Date & Time Started: Sept. 13, 2016 (9:30 AM)
Date & Time Finished: Sept. 15, 2016 (2:30AM)
Group No. 7
Instructor/Supervisor: Engr. Juvyneil Cartel
EXPERIMENT NO. 1 GAS ABSORPTION I.
Introduction Absorption is the unit operation in which one or more components of a gas stream are
removed from the gas mixture by being absorbed onto a non-volatile liquid (called a “solvent”). Absorption is the one of the most commonly used separation techniques for the removal of impurities such as the various gases like H 2S, CO2, SO2 , ammonia and the recovery of valuable chemicals. Cleaning of solute gases is achieved by transferring into a liquid solvent by contacting the gas stream with liquids that offers specific or selectivity for the gases to be recovered. Mechanism of Absorption The most useful concept of the process of absorption is given by the two film theory due to Whitman. According to this theory, material is transferred in the bulk of the phases by convection currents, and concentration differences are regarded as negligible except in the vicinity of the interface between phases. On either side of this interface it is supposed that the currents die out and that there exists a thin film of fluid through which the transfer is effected solely by molecular diffusion. In absorption process material has to diffuse from one phase (gas) to another (liquid). The rate of diffusion in both phases impacts the overall rate of mass transfer
1
II.
Objectives: 1. To measure the absorption of carbon dioxide into water flowing down the tower, using the gas analysis equipment provided. 2. To calculate the rate of absorption of carbon dioxide into water from analysis of liquid solutions flowing down absorption column.
III.
Methodology 3.1 MATERIALS:
Phenolphthalein indicator – used as an indicator in acid–base titrations 0.027M Sodium hydroxide solution – solution needed for the experiment 0.1M Sodium bicarbonate solution – solutions needed for the experiment 300 ml of 1.0 M caustic soda – solutions needed for the experiment Fresh tap water – used as solvent for the solutions 3.2 EQUIPMENT:
Gas Absorption Column – used to efficiently contact the vapor and liquid in absorption
Integral Pressure Regulator (IPR) – regulates gas pressure
3.3 APPARATUS:
Hempel Apparatus – used in gas analysis
Thermometer – used for measuring temperature
Barometer – used for measuring pressure
CO2 Cylinder with IPR – supply vessel of carbon dioxide to the experiment
Safety Gloves – protects the hand from any chemical spillage
Goggles – protects eyes from any chemical splashes
Funnel – used for transferring fluids
Beaker – containment of fluids 2
1.4 Procedure (A) Absorption of carbon dioxide into water flowing down the tower, using the gas analysis equipment provided First the two gloves of the absorption analysis equipment on the left of the panel was filled with 0.1 M caustic soda. Wearing gloves and goggles during the conduct of experiment. Adjusting the level in the gloves to the ‘0’ mark on the sight tube, using drain valve C into a flask to do this. (See step A in the sketch overleaf). Fill the liquid reservoir tank to three-quarters full with fresh tap water. With gas flow control valves C2 and C3 closed, start the liquid pump and adjust the water flow through the column to approximately 6 litre per minute on flow meter F1 by adjusting flow control valve C1. Start the compressor and adjust control valve C2 to give airflow of approximately 10% of full scale on flow meter F 2.Carefully open the pressure-regulating valve on the carbon dioxide cylinder, and adjust valve to give a value C 3 on the flow meter F3 approximately one half of the airflow F2. Ensure the liquid seal at the base of the absorption column is maintained by, if necessary, adjustment of control valve C4. After 15 minutes or so of steady operation, take samples of gas simultaneously from sample points S1 and S2. Analyze this consecutively for carbon dioxide content in these gas samples as shown in the accompanying sketch and following notes. Flush the sample lines by repeated sucking from the line, using the gas piston and expelling the contents of the cylinder to the atmosphere. Note that the volume of the cylinder is about 100 ml. Estimate the volume of the tube leading to the device. Then decide how many times you need to suck and expel. With the absorption glove isolated and vent to the atmosphere closed, fill the cylinder from the selected line by drawing the piston out slowly (Step B). Note volume taken into cylinder V1, which should be approximately 20 ml for this particular experiment (See Warning note below).Wait at least two minutes to allow the gas to come to the temperature of the cylinder.
3
Isolate the cylinder from the column and the absorption glove and vent the cylinder to atmospheric pressure. Close after 10 seconds (Step D). Connect cylinder to absorption glove. The liquid level should not change. If it does not change, briefly open to atmosphere again. Wait until the level in the indicator tube is on zero showing that the pressure in the cylinder is atmospheric. Slowly close the piston to empty the cylinder into the absorption glove. Slowly draw the piston out again (Steps E and F). Note the level in the indicator tube. Repeat steps E and F until no significant change in level occurs. Read the indicator tube marking = V. the represents the volume of the gas sampled. Then repeat the experiments for trials 2 and 3. IV.
Results and Discussion Table 1.1 CO2 into H2O using Hempl Gas Analysis PARAMETERS Air Flow Rate (L/min) Water Flow Rate (L/min) CO2 Flow Rate (L/min) Initial NaOH Reading (mL) Final NaOH Reading (mL) Volume of Sample (mL)
Values of
Vf
A 40 4 16 0.35 3.6 30
B 60 2 16.5 0.35 1.25 30
measured:
1.65 mL, 2.1 mL, 2.5 mL, 3.0 mL, 3.3 mL, 3.6 mL, 3.2 mL
The requirement of good contact between liquid and gas is the hardest to meet, especially in large towers. Ideally the liquid, once distributed over the top of the packing, flows in thin films over all the packing surface all the way down the tower. Especially at low liquid rates much of the packing surface maybe dry, or at best, covered by a stagnant film of liquid. This effect is known as channelling; it is the chief reason for the poor performance of large packed towers. With the liquid flow rate increasing, more liquid would be spread on the packing surface, and this leads to an increase in the interfacial area per unit volume. Besides, the higher liquid flow rate leads to a higher liquid-side mass transfer coefficient in the case of liquid phase controlled mass transfer.
4
Gas flow rate has an effect on the absorption performance in the packed column. Increase in the gas flow rate leads to a higher KGav value especially when the carbon dioxide concentration is high. When the carbon dioxide concentration is low, the enhancement factor would be small, which leads to higher value of the resistance in the liquid phase ( ).
V.
Conclusion Based on the experiment, this phenomenon indicates that the overall CO2 absorption rate is not only dependent upon the gas flow rate, it is also dependent upon the availability of the reactive in the liquid. Thus, the resistance in the gas phase can be negligible. So, the overall mass transfer coefficient is not dependent upon the gas flow rate when the CO2 concentration is low. Whereas, the resistance in the liquid phase ( ) decreased with increasing concentration of CO2, the impact of the resistance in the gas phase becomes increasingly significant.
VI.
References http://pubs.acs.org/doi/abs/10.1021/ie50270a011 - Rate of Absorption of
Carbon Dioxide in Water and in Alkaline Media http://www.ijsrp.org/research-paper-0414/ijsrp-p2885.pdf GEANKOPLIS, C. J. Principles of Transport Processes and Separation Processes. 3rd Edition. Prentice Hall, New Jersey (2003).
VII.
Appendix
Experimental Data (A) Absorption of carbon dioxide into water flowing down the tower, using the gas
analysis equipment provided Operating Temp = 298 K Air Flow rate (entering) = 40 L/min CO2 Flow rate (entering) = 16 L/min H2O Flow rate (entering) = 4 L/min Sample CO2 reading = 3.6 ml Volume of sample = 30 ml
Information Flow Diagram
5
V f ∧V i (@hemptel apparatus)
|¿|=V
−V i ∆V¿
V sample ∆
f
V |¿|
V sample y C 02=¿ y C 02
V i=0.35 mL
SAMPLE CALCULATION:
V sample
= 30 mL Lo +V 2=L1 +V 1=M
Lo x Ao +V 2 y A 2=L1 x A 1+V 1 y A 1=M x AM
V
y A1
L
V ' =V (1− y A 1)
L' =L(1−x A 1 )
V ' =V
L
'
(
x A1
L' =V
x Ao y A2 x A1 y A1 ' ' ' +V =L +V ( ) 1−x Ao 1− y A 2 1−x A 1 1− y A 1
) (
) (
)
NOMENCLATURE: 6
x Ao mole fraction of liquid entering the column y A1 mole fraction of CO2 entering the column
L'
'
V
flowrate of liquid in the Flow rate of gas
CALCULATIONS: V |¿| 1.65 ml−0.35 ml y A 1 = ∆ V sample = ( ¿ = 0.0433 30 ml ¿
V |¿| y A 1 = ∆ V sample = ( ¿
3.3 ml−0.35 ml ¿ = 0.0983 30 ml y A1 =
∆
V |¿| V sample ¿
2.1 ml−0.35 ml ¿ = 0.0583 =( 30 ml
y A1 =
∆
V |¿| V sample = ( ¿
3.6 ml−0.35ml ¿ = 0.1 30 ml V |¿| 2.5 ml−0.35 ml y A 1 = ∆ V sample = ( ¿ = 0.0716 30 ml ¿
V |¿| y A 1 = ∆ V sample = ( ¿
3.2 ml−0.35 ml ¿ =0.095 30 ml V |¿| 3.0 ml−0.35 ml y A 1 = ∆ V sample = ( ¿ = 0.08833 30 ml ¿
L'
(
x Ao y A2 x A1 y +V ' =L' +V ' ( A 1 ) 1−x Ao 1− y A 2 1−x A 1 1− y A 1
) (
) (
)
Since Xao is equal to 0, '
L =L(1−x A 1 ) = 4L/min (1-0) =
4L/min
14.48L/min
V ' =V (1− y A 1) = 16L/min (1-0.095) = 7
L
'
x A1
0 0.1 0.095 ) ( 1−0 )+V ( 1−0.1 )=L ( 1− x )+ V ( 1−0.095 '
'
'
A1
x A 1 =.2
DOCUMENTATION
Taking of Sample of CO2
8
Closer View of the Equipment Measurement of the pressure drop
Date & Time Started: September 13, 2016 Group No. 7
Date & Time Finished: September 13, 2016 Instructor/Supervisor: Engr. Juvyneil E. Cartel
EXPERIMENT NO.2
BATCH DISTILLATION USING BENCH TYPE DISTILING COLUMN
I.
INTRODUCTION Distillation involves the separation of two or more volatile components from a
liquid solution by the application of heat. Due to the differences in the volatilities of the various components, the vapor generated contains improved concentrations of the more volatile components. This vapor is subsequently processed or condensed to generate an enriched concentration different from the original liquid solution. The chemical engineer 9
is involved in the design of various distillation equipment used for batch distillation, flash distillation, fractional distillation, steam distillation, etc. The methods used in distillation practice rely on the basic fact that the vapor is always richer in the more volatile component than the liquid from which it is formed. Among these techniques, the most important is rectification, sometimes referred to as fractional distillation or distillation with reflux. It entails the returning of a portion of the condensate to the still. Flash distillation or simple continuous distillation involves keeping all the vapor and liquid in intimate contact so that the separated vapor is in equilibrium with the residual liquid. In differential distillation or simple batch distillation, a liquid is vaporized, and the vapor is removed from contact with the liquid immediately as it is formed.
II.
OBJECTIVES
To be able to determine the average concentration of a specified volume of the distillate that is obtained from a feed mixture of known composition by operating
the distillation unit at constant reflux. To be able to predict the time required to obtain a particular concentration of the distillate using experimental data.
III.
METHODOLOGY III.1
Materials
Timer/ Stopwatch
III.2
Utilized for measuring the amount of time taken for a particular task to completion
Equipment/Apparatus 10
Thermometer
Used for measuring temperature
Refractometer
Utilized for measuring refractive indices
Beaker
Used for containment of liquids
Graduated cylinder
Used for measuring liquid volumes
Pipette
Used for measuring liquid; moving small amounts of liquid from one place to another
Aspirator
An apparatus for producing suction or collecting materials by suction
Distilling Column
A bench apparatus used in the distillation operations.
III.3
Procedure
Initially, mix specific amounts of ethanol (analytical grade) with distilled water to make solutions which correspond to 20, 40, 60, and 80 percent by weight ethanol. By using a refractometer, measure the refractive index of each solution. Determine the refractive indices of pure distilled water and pure ethanol. These correspond to 0 and 100 percent by weight ethanol, respectively. Check the measured data with those given in a handbook. Make a graph of percent by weight ethanol (y-axis) vs. refractive index (x-axis) at ambient temperature. These are in preparation of standard calibration curves. To prepare the feed, make a solution of ethanol-water containing 80 ml of technical grade ethanol and 250 ml distilled water. Stir it well and take an aliquot to determine its refractive index. Then feed it to the boiler of the distilling column. Heat the solution until it boils. When the first droplet formed at the end of the condenser, start the timer. Record the time when the graduated cylinder gets full. 11
Be sure to record the temperature at the top, middle, and still. Also take samples of the bottoms as well as the middle. Do the same until all the graduated cylinders are filled. Take not of the time each graduated cylinder is filled up to the mark.
IV.
RESULTS AND DISCUSSION Presented here is the tabulation of raw data and graphs of raw data. Graphs that shows important relationships and trends are given as follows. Table 1. Ethanol-Water Solution Calibration Data Ethanol Concentration (% vol)
Refractive Index
0 10 20 30 40 50
1.33025 1.33727 1.3401 1.3406 1.3502 1.3505
Ethanol-Water Solution Calibration Curve 1.36 1.35
Refractive Index
f(x) = 0x + 1.33 R² = 0.93
1.34 1.33 1.32
0
10
20
30
40
50
60
Ethanol Concentration
12
Figure 1. Ethanol-Water Solution Calibration Curve Table 2. Experimental Data of the Distillate Sampl e 1 2 3 4 5 6 7 8 9 10
Volume
Temperature (oC)
(mL) 10 20 30 40 50 60 70 80 90 100
Distillate (D) 74 79 83 86 89 91 94 96 96 96
Refractive Index 1.361 1.3625 1.362 1.3615 1.36 1.359 1.355 1.351 1.345 1.33
Time (Min) 1.52 3.35 5.17 7.25 9.63 12.02 14.98 18.3 21.77 25.73
Plot of t vs RI of Distillate 1.37 1.36
f(x) = - 0x^2 + 0x + 1.36 R² = 0.96
1.35
Refractive Index
1.34 1.33 1.32 1.31 0
2
4
6
8
10
12
time (min)
Figure 2. Plot of t vs RI of Distillate Table 3. Experimental Data of the Bottoms Sampl
Temperature
Refractive Index 13
e 1 2 3 4 5 6 7 8 9 10
(oC) Bottoms (W) 89 90 91 92 93.5 95 96 97 97 97
1.3385 1.339 1.338 1.3365 1.3355 1.3345 1.3345 1.3333 1.3325 1.3325
Figure 3. Plot of t vs RI of Bottoms
Plot of t vs RI of Bottoms 1.34 1.34 1.34 1.34 1.34 1.34 Refractive Index 1.33 1.33 1.33 1.33 1.33 1.33
f(x) = 0x^2 - 0x + 1.34 R² = 0.96
0
2
4
6
8
10
12
time (min)
Table 4. Experimental Data of the Reflux sample
Temperature (oC)
Refractive 14
1 2 3 4 5 6 7 8 9 10 V.
Reflux 75 78 82 85 85 90 92 96 96 96
Index 1.334 1.3405 1.3405 1.351 1.35 1.346 1.3478 1.3385 1.338 1.339
CONCLUSION
When the experiment was performed, there was no problems encountered. The data gathered was Refractive index, time, volume, and temperature of the Distillate, Bottoms, and Reflux. To derive a conclusion from the plot of the time versus Refractive Indexes of Distillate, the Refractive Indexes lowers as the time of distillation increases. It has a polynomial curve and having an order of 2. Likewise, from the plot of the time versus Refractive Indexes of the Bottoms, the Refractive indexes of the Bottoms also decreases as time of distillation increases. It also has a polynomial curve having an order of 2. However, the data gathered was insufficient to calculate the average concentration of a specified volume of the distillate that is obtained from a feed mixture of known composition which was stated in the objectives of this experiment. Moreover, the experimental data was also not applicable to the calculation of the time required to obtain a particular concentration of the distillate.
VI.
REFERENCES GEANKOPLIS, C. J. Principles of Transport Processes and Separation Processes. 3rd Edition. Prentice Hall, New Jersey (2003). OLANO, S. et.al Reviewer for Chemical Engineering Licensure Examination. 3rd Edition. Manila Revie Institute, Inc. (2015) DOCUMENTATION
15
Date & Time Started: September 14, 2016
Date & Time Finished: September 14, 2016 16
Group No. 7
Instructor/Supervisor: Engr. Juvyneil E. Cartel
EXPERIMENT NO. 3 SPRAY DRYING EXPERIMENT I.
INTRODUCTION
In a spray dryer, a liquid or slurry solution is sprayed into a hot gas stream in the form of a mist of fine droplets. The water is rapidly vaporized from the droplets, leaving particles of dry solid which are separated from the gas stream. The flow of gas and liquid in the spray chamber may be countercurrent, concurrent, or a combination of both. The fine droplets are formed from the liquid feed by spray nozzles or high speed rotating spray disks inside a cylindrical chamber. It is necessary to ensure that the droplets of wet particles of solid do not strike and stick to solid surfaces before drying has taken place; hence, large chambers are used. The dried solids leave at the bottom of the chamber through a screw conveyor. The particles produced are usually light and quite porous. In this very experiment, students will be drying a concentrated solution of detergent solution with the aid of an atomizer disk spray dryer.
II. Objectives 1. To be able to perform and understand spray drying equipment and related principles. 2. Produce a relationship between pressure and time, and temperature of air inside the spray dryer and time. Likewise determine the relative humidity of air present prior and after the experiment proper. III.
Methodology
3.1 Equipment:
Atomizer Disk Spray Dryer
3.2 Materials:
500 mL Beaker Graduated Cylinder Stopwatch Detergent Powder Water
3.3 Procedure
17
1. Prepare a detergent solution. Preferably, the detergent powder should be high in amount or concentration. 2. Prepare the dish atomizer spray dryer by turning it on, and opening the steam valve. 3. Measure the volume of the solution. 4. After pouring it in a separatory funnel, place it in an elevated position. From H2O point, determine its experimental flowrate. 5. Place this separatory funnel in the filling place on top of the spray dryer. Turn on necessary adjustment, let the solution be fed into dryer by rotating its valve slowly. The flowrate, preferably should be in droplets. 6. Through a glass window installed on one side of the edge. Observe the happenings inside. 7. Record the time needed, pressure, temperature (heater and inside air), wet and dry bulb temperature. 8. After spray dryer, taker out the jar of the powderized material or simply the product itself. 9. Using the analytical balance, weight the jar with the product. Then take off and clean the jar and weight again. The difference of the initial and final mass shall be considered as the amount of produced dry material. 10. After using the spray dryer, open its cover using hydraulic press. Clean off any remaining content inside the dryer.
IV.
RESULTS AND DISCUSSION
Spray Dying 450 400 350
Pressure vs Time Temp. of Heater vs Time Temp. of Inside Air vs Time
300 250 200 150 100 50 0
0
2
4
6
8 10 12
18
Figure 1. Spray Drying Plot
V.
Conclusion It can be concluded that the experiment went well despite a few setbacks. It can be
proposed that the spray drying experiment could have been improved if only the pressure being set up inside the equipment is high. Likewise, it can be concluded that for a better amount of dry powder to materialize or produce, a drop by drop flowrate should have been done instead and that the detergent solution should be high in concentration.
VI. References GEANKOPLIS, C. J. Principles of Transport Processes and Separation Processes. 3rd
Edition. Prentice Hall, New Jersey (2003). MCCABE & SMITH. Unit Operations of Chemical Engineering. 5th Edition. McGraw Hill International Series (1993
VII.
APPENDIX
Information Flow Diagram
V V o=
V t t
V P
T Heater
19
Plot P vs .t ;
Plot T Heater vs .t ;∧¿
Plot T Inside Air vs . t t
Nomenclature: T Inside Air V0 = Volumetric flow rate in mL/min; t = Time in min; and V = Volume in Ml P = Pressure T Inside Air = Temperature of Inside Air in oC
T Heater
= Temperature of Heater in oC
A. Raw Data Table 1. Experimental Volumetric Flow rate of Detergent Solution for Spray Drying Volume
Time
Volumetric Flowrate
(mL)
(min)
(mL/min)
1
100
47.5
2.105263158
2
100
53.42
1.871958068
3
100
53.65
1.863932898
Trial
Ave.
1.947051375
Sample Computation for Volumetric Flowrate: V0 = V/t = (100 mL)/ (47.5 min) = 2.105263158 mL/min Table 2. Inlet and Outlet Conditions of Spray Dryer Inlet Conditions
Oulet Conditions
Air Temp Outside (oC)
30.1
Air Temp Outside (oC)
Temp of Sol'n (oC)
29.7
Temp of Sol'n (oC)
Wet Bulb (oC)
25
Wet Bulb (oC)
34.2 26
20
Dry Bulb (oC)
Dry Bulb (oC)
32
Concentration (g/mL)
0.16
33
Concentration (g/mL)
-
Table 3. Inside Conditions of the Spray Dryer Temp. of Heater
Temp. of Inside Air
Time
Pressure
(min)
(kPa)
0
0
0
0
1
137
360
90
2
196
380
100
3
157
370
110
4
108
370
110
5
98
360
125
6
88
350
130
7
0
380
140
8
0
390
148
9
0
390
149
10
0
380
142
o
C
o
C
Table 3. Data of Powderized Detergent Solution. Product Obtained (g) Mass of Product + Jar
314.3
Mass of Jar
312.73
Mass of Product
1.57
21
DOCUMENTATION Spray Dryer Equipment
The Atomizer Disk Spray Dryer Setup.
22
Observation on the Equipment before experiment proper
Date & Time Started: Sept. 14, 2016 (9:30 AM)
Group No. 7
Date & Time Finished: Sept. 14, 2016 (1:30 PM)
Instructor/Supervisor: Engr. Juvyneil E. Cartel
EXPERIMENT NO. 4 COOLING TOWER
I.
INTRODUCTION
Forced draft wet cooling tower is a device designed to disperse heat flux in the ambient air, collected by cooling water in the cooled devices. In the cooling tower, the chilled water comes into direct contact with ambient air. Hot water flows into the main collector of water separator. Next, it is distributed through a piping system to sprinkling nozzles. The nozzles dissipate the water jet on drip blocks of the wet deck, forming a water film with a large surface area of contact. Water falling from the lower edges of the drip elements of the wet deck falls as rain to the bottom collection basin from where it is pumped back to the cooled equipment. The cooling of water is mainly due to the evaporation of a small portion of the cooled stream of water (mass transfer) into the flowing air stream, using the latent heat (heat of evaporation) collected from the water stream, and - to a lesser extent - due to convective heat transfer from the water to air (heat transport). Counter-current flow of cold air is caused by the suction action of the axial fan with a capacity adapted to the required cooling parameters. The fan is mounted outside the housing, on the ceiling of the cooling tower. The air is sucked into the cooling tower through the inlet ports equipped with air intake shutters which protect against sucking in solid elements from the environment such as leaves, and against the chilled water splashing outside the cooling tower. Next, the sucked-in air flows through the rain zone under the wet deck, through the wet deck filling, the water splash zone above the wet deck; then it the of the housing of the fan. The degree of chilled water in the wet cooling tower depends on the wet bulb temperature of the air intake from the environment, the amount of air (fan capacity) and the technical solution of the cooling tower itself. Cooling towers are designed to achieve the desired effect of cooling under the most unfavorable conditions (high temperature and humidity, with the need to take away the highest quantity of heat from the water). The fan power is also adjusted for such conditions. When the ambient temperature decreases or less heat is to be dissipated, the installed power is unnecessary. To reduce operating costs and improve operating safety, two-speed 23
(optional) motors can be used to power the fan. In such cases, the speed of fans and the resulting power consumption are determined depending on the temperature of chilled water. In order to ensure a reliable and safe operation of the cooling system, the maintenance of the relevant characteristics of the cooling water should be preserved, as continuous evaporation increases the concentration of chemical contaminants in the mechanical cooling circuit. Suitable desalination, desilting and refilling the cooling system are the main parameters affecting the life of the cooling tower components and other equipment associated with the cooling circuit.
II.
III.
OBJECTIVES
To become familiar with the operation of a cooling tower equipment. To measure wet and dry bulb temperature, apply psychrometric principles to
determine relative humidity, and measure humidity. To determine the cooling effect of the cooling tower through observations and
reading or collecting of data as the water particles are exposed to air. To provide available relationships of several parameters present.
METHODOLOGY III.1 Materials 2 pcs 2- sling psychrometer Meterstick Digital thermometer Stopwatch III.2 Equipment/Apparatus 1. Cooling Tower 2. Heat Exchanger 3.3. Procedure Start by operating the steam valve. Prior to operation, measure the dimensions of the tank and take note of the specifications of the equipment. Fill up the tank with hot water generated by the heat transfer of the tap water and steam in the heat exchanger. Record the temperature of the steam and turn off or close the steam valve. After which, record the height of the liquid inside the tank using a meterstick. At the cooling tower, close the valve for hot water and open the valve for pumping. After opening the valve, turn on the pump and then the blower. Prior to observations, record the dry and wet bulb temperature of the inlet and outlet air flow 24
using the psychrometer. After the pre-determined time interval, measure again the dry and wet bulb, the temperature of the beaker and the temperature of the outflow. During the experiment, it is a must to observer as to comprehend pertinent principles of cooling tower. After observing the cooling effect, turn off the pump button as well as the blower and heater counterparts. Close, likewise, the valve adjacent to pump. IV.
RESULTS AND DISCUSSION When warm liquid is brought into contact with unsaturated gas, part of the liquid evaporates and the liquid temperature drops. Cooling tower lowers the temperature of recirculated water. The reduction in water temperature in cooling tower comes mainly from evaporation, although when air temperature is low there is also some sensible heat transfer to the air. However, even when the air is warmer than the water, water can be cooled by evaporation if the wet bulb temperature is below that of the water. From tabulated data, the air that passes through the tower increases its temperature as it contacts warm water but decreases when the descending water gets colder.
Time (min) Nominal Velocity of Air (m/s) Wet Bulb Approach,
0
5
10
15
20
25
30
35
0.03196 √ ∆ P0.0321 √ ∆ P0.03196 √ ∆ P0.032 √ ∆ P0.032 √ ∆ P0.032 √ ∆ P0.032 √ ∆ P0.032 √ ∆ p -
17.4
13.3
7.8
5.8
2.5
-1.6
-2.1
0.028
0.0325
0.028
0.027
0.0275
0.027
0.026
0.026
℃ H (humidity) kg/kg dry air
V.
CONCLUSION Based on the data derived from the experiment, the temperature of the water gradually decreases as it had undergone the cooling tower. The cooling effect of the cooling tower had been proven as supported by data and observations. The relationship that can be derived here was that as water was being repeatedly processed inside the equipment with known interval of times, the temperature of the
VI.
water decreases. REFERENCES
25
GEANKOPLIS, C. J. Principles of Transport Processes and Separation Processes. 3rd
Edition. Prentice Hall, New Jersey (2003). MCCABE & SMITH. Unit Operations of Chemical Engineering. 5th Edition. McGraw Hill International Series (1993).
VII.
APPENDICES
A. Raw Data Table 4.2. Experimental Data for Liquid under Test Trial 1 2 3 4 5 6 7 8 9 10 11 12
Time (min) 0 5 10 15 20 25 30 35 40 45 50 55
Temp. of Liquid (oC) In Out 64 42.2 58 38 55 36.6 47 35.1 41 34 37 32.8 34 31.2 31 31.1 29 30.2 28 30 27 29.8 26 28.6
Density of Liquid (kg/L) In Out 981.068 990.661 984.73 992.237 985.856 992.763 988.859 993.326 991.111 993.738 992.612 994.189 992.738 994.79 994.865 994.827 991.862 995.165 995.99 995.24 996.366 995.315 996.741 995.39
Table 4.2. Experimental Data during Water Cooling Trial 1 2 3 4 5 6 7 8 9 10 11 12
Time (min) 0 5 10 15 20 25 30 35 40 45 50 55
Wet Temp (oC) In Out 33.4 30 34 30 32.5 30 31.5 29.5 31 28.9 30 29 30 29 28.5 29 29 28.5 29 29 29 28.9 29.5 29
Dry Temp (oC) In Out 35 31 36 31 35 31 34.4 30.5 34 30 33 29.5 32.9 29.9 29.5 30.5 33 29.5 32.8 30.5 32.9 30.2 31 30.2
Relative Humidity In Out 89.49 92.89 87.16 87.16 83.86 92.89 81.83 92.83 80.51 92.05 80.19 96.31 80.78 93.46 92.7 89.35 74.09 92.7 75.21 89.35 74.65 90.68 89.44 91.38
26
CALCULATIONS:
By taking the data obtained when 0% air flow fully closed and 0% heater power: Initial Trial Inlet air wet bulb T = 33.4 oC Outlet water temperature = 42.2 oC Specific volume of air at outlet (by plotting air outlet dry bulb and air outlet wet bulb on the Psychometric Chart) = 0.919 m3kg-1
√
x Air mass flow rate = 0.0137 V B
x was not measured
√
x ṁ = 0.0137 0.919 Air volumetric flow rate = mV B = m x 0.919 = 0.919m m3s-1 Air Velocity =
V A
DESCRIPTIO N Approach to wet bulb Specific volume of air at outlet X
mm H2O
ṁ
kg/s
0.0137
v´
m3/s
V A
m2
77.77
Cross sectional area Air velocity
UNIT
AT 0.5 HP
K
8.8
m3/kg
0.919
√
x 0.919
m/s 27
For heater power 0: From psychometric chart: H2 = 0.0233 kg water/kg air, H1 = 0.022 kg water/kg air L2 = 2(kg/min)/1 min/60 s L2 = 0.3 kg/sec * Water mass balance: L2−L1=G ¿ ( H 2−H 1) * Energy balance: Q G * (H Y 2 H Y1 )
For heater power 0.5 kW: From psychometric chart: H2 = kg water/kg air, H1 = kg water/kg air L2 = 2(kg/min)/1 min/60 s L2 = 0.3 kg/sec * Water mass balance: L2−L1=G ¿ ( H 2−H 1)
* Energy balance: Q G * ( HY 2 HY1 )
Description
Heater Power (kW) 0.5
28
DOCUMENTATION
Turning ON the pump and blower Recording Data’s
Measures the dimensions of the tank Experiment
proper,
where
all
members were busy in their assigned task.
Date & Time Started: Sept.14, 2016 (4:30 PM) Date & Time Finished: Sept. 14, 2016 (5:30 PM) Group No. 7
Instructor/Supervisor: Engr. Juvyneil E. Cartel
29
EXPERIMENT NO. 5 REACTION KINETICS EXPERIMENT USING TUBULAR FLOW REACTOR
I.
INTRODUCTION A plug flow reactor is a pipe-shaped tank where a chemical reaction takes place with
walls coated with a catalyst and an inlet flow of pure reactant. It consists of a cylindrical pipe and is normally operated at steady state, as is the CSTR A simple illustration for what a typical plug flow reactor is:-
Inlet Flow
Outlet Flow Figure 1. Schematic diagram for a plug flow reactor.
A reactant is inserted into tank via inlet flow, after that the reactant is converted into product then flow out the reactor by the outlet flow. Generally, reactors are used in the mostly chemical industry for a million of processes to produce product. There are various different types of reactors due to the numerous different factors that can control the formation of product during the reaction. Plug flow reactors are an idealized scenario where there is no mixing involved in the reactor. It is the opposite of the continuous-stirred tank reactor (CSTR), where the reaction mixture is perfectly mixed. It is impossible to have no mixing at all during a reaction, but the amount of mixing in the reactor can be minimized. There are several advantages to minimizing the amount of mixing so that the reactor closely resembles a Plug Flow Reactor. The plug flow reactor has an inlet flow composed of the reactants. The reactant flows into the reactor and is then converted into the product by a certain chemical reaction. The product flows out of the reactor through the outlet flow. An overview of the reactor can be seen in Figure 1. A schematic of industrial tubular reactors are shown in figure below:
30
Figure 2.
Tubular reactor schematic. Longitudal flow reactor.
Before the reactants are continually flow inside the Plug flow reactor, there are must have a specific assumptions are made about the extent of mixing. The validity of the assumptions will depend on the geometry of the reactor and the flow conditions-: 1. Complete mixing in the radial direction 2. No mixing in the axial direction, i.e., the direction of flow 3. A uniform velocity profile across the radius. 4. Mixing in longitudinal direction due to vortices and turbulence 5. Incomplete mixing in radial direction in laminar flow conditions In the chemical industry, plug flow reactors are frequently used due to the non-mixing property of the reactors. This is because it would be more advantageous than a mixed reactor such as a CSTR. Plug flow reactors are frequently used in biological reactions when the substrate flows into the reactor and is converted to product with the use of an enzyme. Since plug flow reactors have an inlet and outlet stream, they are useful for continuous production. The streams are opposite of a batch reactor, which is a reactor that has a constant volume and has no incoming or outgoing streams. Flow of plug flow reactor is laminar, as with viscous fluids in small-diameter tubes, and greatly deviate from ideal plug-flow behaviour, or turbulent, as with gases. One Plug flow reactor is an ideal tubular reactor with laminar flow behavior. Turbulent flow generally is preferred to laminar flow, because mixing and heat transfer are improved. In this experiment, the Plug Flow Reactor (Model: BP101) is used as it has been properly designed for students' experiment on chemical reactions in liquid phase under isothermal and adiabatic 31
conditions. Included in the unit is a jacketed plug flow reactor; individual reactant feed tanks and pumps, temperature sensors and conductivity measuring sensor. By using this particular unit, students will be capable to conduct the typical saponification reaction between ethyl acetate and sodium hydroxide among the others reaction. Basically, for chemical reactions, it is impossible to proceed to 100% completion. This is because due to the rate of reaction decreases when percent completion gradually increases until the point where the system achieve dynamic equilibrium (no net reaction occurs). In fact, the equilibrium point mostly is less than 100% complete. Thus, distillation is used as a separation process, in order to separate any remaining reagents or by products from the desired product. Sometimes the reagents may be reused at the beginning of the process as a recycle back, such as in the Haber process. For application plug flow reactors are usually which are: 1. High temperature reactions 2. Continuous production 3. Homogeneous or heterogeneous reactions 4. Fast reactions 5. Large scale reactions
II.
OBJECTIVES
To determine the degree of conversion of the reactants mixed in a flask at certain
time. To determine the degree of conversion of the reactants for a given set of conditions of the tubular reactor.
III.
METHODOLOGY 3.1 Materials:
250 mL standardized 0.1 M EtOAc – very volatile and flammable liquid that will be used as working reactant 32
40 g solid caustic soda – chemical used to produce NaOH solution 99 mL pure ethyl acetate – working reactant 250 mL standardized 0.1 M NaOH – used as titrant Phenolphathalein indicator – to be used in titration 100 mL 0.1 M HCl – used as quencher for NaOH and EtOAc solution 20 L distilled water – used for preparing solutions
3.2 Equipment/Devices:
Tubular Flow Reactor – used for the conversion reaction Timer – used for time
3.3 Apparatus: 1 L glass flask and stopper – containment of the working reactants (solutions) 2-10 mL pipette – used for titration 2-50 mL burette – used for titration 2 pcs titration flask – used for titration 3.4 Procedure First, the temperature control unit was set up as described in the commissioning section of the laboratory manual and temperature of the reactor was allowed to reach 30ºC with the stirrer on and both pumps was switched on. Flow rates were adjusted to 0.10 liters/min for each feed and then the product discharges to the pump tray was checked. After 20-30 minutes when the reactor reached a steady state the following readings was noted:
Flow rates of NaOH and EtOAc.
Outlet temperature T, OC.
Ten (10) mL was took at reactor outlet and NaOH inlet tank and analyze for caustic soda concentration. The sampling was repeated and analyzed to ensure steady state conditions. For the reaction in a flask a 250 mL of standardized 0.1 M NaOH and 250 mL of standardized of 0.1 M EtOAc in 1 L flask was mixed and secured with stopper. 2. After 1 hour of mixing, 10 mL sample was placed in the filtration flask. The sample was quenched with 10 mL of 0.1 M HCl and then was added with phenolphthalein indicator. The mixture was titrated with 0.1 M NaOH until end point is reach. The volume of NaOH used was recorded. 33
IV.
RESULTS AND DISCUSSION IV.1
Results
Presented here are graphs that shows important relationships and trends are given as follows.
Trial 1 Plot Xa vs t 0.0700.068 0.066 f(x) = 0x^2 - 0x + 0.07 0.064 0.064 R² = 1
Xa (Conversion) 0.065 0.060
4
6
8 10 12 14 16 18 20 22
t (time)
Figure 1. Plot of conversion vs time for Trial 1
Trial 2 Plot Xa vs t 0.069 0.068 0.067 0.066 0.065 Xa (conversion) 0.064 0.063 0.062 0.061
f(x) = 0x^2 - 0x + 0.07 R² = 1
4
6
8
10 12 14 16 18 20 22
t (time)
34
Figure 2. Plot of conversion vs time for Trial 2
Trial 3 Plot Xa vs t 0.140
0.119 0.120 f(x) = 0x + 0.08 0.103 R² = 0.99 0.1000.093
0.130
0.080
Xa (Conversion 0.060 0.040 0.020 0.000
4
6
8 10 12 14 16 18 20 22
t (time)
Figure 3. Plot of conversion vs time for Trial 3 4.2 Discussion In this experiment, we we’re able to carry a reaction between NaOH and EtOAc in plug flow reactor. These two solutions react together in the PFR to complete saponification reaction. Plug Flow Reactor (PFR) is a type of reactor that consists of a cylindrical pipe and is usually operated at steady state. The feed enter at one end of a cylindrical tube and leaves product from the end of cylindrical tube. The long tube and the lack of provision for stirring prevent complete mixing of the fluid in the tube. At the end of the experiment, we are able to determine the reaction rate constant by using formula and to determine the effect of time on the conversion in the plug flow reactor. The experiment is started by running up the equipment in order to start the saponification process. Conversion, xA is the number of moles of A that reacted per mole of A fed to the system. The conversion is defined with respect to the basis of the calculation and in this case, species A is 35
taken as the basis of the calculation. PFR lacks a good mixing process due to PFR is designed not to stir the solution vigorously to maximize mixing process, the conversion of the reaction by using PFR is fairly low. The experiment also aims to evaluate the reaction rate constants and rate of reaction values of the reaction. Both of these properties have been determined in the result section. We used this formula to determine residence which is use for a function of total flow rates of the feed by time before plotting the graph, τ= Residence Time,
Reactor volume ( L ) ,V L Total flow rate , v0 min
( )
Supposedly, the result of conversion factor is inversely proportional to the residence time expect for trial 3. This is maybe due to the error occurred during conducted the experiment. Thus, when the residence time is increases, the conversion factor also decreases.
V.
CONCLUSION Therefore, from the graph that had been plotted, we can say that the conversion factor is
inversely proportional to the residence time at certain point then a small changes an increase of graph conversion to the residence time . APPENDICES: Raw Data Trial 1 Samp le 1 2 3 4 Trial 2 Samp le
30 NaOH; 30 EtOAC
t 5 10 15 20
Vi 49 45.8 42.6 39.5
Vf 45.8 42.6 39.5 36.8
∆V 3.2 3.2 3.1 2.7
50 NaOH; 30 EtOAC
t
Vi
Vf
∆V 36
1 2 3 4 Trial 3 Samp le 1 2 3 4
5 10 15 20
36.8 34.3 31.8 29.8
34.3 31.8 29.8 27.9
2.5 2.5 2 1.9
30 NaOH; 30 EtOAC
t 5 10 15 20
Vi 27.9 25.3 22.7 20
Vf 25.3 22.7 20 17.4
∆V 2.6 2.6 2.7 2.6
Properties Reactor Volume.
: 400 mL
Concentration of NaOH in the reactor, CNaOH
: 0.02M
Concentration of NaOH in the feed vessel, CNaOH,f
: 0.02M
Concentration of HCl quench, CHCl,s
: 0.1 M
Volume of sample, Vs
: 10mL
SAMPLE OF CALCULATIONS Residence Time For flow rates of 30 ml/min :
Residence Time,
Reactor volume ( L ) ,V L Total flow rate , v0 min
Total flow rate, Vo
= Flow rate of NaOH + Flow rate of Et(Ac)
τ=
( )
= 30 mL/min NaOH + 30 mL/min Et(Ac) = 60 mL/min = 0.06 L/min
37
Hence, 0.4 L Residence Time, τ = 0.06 L/min
= 6.6667 min
placed in Table 7.3
Other residence times were calculated by the same way, and varying the flow rates. Conversion For flow rates of 30 ml/min: Moles of reacted NaOH, n1, n1= Concentration NaOH x Volume of NaOH titrated = 0.02 M x (3.2x 10-3) L = 6.4x 10-5mole DOCUMENTATION
All members are working according to assigned task
38
A Closer View of the Equipment
Titration of the
Sample
Date & Time Started: Sept. 14, 2016 (2:30PM) Date & Time Finished: Sept. 14, 2016 (3:30 PM) Group No. 7
Instructor/Supervisor: Engr. Juvyneil E. Cartel
EXPERIMENT NO. 6 FIRST STEP RESPONSE ORDER SYSTEM
I. INTRODUCTION The step response of a system in a given initial state consists of the time evolution of its outputs when its control inputs are Heaviside step functions. In electronic engineering and 39
control theory, step response is the time behavior of the outputs of a general system when its inputs change from zero to one in a very short time. The concept can be extended to the abstract mathematical notion of a dynamical system using an evolution parameter. From a practical standpoint, knowing how the system responds to a sudden input is important because large and possibly fast deviations from the long term steady state may have extreme effects on the component itself and on other portions of the overall system dependent on this component. In addition, the overall system cannot act until the component's output settles down to some vicinity of its final state, delaying the overall system response. Formally, knowing the step response of a dynamical system gives information on the stability of such a system, and on its ability to reach one stationary state when starting from another II. OBJECTIVES
To plot the response of first order liquid level system as a function of time and to evaluate the flow resistance R of a first order liquid level system.
III.
METHODOLOGY 3.1 Equipment
PCT 9 process module PCT 10 electrical console
3.2 Procedure Primarily, the PCT 9 Motorized valve was set fully open, solenoid valve 3, open, V3 and V4 closed. The flow meter was adjusted to 0.50 L/min and recorded steady state height. When the height of the liquid was steady, the flow meter was adjusted to 0.70 L/min manually in the PCT 10 simultaneous with the timer. Time was recorded for every 5mm increase in liquid level. IV. RESULTS AND DISCUSSION
40
45 40 f(x) = 0x^4 - 0x^3 + 0x^2 - 0.01x + 33.44 35 R² = 0.94 30
Temperature (˚C)
25 20 15 10 5 0
0
1000 2000
Time (second) Processed Data
Figure 1. Plot of temperature versus time V.
Conclusion Liquid level system is an example of a first order system. The general form of transfer function for this system is represented by this equation
Based on the data obtained, we can conclude that it takes a longer time to respond when the level of the water becomes high. Indeed, we can say that they are directly proportional to one another. The plot of water level versus time obtained a straight line. Thus, the water level increases linearly with time.
VI.
REFERENNCES Unit Operations of Chemical Engineering, 4th Edition (McCabe, W.L., et.al,) .Principles of Transport Processes and Separation Processes (Geankoplis, C.J.)
VII.
APPENDIX 41
Table 6.1 Reading of temperature at each time interval
Trial 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
Time (seconds) 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350
Compact Control Temperature (˚C) 31.5 32.25 33.41 33.51 33.65 33.8 33.97 34.11 34.2 34.4 34.6 34.8 34.9 35.1 35.3 35.5 35.7 35.9 36 36.2 36.4 36.5 36.7 36.9 37.1 37.2 37.4 37.6 37.8 37.9 38.1 38.2 38.4 38.5 38.6 38.7 42
36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76
360 370 380 390 400 410 420 430 440 450 460 470 480 490 500 510 520 530 540 550 560 570 580 590 600 610 620 630 640 650 660 670 680 690 700 710 720 730 740 750 760
38.9 39 39.1 39.2 39.3 39.4 39.5 39.5 39.6 39.7 39.7 39.9 39.9 39.9 40 40 40.1 40.1 40.1 40.2 40.2 40.3 40.3 40.4 40.4 40.4 40.4 40.4 40.4 40.4 40.4 40.6 40 38.7 38.1 37.3 36.8 36.2 35.8 35.4 35.1 43
77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103
770 780 790 800 810 820 830 840 850 860 870 880 890 900 910 920 930 940 950 960 970 980 990 1000 1010 1020 1030
34.8 34.5 34.3 34.1 34 33.9 33.7 33.6 33.5 33.3 33.3 33.2 33.2 33.2 33.2 33.1 33.1 33.1 33 32.9 32.9 32.9 32.9 32.9 32.9 32.9 32.9
DOCUMENTATION
44
Overall View of the Equipment
45
Closer View at the Upper part
Closer view at the Lower part
Date & Time Started: Sept. 15, 2016 (10:00 AM)
Date & Time Finished: Sept. 15, 2016 (12:30 NN)
Group No. 7
Instructor/Supervisor: Engr. Juvyneil E. Cartel
EXPERIMENT NO. 7 BATCH SEDIMENTATION I.
INTRODUCTION Sedimentation is a unit operation that utilizes gravitational forces in order to separate
solid particulates in a liquid medium. Its industrial use is already very established such that it has become a frequent option for solid-liquid separation. Among its uses include settling of crystals from another mother liquor, of food particles from a liquid food mixture, of slurry from a soybean leaching process. Most recently, when industries started to embrace environmental protection strategies, sedimentation has become a primary component of wastewater treatment facilities. This experiment therefore allows the students to investigate the process of sedimentation, determine the settling characteristics of specific slurry and eventually to utilize the data gathered in the design of an industrial scale equipment for this valuable unit operation. II. OBJECTIVES 1. To investigate batch sedimentation process. 2. To determine the sedimentation characteristics and parameters of a slurry of varying concentrations under batch process. III.
METHODOLOGY 3.1 APPARATUS & MATERIALS
46
3 250 mL Graduated Cylinders 1 500 mL Graduated Cylinder 2 500 mL Beakers 1 1000 mL Beaker 2 Funnels 3 Stirring Rods 2 Stopwatches Ruler or Meterstick Kaolin
3.2 Procedure 1. Prepare approximately 350 mL of each of 8% (w/w) Kaolin and 16% (w/w) Kaolin slurry and 900 mL of 4% (w/w) of Kaolin slurry. Make sure that all the solid particles are uniformly dispersed by carefully mixing the suspension. Avoid too much agitation or else some of the solid particles might break up into much smaller particles which will make the experiment difficult to conduct due to wide ranges of particle sizes. 2. With careful agitation, pour the mixture separately in the three 250 mL graduated cylinders, and a portion of the 4% slurry in the 500 mL graduated cylinder. The initial level of the slurry must be the same level. 3. Record the temperature of the slurry and measure the diameter of the cylinders. 4. Slightly stir the mixture to uniformly disperse the particles or with your palm covering the top of the cylinder turn it upside down quickly to distribute the particles, and then allow the mixture to stand undisturbed. By means of a stopwatch and ruler, collect a data of observed height of interface of clear liquid and slurry (Zone A & B) versus time. If it is observable, record also the increase in the height of the concentrated sludge (Zone D) building up at the bottom of the cylinder. To help in the identification of the layers, read the level against a source of light. Take note of the observed critical height of interface. 5. When the level has reached a point such that a change in level will take an unreasonably long time, repeat the trial again by shaking the contents of the cylinder to disperse the particles. Let the cylinders stand undisturbed and record the height versus time. 6. Allow the samples to stand overnight being careful not to disturb the contents and determine the final height of the slurry. 7. Do not throw the slurry, but give them to the technician, for safekeeping.
47
IV.
RESULTS AND DISCUSSION
A. Processed Data
Kynch Table 25 f(x) = - 0.04x + 23.22
20 15
INTERFACE HEIGHT (cm)
10 5 0
0
f(x)100 =
200
300
400
500
600
500
600
Time ɵ (s)
Figure 1. 4% solution in 250 mL graduated cylinder
Kynch Table 5 4.5 4 3.5 3 2.5 INTERFACE HEIGHT (cm) 2 1.5 1 0.5 0
f(x) = 0.01x + 0.23
0
f(x)100 =
200
300
400
Time ɵ (s)
48
Figure 2. 4% solution in 500 mL graduated cylinder
Kynch Table 20 18 16 14 12 INTERFACE HEIGHT (cm) 10 8 6 4 2 0
f(x) = - 0.02x + 18.33
0
100
200
300
400
500
600
500
600
Time ɵ (s)
Figure 3. 8% solution in 250 mL graduated cylinder
Kynch Table 18 16
f(x) = - 0.02x + 17.25
14 12 10
INTERFACE HEIGHT (cm)
8 6 4 2 0
0
100
200
300
400
Time ɵ (s)
Figure 4. 16% solution in 250 mL graduated cylinder
VIII. CONCLUSION
49
The separation of a dilute slurry or suspension by gravity settling into a clear fluid and a slurry of higher solids content is called sedimentation (Geankoplis, 2012). During batch sedimentation, a suspension of particles is allowed to stand in a settling tank or column. Settling of the particles occurs through the gravity’s action, leading to the formation of distinct settling layers and a sludge layer (Latsa,Assimacopoulos, Stamou, Markatos, 2005). In this experiment, the slurry height of different mass concentrations: 8% (w/w), 4% (w/w) and 16% (w/w) were recorded as time elapsed. The effects of the slurry concentration on sedimentation characteristics were determined using the sedimentation curves. The slurry showed an example of a hindered settling. Results showed that the slurry concentration affects the kaolin’s sedimentation characteristics.
VII.
REFERENCES
GEANKOPLIS, C. J. Principles of Transport Processes and Separation Processes. 3rd
Edition. Prentice Hall, New Jersey (2003). MCCABE & SMITH. Unit Operations of Chemical Engineering. 5th Edition. McGraw
Hill International Series (1993). https://www.coursehero.com/file/14331486/Experiment-1pdf/
VIII. APPENDIX A. Information Flow Diagram Interface Height
Time
Plot Interface Height vs . Time
Nomenclature: Interface Height = in cm Time = in seconds
B. Sample Calculations Amount of Kaolin needed = 350 mL(0.08) = 28 mL or 28 g Kaolin 50
Amount of Water needed = 350 mL – 28 mL = 322 mL Amount of Kaolin needed = 350 mL(0.16) = 56 mL or 56 g Kaolin Amount of Water needed = 350 mL – 56 mL = 294 mL Amount of Kaolin needed = 900 mL(0.04) = 36 mL or 36 g Kaolin Amount of Water needed = 900 mL – 36 mL = 864 mL C. Raw Data Table 1. Data for Sedimentation of 4% Kaolin Solution in 250 mL Graduated Cylinder 4% Kaolin in 250 mL Initial Height = 24 cm Diameter = 3.45 cm Temperature = 30 oC t (s) Zone A Zone B 30 1 23 60 2.7 21.3 90 4.2 19.8 120 6 18 150 7.5 16.5 180 9 15 210 10.5 13.5 240 12 12 270 13.8 10.2 300 15 9 330 16.7 7.3 360 18.5 5.5 390 18.7 5.3 420 19.2 4.8 450 19.4 4.6 480 19.6 4.4
Zone D 2.6 2.8 2.9 3 3.2 3.3 3.5 3.6 3.8 3.9 4 4.1 4.3 4.6 4.8 5
Table 2. Data for Sedimentation of 4% Kaolin Solution in 500 mL Graduated Cylinder 4% Kaolin in 500 mL Initial Height = 24.5 cm Diameter = 4.7 cm Temperature = 31 oC t (s) Zone A Zone B 30 1.5 23 60 4 20.5
Zone D 0.5 0.8 51
90 120 150 180 210 240 270 300 330 360 390 420 450 480
6 8 10.5 13.2 14.7 19 21.5 21.6 21.7 21.8 21.9 -
18.5 16.5 14 11.3 9.8 5.5 3 2.9 2.8 2.7 2.6 -
1 1.3 1.7 2.7 3.3 3.5 3.7 3.8 3.9 4.1 4.3 -
Table 3. Data for Sedimentation of 8% Kaolin Solution in 500 mL Graduated Cylinder 8% Kaolin in 500 mL Initial Height = 24.5 cm Diameter = 4.7 cm Temperature = 29 oC t (s) Zone A Zone B 30 1.2 18.3 60 2.1 17.4 90 2.7 16.8 120 3.6 15.9 150 4.5 15 180 4.6 14.9 210 5.7 13.8 240 6.1 13.4 270 6.6 12.9 300 7.1 12.4 330 7.8 11.7 360 8.3 11.2 390 8.7 10.8 420 9.2 10.3 450 9.7 9.8 480 10 9.5 510 10.3 9.2 540 10.6 8.9 570 10.9 8.6
Zone D 52
600 11.1 8.4 Table 4. Data for Sedimentation of 16% Kaolin Solution in 500 mL Graduated Cylinder 16% Kaolin in 500 mL Initial Height = 24.5 cm Diameter = 4.7 cm Temperature = 29.5 oC t (s) Zone A Zone B 30 1 17 60 1.7 16.3 90 2.7 15.3 120 3.4 14.6 150 4.5 14 180 5.2 13.5 210 2.8 12.2 240 6.6 11.4 270 7.4 10.6 300 8.1 9.9 330 8.6 9.4 360 9.1 8.9 390 9.8 8.3 420 10 8 450 10.4 7.6 480 10.6 7.4 510 10.8 7.2 540 11.2 6.8 570 11.4 6.6 600 11.6 6.4
Zone D -
Data gathered after settling: Final height of slurry (4%) = 2.9 cm (in the 250 mL graduated cylinder) & 1.15 cm (in the 500 mL graduated cylinder Final Height of slurry (8%) = 3.85 cm Final Height of slurry (16%) = 8.7 cm
53
DOCUMENTATION
Waiting until such time that the kaolin settles, and the height of the suspended particles was recorded
Pouring the Kaolin solution into the graduated
Preparation of the 4%, 8%, 16%
Cylinder
Kaolin solution and recordings
54
Date & Time Started: September 13, 2016 Group No. 7
Date & Time Finished: September 13, 2016 Instructor/Supervisor: Engr. Juvyneil E. Cartel
EXPERIMENT NO. 8 SIZE REDUCTION AND PARTICLE SIZE MEASUREMENT BY SCREEN ANALYSIS
I. INTRODUCTION Size Reduction or Commination is the process of reducing substance to smaller particles. It is a process in which particles of desired sizes are separated from other fractions. Size reduction leads to increase of surface area. For example, the rate of dissolution of solid drug particles increase many folds after size reduction. Size Reduction produces particles in narrow size range so as mixing of powders with narrow size range is easier. Pharmaceutical suspensions require finer particle size. It reduces rate of sedimentation. Any solid material, after size reduction, never gives particles of the same size but contains particles of varying sizes. The size-reduced particles are then passed through sieves to get fractions of narrow size range. II.
OBJECTIVES 1. To determine the screen analysis of the product obtained from the crusher and pulverizer. 2. To construct fractional distribution plot, cumulative distribution plot, and histogram presentation of the screen analysis of the given samples. 3. To determine the true arithmetic average diameter, mean surface diameter, mean volume diameter/mean mass diameter and the specific surface (surface area per unit mass) of the products from the crusher and pulverizer. 4. To estimate the energy requirements and the Rittinger’s Number for the crusher and pulverizer. 5. To estimate the crushing efficiency of the crusher and pulverizer.
III.
METHODOLOGY 55
3.1 Materials/Equipment Needed: About 1 kg of small rocks practically uniform size from 1-1.5 inches in diameter Ro-tap Sieve Shaker Standard Tyler screen series composted of the following screens: 200, 150, 100,
80, 60, 40, 30, …, mesh including cover and pan Crusher Pulverizer Weighing Instrument, Soft/Nylon Bristle Brush, Extra Pan
3.2 Procedure A. Develop/Outline procedure followed n size reduction of small rocks using the crusher and pulverizer. B. Preparation of screen analysis of the products obtained from the crusher and pulverizer. Basic Operations of Ro-Tap Sieve Shaker 1. Assembles a stack of sieves, beginning with a top cover and then the coarsest (largest) sieve opening on top and a pan on the bottom. Place them into the shaker. When placing the sieves into the Ro-Taps, the hammer should be tilted up and out of the way. 2. Place the sieve cover, with the cork installed, on the top of the stack. 3. Adjust the sieve support clamp bar with the two wing nuts, bringing the top of the sieve cover flush with the upper carrying plate. Hammer Drop Adjustment Note: Prior to hammer adjustment; make sure cork in sieve cover is seated firmly. Make sure sieve cover has top edge flush with upper carrying plate. 1. 2. 3. 4. 5.
Remove pedestal cover Jog machine until hammer rises to a maximum height, check height with scales. Set height 10 1 5/16 +- 1/16 by loosening screw on coupling and adjusting lift rod. Tighten screw on coupling. Replace pedestal cover. Starting the Shaker
1. Make sure a sieve stack is in place at this time. Set the test run in time, by simply turning the thumb wheel + (plus) or – (minus) to the desired time in the digital window. 56
2. Push the start bar to start test and note countdown time. An audible tone will be heard at the end of the test. You can stop or interrupt the test at any time, by simply pushing the stop bar. Note that the remaining test time is frozen on the readout. To continue, simply push the start bar. Note: the timing device also has a clock function. To use this option, hold the “clock” button and adjust to the proper time with the thumb dial. Performing a Sieve Analysis 1. Select a set of test sieves with mesh openings that will reveal particle distribution at critical sizes. Critical sizes are usually stated in a product specification or are determined by material processing requirements. 2. Assemble a stacked of test sieves (one of top of the other) with coarsest (largest) opening on the top of the stack. A proper sample amount should cover the wire mesh of the top sieve, but not overload the surface. Overloading will cause blinding or blocking of the openings, not allowing the sample to be properly processed. 3. Place the test sieve stack into the sieve shaker, and place the cover on the top of the stack. The sieves must be secured into place. The shaker should be activated and set to operate for their proper length of time. 4. After completion of the agitation, weigh the material retained on each sieve in order to record the data. Weighing should be by grams, with a balance scale having at least a capacity of 500 grams and a sensitivity of 1/10 gram. 5. Using the extra bottom pan, empty the materials retained on the coarsest sieve into the pan. A soft or nylon-bristle brush should be used to gently brush the underside of the sieve, thoroughly removing all of the remaining particles into the pan. The sieve frame can be tapped with the handle of the brush to clean any remaining material on the sieve. Weigh the contents in the pan to the nearest 1/10th gram immediately record the data. 6. If several extra pans are available, it is best not to discard this portion of the sample until the entire process is completed. This same procedure should be repeated on all sieves in the stack. The material passing through the finest sieve into the bottom pan must also be weighed to obtain the total weight for percentage calculations. The total weight of the material retained on the various sieves and in the bottom pan should be extremely close to the weight of the original sample. IV.
RESULTS AND DISCUSSION 57
a. Results Presented here are graphs that shows important relationships and trends are given as follows.
Fractional Distribution Plot 100.00 80.00 60.00
% Wt. Fraction
Crusher
40.00
Pulverizer
20.00 0.00 0.000 -20.00
0.500
1.000
1.500
2.000
2.500
Sieve Opening, mm
Figure 1. Plot of Fractional Distribution
Cumulative Distribution Plot 100.00 90.00 80.00 70.00 60.00
% Cumulative
Crusher
50.00
Pulverizer
40.00 30.00 20.00 10.00 0.00 0.000
0.500
1.000
1.500
2.000
2.500
Sieve Opening, mm
Figure 2. Plot of Cumulative Distribution
58
Fractional Distribution Histogram
E2
9 99
96
99 99 99
99
99
99 99
99 39
14
7.
0.
0.
17
69
89
99
99
99
99
99
99
99
99
99
9
25
0.
0.
85
1
7 1.
2
% Wt. Fraction
90.00 80.00 70.00 60.00 50.00 40.00 30.00 20.00 10.00 0.00
Sieve Opening, mm Crusher
Figure 3. Plot of Fractional Distribution Histogram (CRUSHER)
Fractional Distribution Histogram
E2
9 99
99
96
99
7.
39
99
99
99
99
99
99
99 99 99 89
14 0.
0.
17
69
99
99
99
99
99
99
9
25 0.
85 0.
1
7 1.
% Wt. Fraction
2
30.00 25.00 20.00 15.00 10.00 5.00 0.00
Sieve Opening, mm Pulverizer
Figure 4. Plot of Fractional Distribution Histogram (PULVERIZER)
59
True Arithmetic Average Diameter in the Crusher and Pulverizer: 2.00+ 1.70+1.00+0.250+0.177+ 0.149+0.074 8
DA =
DA=0.66875 mm Mean Volume Diameter: Crusher:
√
Dv= 3
1 0.0036 0.0126 0.0036 0.0755 0.0018 0.0018 0.0036 + + + + + + 1.853 1.353 0.9253 0.5353 0.214 3 0.1633 0.1123
Dv=.6486 mm
Pulverizer:
√
Dv= 3
1 0.0868 0.2422 0.0404 0.113 0.0888 0.0141 0.0565 + + + + + + 1.853 1.35 3 0.9253 0.5353 0.2143 0.1633 0.1123
Dv=0.2655 mm
Mean Mass Diameter: Crusher:
Dw=0.8489 ( 0 ) +0.0036 ( 1.85 ) +0.0126 ( 1.35 ) +0.0036 ( 0.925 )+ 0.0755 ( 0.535 )+ 0.0018 ( 0.2
Dw=0.06847 mm
Pulverizer:
Dw=0.222 ( 0 ) +0.0868 ( 1.85 ) +0.2422 ( 1.35 )+ 0.0404 ( 0.925 ) +0.113 ( 0.535 )+ 0.0888 ( 0.214
Dw=0.03187 mm
60
4.2 Discussion Particle size reduction is technology choice to reduce the size of a particle in the manufacturing process to improve an active ingredient. There are numerous industries that depend on size reduction to improve performance or to meet specifications. The pharmaceutical, chemical, and food industries all depend on particle size reduction. Based from the results of differential and cumulative analysis obtained from the size reduction analysis. V.
CONCLUSION We can conclude that size reduction using pulverizers is more efficient than crushers if the desired product from size reduction is a very very small particle. Otherwise, crushers should be used instead of pulverizers. In pharmaceutical industry where particles are required to have a smaller size, pulverizer is most applicable to use than the crusher. There are also some industrial applications that require bigger particle size and for these types, crushers is most likely to use.
61
APPENDICES: Raw Data Table 1.3 Crusher Partial Anaylysis Total mass of Feed (orig sample) Total mass of product (b4 screening) Total mass of product (after screening) Weight of Weight of Screen Mesh Empty Screen Including the Solids Number (g) (g) 10 (2mm) 490 1434 12 (1.7 mm) 454 458 18 (1.00mm) 440 454 20 (850um) 428 432 60 (250um) 462 378 80 (180um) 362 360 100 (150um) 348 350 200 (75um) 340 344
1112 992 991 Weight of the Solids (g)
grams grams grams Ave. Particle Diameter,
944 4 14 4 84 2 2 4
D pi
1.85 1.35 0.925 0.535 0.214 0.163 0.112
Table 1.4 Pulverizer Partial Analysis Total mass of Feed (orig sample) Total mass of product (b4 screening) Total mass of product (after screening)
991 grams 966 grams 962 grams
62
Mesh Number
Weight of Empty Screen (g)
Weight of Screen Including the Solids (g)
Weight of the Solids (g)
490 454 440 428 462 362 348 340
710 540 680 468 574 450 362 396
220 86 240 40 112 88 14 56
10 (2mm) 12 (1.7 mm) 18 (1.00mm) 20 (850um) 60 (250um) 80 (180um) 100 (150um) 200 (75um)
Ave. Particle Diameter,
D pi
1.85 1.35 0.925 0.535 0.214 0.163 0.112
SAMPLE OF CALCULATIONS
Weight Percent %wt=
100∗wt of solid on sieve wt of sample
For Mesh 10 %wt=
100∗944 =84.89 1112
Cumulative Weight Percent Retained %cumulative wt retained=
100∗wt of solid on sieve +wt of solid on sieves above wt of sample
For Mesh 40 %cumulative wt retained=
100∗4+ 944 =85.25 1112
Average Particle Diameter = (D1+D2)/2
63
For Mesh 12 = 2.00 + 1.7 = 1.85
INFORMATION FLOW DIAGRAM AND EQUATIONS AVERAGE PARTICLE SIZE
i.
Volume Surface Diameter 6 −D s= ∅s A w ρ p
ii.
Arithmetic Mean Diameter x i Dγi ¿ ¿ n
∑¿ i=1
−D n=¿ iii.
Mass Mean Diameter n
−D w =∑ X i −D γi i=1
iv.
Mean Surface
v.
Volume Mean Diameter Xi D3γi ¿ ¿ n
∑¿ i=1
1 ¿ −D v =¿ A. Specific Surface Mixture 6m A=Ns p= ∅ sρpDp A w 6 m n xi = ∑ m ρp ∅ s i−1 Dpi
64
B. Rittinger’s Number dE −C = dX X n C. Crushing Efficiency M ℜ q' d ¿ ¿ M T x 100 Efficiency=¿
INFORMATION FLOW DIAGRAM
ɸs
Information flow diagram
6m A= ɸ sρpD p
n
6m xi A w= ∑ ρp ɸ s i−1 Dpi
Dp ρp
65
6 −Ds= ∑ (xi D pi ) ɸs Aw ρp −Dn= i=1 n
ɸs
m
ρp
Dp
m
n
Dpi
xi
Aw
ɸs
ρ p❑ NT D pi
xi n n
xi
−DW =∑ x i ‾ i=1
‾ D pi
n −D v =
xi
1 n
∑ i=1
D pi
xi
( ) 3
D pi
n Xn C
dE −C = dX X n
dX
DOCUMENTATION
66
Date & Time Started: September 13, 2016 Group No. 7
Date & Time Finished: September 13, 2016 Instructor/Supervisor: Engr. Juvyneil E. Cartel
EXPERIMENT NO. 9 67
POWER REQUIREMENT FOR AGITATION I.
INTRODUCTION There are two classes of impeller agitators: axial-flow and radial-flow. Axial-flow impellers generate currents parallel with the axis of the impeller shaft. Radial-flow impellers generate currents in a tangential or radial direction to the axis of the impeller shaft. Within the two classes of impellers there exist three main types of impeller design. The three types are: propeller, turbine, and paddle. The three main types are utilized in about 95 percent of most batch liquid agitation systems. Standard propellers have three blades, but can be two-bladed, four-bladed, or encased by a circular guard. A revolving propeller traces out a helix in the fluid. One full revolution moves the liquid a fixed distance. The ratio of this distance to the propeller diameter is known as the pitch. Propellers are a member of the axial class of impeller agitators. Turbines are six or more blades mounted at the end of the agitator shaft. They are a member of the radial class of impeller agitators. Turbine diameter is typically 30 to 50 percent of the vessel diameter. Paddles are two or four blades mounted on the end of the agitator shaft. They are a subset of the radial class of impeller agitators. Typically the impeller diameter of paddles is 50 to 80 percent of the tank diameter. The agitator impeller is, in essence, a pumping device operating without the typical confines of a casing or directed inlet and outlet flows. As the impeller blade rotates, fluid is forced outward from the blade tip. Mechanical agitator power requirements for liquid batches are calculated by determining the power number for a given system and correcting for motor, gearing and bearing losses. Design specification of the motor is then determined by selecting the closest higher standard size. The system turbulence is checked by calculating the Reynolds number for the agitation system. Adequate turbulence is defined at Reynolds numbers greater than 10,000.
II.
OBJECTIVES
68
To be able to determine the effect of impeller speed on the power requirement for
agitation with and without baffles. To be able to determine the effect of impeller dimensions (straight blade turbine) on the power requirement for agitation with and without baffles.
III.
MATERIALS, EQUIPMENT & APPARATUS Apparatus/Equipment
Agitator
-
Use Used in mixing, promoting reactions, homogenizing mixture & increase heat
Wrench
-
transfer (heating or cooling) Used to provide grip & mechanical advantage in applying torque to turn
1 pc 2-L Plastic Graduated Cylinder
-
1 pc 5-L Plastic Beaker
other substances together for scientific
1 pc 100-ml glass beaker 1 pc Vernier Caliper
objects. Measures liquid volume Used to mix chemicals, liquids and testing Measures
internal
and
external
distances extremely accurately.
1 pc Ruler 20 L distilled water IV.
METHODOLOGY A. Experimental Design Preliminary Steps: 1. Disconnect the cord between the torque arm and the balance before removing the motor or baffles. 2. Measure the dimensions of the impeller and attach the shaft assembly. Record the relevant dimension of the baffles and the tank, i.e. width, height, and diameter. 3. Place baffles in the tank, tighten the screw by hand, and attach the cord of the balance back to the torque arm. Check the dynamometer balance for correct setting. 4. Close the discharge valve before filling the tank with water. The liquid height should not exceed 350 mm. 69
5. Record the water temperature and determine the density and absolute viscosity from appropriate tables in available literature. 6. Ensure that the speed control knob (next to the on/off switch) is set at zero. Release the support screw and let the balance come to rest. Tighten the support screw when the balance is in its rest position and record the initial value. Experiment Proper in Determining Power Requirements: 1. Switch on the agitator and ensure that the red indicator is lit.
2. Conduct the experiment using the settings shown in Table 1 V.
RESULTS & DISCUSSION: The table below shows the result of the experiment conducted. With Baffles Ʈ (Nm) B
P ( J/s)
rad
Ni( ) 78.58 s 90.27 101.46 105.66 109.64 112.47
1 2 3 4 5 6
0.02275 0.03575 0.052 0.06825 0.07475 0.07475
1.79 3.23 5.28 7.21 8.20 8.41
1 2 3 4 5 6
0.1105 0.14625 0.13 0.13325 0.13325 0.13975
27.98 29.34 29.63 29.54 29.38 29.35
3.09 4.29 3.85 3.94 3.92 4.10
1 2 3 4 5 6
0.12025 0.1235 0.1235 0.12025 0.11375 0.11375
21.42 21.67 21.84 21.70 21.86 21.65
2.58 2.68 2.70 2.61 2.49 2.46
C
D
V. CONCLUSION
70
Therefore in the experiment we can conclude the theory that when speed increases the power requirement also increases and that the baffles used helped in the agitation of fluid shown by the decrease in power requirement. REFERENCES: Geankoplis, C.J. (2003). Transport Processes and Separation Process Principle, 4 th edition. New York: Prentice Hall.
APPENDICES I.
RAW DATA With Baffles Impeller Speed (rpm)
Current (ampere)
Voltage ( volts)
Torque ( N)
A Small Propeller
1 2 3 4 5 6
626.5 731 626.5 626.5 626.5 1106
388 403 422 450 466 503
4.892 5.69 6.21 7.15 7.66 8.61
0 0 0 0 0 0
1 2
750.4 862
654 746
6.63 7.57
0.07 0.11
B Big Propeller
71
3 4 5 6
968.9 1009 1047 1074
855 897 937 971
8.54 9.08 9.4 9.66
0.16 0.21 0.23 0.23
1 2 3 4 5 6
267.2 280.2 282.9 282.1 280.6 280.3
1179 1173 1169 1167 1167 1166
4.27 4.658 4.643 4.579 4.522 4.492
0.34 0.45 0.4 0.41 0.41 0.43
1 2 3 4 5 6
204.5 206.9 208.6 207.2 208.7 206.7
1177 1178 1176 1179 1179 1182
4.015 3.968 3.934 3.899 3.893 3.881
0.37 0.38 0.38 0.37 0.35 0.35
C Two Blades
D Four Blades
Impell er Speed (rpm)
Without Baffles Curren t (amper e) Voltage ( volts)
Torque ( N)
A Small Propeller 1 2 3 4 5 6
558.3 651.7 742.5 852.6 922.7 1032
370 379 388 406 416 438
4.75 5.37 5.93 6.74 7.22 8.11
0 0 0 0 0 0
1 2 3 4
656.8 730.6 767.2 823.4
513 553 574 608
5.53 6.06 6.36 6.78
0 0 0 0.08
B Big Propeller
72
5 6
871.1 939.9
642 662
7.18 7.69
0.07 0.07
1
389.7
733
4.131
0.12
2 3 4 5 6
410.4 437.4 459.2 489.5 525.2
750 768 797 853 876
4.295 4.494 4.645 4.951 5.46
0.11 0.11 0.12 0.16 0.17
1 2 3 4 5 6
373.6 387.2 412.1 433.4 466.3 527.8
784 825 892 935 995 1073
4.295 4.479 4.759 5.026 5.36 5.86
0.12 0.14 0.16 0.19 0.23 0.29
C Two Blades
D Four Blades
Physical Properties Density of 1000 water (g/ml) Viscosity of 0.0007 water (Pa.s) 98 Volume of 0.0191 water in the 3 tank Tank Dimensions A B C Diameter of the tank (m) Water lever or height (m) Length of lever arm (m)
D
0.2
0.2
0.2
0.2
0.19
0.19
0.19
0.19
0.331
0.325
0.325
0.325
Impeller 73
Dimensions Impeller width
0.001
0.001 5
0.001 5
0.001 5
Impeller Diameter
0.047
0.074
0.095
0.095
0.016
0.016
0.016
0.016
Baffle Dimensions Bafle diameter
B. Information Flow Diagram:
Plotting P vs. Impeller Speed Nomenclature: P
- Power in J /s
τ
- Torque in N .m
Ni F
- Impeller speed in rpm – Force in
N
l - Lever arm length in m equal to 0.098 m as measured
2π 60
- Conversion factor to convert impeller speed rpm¿ rad / s
74
DOCUMENTATION
75
76
Date & Time Started: Sept. 15, 2016 (1:30 PM)
Date & Time Finished: Sept14, 2016 (5PM)
Group No. 7
Instructor/Supervisor: Engr. Juvyneil E. Cartel
EXPERIMENT NO. 10 TRAY DRYING
I.
INTRODUCTION Technically, drying is a mass transfer process resulting in the removal of water moisture
or moisture from another solvent, by evaporation from a solid, semi-solid or liquid to end in a solid state. To achieve this, there must be a source of heat, and a sink of the vapor thus produced. In the most common case, a gas stream, e.g., air, applies the heat by convection and carries away the vapor as humidity. Other possibilities are vacuum drying, where the source of heat may be by conduction or radiation and the vapor is removed by the vacuum system. Another possibility is drum drying, where a heated surface is used in connection with aspirators to draw the vapor outside the site. The term "drying" is a relative one, and simply means that there is a further reduction in the moisture content from some initial level provided by mechanical dewatering to some acceptable lower level. For example, a moisture content of 10-20% by volume would normally allow particles to flow freely, yet suppress dust formation. The necessity for drying may be to make a product suitable for sale (e.g. paint pigments), or for subsequent processing. When a solid dries, two fundamental and simultaneous processes occur: (1) heat is transferred to evaporate liquid; (2) mass is transferred as a liquid or vapor within the solid and as a vapor from the surface. These factors governing the rates of these processes determine the drying rate. Commercial drying operations may utilize heat transfer by convection, conduction, radiation, or a combination of these. Industrial dryers differ fundamentally by the methods of heat transfer employed. However, irrespective of the mode of heat transfer, heat must flow to the outer surface and then into the interior of the solid.
77
II.
OBJECTIVES 1. To produce drying and drying rate curves for a wet solid being dried with air of fixed temperature and humidity. 2. To determine the critical and equilibrium moisture contents, bound and unbound moisture of the wet solid being dried.
III.
METHODOLOGY 3.1 Materials: 1. 2. 3. 4. 5. 6. 7. 8.
Sand Sieved to approximately 500 microns 2-sling psychrometers 8-thermometers Weighing instrument Oven (if necessary) Stop Watch Water Container
3.2 Equipment/Devices: 1. Tray Drier 2. Sieve Shaker
3.3 Procedure Design a detailed procedure that will attain the experimental objectives. Partial Procedure:
Screen sufficient dry sand (bone dry) to approximately 500 mesh using sieve
shaker to fill the four drying trays to a depth of about 10 mm each. Weigh accurately the dry sand that will be loaded to four drying trays. Also,
weigh accurately each empty tray. Place the sand on a suitable container and saturate it with water. Remove the sand from the container and drain the excess free water. Load the sand evenly and smoothly into the drying trays, taking care to avoid any spillage. The total weight of the wet sand should be noted before drying commences.
IV.
RESULTS AND DISCUSSION 78
IV.1
Results
Presented here is the tabulation of computed results. Graphs that shows important relationships and trends are given as follows. Table 1. Calculated moisture of sand using its mass per time interval Time (min) 0 5 10 15 20 25 30 35 40 45 50 55 60 65
Mass of Sand (g) 1830 1810 1790 1770 1740 1705 1670 1650 1625 1605 1580 1571 1543 1500
Moisture 0.16120 0.15193 0.14246 0.13277 0.11782 0.09971 0.08084 0.06970 0.05538 0.04361 0.02848 0.02292 0.00518 0
moisture vs time 0.18000 0.16000 0.14000 0.12000 0.10000 Moisture Content, Xe
0.08000 0.06000 0.04000 0.02000 0.00000
0
10
20
30
40
50
60
70
Time (t)
Figure 1. Moisture content versus time. 79
IV.2 Discussion In this experiment, medium fine sands were used because sand requires short drying time due to its given particle size. The solids (sand) were oven dried to determine its moisture content. MC should be at lowest since the sand was intended to be bone dried. From the graph of it was shown that the highest drying rate is found at the initial condition wherein highest moisture content is also present. It was also observed that the moisture content decreases with respect to time from 0.16120 to 0.00518 in just an hour of drying using the tray dryer equipment.
V.
CONCLUSION According to the data obtained, the weight of the tray of sand is decreasing as time proceeds. This is also shown in the graph of free moisture content vs. time. In this case, the graph plotted has negative gradient. The drying rate can be determined from the gradient of the graph. Raw data of the weight of the wet sand at an increasing time, dry bulb and wet bulb temperature, weight of bone dry sand are found in the appendix. From the raw data obtained, a series of calculations were made as seen in the appendix and the values of the free moisture content, equilibrium moisture and drying rate are tabulated in table 1. Data from the table were plotted in a graph as shown in figures 1 & 2. Relationship of the different parameters can now be established VI.
APPENDICES
RAW DATA Table 1. Conditions of entering and leaving air in the tray dryer. Time (min) 0 5 10 15 20
Mass of Sand (g) 1830 1810 1790 1770 1740
Conditions of ENTERING air Dry Temp Wet Temp 33 24 35 26 35 24 36 25 24 33
Conditions of LEAVING air Dry Temp Wet Temp 34 30 38 34 40 36 40 36 40.5 37 80
25 30 35 40 45 50 55 60 65
1705 1670 1650 1625 1605 1580 1571 1543 1500
24 32 33 33 35 35 35 35 33
33 23 24 24 25 25 25 25 24
38 33 40 42 40 38 43 40 40
38 39 40 43 40 36 38 39 39
Table 2. Average temperature of all points. Time 0 5 10 15 20 25 30 35 40 45 50 55 60 65
Point 1 32.4 34.6 34.9 35.3 34.6 34.1 33.6 33.8 33.9 34.4 35.1 35.4 35.2 34.3
Temperature of Preheated Air (Drying Medium), ˚C Point 2 Point 3 Point 4 Point 5 Point 6 Point 7 Average Temp 30.7 33.6 44.7 33.8 47.7 57 39.99 32.4 34.8 69.8 67.7 67.7 56.5 51.93 32.3 32.7 69.6 67.9 66.2 66.9 52.93 33 33.1 68.6 66.6 67.3 64.7 52.66 32 32.3 69.7 67.7 67.3 64.7 52.61 31.4 31.9 67.1 65.1 64.4 64.6 51.23 31 31.3 63.2 64.8 64.6 62.7 50.17 31.3 31.5 68.2 66.1 65.9 65.6 51.77 31.3 31.7 65.8 64.1 63 63.9 50.53 31.9 32.2 70.7 68.4 69.3 66.9 53.40 32.6 32.7 65.3 63.7 63.5 64 50.99 32.8 32.2 70.3 69.1 67.1 69.4 53.76 32.7 32.4 67.7 66.5 67.5 65.2 52.46 31.9 33.4 62.4 61.9 62.1 60.9 49.56
SAMPLE CALCULATION Moisture content can be calculated by using below equation: MC=
Mi−Mf Mi
= 0.914 (data from group 9)
Ws = (1 – MC) W = (1-0.914) x 1830 = 1535
81
Xt
Xt
=
W −Ws =¿ W
1830−1535 1830
= 0.16120
Free MC=Mi- Mf*
free MC X*= Dry Solids X =X t −X ¿
The drying rate R was not calculated since no air velocity data was recorded.
DOCUMENTATION
82
Date & Time Started: September 13, 2016 Group No. 7
Date & Time Finished: September 13, 2016 Instructor/Supervisor: Engr. Juvyneil E. Cartel
EXPERIMENT NO. 11 HYDRODYNAMICS IN PACKED COLUMN
I.
Introduction Packed columns are used for efficient gas-liquid contact processes.It is used in processes like gas absorption, desorption(stripping), distillation etc.The liquid entering at the top normally flows downward through the column, driven by the gravitational force. In gas absorption, the gas entering at the bottom must be moved by the blower or fan. In order to maintain the upward flow of gas or vapor, the pressure at the top of the column must be less than at the bottom. This pressure drop is an important factor 83
in the design of the packed column. Because the liquid downflow occupies the same channels as the gas upflow, the pressure drop is really a function of both flows. II.
Objective(s) of the Experiment 1. To determine the pressure drop across the dry packed column as a function of the air flow rate. 2. To determine the effect of liquid flow rate on the pressure drop along a packed column. 3. To study the hydrodynamic behavior of the column by identifying loading and flooding conditions.
III.
Methodology 3.1 Materials and Equipment: Materials/ Equipment Gas Absorption Column
CO2 cylinder with integral P regulator 300 mL of 1.0 M Caustic Soda Standard 0.0277 M NaCl
Standard 0.1 M Na2CO3
Phenolphthalein Indicator
Uses The purpose of a packed bed is typically to improve contact between two phases in a chemical or similar process. A packed column is a pressure vesselthat has a packed section. This serves as the CO2 supply vessel for the overall experiment This alkali is deliquescent and readily absorbs moisture and carbon dioxide in air. Sodium chloride is the salt most responsible for the salinity of seawater and of the extracellular fluid of many multicellular organisms. Pure sodium carbonate is a white, odorless powder that is hygroscopic (absorbs moisture from the air). Phenolphthalein is often used as an indicator in acid–base titrations. For this application, it turns colorless 84
inacidic solutions and pink in basic solutions. Hempl Apparatus Tap Water Thermometer Barometer
For Dilution purposes of the sample It is utilize to determine the exact and accurate temperature change For the pressure measurement and monitoring.
3.2 Procedure 1. We make sure that the reservoir tank contains about three-quarters full of water. 2. Turned on the water pump and allow water to flow down the column at 3 liters per min for about a minute. Closed the water valve then switch off the pump. Allowing the water to drain for about 5 minutes. 3. Turned on the air compressor. Adjusting the air flow rates and get corresponding pressure drop. Repeating the procedure to get eight readings for increasing flow rates and eight readings for decreasing flow rates. 4. Turned on the water pump. Allowing water to flow down the column at a constant flow rate. Repeating the procedure by increasing the air flow rate and noting the state of the liquid flow through the packing. It might be necessary to reduce the interval of the air flow rate in order to get well-defined phases of pressure drop behavior. Also, pressure drop may not become constant when flooding point is being approached. Adjustment of the gas flow rates might be necessary. 5. Repeating the procedure for two more liquid flow rates until inversion is reached where the pressure drop become unstable. Taking note and record the point where air flow rates start to induce flooding. 6. When pressure drop becomes very high and unstable, lower the air flow just enough to avoid water overflowing and then proceed repeating the process except that at this time the air flow is being decreased. 85
7. It is interesting to try repeating one of the trials at the same air and water flow rates after a flooding condition has been obtained and then comparing the results. 8. When the experiment is finished, we closed the valves then turn off the compressor and the pump. Clean the surrounding.
IV.
Results and Discussion IV.1 Results: Air flowrate only
Air Flowrate 20 40 60 80 100 120 140 160
Pressure P1 0.2 0.4 0.8 1.6 2.6 4 5.4 6.4
P2 -0.4 -1 -1.2 -2 -3.2 -4.2 -6 -7
Pressure Drop 0.6 1.4 2 3.6 5.8 8.2 11.4 13.4
86
Air Flowrate vs. Pressure Difference 10 8 6
Pressure Diference
4 2 0 0
20
40
60
80
100
120
140
Air Flowrate x
I.
Air flowrate with Water flowrate Water Flowrate 1.0 2.0 4.0 6.0 8.0
20 0.3 2.2 3.6 8.8 84.0
40 2.0 3.8 10.8 71.0 89.8
60 3.6 6.2 56.0 72.4 93.7
Air Flowrate 80 100 7.6 11.8 13.2 21.8 60.8 70.6 87.0 95.6 96.0 99.3
120 18.0 46.6 76.0 88.5
140 26.6 70.6 88.8 93
160 39.2 89.2 94.4 95.6
87
Pressure Drop vs. Airflowrate at Different Water Flowrates 180 160 140
at 1L/min water flowrate
120
at 2.0 L/min water flowrate
100
at 4 L/min a\water fowrate
PRESSURE DROP 80 60
at 6 L/min water flowrate
40
at 8 L/min water flowrate
20 0 0
50
100
AIR FLOWRATE
V.
Conclusion We concluded, that all of the objectives were achieved based on the performed experiments and the data gathered and collected. The pressure drop was determined as a function first of air flow. Effects of the varying of liquid flow rates to the pressure drop could be observed and data were also collected. Sudden change of the values was observed as we change the flow rates. As the flow rates increases, tendency of flooding also increases.
VI.
References GEANKOPLIS, C.J. Transport Processes and Unit Operations, 3rd Edition, PrenticeHall International Inc., New Jersey(1993) Unit Operations of Chemical Engineering, 4th Edition (McCabe, W.L., et.al,)
88
Republic of the Philippines EASTERN VISAYAS STATE UNIVERSITY Tacloban City
CHEMICAL ENGINEERING DEPARTMENT
COMPILATION OF EXPERIMENTS in ChE 512L Chemical Engineering Laboratory II 89
Submitted by: Hannah Mae Gepiga Micah Mae Morbos Rhea Orevillo Floila Jane Ymas BSChE 5A Submitted to: Engr. Juvyneil E. Cartel Instructor, ChE 512L In partial fulfilment of the requirements in Bachelor of Science in Chemical Engineering
September 26, 2016
TABLE OF CONTENTS
Venue
(DLSU)
Title of Experiment
Rating
Experiment No. 1: Pressure Drop and Gas Absorption in Packed Columns
(DLSU)
Experiment No. 2: Binary Batch Distillation
(AdU)
Experiment No. 3: Spray Dryer Experiment
(AdU)
Experiment No. 4: Cooling Tower Experiment
(DLSU)
Experiment No. 5: Reaction Kinetics Experiment using Tubular Flow Reactor 90
(DLSU)
Experiment No. 6: Step Response for First Order System
(AdU)
Experiment No. 7: Batch Sedimentation
(AdU)
Experiment No. 8: Size Reduction and Screening
(DLSU)
Experiment No. 9: Agitation and Mixing Experiment
(AdU)
Experiment No. 10: Drying at constant drying conditions
(DLSU)
Experiment No. 11: Hydrodynamics in Packed Column
91
