Gas Absorption Draft Standard Operating Procedure R.C. 9-14 Scope Page 1 Equipment Overview Page 1 Safety Page 2 Operating Procedure Page 4 Equipment Description Page 16
Gas Absorption Experiment Draft Standard Operating Procedure R.Cox 9/2014 Scope This document is intended to serve as a guide to the operation of the gas absorption experiment located in the Senior Laboratory at the Department of Chemical Engineering, University of Utah. This procedure details system operation using column # 1 with blower # 2. Before operating this equipment, all personnel must receive equipment specific training from the lab manager. Be sure to read this entire document before beginning you experiment. Equipment description In gas absorption a soluble component is absorbed by contact with a liquid phase in which the component is soluble. This system is used for scrubbing gas streams of components such as sulfur dioxide, carbon dioxide and ammonia. In this experiment, a mixture of water and sodium hydroxide is used to remove CO2 from air. The system demonstrates mass transfer for two-phase systems. The gas absorption experiment consists of two columns, each filled with different packing material. The gas absorber experiment is comprised of the following systems: Absorption columns Column number 1 is packed with ceramic Berl saddles. Column number 2 is packed with metal Pahl Rings. Both columns have a six -inch inside diameter and a length of approximately nine and one-half feet. Liquid Circuit The liquid circuit consists of two 140-gallon tanks; an 80 gallon jacketed mixing tank, and associated pumps & valves. In addition, the liquid circuit includes two heat exchanges that are currently not operational. All piping for the liquid circuit is 1-inch schedule 80 CPVC, 1-inch schedule 40 PVC or 1-inch 304 stainless steel. 1
Air circuit The air circuit consists of two blowers, associated valves and 2-inch schedule 80 PVC rated to 400 PSI. The gas injection and analysis system consist of a CO2 cylinder, regulator, regulator heater, rotameter and associated gas analyzers. A detailed list of the equipment incorporated in the gas absorption experiment is included at the end of this document. Safety Safety glasses and hardhats must be worn when operating this equipment. Do not operate this equipment alone. Note that certain procedures require the coordinated efforts of two people. When filling the mixing tank do not exceed the 50-gallon level. Under no circumstances should this equipment be left unattended while in operation. The use of caustic solutions, compressed gas, large volumes of water and multiple sources of electrical power make attention to safety paramount when operating this equipment. Accidental flooding will result in caustic liquid exposure to equipment and personnel working on both floors below the gas absorber experiment. Sodium Hydroxide is extremely corrosive and highly reactive. Use Chloroflex gloves and wear safety glasses and a face shield when mixing sodium hydroxide and water. Never add water to a corrosive. Always add corrosives to water. When mixing with water, stir in small amounts of corrosives slowly. Label containers. All chemical containers must be clearly labeled with the chemical contents and concentrations. Keep containers closed when not in use. Empty containers may contain residues which are hazardous. Triple rinse all empty containers before discarding them to the trash. Anytime the basement neutralization tank is in use, a team member must remain in room 2505 to monitor the basement tank system for leaks. 2
Operating Procedure This procedure describes the operation of the gas absorber experiment with the following restrictions. Some valves are not labeled or mentioned in this SOP these valves should not be adjusted. Heat exchangers are not used Cooling water is not used This operating procedure details system operation using column # 1 with blower # 2. Prior to startup: Disconnect the gas sample lines from both the desiccant modules. Verify that all tanks are empty, including the basement neutralization tank. Both tanks have a sight glass indicating the tank level, however, the sight glass does not read to the bottom of the tank. If the sight glass does not indicate liquid in the tank, it is possible that the tank may contain liquid below the level of the sight glass. To confirm that the tanks are empty the tank pumps must be operated until no flow is observed. Care must be taken not to run the pumps without liquid in the line. Consult the lab manager for assistance. Verify that the column pressure transducers are connected to the column you will be using. Switch on the Validyne pressure sensor module located below the computer. Open both the 9500 and 9510 gas analyzer bypass needle valves. To feed column # 2 set the liquid circuit valves as listed above but close V8L and open V9L. A. Startup B. Log on to the computer control system. C. The password and user name are posted on the computer monitor. D. Double-click on the GAS ABSORBER icon located on desktop. E. The event log viewer screen is displayed, you will see a series of about five messages, close the event log viewer. F. The opening control window is displayed; note the information regarding system operation and data storage. G. Select start. The main control window is displayed. 3
H. Tank level alarms may be active depending on tank levels. I. If a high level alarm is active stop operation and neutralize and drain tanks as required. 2. Set Valves to fill mixing tank. A. Close V1L and V2L. B. Close V16L, basement tank main output valve. C. Before filling the mixing tank with water: The water supply line incorporates a totalizing meter, before opening the main water valve note the reading on the totalizer, once you have filled the mixing tank to the 50 gallon level shut of the main water feed valve and again note the reading on the totalizer. Use these totalizer readings to verify the amount of water in the mixing tank. Do not fill the mixing tank above the 50-gallon mark. 3. Fill the mixing tank. Before operating with caustic, the system should be tested with water. Once the correct flow rates are established using water, then the system may be operated with caustic. A. Place the water feed hose in the mixing tank, while one person is firmly holding the water hose a second person will slowly open the main water supply valve (green ball valve) located behind and to the left of the mixing tank. B. Fill the mixing tank to the 50-gallon mark. 4. Adding sodium hydroxide: o o o Never add water to a corrosive. Always add corrosives to water in small amounts. Wear lab coat, safety glasses, Chloroflex gloves and a face shield when mixing NaOH & water. Gently mix the solution using the detachable mixer located next to the mixing tank. 5. Set the valves to pump liquid from the mixing tank to the feed tank. Open: V1L Close: V2L 4
V3L V4L This valve must always be closed Once you are ready to pump the contents of the mixing tank to the feed tank, set the mixing / feed valves as indicated above. The mixing tank pump is controlled by two switches; 17C located on the rear switch panel and a second 17C switch located on the front switch panel. The 17C (mixing tank switches) must both be in the on position to power the mixing tank pump. 6. Pump from the mixing tank to the feed tank. A. Confirm that the mixing tank pump switch located on the rear panel is in the off position. B. Turn on the mixing tank pump switch located on the front switch panel. C. The mixing tank pump may now be controlled by switch 17C on the rear switch panel, this allows the operator to monitor the tank level and stop the pump before the mixing tank runs dry or before the feed tank is over-filled. D. Stop mixing tank pump as soon as the mixing tank is empty. E. Repeat procedures 1-3 as required to fill the feed tank to the desired level. F. Constantly monitor the level of the feed tank do not allow the feed tank to fill above the 115 gallon / 43 inch mark on the sight glass. 7. Set liquid flow valves to pump liquid from feed tank to column 1. Open V5L recycle valve V6L Close V9L V3L V8L V10L V12L V14L To feed column # 2 set the liquid circuit valves as listed above but close V8L and open V9L then adjust column 2 liquid input flow using V11L. Adjust column 2 output flow using V15L. 8. Set airflow valves 5
A. Open airflow vent valve 1A 100% B. Set air flow column select valve 2A to direct flow to the desired column. 9. Select blower -Only one air blower may be operated at a time A. Adjust the blower select valve (yellow ball valve located between the blowers) to select blower #2. B. Before operating the blowers make sure that there are no power cords or materials obstructing the rear intake side of the blower. C. Open the main airflow bleed valve V1A to 100% open. D. Verify that the blower #1 power switch (13A) and blower #2 power switch, located on the front panel, are in the off position. E. Insert the Blower # 2 power cord into the blower #2 (13A) outlet located on the wall above the blower. F. If you select blower #1, plug it into the outlet labeled blower #1. Read Section 10 and 11 Before Pumping Liquid into the Column. 10. Pump liquid from the feed tank to the column. A. Verify that the feed tank recycle valve - valve 5L is open 100 %. B. Switch on the feed tank (Tank 1) pump. The switch is located on the front switch panel. C. With the feed pump on, the column flow must be constantly monitored for flooding. Do not leave the column unattended. D. Monitor liquid flow to column 1 using the flow meter located below V10L. 11. Adjust the liquid feed flow-rate. Liquid flow is controlled by adjust the recycle / flow control valve V5L This procedure requires two people: one to adjust valve 5L and one to monitor the liquid flow rate on rotameter. 6
To adjust the flow rate to column 1, verify that feed valve V10L and drain valve V14L are open 100% then gradually close the recycle valvev5l on the feed tank until the desired flow rate is achieved. For fine flow rate adjustment use a combination of recycle valve 5L and valve 10L. It will take a few minutes for the liquid flow to stabilize within the column. Once the flows are reasonably stable, adjust V14L located at the bottom of column #1 by slightly closing valve V14L to maintain a level of liquid in the bottom of the column that just reaches the wide part of the column, about 4 inches of liquid in the bottom of the column. This will prevent gas from going out the bottom of the column. Monitor the liquid flow out of the column, watch for flooding at the bottom of the column, if liquid backs up at the bottom of the column to the point where it is about to enter the gas flow inlet immediately reduce the flow of liquid into the column and open V14L. 12. Switch on the air blower A. Once the liquid flows are stable, switch on the selected air blower. B. The blower are switched on and off from the switches located on the front panel. C. Monitor airflow by measuring the pressure drop across orifice plate # 1 as displayed on the Fluke 725 meter and on the computer. The system is generally operated at an airflow that is lower than the air flow rotameter range. D. The air flow is controlled by venting part of the blower output to atmosphere using valve 1A. E. Adjust air and liquid flow to the desired set points taking care not to flood the bottom of the column. F. Once the air and liquid flows have stabilized, adjust the CO2 flow as described in the next section. Gas sampling instruments System description The 9510 and 9500 gas analyzers measure volumetric percent of gas concentration, the range on both instruments is 0 25 %. Refer to the instrument documentation for further information. Exceeding the pressure and flow ratings for the gas analyzers will permanently damage the gas analyzers. 7
Follow the procedure below to insure that the sample gas pressures and flows are within the operating parameters for the gas analyzers. The maximum pressures and flow rates are: 9510 CO2 Monitor: 100-300 ml/min at 2.0 psig (55.35 inches of water) maximum. 9500 O2 & CO2 Monitor: 0.5 1.0 L/min at 1 psig (27.68 inches of water) maximum. The gas flow to each analyzer is feed through a desiccant to remove moisture prior to entering the pressure and flow measurement apparatus. This pressure and flow measurement equipment which consist of a magnehelic pressure gauge and flow meter for each instrument, allows the user to measure the pressure and flow of the gas sample before it is fed to the gas analyzers. Before connecting the column pressure lines to the desiccant connection points make sure that the analyzer bypass valves are 100% open. 13. Connecting the gas sampling instruments All measurements should be taken with the air and liquid systems running at steady state. A. Before connecting the gas sample line to the analysis equipment. Open the gas analyzer bypass valves 100%, these valves are located on the back / inlet of each gas analyzer. With the bypass valves open monitor the pressure and flow gauges to insure the system does not exceed the analyzers maximum ratings. B. Once the gas and liquid flows have reached steady state connect the gas sample line labeled (Bottom of column 1) to the input of the desiccant labeled bottom of column to 9510 then connect the gas sample line labeled (Top of Column 1) to the input side of the small desiccant labeled top of column to 9500. C. Partially close both the 9500 and 9510 needle valves to establish optimal flow and pressure to the analyzers. Consult the lab manager for assistance if needed. 14. Adjust the CO2 flow. A. Plug the regulator heater into the power strip, turn on the power strip and set the regulator heater to 25 % power. The normal operating range for the heater is 25 50 %. B. Verify that the CO2 regulator adjustment is rotated counter-clockwise such that the regulator output pressure will be zero when the main tank valve is opened. C. Open the CO2 flow needle valve 100%. This valve is located at the input to the CO2 rotameter. D. Open the main CO2 cylinder tank valve ½ turn. 8
E. Slowly rotate the regulator output pressure adjustment to the right until the tank outlet pressure displayed on the 0-100 psi regulator gauge on the left- reads ~ 10 psi. F. Read the CO2 flow on the rotameter. Adjust the CO2 flow rate by adjusting the regulator outlet pressure and the needle valve at the input to the rotameter. The regulator is the primary means of flow the control the needle vale is for fine control. G. Monitor the CO2 regulator and copper feed line for accumulation of frost. If the regulator and line are becoming too cold increase the regulator heater out level. Consult the lab manager for more detailed information regarding regulator freezing. H. If the regulator becomes so cold that control of the CO2 flow is lost, immediately close the main CO2 cylinder valve. 15. Reading CO2 in the Gas Stream A. Once the CO2 flow has reached steady state and this might take a minute - you should see an increase on the CO2 meter displays. B. If the 9510 analyzer is not reading gas flow try turning on the 9510 sample pump to pull gas into the instrument, the pump switch is located on the top right side. C. Constantly monitor the pressure and flow to insure that you do not exceed the ratings for the gas analyzers. 16. A. Complete the run until the feed tank is empty. B. Constantly monitor the basement tank level to insure that it does not exceed 100 gallons. C. Constantly monitor the computer display to insure that a high level alarm is not triggered. If a high level alarm is triggered immediately shut off the pump, then neutralize the basement tank contents if required. Once neutralized the basement tank contents may be pumped to drain as outlined in the following steps. 17. Set valves to recycle basement / neutralization tank Verify that the ph of the liquid in the basement / neutralization tank is within disposal range. A. Set neutralization / basement tank valves to recycle the contents of the basement tank. 9
B. Set V19L flow output to the right C. Open V16L 18. Switch OFF the basement tank pump power switch located next to the neutralization tank. Switch ON the neutralization tank switch that is located on the front system control panel. Once the operator is in front of the basement neutralization tank you can now switch the tank pump onn and off as desired suing the switch next to the tank. Switch on the basement / neutralization tank pump. Monitor the ph reading on the computer, if the ph does 19. Set valves to pump from neutralization tank in basement to mixing tank Do not pump more that 50 gallons at a time into the mixing tank. Open V16L V18L Close V2L V4L Set V19L to the left Set V20 L to PVC pipe 20. Neutralizing caustic prior to disposals Wear Chloroflex gloves, lab coat and face mask when working with concentrated acid. Mix all concentrated acid solutions in the fume hood. A. Set neutralization / basement tank valves to recycle the contents of the basement tank. B. Set V19L flow output to the right C. Open V16L D. Calculate the amount of acid required to lower the ph of the liquid in the basement tank to within the safe disposal range of (5 10pH). E. Disconnect the acid container from the metering pump located next to the feed tank. Take the acid container to a fume hood and add the required amount of acid. 10
F. Cap the acid container and return it to the the metering pump. Connect the metering pump acid feed line to the acid container. G. Verify that the metering pump output line is connected to the PVC acid line. H. Start the basement neutralization pump. I. Start the acid metering pump at 10 ml/min. J. Monitor the ph in the basement neutralization tank. K. Adjust the flow rate of the acid metering pump as required. L. Stop the acid metering pump as soon as the ph of the neutralization tank drops below a ph of 10. M. Disconnect the acid metering pump line from the acid container and cap the acid container. N. Place the acid metering pump feed line and cap on an 8 liter water container that is 50 % full of water. O. Label the water container. P. Store any remaining acid in the 8-liter Nalgene container remember to label the container with the contents and concentration. 21. Set the neutralization tank valves to pump the contents of the neutralization tank to drain. A. Open V16L B. Set V19L to flow to the left, towards V20L. C. Set V20L to flow to the hose. D. Verify that V16L is open. 22. Pump liquid from the neutralization / basement tank to drain Two person procedure: Coordinate with team to switch on the basement /neutralization tank pump, while the pump is on, a team member must remain in room 2505 to monitor the flow of liquid until the tank is empty. Once the tank is empty, immediately notify the pump operator to shut off the pump. 23. Final Shutdown: 11
A. Verify that all pump and blower power switches on both the outlet panel and the equipment control panel are in the off position B. Close the main CO2 tank valve C. Close basement tank main valve V16L D. Set basement valve V19L to flow output to the right E. Close Feed tank main valve V6L F. Unplug all blowers G. Close the mixing tank outlet valves V1L, V2L and V3L H. Properly label and store any chemicals in use I. Exit the Opto22 control software; do not log off the computer J. Switch off the power to the Validyne pressure module. K. Check out with the lab manager Gas Absorber Valve Directory Do not adjust equipment valves that are not listed Liquid Circuit Valves Location Function Comments V1L Main Mixing tank out V2L V3L Mixing tank drain Mixing tank to feed tank V4L Mixing tank to heat exchanger ALWAYS CLOSED V5L V6L V7L V8L V9L Feed tank recycle Feed tank main output valve Not Used Column # 1 feed Column # 2 feed 12
V10L V11L Column #1 flow control Column #2 flow control V12L Column # 1 feed ALWAYS OPEN V13L Column # 2 feed ALWAYS OPEN V14L V15L Column #1 drain Column #2 drain V16L Basement- Room 2505 Neutralizing tank, (tank 2) main output valve V17L Basement Not Used V18L Basement Basement pump output : Refer to flow indicator arrows on valve V19L Basement Basement pump output: 3-way: Recycle / To Mixing Tank / To Drain Location Function Comments Main Air Blower Selection Yellow Ball Valve Air flow control Main Air Flow Control 13
Gas Absorption Experiment Equipment Description Air Flow Circuit Blower #1 Spencer Turbo-Compressor 30 CFM - 64 oz, s/n 51219, lot # 35108 Blower motor: Black & Decker 2 HP, 60 cycle, 240 VAC, 10 Amp, 10,000 RPM, Type CSC Blower #2 Spencer Turbo-Compressor 12 CFM - 35 oz, s/n 43903, lot # 33662 Rotometer: Air Flow Omega Engineering FL45200A series Range: 40-240 SCFM Air velocity transmitter: JLC International model EE66 Range 0-400 ft/min Orifice Plate #1: 0.814 inches i.d, no bevel - Pipe Size 1.9 inch o.d, 1.5 inch i.d Orifice Plate # 2: 0.530 inches i.d, no bevel - Pipe size 1.4 inch o.d, 1.0 inch i.d Liquid Circuit Rotometer: Liquid Flow 14
Omega Engineering FL46300 series Range: 0-17 GPM Mixing tank Capacity: 80 Gal Maximum allowable level - mixing tank: 50 Gal Capacity of feed & neutralization tanks: 115 Gal ph transmitter - neutralization tank: Alpha ph 500 transmitter ph probe: Cole-Parmer p/n 35811-71 Pump data Mixing tank pump motor: AMT Model 3696-975-97, Pump head # 3690-002-00 Feed Tank Pump: Eastern Industries, model B 34 Max flow rate into column #1 = 10 GPM adjustable from 1-10 GPM Neutralization Tank Pump: Same as feed pump Metering Pump: Pulsatron E Plus Series, Maximum flow 630.9 mil/min, Min flow 6.3 mil/min CO2 Flow Control CO2 gas feed system Mass Flow Controller Omega model FMA5542 / Rotameter - manual valve 15
Range = 0-80 L/min CO2 insertion points: Multiple locations CO2 Measurement System Alpha Omega Instruments: Series 9510 CO2 Analyzer Maximum input sample pressure: < 2.0 psi Sample flow rate: 100-300 ml/min, 300 ml/min maximum Range 0-25 % Alpha Omega Instruments: Series 9500 CO2 / O2 monitor: O2 / CO2 range: 0-25 % Sample flow rate 0.5-1.0 L/min Maximum input sample pressure < 1.0 psi Calibration standard: 20% CO2 in nitrogen balance Temperature Measurement Type T Thermocouples Control & data logging Opto22 16