Manufacture of Sugar

PROJECT REPORT on

MANUFACTURE OF SUGAR FROM SUGAR CANE Submitted in partial fulfillment for the award of the degree of

BACHELOR OF TECHNOLOGY in

CHEMICAL ENGINEERING by

RAJASEKAR .V (10704014) SATHIYA NARAYANAN .S (10704017) under the guidance of

Mr. M. MAGESH KUMAR, M.Tech., (Senior Lecturer, Department of Chemical Engineering)

FACULTY OF ENGINEERING AND TECHNOLOGY

SRM UNIVERSITY (under section 3 of UGC Act,1956)

SRM Nagar, Kattankulathur – 603 203 Kancheepuram Dist. May 2008

BONAFIDE CERTIFICATE Certified that this project report on “MANUFACTURE OF SUGAR FROM SUGAR CANE ” is the bonafide work of “RAJASEKAR .V (10704014) and SATHIYA NARAYANAN .S (10704017)” who carried out the project work under my supervision.

HEAD OF THE DEPARTMENT

INTERNAL GUIDE

Date:

EXTERNAL EXAMINER

DATE :

INTERNAL EXAMINER

ACKNOWLEDGEMENT We are extremely thankful to Dr.R.KARTHIKEYAN, B.E., PhD, Professor and Head, School of Chemical Engineering, S.R.M University, for permitting us to venture on this project and providing us with good support and guidance. We would like to thank Mr. M.MAGESH KUMAR, B.Tech, .M.Tech, Faculty, School of Chemical Engineering, S.R.M University, for his encouragement and guidance at all stages of this project. We extend our sincere thanks to all the staff members of the School of Chemical Engineering, S.R.M University, for their support and assistance.

ABSTRACT This project deals with the manufacture of sugar from sugarcane. Since the demand for sugar has been increasing day by day. A detailed process Flow sheet, Material Balance, Energy Balance have been done. A detailed Design of equipments, Cost Estimation of plants, Plant layout and Safety aspects have been discussed.

CONTENTS S. NO

CONTENTS

PG NO

1

Introduction

1

2

Properties

5

3

Process description

8

4

Material balance

16

5

Energy balance

25

6

Equipment design

37

7

Process control

46

8

Pollution control

49

9

Cost estimation

56

10

Plant location and site selection

67

5

1.INTRODUCTION

6

INTRODUCTION Sugar industry is one of the most important agro-based industries in India and is highly responsible for creating significant impact on rural economy in particular and country’s economy in general. Sugar industry ranks second amongst major agrobased industries in India. As per the Government of India’s recent liberalised policy announced on 12th December, 1986 for licensing of additional capacity for sugar industries during 7th five-year plan, there will be only one sugar mill in a circular area of 40 sq km. Also the new sugar mill is allowed with an installation capacity of 2500 TCD (Tonne Sugar Cane crushed per day) as against the earlier capacity norms of 1250 TCD. Similarly, the existing sugar mills with sugar cane capacity of about 3500 TCD can crush sugar cane to the tune of 5000 TCD with a condition imposed that additional requirement of sugar cane be acquired through increased productivity and not by expansion of area for growing sugar cane. Cane sugar is the name given to sucrose, a disaccharide produced from the sugarcane plant and from the sugar beet. The refined sugars from the two sources are practically indistinguishable and command the same price in competitive markets.However, since they come from different plants, the trace constituents are different and can be used to distinguish the two sugars. One effect of the difference is the odor in the package head space, from which experienced sugar workers can identify the source. In the production scheme for cane sugar, the cane cannot be stored for more than a few hours after it is cut because microbiological action immediately begins to degrade the sucrose. This means that the sugar mills must be located in the cane fields. The raw sugar produced in the mills is item of international commerce. Able to be stored for years, it is handled as raw material – shipped at the lowest rates directly in the holds of ships or in dump trucks or railroad cars and pushed around by bulldozers. Because it is not intended to be eaten directly, it is not handled as food. The raw sugar is shipped to the sugar refineries, which are located in population centers. There it is refined to a food product, packaged, and shipped a short distance

7

to the market. In a few places, there is a refinery near or even within a raw-sugar mill. However, the sugar still goes through raw stage. The principle by-product of cane sugar production is molasses. About 10 – 15% of the sugar in the cane ends up in molasses. Molasses is produced both in the raw-sugar manufacture and also in refining. The blackstrap or final molasses is about 35 – 40% sucrose and slightly more than 50% total sugars. In the United States, blackstrap is used almost entirely for cattle feed. In some areas, it is fermented and distilled to rum or industrial alcohol. The molasses used for human consumption is of a much higher grade, and contains much more sucrose. Sugarcane characteristics: Sugarcane contains not only sucrose but also numerous other dissolved substances, as well as cellulose or woody fibre. The percentage of sugar in the cane varies from 8 to 16% and depends to a great extent on the variety of the cane, its maturity, condition of the soil, climate and agricultural practices followed. The constituents of ripe cane vary widely in different countries and regions but fall generally within the following limits: Constituent

Percentage range

Water

69.0 – 75.0

Sucrose

8.0 – 16.0

Reducing sugars

0.5 – 2.0

Organic matter other than sugar

0.5 – 1.0

Inorganic compounds

0.2 – 0.6

Nitrogenous bodies

0.5 – 1.0

Ash

0.3 – 0.8

Fibre

10.0 – 16.0

8

Organic matters other than sugar include proteins, organic acids, pentosan,colouring matter and wax. Organic acids present in cane are glycolic acid, malic acid, succinic acid and small quantity of tannic acid, butyric acid and aconitic acid. These vary from 0.5 to 1.0% of the cane by weight. The organic compounds are made up of phosphates, chlorides, sulphates, nitrates and silicates of sodium, potassium, calcium,magnesium and iron chiefly. These are present from 0.2 to 0.6%.The nitrogenous bodies are albuminoid, amides, amino acids, ammonia, xanthine bases, etc. These are present to the extent of 0.5 to 1.0%. Fibre is the insoluble substance in the cane. Dry fibre contains about 18.0% lignin, 15% watersoluble substances, 45% cellulose and the rest hemicellulose.The juice expressed from the cane is an opaque liquid covered with froth due to air bubbles entangled in it. The colour of the juice varies from light grey to dark green. Colouring matter is so complex that very little is known about them and there is a great need for research in this direction. ‘Colouring matters’ consist of chlorophyll, anthocyanin, saccharatin and tannins. Canes which have been injured or which are over-ripe contain ordinarily invert sugar as well. When severe frost damages sugarcane, all buds are killed and the stalk split. Then the juice produced has low purity, less sucrose, high titrable acidity, and abnormal amounts of gum, which make processing difficult and at times impossible. Frost is generally not a very common phenomenon in Indian crops. Insects and pests cause a greater damage. Cane juice has an acidic reaction. It has a pH of about 5.0. The cane juice is viscous owing to the presence of colloids. The colloids are particles existing in a permanent state of fine dispersion and they impart turbidity to the juice. These colloids do not settle ordinarily unless conditions are altered. The application of heat or addition of chemicals brings about flocculation or coagulation. They may be coagulated by the action of electric current and adsorption by sucrose attractions using porous or flocculent material. Some colloids are flocculated easily while others do so with great difficulty. Each colloid has a characteristic ‘pH’ at which flocculation occurs most easily. It is known as the isoelectric point of the colloid. The cane juice is turbid owing to the presence of such colloidal substances as waxes, proteins, pentosans, gums, starch and silica.

9

2.PROPERTIES

10

PROPERTIES Physical properties Molecular weight

342

Specific heat capacity

0.28 kcal/kg

Density

1.63 g/cm^3

Melting point

184 centigrade

Specific gravity

1.58056

Solubility Temperature

sucrose g/100 water

0

180.9

10

188.4

20

199.4

30

214.3

40

233.4

50

257.6

60

324.6

11

Chemical properties Hydrolysis Sucrose is easily hydrolyed in the presence of hydrogen ion,ammonium ion and certain enzymes all acting as catalysts to a mixture of d-glucose and d-fructose called”invert suger”because of a reversal in direction of optical rotation. Oxidation Vigorous oxidation of sucrose with strong nitric acid produes equimolar quantities of oxalic acid and tartanic acid.when the oxidation with nitric acid is carried out in the presence of sodium metavanadate. Hydrogenation In the presence of raney-nickel catalyst inverted sucroses is hydrogenated to a mixture to a sorbitol and d-mannitol. Hydrogenolysis Under more drastic conditions the sugar chain are severed and good yields of glycerol and propylene glycol are formed. Alkaline degradation Sucroses autoclaved with aqueous calcium hydroxide yields up to 70%of lactic acid. Acid degradation Hot mineral convert sucrose to 5-hydroxy methyl-furfural.by variation ,the reaction can yield equimolar amounts of levulic and formic acids.

12

3.PROCESS DESCRIPTION

13

PROCESS DESCRIPTION At the sugar factory, the cane is piled as reserve supply in the cane yard so that the factory, which runs, 24 hr/day will always have cane to grind. The delivery of the cane to the factory depends upon the time of day, weather, and some other factors. Very closely controlled operations never have more than a few hours worth of cane in the cane yard, but more generally, the cane yard is fairly full toward evening and nearly empty the next morning. The cane is moved from the cane yard or directly from the transport to one of the cane table. Feed chains on the tables move the cane across the tables to the main cane carrier, which runs at constant speed carrying the cane into the factory. The operator manipulates the speed of the various tables to keep the main carrier evenly filled.In order to remove as much dirt and trash as possible, the cane washed on the main carrier with as much water as is available. This includes decirculated wash water and all of the condenser water. Of the order of 1 –2 % of the sugar in the cane is washed out and lost in the washing, but it is considered advantageous to wash. In areas where there are rocks in the cane, it is floated through the so- called mud bath to help separate the rocks. The sugar recovered is normally 10-wt % of the cane, with some variation from region to region. Sugar cane has the distinction of producing the heaviest yield of all crops, both in weight of biomass and in weight of useful product per unit area of land. Extraction of juice: The juice is extracted from the cane either by milling, in which the cane is pressed between the heavy rolls, or by diffusion, in which the sugar is leached out with water. In either case, the cane is prepared by breaking into pieces measuring a few centimeters. In the usual system, the magnets first remove the tramp iron, and the cane then passes through two sets of rotating knives. The first set, called cane knives turns at about 700 rpm, cuts the cane into pieces of 1 – 2 dm length, splits it up a bit, and also act as a leveler to distribute the cane more evenly on the carrier. The second set, called shredder knives turn faster and combine a cutting and a hammer action by having a closer clearance with the housing. These quite thoroughly cutter and shred the cane into a fluffy mat of pieces a few centimeters in the largest dimensions. In

14

preparing cane for diffusion, it is desirable to break every plant cell. Therefore the cane for diffusion is put through an even finer shredder called a buster or fiberizer. No juice is extracted in the shredders. In milling, the cane then goes to the crusher rolls, which are similar to the mills, but have only two rolls, which have large teeth and are widely spaced. These complete the breaking up of the cane to pieces of the order of 1 – 3 cm. The large amount of juice is removed here. Milling: The prepared cane passes through a series of mills called a tandem or milling train. These mills are composed of massive horizontal cylinders or rolls in groups of three, one on the top and two on the bottom in the triangle formation. The rolls are 50 –100 cm diameter and 1 –3 m long and have grooves that are 2 –5 cm wide and deep around them. There may be anywhere from 3 – 7 of these 3 roll mills in tandem, hence the name. These mills, together with their associated drive and gearing, are among the most massive machinery used by industry. The bottom two rolls are fixed, and the top is free to move up and down. The top roll is hydraulically loaded with a force equivalent about 500 t. The rolls turn at 2 – 5 rpm, and the velocity of the cane through them is 10- 25cm/s. After passing through the mill, the fibrous residue, from the cane, called bagassae, is carried to the next mill by bagassae carriers and is directed from the first squeeze in a mill to the second by turn plate. In order to, achieve a good extraction, a system of imbibition is used, bagassae going to the final mill is sprayed with water to extract whatever sucrose remains; the resultant juice from the last mill is then sprayed on the bagasse mat going to the next to last mill, and so on. The combination of all these juices is collected from the first mill and is mixed with the juice from the crusher. The result is called the mixed juice and is the material that goes forward to make the sugar. The mills are powered with individual steam turbines. The exhaust steam from the turbines is used to evaporate water from the cane juice. The capacity of the sugarcane mills is 30 – 300 t of cane per hour.

15

Bagasse: The bagasse from the last mill is about 50-wt% water and will burn directly.Diffusion bagasse is dripping wet and must be dried in a mill or some sort of bagasse press. Most bagasse is burned in the boilers that run the factories. Clarification: The juice from either milling or diffusion is about 12 – 18% solids, 10 – 15 pol (polarization) (percent sucrose), and 70 – 85% purity. These figures depend upon geographical location, age of cane, variety, climate, cultivation, condition of juice extraction system, and other factors. As dissolved material, it contains in addition to sucrose some invert sugar, salts, silicates, amino acids, proteins, enzymes, and organic acids; the pH is 5.5 – 6.5. It carries suspension cane fibre, field soil, silica, bacteria,yeasts, molds, spores, insect parts, chlorophyll, starch, gums, waxes, and fats. It looks brown and muddy with a trace of green from the chlorophyll. In the juice from the mill, the sucrose is inverting (hydrolyzing to glucose and fructose) under the influence of native invertase enzyme or an acid pH. The first step of processing is to stop the inversion by raising the pH to 7.5 and heating to nearly 100oC to inactivate the enzyme and stop microbiological action. At the same time, a large fraction of the suspended material is removed by settling. The cheapest source of hydroxide is lime, and this has the added advantage that calcium makes many insoluble salts.Clarification by heat and lime, a process called defecation, was practiced in Egypt many centuries ago and remains in many ways the most effective means of purifying the juice. When the mud settles poorly, polyelectrolyte flocculants such as polyacrylamides are sometimes used.The heat and high Ph serve to coagulate proteins, which are largely removed in clarification. The equipment used for clarification is of the Dorr clarifier type. It consists of a vertical cylindrical vessel composed of a number of trays with conical bottoms stacked one over the other. The limed raw juice enters the centre of each tray and flows toward the circumference. A sweep arm in each tray turns quite slowly and sweeps the settled mud toward a central mud outlet. The clear juice from the top circumference overflows into a header. Diffusion juice contains less suspended solids than mill juice. In many diffusion operations, some or all of the clarification is carried out in the diffuser by adding lime. The mud from clarification is removed. The mud mostly consists of field soil and very 16

fined divided fibre. It also contains nearly all the protein (0.5 wt% of the juice solids) and cane wax. The mud is returned to the fields. Although the clarification removes most of the mud, the resulting juice is not necessarily clear. The equipment is often run at beyond its capacity and control slips a little so that the clarity of the clarified juice is not optimum. Suspended solids that slip past the clarifiers will be in the sugar. Clarified juice is dark brown. The colour is darker than raw juice because the initial heating causes significant darkening. Evaporation: Cane juice has sucrose concentration of normally 15%. The solubility of sucrose in water is about 72%. The concentration of sucrose must reach the solubility point before crystals can start growing. This involves the removal by evaporation of 93% of the water in the cane juice. Since water has the largest of all latent heats of vaporization, this involves a very large amount of energy. In the energy crunch of the late 1970s, the DOE found that the sugar industry was one of the largest users of energy. The sugar industry already knew this very well and had been using multipleeffect evaporators for saving energy for more than a century. The working of multiple-effect evaporator can be seen in fig. In each succeeding effect, the vapours from the previous effect are condensed to supply heat. This works only because each succeeding effect is operating at a lower pressure and hence boils at lower temperature.The result is that 1 kg of steam is used to evaporate 4 kg of water. The steam used is exhaust steam from the turbines in the mill or turbines driving electrical generators. The steam has therefore already been used once and here in the second use it is made to give fourfold duty. The usual evaporator equipment is a vertical body juice-in-tube unit. Several variations are in use, but the result is the same. The only auxiliary equipment is the vacuum pump. Today, steam-jet-ejectors are general, although mechanical pumps were formerly used. Since the cane juice contains significant amounts of inorganic ions, including calcium and sulfate, the heating surfaces are quick to scale and require frequent cleaning. In difficult cases, the heating surfaces must be cleaned every few days. This requires shutting down the whole mill or at least one heat-exchanger unit while the cleaning is done. Inhibited hydrochloric acid or mechanical cleaners are usually employed.

17

Magnesium oxide is sometimes used instead of lime as a source of hydroxide. Magnesium costs more, but it makes less boiler scale on the heaters. It is also easier to remove because it is more soluble; however, for the same reason, more gets into the sugar. Whether it is used or not depends upon the influence, standing, and persuasiveness of the chief engineer who must keep the plant running and the chief chemist who must make good sugar.The evaporation is carried on to a final brix of 65 – 68. The juice, after evaporation, is called syrup and is very dark brown, almost black, and a little turbid. Vacuum pans: Vacuum pans have a small heating element in comparison to the very large liquor and vapour space above it. The heating element was formerly steam coils but is now usually a chest of vertical tubes called calandria. The sugar is inside the tubes. There is a large center opening (downcomer) for circulation. The vacuum pan has a very large discharge opening: typically 1 m dia. At the end of a strike, the massecuite contains more crystals than syrup and is therefore very viscous.This large opening is required to empty the pan in a reasonable time. At the top or down of the pan, there are viscous entrainment separators. The pan may also be equipped with a mechanicalstirrer. This is usually an impeller in or below the central downcomer, driven by shaft coming down all the way from the top. The strike is started with liquor just above the top of the calandria. The strike level cannot be very near the top because of vapour space must be allowed for separation of entrainment. In operation, the boiling is very vigorous with much splashing of liquid. The vacuum is maintained mostly by condensing the vapours in a barometric condenser. In some cases, a surface condenser is used. This serves as a source of distilled water and recovers heat. More often, however, a jet condenser is used in which the cold condensing water is sprayed into the hot vapour and both condensate and condenser water are mixed. A supplementary vacuum pump is required to remove non condensable gases. Centrifuging: The massecuites from the vacuum pans enter a holding tank called a mixer that has a very solely turning paddle to prevent the crystals from settling. The mixer is

18

a feed for the centrifuges. In a batch-type centrifuge, the mother liquor is separated from the crystals in batches of about 1 t at a time. Boiling systems: In raw-sugar manufacture, the first strike of sugar is called the A strike, and the mother liquor obtained from this strike from the centrifuges is called A molasses. The pan yield in sugar boiling is about 50%. Because crystallization is an efficient purification process, the product sugar is much purer than the cane juice and the molasses much less pure. As an approximation, crystallization reduces the impurities by factor of 10 or more in the product sugar. Therefore, almost all of the impurities remain in the molasses. Enough molasses accumulates from boiling two first strikes to boil a second strike. The B sugar from the second strike is only half as pure as that from the first strike,but the B molasses is twice as impure. This can go on to a third strike. At this point, 7/8 of the sugar from the cane juice is in the form of crystals and 1/8 in the C molasses. In practice, three strikes is about all that can be gotten from cane juice. The trick is to maneuver to obtain good sugar, but at the same time have the C or final molasses as impure as possible. The purity of the feed to the final strike is adjusted to obtain the lowest possible purity of final molasses. Some of the C sugar is redissolved and started over, some is used as footing for A and B strikes. The C sugar is of very small crystal size so it is taken into the A or B pans as seed and grown to an acceptable size. This practice is actually a step backward because it hides impure C sugar in the center of better A and B sugars. The product raw sugar is a mixture of A and B sugars. There are many variations in the boiling scheme, such as two and four billings, blending molasses, and returning molasses to the same strike from which it came. All of these tricks are used, depending on cane purity and capabilities of the equipment available. Coolers: When the steam is turned off at the end of a sugar boiling, evaporation ceases immediately and the mixture of crystals and supersaturated syrup in the pan starts toward equilibrium, which is the point of saturation. In relatively pure sugar solutions, this equilibrium is reached in few minutes well before the syrup crystallization is slower and reaching equilibrium can take a significant amount of time. In the final

19

strike, the time an amount to days, so final strikes are not sent directly to the centrifuges, but instead to crystallize, holding tank is in which the crystals grow as much as possible and the super saturation in the molasses is reduced to 1.0. Since the intention in handling the final molasses is to remove as much sugar as possible, advantage is taken of the small temperature coefficient of solubility and the massecuite is also cooled. The crystallizers are large tanks, some open-top, with a slow-moving stirrer that is sometimes also a cooling coil. At the end of the holding time, the massecuite is warmed slightly as it enters the centrifuge to lower the viscosity and achieve better separation. The limiting factor in exhaustion of masses is the viscosity. A little more water can always be boiled out, but the molasses must remain fluid enough to run out of the pan, into the centrifuge and to flow between the sugar crystals on the centrifuge screens. Packing, storing and shipping: Sugar is sometimes stored in bulk and then packaged as needed. Others package the sugar and then warehouse the packages. The present trend is away from consumer sized packages and toward bulk shipments.

20

4. MATERIAL BALANCE

21

MATERIAL BALANCE BASIS – 100 TONS/DAY OF SUGAR CANE MILLING Cane – 100 tons Water – 70 tons

Juice – 105 tons solid – 15 tons

MILLING

Solid – 16 tons

water – 90 tons

Fibre – 14 tons

Bagasse – 30 tons Solid – 1 ton Water – 15 tons Fibre – 14 tons

Cane

+

100

water 35

Total inlet – 135 tons

=

Juice 105

+

bagasse 30

Total outlet – 135 tons

RAW JUICE HEATER Juice – 105 tons

Raw Juice Heater

Juice – 105 tons

Solid- 15 tons

Solid- 15 tons

Water – 90 tons

Water – 90 tons


Total outlet- 105 tons

22

JUICE SULPHITOR Juice – 105 tons

Juice Sulphitor

Juice – 105 tons

Solid- 15 tons

Solid- 15 tons

Water – 90 tons

water- 90 tons

Lime – 0.05 ton

lime – 0.05 ton

So2 – 0.02 ton

so2 – 0.02 ton

Lime – (0.05 x(100/100))= 0.05 ton So 2 - (0.02 x(100/100))= 0.02 tons Total inlet – 105.07 tons

Total outlet – 105.07 tons

JUICE HEATER Juice – 105.07 tons Solid- 15 tons

juice – 105.07 tons Juice Heater

Solid- 15 tons

Water – 90 tons

water- 90 tons

Lime – 0.05 ton

lime – 0.05 ton

So2 – 0.02 ton

so2 – 0.02 ton

Total inlet – 105.07 tons


23

JUICE CLARIFIER Juice – 105.07 tons

Juice – 101.57 tons Juice clarifier

Solid- 15 tons

Solid- 14.195 tons

Water – 90 tons

Water- 87.375 tons

Lime – 0.05 ton So2 – 0.02 ton

Cake – 3.5 tons Solid – 0.815 ton Water - 2.625 tons Lime & So2 – 0.06 ton



EVAPORATOR 1 Vapour – 21.355 tons(82.50-63.09)

86 % water Juice – 101.57 tons Solid- 14.195tons

65 % water Juice – 80.21 tons

Evap 1

Solid- 14.195 tons

Water – 87.375 tons

water-66.02 tons

Water –(0.65 x101.57= 66.02 tons) Total inlet – 101.57 tons

Total outlet – 80.21(101.57- 21.355)

24

EVAPORATOR 2 Vapour – 10.1tons(87.375-55.86) 65%water

55 % water

Juice – 80.21 tons


Evap 2

Solid- 14.195tons

Solid- 14.195 tons


water-55.86tons Water – (0.55 x101.57= 55.86 tons)

Total inlet – 80.21tons

Total outlet – 67.94tons(80.21- 10.16)

EVAPORATOR 3 Vapour – 10.16tons(55.86-45.70)

55 % water

45 % water


Juice – 59.89 tons Evap 3

Solid- 14.195tons

Solid- 14.195 tons


Water-45.70 tons Water –(0.45 x101.57= 45.70 tons)


Total outlet – 59.89 tons(67.94-10.16)

25

EVAPORATOR 4 Vapour – 5.08 tons(45.70-40.62) 45 % water

40 % water

Juice – 59.89 tons Solid- 14.195tons Water – 45.70 tons

Juice – 54.81 tons Solid- 14.195 tons

Evap 4

Water – 40.62tons

Water – (0.40 x101.57= 40.63tons) Total inlet – 59.89 tons


VACUUM PAN A Vapour – 30.47tons(45.70-40.62) 40 % water

Solid- 14.195tons Water – 40.62 tons

15 % water

Vac pan A

Solid- 14.195 tons water – 10.15tons

Water –(0.15 x101.57= 10.15tons) Total inlet – 54.81 tons


26

VACUUM PAN B Vapour – 8.07 tons(14.533-6.7914)

2% water Solid- 4.915tons Water – 10.10 tons

Vac pan B


Water –(0.02 x101.57= 2.06tons) Total inlet – 15.01tons


VACUUM PAN C Vapour – 1.28 tons(2- 0.72)

Solid- 3.642ons

Solid- 3.642 tons

Vac pan C



water – 0.72tons


27

CENTRIFUGAL A

Centrifugal A

Solid – 14.195 tons

Molasses – 15.02 tons


Water – 10.10 tons Solid – 4.915 tons Crystal sugar – 9.25 tons Sugar loss – 0.03 ton Outlet – 9.3tons(9.25+0.05) Outlet – 15.025tons(10.10+4.915)

Inlet – 24.34tons(10.15 + 14.195 )

Total –24.34tons(15.02+9.3+0.03)

CENTRIFUGAL B Solid – 4.195 tons

Molasses – 10.662 tons

Centrifugal B


Water – 2.000 tons Solid – 3.642 tons

Crystal sugar – 1.253 tons Sugar loss – 0.02 ton Outlet – 3.15tons(3.1+0.05) Outlet – 10.662tons(6.7414+3.921) Inlet – 6.945tons(4.915+2.030 )

Total – 6.945(1.283+5.642+0.02)

28

CENTRIFUGAL C Solid – 3.642tons

Molasses – 3.5 tons Centrifugal C

Water – 0.72 tons

Water – 0.7 tons Solid – 2.8 tons

Crystal sugar – 0.832tons `

Sugar loss – 0.01 ton

Inlet – 4.362tons(0.72 + 3.642 )

Total – 4.362tons(0.852+3.5+0.01 )

CONVEYOR Sugar 1 – 9.3 tons Conveyor Sugar 2 - 1.283 tons

SUGAR – 11.435tons

Sugar 3 - 0.852 tons (9.3 + 1.283 + 0.852 )= 11.435 DRYER Moisture – 0.04 ton Sugar – 11.435

SUGAR – 11.395 tons Dryer

Moisture – 0.1 tons

Moisture – 0.06 tons

Hot air – 0 %moisture content

29

5. ENERGY BALANCE

30

ENERGY BALANCE RAW JUICE HEATER Juice – 105 tons

Raw Juice Heater

Juice – 105 tons

Solid- 15 tons

Solid- 15 tons

Water – 90 tons

Water – 90 tons


Total outlet- 105 tons

Cp of sucrose (solid)

0.299 kcal/kg

Enthalpy of solid in

15 x 0.299(32-25) x103 = 31395kcal

Enthalpy of water in

90 x 0.999(32-25) x 103 = 629370kcal

Enthalpy of solid out

15 x 0.299(71-25) x 103 = 206310kcal

Enthalpy of water out

90 x 0.999(71-25) x 103 = 4156560kcal

Enthalpy of vapor out

0

Total enthalpy in

660765(31395+629370)kcal

Total enthalpy out

4362870(206310+4156560)kcal

Mass total steam required

8071.9149(3702105/540.5)kcal

Total heat required

3702105(total E out-total E in)kcal

31

JUICE SULPHITOR Juice – 105 tons Solid- 15 tons

Juice – 105 tons JUICE SULPHITOR

Solid- 15 tons

Water – 90 tons

water- 90 tons

Lime – 0.05 ton

lime – 0.05 ton

So2 – 0.02 ton

so2 – 0.02 ton


15 x 0.299(71-25) x 103 = 206310kcal


90 x 1.004(71-25) x 103 = 4156560kcal

Cp of Ca(oH)2

21.4cal/mol – 21.4/74 = 0.289kcal/kg

Enthalpy of Ca(oH)2 in

0.05 x0.289(71-25) x 103 = 664.7kcal

Cp of So2

7.7+0.0053T-0.00000083T-2 =8.072 cal/mol = 8.072/64 kcal/kg =0.126 kcal/kg

Enthalpy of So2 in

0.02 x 0.126(71-25) x 103 = 115.92kcal/kg


15.07 x0.299(70-25) x 103 = 202766.85kcal


90 x 1.004(70-25) x 103 = 4066200kcal

Total enthalpy in

4363650.62 kcal

Total enthalpy out

4268966.85kcal

Total heat required

94683.77kcal(total E out-total E in)

32

JUICE HEATER Juice – 105.07 tons Solid- 15 tons

Juice – 105.07 tons Juice Heater

Solid- 15 tons

Water – 90 tons

water- 90 tons

Lime – 0.05 ton

lime – 0.05 ton

So2 – 0.02 ton

so2 – 0.02 ton


15.07 x0.299(70-25) x103 = 202766.85kcal


90 x1.004(70-25) x103 = 4066200kcal


15.07 x 0.299(103-25) x103 = 351462.54kcal


90 x 1.012(103-25) x 103 = 7104240kcal


0

Total enthalpy in

4268966.85kcal

Total enthalpy out

7455702.54kcal

Mass total steam required

5895.9032kg

Total heat required

3186735.69kcaltotal E out-total E in)

33

JUICE CLARIFIER Juice – 105.07 tons Solid- 15 tons

Juice – 101.57 tons JUICE CLARIFIER

Water – 90 tons

Solid- 14.195 tons Water- 87.375 tons

Lime – 0.05 ton So2 – 0.02 ton

Cake – 3.5 tons Solid – 0.815 ton Water - 2.625 tons Lime & so2 – 0.06 ton


15.07 x 0.299(103-25) x 103 = 349830kcal


90 x 1.004(103-25) x 103 = 7048080kcal


14.195 x 0.299(102-25) x 103 = 326696.37kcal


87.375 x1.012(102-25) x 103 = 6808609.5kcal

Enthalpy of mud juice out

3.44 x0.126 x(102-25) x 103 = 33.3748 x103 kcal

Enthalpy of Lime out Enthalpy of so2 out

0.045x 0.289(102-25)x103 = 1.0013 x103 kcal 1.3987 x 102 kcal

Total Enthalpy in

7397.91 x103 kcal

Total Enthalpy out

7171.0803 x103 kcal

Total heat released

226.8297 x103 kcal

34


65 % water



Solid- 14.195tons

Solid- 14.195 tons


Water-66.02 tons

Clear juice in – Hf = mCp∆t ∆T = 102-102 = 0 Cp = 0.96 kcal/kg M = 101.57 ton Hf = 0 Similarly Hp = 0 Enthalpy of steam in

Sλs

Latent heat at 126 C

540. 5 kcal/kg


mλ

Enthalpy at 102

536.45 kcal/kg = 21.355 x 536.45 = 11455.88 x 103 kcal

Balance equation Hf

+

0

+

Sλ S x540.5 S

=

Hp

+

=

0

+

=

21.9498 x 103 kg

35

mλ 11455.88


55 % water



Evap 2

Solid- 14.195tons

Solid- 14.195 tons


Water-55.86tons

Hf = mcp∆t Cp

= 0.96 kcal /kg

∆T

= 107-78 = 24

Hf

= 80.21 x 0.96 x24 = 1848.03 x 10 3 kcal

Enthalpy of vapor in

V1 λv

Λv = 536.45

V1 x 536.45

Hp = mcp∆t ---∆t=0 Enthalpy of vapor out

m λv 10.16 x531.11 = 5396.07 x 103 kcal

Balance equation :Hf

+

mλ

=

Hp

+

1848.03 x 10

+

V1 x 536.45

=

0

+

V1

=

6.613 x 103 kg

36

vapor out enthalpy 5396.07 x 103

EVAPORATOR 3 Vapour – 10.16tons(55.86-45.70) 55 % water

45 % water



Solid- 14.195tons

Solid- 14.195 tons


water-45.70 tons

Hf = mcp∆t Cp = 0.96 kcal /kg ∆T = 66-55 = 11 Hf = 59.89x 0.96 x11 = 632.43 x 10 3 kcal Enthalpy of vapor in

V1 λv Λv = 531.11 V1 x 531.11

Hp = mcp∆t ---∆t=0 Enthalpy of vapor out

m λv = 10.16 x529.18 = 5376.46x 103 kcal


+

806.976 x 103 +

mλ

=

Hp

+

vapor out enthalpy

0

+

5376.46 x 103

V1 x 531.11 = V1

=

8.603 x 103 kg

37


40 % water



Solid- 14.195tons

Solid- 14.195 tons

Evap 4


Water – 40.62tons

Hf = mcp∆t Cp = 0.96 kcal /kg T = 78-66 = 12 Hf = 70.05 x 0.96 x12 = 806.97 x 10 3 kcal Enthalpy of vapor in

V1 λv Λv = 534.211 =V1 x 534.211

Hp = mcpt ---t=0 Enthalpy of vapor out

m λv = 5.08 x529.18 = 2683.51x 103 kcal


+

632.43 x 103 +

mλ

=

V1 x 534.211 = V1

=

Hp

+

vapor out enthalpy

0

+

2683.51 x 103

3.8394 x 103 kg

38

VACUUM PAN A Vapour – 30.47tons(45.70-40.62) 40 % water

15 % water

Solid- 14.195tons

Solid- 14.195 tons


Vac pan A

Enthalpy of juice in

= mcpΔt

water – 10.15tons

= 54.81 x0.96 x(55-25) = 1578.528 x 10 kcal Vapor in

= Sλ = S(540.5)

Enthalpy of juice out

= enthalpy of crystallization + sensible heat = (9.3 x 526) + (14.995 x0.96x(60-25) = 5395.632 x 10 3 kcal

Vapor out

= 30.46 x 540.5 = 16463.63 x 10 3 kcal

Heat balance 1578.528 x 103

+ 540.5 S

= S

5395.632 x 103

= 37.5221 x 10 3 kg

39

+

16463.63

VACUUM PAN B Vapour – 8.07 tons(14.533-6.7914) 2% water Solid- 4.915tons Water – 10.10 tons


Vac pan B


= mcpΔt = 15.015 x0.96 x(60-25) = 1578.528 x 10 kcal

Vapor in

= Sλ = S(540.5)


= enthalpy of crystallization + sensible heat = (1.283 x 526) + (5.632 x0.96x(65-25)) = 891.1268 x 10 3 kcal

Vapor out

= 30.46 x 540.5 = 4071.315 x 10 3 kcal

Heat balance 504.504 x 103 +540.5 S = 891.1268 x 103 +4071.315 S = 8.8363 x 10 3 kg

40

VACUUM PAN C Vapour – 1.28 tons(2- 0.72)

Solid- 3.642ons

Solid- 3.642 tons

Vac pan C



water – 0.72ton

= mcpΔt = 5.642 x0.96 x(70-25) = 243.734 x 10 kcal

Vapor in

= Sλ = S(540.5)


= enthalpy of crystallization + sensible heat = (0.832x 526) + (3.51 x0.96x(70-25) = 589.264 x 10 3 kcal

Vapor out

= 1.28 x 540.5 = 645.76 x 10 3 kcal

Heat balance 243.734 x 103

+

540.5 S

=

589.264 x 103

S = 37.5221 x 10 3 kg

41

+

645.76

6. EQUIPMENT DESIGN

42

EVAPORATOR DESIGN Feed to the first effect F = 101.57 tons/day = 1.1756 kg/s Liquid out from last effect = 54.81 tons/day = 0.6261 kg/s Evaporator load = 1.1756 – 0.6261 = 0.5495 kg/s EFFECT

Liquid out (Kg/s)

Vapour out (Kg/s)

1

L1 = 0.9283

V1 = 0.2471

2

L2 = 0.7863

V2 = 0.1175

3

L3 = 0.6932

V3 = 0.1175

4

L4 = 0.6343

V4 = 0.0588

To calculate ∆T :Steam at 1st effect Ps = 1.634 bar T1s = 126 C Pr in fourth effect = 660mmHg->0.1356 bar T5s = 55 C Therefore ∆T = T1s – T5s->126 – 55 = 71 C Calculate ∆t in each effect :q1 = q2 =q3 =q4 u1A1∆T1 = u2A2∆T2= u3A3∆T3= u4A4∆T4 Usually the areas in all the effects are equal Therefore u1∆T1 = u2∆lT2= u3∆T3= u4∆T4

43

According to Hugot the overall heat transfer coefficent in each effects are given as Effect U(Btu/hr ft F)

1

2

3

4

400-500

275-375

200-275

125-150

Assuming overall heat transfer coefficient in each effect as follows Effect

1

2

3

4

U(Btu/hr ft F)

450

325

250

140

U(W/m2 K)

2555

1845

1420

795

∆T2 /∆ T1 = U1/U2 ∆T2 / ∆T1 = (2555/1845) = 1.385 ∆T2 = 1.385 ∆T1 ∆T3 / ∆T2 = U2/U3 ∆T3 / ∆T2 =(1845/1420) = 1.299 ∆T3 = 1.299 ∆T2 ∆T4 / ∆T3 = U3/U4 ∆T4 / ∆T3 =(1420/795) = 1.7862 ∆T4 = 1.7862 Del T3 t1 + t2 +t3 +t4 = 71 C t1 (1+1.385+1.299x1.385+1.299x1.385x1.7862) = 71 t1 = 71/7.58 = 9.37 C t2 = 1.385 x t1 = 12.98 C t2 = 1.299 x t2 = 16.87 C t4 = 1.786 x t3 = 30.13 C Steam S = 21.9498 tons/day = 0.2540 kg/s To calculate area in each effect :44

Enthalpy 1s = 2218.2 KJ/kg Enthalpy 2s = 2246.02 KJ/kg Enthalpy 3s = 2272.21 KJ/kg Enthalpy 4s = 2315.66 KJ/kg q1 = S x Enthalpy 1s =0.2540 x2218.2 =563.4228 Kw q2 = V1 x Enthalpy 2s =0.2471 x 2246.02 =554.9915 Kw q3 = V2 x Enthalpy 3s =0.1175 x 2272.21 =266.9846 Kw q4 = V3 x Enthalpy 4s =0.1175 x 2315.66 =272.09 Kw A1 = (q1/u1t1) = 563.4228 x (103 /2555 x 282.37) = 0.7809 m2 A2 = (q2/U2t2) = 554.9915 x (103 /1845 x 285.98) = 1.0518 m2 A3 = (q3/u3t3)

t3--16.87 C = 289.87 K

= 266.9846 x (103 /1420 x 289.87) = 0.6486 m2 A4 = ( q4/u4t4)

45

= 272.09 x (103 /795 x 303.13) = 1.1290 m2 Detailed design :- Evaporators are designed On the basis of the highest heating area Hence area of each effect = 1.1290 m2 Let us select 50 mm O.D(40mm I.D) tubes each of 2m arranged on 65mm sq.pitch. N =No of tubes in the chest 3.14 xDo x L x N = 1.1290 3.14(0.05) 2 N = 1.1290 N= 3.6 = 4 Down take area(Ad) Ad

= (3.14/4) D2i N x 0.17 = (3.14/4)(0.04)2 x 4 x 0.75 = 0.004 m2

Diameter of downtake = sq root of( Ad x 4/3.14) = sq root of (0.004 x 4/3.14) =0.071 m Annular area = Np2t =4 x (0.065)2 = 0.02 m2 Height of evaporator = 3 x tube length = 3 x 2 = 6m Surface area of each tube a = 3.14 x d0 x L = 3.14 x 0.05 x 2 =0.314 m2

46

Area occupied by tubes = N x (1/2) x P2t x sin α α = 60 =4 x (1/2) x 90.065)2 x 0.866 =0.0073 m2 But actual area is more than this. Hence this area is to be divided by factor which varies from 0.8 to 1.0. Let this factor be 0.9 Therfore actual area required = (0.0073/0.9) Æ0.0081m2 Total area of tube sheet in evaporator = downtake area +area occupied by tubes = 0.004 + 0.0081 = 0.0121 m2 Thus tube sheet diameter = sq root of (4 x area of tube sheet) /3.14 Evaporator diameter

= 0.1241m

Design specification :Evaprator height = 6m Evaporatr diameter = 0.1241m

47

CENTRIFUGAL DESIGN Gravity factor = centrifugal force/gravitational force G

= mw2r/mg

M – is the mass W – is the angular velocity r- is the radius of the basket of the centrifugal machine g- is the gravitational force = 9.81 m/s2 Angular velocity (w) = (2x3.14 x r.p.m of the machine)/60 Centrifugal force mw2r = (m x (2 x 3.14 x r.p.m) 2x r)/602 Therefore Gravity factor (G) = (m x (2x3.14 x r.p.m)2x r)/(m x 9.81 x 602) G = (r.p.m) 2 x r / 900 =(r.p.m)2 x d /1800 D= diameter of the basket centrifugal machine. D iameter will be in the range of (1.05-12.22m) Assume D= 1.22m, r.p.m = 1500 G= (1500)2 x 1.22/1800 = 1525 Capacity 1.The capacity to handle the quantity of syrup per hour or per cycle 2. capacity of sugar produced/hr or per cycle The capacity depends on the following screen a. Surface area of the basket screen b. Thickness of the massecuite layer over the screen

48

The layer of massecuite is generally 14 to 15% of the diameter of the basket.but considered for safe working as 10 to 14 % Hence it is suggested to take the 1. Maximum layer thickness as 0.14D 2. Minimum layer thickness as 0.12D D = diameter of the basket Capacity then can be calculated by the formula on volume basis V = 3.14 x e x H x (D-e) for flat bottom machines Where V = volume of massecuite in (dm3) or litres E = Thickness of massecite in dm3 H = Interior height of the basket in dm D = Inside diameter of the basket in dm So e =(0.14 x 1.22)=0.1708m Assume H = 0.76m ( range from 0.61-0.76m) V = 3.14 x 0.1708 x 0.76 x (1.22-0.1708) V

= 0.4278 m3 = 428 dm3

Formula may be verified the values given by Hugot very closely to the following formula 1. Theoretical V = 390 x (1.22)2 x 0.76 = 428m3 2. Practical V = 340 x (1.22)2 x 0.76 = 441 m3 D = diameter of meters H = Height in meters

49

As per hugot it is assumed that sugar obtained/m3 of massecuite is 800 kg on this basis and the value given as per Hugot the capacity can be calculated in the formula as Weight of sugar(kg)/m3 volume of massecuite = 800 x m3 of massecuite as given by Hugot So Weight of sugar

= 800 x 0.4278 =342.29 kg

Capacity of machine at different size/cycle are in weight of sugar/cycle.

Power requirement Power required (hp) = D4 x H x (r.p.m)2 x (1+4 x r.p.m) x (105/75) =(1.22)4 x 0.76 x (1500)2 x (1+4 x 1500)(105/75) hp

= 37.1

1hp

= 0.74kw

So power required = 27.8kw

50

7. PROCESS CONTROL

51

PROCESS CONTROL The even operation of a process is dependent upon the control of the process variables. when the flowsheet is laid out for the processs, the temperature, pressure and fluid flow quantites are theoretically fixed in accordance with the heat, pressure and material balance.The translation of flowsheet into an operable plan requires that special provision be made to assure the relative constancy of the various quantites and qualities. Automatic control is employed to measure suppress and correct and modify changes of four principal types of process variation. 1. Temperature control 2. Pressure control 3. Flow control 4. Level control It is the objective of all controllers to regulate process variables, and to do so they must be capable of first measuring the variables. Some instruments are equipped to indicate the variable in a continuously readable from and others recorders are equipped with pen and ink on a traveling chart calibrated for time. In modern process industries,digital control systems(DCS) is used for effective control of process variables. Flow metering The measurement of flow rate is done for the purpose of determining the properties of the materials introduced, the amount of material evolve by the process. Secondly flow measurement are made for the purpose of cost accounting usually for steam and water services. Instruments like ventriument, orificement, rotameter are used to measure the flow rate.

52

VARIABLE

MODE OF CONTROL

Temperature

P,PI,PID

Pressure

P,PI,PID

Flow

P,PI,PID

Control station Well engineered display is important in individual indicating and recording instruments becomes crucial in control room design when data on large and often critical process operations must be used by a human operator. Indicator and recorders must be coordinated with controls, switches, alarms and auxillary equipments so as to present a clear easily grasped display of the process condition. There are four essential parts of every control station. They are 1. Process variable indicator 2. A set point mechanism 3. An adjustment device called manual ,that directly manipulates signal to contol valves. 4. An output signal indicator.

53

8. POLLUTION CONTROL AND SAFETY

54

POLLUTION CONTROL AND SAFETY Sugar industry is basically seasonal in nature and operates only for 120 to 200days in a year (early November to April). A significantly large volume of waste is generated during the manufacture of sugar and contains a high amount of pollutional load particularly in terms of suspended solids, organic matter, and press mud, bagasse and air pollutants. Therefore an attempt has been made to present an overview of waste management in sugar industry in India. WASTE GENERATION: (A) WASTEWATER Mill house: Mill house wastewater is derived from continuous gland cooling and intermittent floor washing and contains high amounts of oils and grease and sugar from pills and leaks. Boiler Blow-down: Boiler blow-down is fairly clean water except that it contains high dissolved solids and phosphates. Rotary filter: Filter cloth is periodically washed and constituents a source of waste water. Condensates: The vapours from the last effect evaporator and pan boiling are Separately cooled in barometric condensers and the condensate goes to the pond. A part of the cooled water from the pond is recycled into the sugar mill, but a large portion is discharged as wastewater. If the mill operates without overloading, the evaporator and vacuum pan condensate is quite clean and the entire quantity can be reused. But many a times, overloading and poor operating conditions can lead to significant sugar losses in the condensates through entrainment and thus polluting the water. Occasional Spills and Leaks: Leaks from pumps and pipes in the evaporators and centrifuge house, along with periodical floor washings, constitute another source of waste water. Although the flow is intermittent and volume discharged is not large, it represents the most polluting fraction of sugar mill wastewater.

55

Condensate Washings: Evaporators, juice heaters, pans, etc are cleaned once in 20 Days for removal of deposited scales. Caustic soda, sodium bicarbonate and hydrochloric acid are used for scale removal. Normally the caustic soda washings are stored and reused for cleaning operations. However, in India, most of the sugar mills discharge these chemicals into the drains. After the equipment is boiled with caustic soda and rinsed with fresh water, it is cleaned with dilute hydrochloric acid using an inhibitor. The wastewater is discharged into the drains, as the recovery of the chemicals may not prove to be economical. It is seen that the wastewater has small organic load but inorganic content may be high to pose a shock-load to wastewater treatment facility (occasional discharge, once in fortnight). It is suggested to have a holding tank and mix this wastewater gradually to the final effluent to avoid shock loading on the treatment plant. Sulphur and Lime Houses: The washings of sulphur and lime house would contain a considerable amount of inorganic solids, which include carbonates and sulphates. The effluents from these two units when combined would give neutral pH value of waste.This wastewater does not contribute to organic pollution but can be characterized as inorganic wastewater. WASTEWATER PARAMETERS BOD: - This is the measure of the oxygen consuming capabilities of organic matter.During decomposition, organic effluents exert a BOD that can deplete oxygen supply BOD is generally measured and expressed in parts per million or milligrams per litre.The effluents from a raw sugar factory can vary between hundred to several thousands mg/l. Dissolved Oxygen: - This is water quality constituent. It is measured and expressed as parts per million or mg/l. Total Suspended Solids (TSS): - Suspended solids when they settle form sludge on the stream, lakebed and they are most damaging to the life in water.The different modes of disposal of wastes are:

56

1. Disposal into water bodies 2. Evaporation in open pits 3. Disposal into ocean 4. Press mud for fertilizer 5. Bagasse for paper and pulp and fibre (B) SOLID WASTES Bagasse: It is estimated that bagasse contributes to 33.3% residue of the total cane crushed. It has a calorific value of about 1920 kcal/kg and is mainly used as fuel in boilers for steam generation. Press Mud: It contains all non-sucrose impurities along with CaCO3 precipitate and sulphate. Press mud from double sulphitation process contains valuable nutrients like nitrogen, phosphorous, potassium, etc, and therefore used as fertilizer. The press mud from double carbonation process is used for land filling and is not used as manure . (C) AIR POLLUTANTS The bagasse, on burning, produces particulates, viz., unburnt fibres, carbon particles and gaseous pollutants like oxides of nitrogen, water vapour and other organic compounds. Of the particulate waste, the heavier particles slowly settle down in the surrounding area. Such dust fall leads to the problems of cleaning, reduction in property value, effect on vegetation, etc. The main gaseous pollutants are CO, which is altogether not measured by any unit, and CO2 is reported to be in the range of 12 – 14%.

57

WASTEWATER REDUCTION AND BY-PRODUCT RECOVERY: The following areas are important to economize the usage of water. (A) COOLING WATER 1. Mainly used for condenser, bearing cooling, sulphur/lime houses and crystallizer for formation of crystal 2. In condenser, water gets mixed with vapour. However, adjusting pH along with make-up water to keep dissolved solids in check can recycle it. 3. Evaporator cooling water contains entrained sugar and acid because of excess of SO2 and can be recycled. Improvement in the designs of evaporator/pan boiler can Reduce the loss. Losses will also be due to evaporation, splashing and percolations. 4. Keeping the temperature of incoming water between 30o and 35oC can reduce losses due to evaporation. Splashing and percolation can be checked by proper maintenance. 5. Cooling water for bearings, power generation, etc., can be reused safely. (B) PROCESS WATER Sugar mill employs both hot and cold water for its various processes such asFilter cake washing, lime preparation, dilution for lowering brix, Dilution in evaporators and pans, Massecuite, Magma making and Crystal washing in centrifugals. 1. Water requirement before evaporator storage is about 1/5 to ¼ of steam used whilethat used after evaporator requires approximately equal amounts, as for steam.Careful attention is required after evaporator stage to control water usage. 2. Hot water can be used in place of cold water to reduce the quantity of steam required. 3. It is preferable to use 18 – 20% maceration by equally adjusting it from the top andthe bottom of bagasse bed feeding to the last mill at a pressure of 7 – 14 58

kg/cm2 rather than merely pouring the same at 25 to 30% of cane (about 5 – 7% water can be saved). 4. If maceration is high enough, there will not be any need of dilution water for juice. 5. To reduce water quantity, light molasses can be used for magma making. Washing Water: Wash water may contain sugar and therefore requires treatment and should not be recycled. Periodic cleaning results in high BOD and it also contain caustic soda and weak acids. Returning it to the service water tank can reuse water. Testing Water: This water is safe for returning it to the service water tank.Oil and Grease providing suitable oil and grease traps can eliminate this. Chemical Reuse: The stored and settled supernatant can be reused with a little addition of fresh caustic soda for next cleaning operation. Molasses Handling: It is necessary to store molasses in RCC tanks or steel tanks above ground level. Otherwise, there is a possibility of ground water contamination. The high BOD of molasses may cause pollution problems due to mishandling. (C) PRODUCT RECOVERY The by-products available from sugar mills are bagasse, furnace ash, molassesand filter mud. The uses of these by products are given below. If all the by products are used for transformation into value added products, (resource recovery), it will minimize the pollution to large extent. Bagasse: These are used for steam, power, charcoal, briquettes and methane & producer gas. Molasses: These are used for fertilizer and cattle feed. Filter mud: For fertilizer. Boiler ash: For foundry material. 59

SAFETY: Sugar in boiler feed water causes water to foam, which will lead accidents. If notpresent in large quantity. It is decomposed by heat into products that are detrimental to the tubes and shells of boilers causing pitting and overheating.If sugar is present in small amounts their traces will be eventually accumulated on the boiler tubes as a harmful and dangerous carbonaceous deposit. the break down of sugar also forms harmful organic acids. To prevent this lime is added to feed water to maintain pH = 8.0. A pronounced odour develops in the steam if boiler water contains sugar. Under such conditions the contaminated feed water is turned to sewer and the boilers are blown off. To prevent these hazards tests are conducted to determine amount of sugar traces in water. The most commonly used tests are Naphthol test and Aresenomolybdate test.

60

9. COST ESTIMATION AND ECONOMICS

61

COST ESTIMATION AND ECONOMICS Given in the literature is the cost versus size Nomograph, from which the cost of cane sugar plant within the crushing capacity between 100 – 500 TPD can be calculated. The cost for 5000 TPD crushing capacity plant with Chemical Engineering Plant Cost Index (CE) =130 (Basis = 1957 -59; CE = 100) is as follows: Cost for 100 TPD crushing capacity = Rs. 2.05 x 106 To find present cost: A cost index is merely an index value for a given point in time showing the cost at that time relative to a certain base time. If the cost at some time in past is known, the equivalent cost at the present time can be determined by multiplying the original cost by the ratio of the present index value to the index value applicable when the original cost was obtained. Obtained from the Internet that Chemical Engineering Plant Cost Index is given as: Cost index in 2002 = 402 Original cost value is obtained when cost index was 130. Thus, Present cost of Plant = (original cost) x {(present cost index)/(past cost index)} = (2.05 x 106) (402/130) = Rs. 6.34 x106 Fixed Capital Investment (FCI) = Rs. 6.34 x106 Generally fixed capital investment cost is 85% of total capital investment. Therefore Total Capital Investment = (FCI)/0.85 = Rs 7.457 x 106

62

Estimation of Total Capital Investment Cost: (I) Direct Costs: (A) Material and labour involved in actual installation of complete facility (70-85% of fixed-capital investment) a) Equipment + installation + instrumentation + piping + electrical + insulation + painting (50-60% of Fixed-capital investment) a. Purchased equipment cost (PEC): RANGE = 15-40% of Fixed-capital investment Let Purchased Equipment Cost = 30% of Fixed-capital investment PEC = 30% of Rs. 6.34 x106 = Rs. 1.902 x106 b. Installation, including insulation and painting: RANGE = 25-55% of purchased equipment cost. Let Installation Cost = 35% of Purchased equipment cost = 35% of Rs. 1.902 x106 = Rs. 0.6657 x106 c. Instrumentation and controls, installed: RANGE = 6-30% of Purchased equipment cost. Let Instrumentation Cost = 10% of Purchased equipment cost = 10% of Rs. 1.902 x106 = Rs. 0.1902 x106

63

d. Piping Installed: RANGE = 10-80% of Purchased equipment cost Let Piping Cost = 40% of Purchased equipment cost = 40% of Rs. 1.902 x106 = Rs. 0.7608 x106 e. Electrical, installed: RANGE = 10-40% of Purchased equipment cost Let Electrical cost = 25% of Purchased equipment cost = 25% of Rs. 1.902 x106 = Rs. 0.4755 x106 Therefore Total cost for (A) = Rs. 4 x106 (B) Buildings, process and Auxiliary: RANGE = 10-70% of Purchased equipment cost Let Buildings, process and auxiliary cost = 30% of PEC = 30% of Rs. 1.902 x106 = Rs. 0.5706 x106 (C) Service facilities and yard improvements: RANGE = 40-100% of Purchased equipment cost Let Facilities and yard improvement cost = 50% of PEC = 50% of Rs. 1.902 x106 = Rs. 0.951 x106

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(D) Land: RANGE = 4-8% of Purchased equipment cost Let the cost of land = 6% of PEC = 6% of Rs. 1.902 x106 = Rs. 0.1141 x106 Therefore Total Direct Cost = 5.635 x106 (II) Indirect costs: Expenses, which are not directly involved with material and labour of actual installation of complete facility (15-30% of Fixed-capital investment) (A) Engineering and Supervision: RANGE = 5-30% of Direct costs Let the cost of engineering and supervision = 10% of Direct costs = 10% of Rs. 5.535 x106 = Rs. 0.5635 x106 (B) Construction Expense and Contractor’s fee: RANGE = 6-30% of Direct costs Let construction expense & contractor’s fee = 15% of Direct costs = 15% of Rs. 5.635 x106 = Rs. 0. 8452 x106 (C) Contingency: RANGE = 5-15% of Fixed-capital investment Let the contingency cost = 8% of Fixed-capital investment = 8% of 6.34 x106 = Rs. 0.5072 x106 Thus, Total Indirect Costs = Rs. 1.916 x106 65

(III) Fixed Capital Investment: Fixed capital investment = Direct costs + Indirect costs = Rs 7.5509 x106 (IV) Working Capital: RANGE = (10-20% of Total-capital investment) Let the Working Capital = 15% of Total-capital investment = 15% of 7.457 x106 = 0.15 X 7.457106 = Rs. 1.1181 x106 (V) Total Capital Investment (TCI): Total capital investment = Fixed capital investment + Working capital = 8.6694 x106 Estimation of Total Product cost: (I) Manufacturing Cost = Direct production cost + Fixed charges + Plant overhead cost. (A) Fixed Charges: (10-20% total product cost) i. Depreciation: (depends on life period, salvage value and method of calculationabout 10% of FCI for machinery and equipment and 2-3% for Building Value for Buildings) Consider depreciation = 10% of FCI for machinery and equipment and 2.5% for Building Value for Buildings) i.e. Depreciation = (0.10 x 7.5509 x 107) + (0.025 x0.025 x 107) = Rs. 0.7693 x 106

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ii. Local Taxes: (1-4% of fixed capital investment) Consider the local taxes = 2% of fixed capital investment i.e. Local Taxes = 0.02 x 7.5509 x 106 = Rs. 0.1510 x 106 iii. Insurances: (0.4-1% of fixed capital investment) Consider the Insurance = 0.6% of fixed capital investment i.e. Insurance = Rs. 0.0453 x 106 iv. Rent: (8-12% of value of rented land and buildings) Consider rent = 10% of value of rented land and buildings = Rs. 0.0.05706 x106 Thus, Total Fixed Charges = Rs. 1.0227 x106 (B) Direct Production Cost: (about 60% of total product cost) Now we have Fixed charges = 10-20% of total product charges – (given) Consider the Fixed charges = 15% of total product cost Total product cost = Total fixed charges/0.15 Total product cost = 1.02271 x 106/0.15 Total product cost (TPC) = Rs. 6.8181 x106 i. Raw Materials: (10-50% of total product cost) Consider the cost of raw materials = 25% of total product cost Raw material cost = 25% of 6.8181 x106 = Rs. 1.7045 x106 ii. Operating Labour (OL): (10-20% of total product cost) Consider the cost of operating labour = 12% of total product cost Operating labour cost = 12% of 6.8181 x106 = 0.12 x6.8181x106 = Rs. 0.8181 x106

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iii. Direct Supervisory and Clerical Labour (DS & CL): (10-25% of OL) Consider the cost for Direct supervisory and clerical labour = 12% of OL Direct supervisory and clerical labour cost = 12% of 08181 x 106 = 0.12 x 0.8181 x 106 Direct supervisory and clerical labour cost = Rs. 0.096 x106 iv. Utilities: (10-20% of total product cost) Consider the cost of Utilities = 12% of total product cost Utilities cost = = Rs. 0.8181 x106 v. Maintenance and repairs (M & R): (2-10% of fixed capital investment) Consider the maintenance and repair cost = 5% of fixed capital investment i.e. Maintenance and repair cost = 0.05 x7.5509x 106 = Rs. 0.37754 x106 vi. Operating Supplies: (10-20% of M & R or 0.5-1% of FCI) Consider the cost of Operating supplies = 15% of M & R Operating supplies cost = 15% of Rs. 0.37754 x106 = 0.15 x Rs. 0.37754 x106 = Rs. 0.05663 x106 vii. Laboratory Charges: (10-20% of OL) Consider the Laboratory charges = 14% of OL Laboratory charges = 14% of 0.8181 x 106= 0.1145 x106 viii. Patent and Royalties: (0-6% of total product cost) Consider the cost of Patent and royalties = 2% of total product cost Patent and Royalties = 2% of 6.8181 x 106 = 0.1363 x 106 Thus, Direct Production Cost = Rs. 4.1236 x106

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(C) Plant overhead Costs: (50-70% of Operating labour, supervision, and maintenance or 5-15% of total product cost); includes for the following: general plant upkeep and overhead, payroll overhead, packaging, medical services, safety and protection,restaurants, recreation, salvage, laboratories, and storage facilities. Consider the plant overhead cost = 10% of Total Product Cost Plant overhead cost = 10% of 6.8181 x106 = Rs. 0.68181 x106 Thus, Manufacturing cost = Direct production cost + Fixed charges + Plant overhead costs Manufacture cost = (4.1236 x106) + (1.022715 x106) + (0.68181 x106) Manufacture cost = Rs. 5.828125 x106 (II) General Expenses = Administrative costs + distribution and selling costs + research and development costs (A) Administrative costs:(2-6% of total product cost) Consider the Administrative costs = 5% of total product cost Administrative costs = 0.05 x 6.8181x 106 Administrative costs = Rs. 0.3409 x 106 (B) Distribution and Selling costs: (2-20% of total product cost); includes costs for sales offices, salesmen, shipping, and advertising. Consider the Distribution and selling costs = 15% of total product cost Distribution and selling costs = 15% of 6.8181 x106 = 0.15 x 6.8181 x106 = Rs. 1.02275 x106

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(C) Research and Development costs: (about 5% of total product cost) Consider the Research and development costs = 5% of total product cost Research and Development costs = 5% of 34.07 x 106 = 0.05 x6.8181 x106 = Rs. 0.3409 x106 (D) Financing (interest): (0-10% of total capital investment) Consider interest = 5% of total capital investment i.e. interest = 5% of 8.6694 x 106 = 0.05 x8.6694x 106 = Rs. 0.4334.7 x106 Thus, General Expenses = Rs. 2.1379 x 106 (III) Total Product cost = Manufacture cost + General Expenses = (5.828125 x 106) + (2.1379 x106) Therefore Total product cost = Rs. 7.96604 x106 Gross Earnings/Income: Wholesale Selling Price of cane sugar per T = Rs. 8000 /As we know sugar factory operates only 120 - 200 days in a year and the production of cane sugar per hour is 26.4818 T per hour (from material balance). The working hours per day are 20. Assuming factory operates only 150 days in a year. Total Income = Selling price per T x Quantity of product manufactured (T/year) = 8000 x (11.395) T/day x 150 days/year Total Income = Rs. 13.614 x106

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Gross income = Total Income – Total Product Cost = (Rs. 13.614 x106) – (Rs. 7.96604 x106) Gross Income = Rs. 5.64796 x106 Let the Tax rate be 40%. Taxes = 40% of Gross income = 40% of Rs. 5.64796 x106 = 0.40 x Rs. 5.64796 x106 Taxes = Rs. 2.25184 x106 Net Profit = Gross income - Taxes = Gross income x (1- Tax rate) Net profit = (Rs. 5.64796 x106 ) x ( Rs. 2.25184 x106 ) = Rs. 3.3887 x106 Rate of Return: Rate of return = (Net profit x100)/ Total Capital Investment Rate of Return = (Rs. 3.3887 x106 x100)/ (8.6694 x106 ) Rate of Return = 39.088% Payout period = (FCI)/(Net profit + Depreciation) = (7.5509 x106)/( 3.3887 x106 +0.7693 x106) = 2 years

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10. PLANT LOCATION AND SITE SELECTION

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PLANT LOCATION AND SITE SELECTON The geographical location of the final plant can have strong influence on the success of the industrial venture. Considerable care must be exercised in selecting the plant site, and many different factors must be considered. Primarily the plant must be located where the minimum cost of production and distribution can be obtained but other factors such as room for expansion and safe living conditions for plant operation as well as the surrounding community are also important. The location of the plant can also have a crucial effect on the profitability of a project. The choice of the final site should first be based on a complete survey of the advantages and disadvantages of various geographical areas and ultimately, on the advantages and disadvantages of the available real estate. The various principal factors that must be considered while selecting a suitable plant site are briefly discussed in this section. The factors to be considered are: 1. Raw material availability 2. Location (with respect to the marketing area) 3. Availability of suitable land 4. Transport facilities 5. Availability of labors 6. Availability of utilities (Water, Electricity) 7. Environmental impact and effluent disposal 8. Local community considerations 9. Climate 10. Political strategic considerations 11. Taxations and legal restrictions Raw Materials Availability: The source of raw materials is one of the most important factors influencing the selection of a plant site. This is particularly true for the cane sugar plant because a large volume of sugar cane is consumed in the process, which will result in the reduction of the transportation and storage charges. Attention should be given to the 73

purchased price of the raw materials, distance from the source of supply, freight and transportation expenses, availability and reliability of supply, purity of raw materials and storage requirements. Location: The location of markets or intermediate distribution centers affects the cost ofproduct distribution and time required for shipping. Proximity to the major markets is an important consideration in the selection of the plant site, because the buyer usually finds advantageous to purchase from near-by sources. Availability Of Suitable Land: The characteristics of the land at the proposed plant site should be examined carefully. The topography of the tract of land structure must be considered, since either or both may have a pronounced effect on the construction costs. The cost of the land is important, as well as local building costs and living conditions. Future changes may make it desirable or necessary to expand the plant facilities. The land should be ideally flat, well drained and have load-bearing characteristics. A full site evaluation should be made to determine the need for piling or other special foundations Transport: The transport of materials and products to and from plant will be an overriding consideration in site selection. If practicable, a site should be selected so that it is close to at least two major forms of transport: road, rail, waterway or a seaport. Road transport is being increasingly used, and is suitable for local distribution from a central warehouse.Rail transport will be cheaper for the long-distance transport. If possible the plant site should have access to all three types of transportation. There is usually need for convenient rail and air transportation facilities between the plant and the main company head quarters, and the effective transportation facilities for the plant personnel are necessary. Availability Of Labors: Labors will be needed for construction of the plant and its operation. Skilled construction workers will usually be brought in from outside the site, but there should

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be an adequate pool of unskilled labors available locally; and labors suitable for training to operate the plant. Skilled tradesmen will be needed for plant maintenance. Local trade union customs and restrictive practices will have to be considered when assessing the availability and suitability of the labors for recruitment and training. Availability Of Utilities: The word “utilities” is generally used for the ancillary services needed in theoperation of any production process. These services will normally be supplied from acentral facility and includes Water, Fuel and Electricity which are briefly described as follows: Water: - The water is required for large industrial as well as general purposes, starting with water for cooling, washing and steam generation. The plant therefore must be located where a dependable water supply is available namely lakes, rivers, wells, seas.If the water supply shows seasonal fluctuations, it’s desirable to construct a reservoir or to drill several standby wells. The temperature, mineral content, slit and sand content, bacteriological content, and cost for supply and purification treatment must also be considered when choosing a water supply. De-mineralized water, from which all the minerals have been removed, is used where pure water is needed for the process use, in boiler feed. Natural and forced draft cooling towers are generally used to provide the cooling water required on site. Electricity: - Power and steam requirements are high in most industrial plants and fuel is ordinarily required to supply these utilities. Power, fuel and steam are required forrunning the various equipments like generators, motors, turbines, plant lightings and general use and thus be considered, as one major factor is choice of plant site. Environmental Impact And Effluent Disposal: Facilities must be provided for the effective disposal of the effluent without any public nuisance. In choosing a plant site, the permissible tolerance levels for various effluents should be considered and attention should be given to potential requirements for additional waste treatment facilities. As all industrial processes produce waste products, full consideration must be given to the difficulties and coat

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of their disposal. The disposal of toxic and harmful effluents will be covered by local regulations, and the appropriate authorities must be consulted during the initial site survey to determine the standards that must be met. Local Community Considerations: The proposed plant must fit in with and be acceptable to the local community. Full consideration must be given to the safe location of the plant so that it does not impose a significant additional risk to the community. Climate: Adverse climatic conditions at site will increase costs. Extremes of low temperatures will require the provision of additional insulation and special heating for equipment and piping. Similarly, excessive humidity and hot temperatures pose serious problems and must be considered for selecting a site for the plant. Stronger structures will be needed at locations subject to high wind loads or earthquakes. Political And Strategic Considerations: Capital grants, tax concessions, and other inducements are often given by governments to direct new investment to preferred locations; such as areas of high unemployment. The availability of such grants can be the overriding consideration in site selection. Taxation And Legal Restrictions: State and local tax rates on property income, unemployment insurance, and similar items vary from one location to another. Similarly, local regulations on zoning, building codes, nuisance aspects and others facilities can have a major influence on the final choice of the plant site. PLANT LAYOUT After the flow process diagrams are completed and before detailed piping,structural and electrical design can begin, the layout of process units in a plant and the equipment within these process unit must be planned. This layout can play an

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important part in determining construction and manufacturing costs, and thus must be planned carefully with attention being given to future problems that may arise. Thus the economic construction and efficient operation of a process unit will depend on how well the plant and equipment specified on the process flow sheet is laid out. The principal factors that are considered are listed below: 1. Economic considerations: construction and operating costs 2. Process requirements 3. Convenience of operation 4. Convenience of maintenance 5. Health and Safety considerations 6. Future plant expansion 7. Modular construction 8. Waste disposal requirements Costs: Adopting a layout that gives the shortest run of connecting pipe between equipment, and least amount of structural steel work can minimize the coat of construction. However, this will not necessarily be the best arrangement for operation and maintenance. Process Requirements: An example of the need to take into account process consideration is the need to elevate the base of columns to provide the necessary net positive suction head to a pump. Convenience Of Operation: Equipment that needs to have frequent attention should be located convenient to the control room. Valves, sample points, and instruments should be located at convenient positions and heights. Sufficient working space and headroom must be provided to allow easy access to equipment.

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Convenience Of Maintenance: Heat exchangers need to be sited so that the tube bundles can be easily with drawn for cleaning and tube replacement. Vessels that require frequent replacement of catalyst or packing should be located on the out side of buildings. Equipment that requires dismantling for maintenance, such as compressors and large pumps, should be places under cover. Health And Safety Considerations: Blast walls may be needed to isolate potentially hazardous equipment, and confine the effects of an explosion. At least two escape routes for operators must be provided from each level in process buildings. Future Plant Expansion: Equipment should be located so that it can be conveniently tied in with any future expansion of the process. Space should be left on pipe alleys for future needs, and service pipes over-sized to allow for future requirements. Modular Construction: In recent years there has been a move to assemble sections of plant at the plant manufacturer’s site. These modules will include the equipment, structural steel, piping and instrumentation. The modules are then transported to the plant site, by road or sea. The advantages of modular construction are: 1. Improved quality control 2. Reduced construction cost 3. Less need for skilled labors on site The disadvantages of modular construction are: 1. Higher design costs & more structural steel work 2. More flanged constructions & possible problems with assembly, on site 78

BIBLIOGRAPHY

1. M.GOPALA RAO, MARSHALL SITTIG, OUTLINES OF CHEMICAL TECHNOLOGY, 3RD EDITION, Pg No 314 – 319 2. Dr. G.K. ROY, SOLVED EXAMPLES IN CHEMICAL ENGINEERING, KHANNA PUBLISHERS, Pg No 285 – 297 3. KIRK & OTHMER, ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY, Vol 19, Pg No 151-233 4. ULLMAN, ENCYCLOPEDIA OF INDUSTRIAL CHEMISTRY, Vol .A 25, Pg No 393-407 5. HUGOTE, HANDBOOK OF CANE SUGAR ENGINEERING 6. SUDHAKAR VASUDEO KARMARKAR, INTRODUCTION TO CANE SUGAR TECHNOLOGY 7. R.H. PERRY AND DON W. GREEN, PERRY’S CHEMICAL ENGINEER’S HAND BOOK, Mc GRAW HILL INTERNATIONAL EDITION, VOLUME –6 8. R. K. SINNOTT, BUTTER WORTH-HEINEMANN, COULSON AND RICHARDSON’S CHEMICAL ENGINEERING SERIES, 3RD EDITION, VOLUME – 6 9. JOSHI M .V, PROCESS EQUIPMENT DESIGN, MC-MILLAN INDIA LTD, 2ND EDITION

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Manufacture of Sugar

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