Gas Absorption Draft Standard Operating Procedure

R.Cox 1-2012

Scope Page 1

Equipment Overview Page 1

Safety Page 2

P&ID Page 3

Operating Procedure Page 4

Valve Directory Page 14

Equipment Description Page 16

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Gas Absorption Experiment – Draft Standard Operating Procedure

R.Cox 11/8/11

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.

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.

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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 mass flow controller and associated measuring devices.

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.

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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:

• Meet with the lab manager to verify that all tanks are empty. 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, which could result in flooding. To confirm that the tanks are empty the tank pumps must be operated until no flow is observed. This procedure must be performed with the assistance of the lab manager.

• Close both the 9500 and 9510 gas analyzer input needle valves.

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.

1. 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.

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2. Fill the mixing tank.

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.

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.

3. Adding sodium hydroxide:

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.

4. Set the valves to pump liquid from the mixing tank to the feed tank.

Open: Close:

V1L V2L

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.

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5. 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 114 gallon / 43 inch mark on the sight glass.

6. Log on to the computer control system.

The password and user name are posted on the computer monitor.

Double-click on the GAS ABSORBER icon located on desktop.

The event log viewer screen is displayed, you will see a series of about five messages, close the event log viewer.

The opening control window is displayed; note the information regarding system operation and data storage.

Select start. The main control window is displayed.

Tank level alarms may be active depending on tank levels.

The CO2 flow control is located in the upper right of the window.

For manual CO2 control, use the needle valve and rotameter located next to valve the main air vent valve V1A.

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7. Set liquid flow valves to pump liquid from feed tank to column 1.

Open Close

V5L V9L

V6L 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

Set the airflow valves to the default positions listed below. Refer to the Valve Directory for valve V2A – V10A settings.

Air Flow Valve Default Settings – Air flow to column #1

Open Closed

V15A V16A

V14A V13A

V11A

V12A

V1A

To select airflow to column #2, make the following adjustments to the valve settings as shown in the valve directory.

• Set V9A to allow flow in from the top and out through the right side.

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• Close V11A.

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.

10. Pump liquid from the feed tank to the column.

A. Switch on the feed tank (Tank 1) pump. The switch is located on the front switch panel.

B. With the feed pump on, the column flow must be constantly monitored for flooding. Do not leave the column unattended for any reason.

C. Monitor liquid flow to column 1 using the flow meter located below V10L.

11. Adjust the liquid feed flow-rate.

To adjust the flow rate to column 1, verify that V10L and V14L are open 100% then close the recycle valveV5L on the feed tank and then adjust the liquid flow to column #1 using V10L.

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 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.

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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. The system is generally operated at an airflow that is lower than the column 1 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.

Verify 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 needle valve, pressure regulator and desiccant – to remove moisture – prior to entering the pressure and flow measurement apparatus. This pressure and flow measurement equipment allows the user to measure the pressure and flow of the gas sample before it is fed to the gas analyzers. Note that the desiccant on the 9510 incorporates a bypass valve.

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13. Connecting the gas sampling instruments

A. All measurements should be taken with the air and liquid systems running at steady state.

B. Verify that both the 9500 and 9510 gas analyzer input needle valves are closed.

C. Set the both valves on the pressure and flow measurement apparatus to Plug, this will block the gas flow and allow the user to measure the maximum pressure to the analyzers.

D. Set the desiccant bypass valve on the 9510 system to flow gas through the desiccant.

E. Connect the gas sample line labeled (Top of Column 1) to the input side of the 9500 system needle valve.

F. Connect the gas sample line labeled (Bottom of column 1) to the input of the 9510 system needle valve.

G. With both sensor select valves set to the plug setting, slowly open the 9500 input needle valve until the line pressure is displayed on the magnehelic. Repeat this procedure, adjusting the needle valve on the 9510 system, to measure the pressure on the 9510 magnehelic.

H. If the pressure on either system exceeds the pressure limits listed above, consult the lab manager.

I. Close both the 9500 and 9510 needle valves.

J. Rotate the 9510 analyzer select valve to the sensor position.

K. Slowly open the 9510 needle valve while monitoring the gas flow rate to the analyzer.

L. Adjust the needle valve so that the gas flow is below 300ml/min as indicated by the yellow tape on the 9510 flow meter.

M. Repeat the previous three steps to set the flow for the 9500 analyzer. Note the yellow tape on the 9500 analyzer marks the maximum flow of 1 L/min for the 9500 analyzer.

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14. Adjust the CO2 flow.

A. Open the main CO2 cylinder tank valve ½ turn.

B. On the computer control window, set the CO2 mass flow controller to the desired set point.

C. During operation, constantly monitor the feed tank level.

D. Shut off the feed pump as soon as the feed tank level is below the sight glass scale.

15. 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.

B. Set V19L flow output to the right

C. Open V16L

D. Switch on the basement / neutralization tank pump.

Monitor the pH reading on the computer, if the pH does

16. 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 Close

V16L V2L

V18L V4L

Set V19L to the left

Set V20 L to PVC pipe

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17. 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.

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.

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P. Store any remaining acid in the 8-liter Nalgene container – remember to label the container with the contents and concentration.

18. 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.

19. 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.

20. Final Shutdown:

A. Verify that all pump and blower power switches are in the off position

B. Close the main CO2 tank valve

C. Close basement tanks 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

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J. 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

Mixing tank drain

V3L

Mixing tank to feed tank

V4L

Mixing tank to heat exchanger ALWAYS CLOSED

V5L

Feed tank recycle

V6L

Feed tank main output valve

V7L

Not Used

V8L

Column # 1 feed

V9L

Column # 2 feed

V10L

Column #1 flow control

V11L

Column #2 flow control

V12L

Column # 1 feed ALWAYS OPEN

V13L

Column # 2 feed ALWAYS OPEN

V14L

Column #1 drain

V15L

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

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V19L Basement Basement pump output: 3-way: Recycle / To Mixing Tank / To Drain

When the flow indicating arrows on the valves V2A - V12A listed below are oriented as indicated by the arrows, air flow will be directed to column #1.

Air Circuit Valves Location Function Comments

Blower Select Valve Main Air Blower Selection Yellow Ball Valve

V1A Gate Valve

Air flow control Main Air Flow Control

V2A

V3A

V4A

V5A

V6A

V7A

V8A

V9A

V10A

V11A

V12A

V13A

Column #2 output

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V14A

Column # 1 output

V15A

2 inch line out Orifice plate

V16A

1 inch line out Orifice plate

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

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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

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:

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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

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