance from gasket load reaction to bolt circle, mm.

H

= Total hydrostatic end force.

t1

= Flange thickness

F

= Vessel clearance from foundation to vessel bottom, meter.

H

= Height of the vessel above the foundation, meter.

h

= Height of the vessel, meter.

K

= Constant.

n

= Number of brackets

P

= Total force due to wind load acting on the vessel, Kg/mm2.

w = Maximum weight of the vessel with load attachment and contents. Kg. a

= Constant, cm.

b

= Constant, cm.

f

= Bending stress for the structural steel, Kg/cm2

Pav

= Average Pressure of the plate, mm.

T1

=Thickness of the web plate, mm.

A

= Area of cross section.

Zyy

= Modules of section

YY

= Radius of Gyration.

le

= Equivalent length, meter. fc

= Compressive stress, Kg.cm2

Pb

= Bearing Pressure, Kg/ cm2

129


IN GENERAL USES T

= Shell thickness

Rc

= Crown Radius, mm

W

= Stress intensification factor, mm.

R1

= Knuckle radius, mm.

th

= Head thickness, mm.

b

= Effective gasket or joint contact surface width under pressure.

L

= Length of the column, meter.

D

= Diameter, mm.

W

= Mass flow rate of fluid, Kg/ hr.



= Density of fluid, Kg/m3

P

= Pressure in atm.

M

= Average molecular weight of gas

R

= Gas constant.

T

= Temperature in 0C or 0K

P

= Design Pressure Kg/ cm2

J

= Joint Efficiency

f D1

= Design on permissible stress at design temperature, Kg/mm2 = Internal Diameter of shell, mm

F

= Vessel clearance from foundation to vessel bottom, meter.

H

= Height of the vessel above the foundation, meter.

h

= Height of the vessel, meter.

130


K

= Constant.

n

= Number of brackets

P

= Total force due to wind load acting on the vessel, Kg/mm2

b0

= Basic gasket seating width

G

= Diameter of gasket load reaction

Ya

= Minimum design seating stress, Kg / cm2

fb

=

Permissible stress in bolts under operating condition.

Wm1

= Bolt load at atmospheric condition, Kg.

Wm2

= Bolt load under operating condition, Kg.

Am2

= Total bolting area, cm2

m

= Gasket factor.

B

= Bolt circle diameter, mm.

C

= Corrosion allowance.

Wm

= Total bolt load, Kg.

hG

= Radial distance from gasket load reaction to bolt circle, mm.

H

= Total hydrostatic end force.

t1

= Flange thickness

P

= Total force due to wind load acting on the vessel, Kg/mm2 .

w = Maximum weight of the vessel with load attachment and contents. Kg. a

= Constant, cm.

b

= Constant, cm.

f

= Bending stress for the structural steel, Kg/cm2

131


Pav

= Average Pressure of the plate, mm.

T1

= Thickness of the web plate, mm.

A

= Area of cross section.

Zyy

=Modules of section

YY

=Radius of Gyration.

le

= Equivalent length, meter.

fc

= Compressive stress, Kg.cm2

Pb

= Bearing Pressure, Kg/ cm2

************************************

132


CHAPTER-12 BIBLIOGRAPHY

133


BIBLIOGRAPHY HISTORY: Bibliography (from Greek bibliographia, literally "book writing"), as a discipline, is traditionally the academic study of books as physical, cultural objects; in this sense, it is also known as bibliology. Carter and Barker (2010) describe bibliography as a twofold scholarly discipline -- the organized listing of books (enumerative bibliography) and the systematic, description of books as physical objects (descriptive bibliography). These two distinct concepts and practices have separate rationales and serve differing purposes. Innovators and originators in the field include W. W. Greg, Fredson Bowers, Philip Gaskell, and G. Thomas Tanselle. Bowers (1949) refers to enumerative bibliography as a procedure that identifies books in “specific collections or libraries,” in a specific discipline, by an author, printer, or period of production (3). He refers to descriptive bibliography as the systematic description of a book as a material or physical artifact. Analytical bibliography, the cornerstone of descriptive bibliography, investigates the printing and all physical features of a book that yield evidence establishing a book's history and transmission (Feather 10). It is the preliminary phase of bibliographic description and provides the vocabulary, principles and techniques of analysis that descriptive bibliographers apply and on which they base their descriptive practice.

BIBLIOGRAPHY FOR THIS PROJECT

134


1. Encyclopedia of Chemical Technology, by Kirk- Othmer, 5th ed. John Wiley, New Yark. 2. Reklaitis, G.V. & Schneider, D.R. , Introduction to Material and Energy Balances, John Wiley & Sons, New York. 3. Elements of Chemical Reaction Engineering, by H.Scott Fogler and M. Nihat Gurmen. 4th ed., Prentice-Hall of India Pvt Ltd, 2008. 4. Joshi, M. V., Process Equipment Design, Macmillan India Ltd., 1981. 5. Kern, D. Q., Process Heat Transfer, McGraw Hill, 1965. 6. Austin G T, “Shreve’s chemical Process Industries”,Mc Graw Hill Book Company, New Delhi 5th Edn. (1986). 7. Dryden. C.F ,”Outlines of Chemical Technology”, East West Press Pvt. Ltd., New Delhi, 2nd Edition (1973). 8. Shukla S D and Pandey G.N., “A test book of Chemical Technology Vol I”, Vikas Publishing House Pvt. Ltd., New Delhi. 9. Shukla S D and Pandey G.N., “A test book of Chemical Technology Vol II”, Vikas Publishing House Pvt. Ltd., New Delhi 10. McCabe, W.L., Unit Operations of Chemical Engineering, McGraw Hill, 1988. Koppel, L.B., & Coughanower, B. R., Process System and Analysis and Control, McGraw Hill, 1965. 11. Sundaravadivel, S., & Chaudhary, D. S., Environmental Management, SciTech Publications Pvt. Ltd. 12. Hougen, O.A., Chemical Process Principles, Vol.-1, Indian Edition, Asia Publishing House.

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13. Geankoplis, C. J., Transport Process and Unit Operation, 3rd edition, PHI, 2000. 14. Peter, M., and Timmerhaus, K. D., Plant Design and Economics for Chemical Engineers, 4th edition, McGraw Hill. 15. Koppel, L.B., & Coughanower, B. R., Process System and Analysis and Control, McGraw Hill, 1965. 16. J.M. Coulson and J.F.Richardson-Vol. V- Chemical Engineering. 17. Trybal, R. E. Mass Transfer Operation, McGraw Hill, Kogakusha Ltd., 1981 18. Perry,R.H.,”Chemical Engineer’s Handbook”, McGraw Hill, 1984. 19. Holman, J. P., Heat Transfer, McGraw Hill, 1989. 20. Stephanopoulas, G.,”Chemical Process Control, Prentice-Hall of India Pvt Ltd, 1990. 21. Odum, E.P., Fundamental of Ecology, W.B. Sounders Company Ltd., 1971. 22. Badger, W. L., and Banchero, J. T., Introduction to Chemical Engineering, McGraw Hill, Kogakusha Ltd.

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Design a Plant to Manufacturing of Ferrous Sulfate Monohydrat

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