MPTL Plug Flow Reactor SOP

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Standard Operating Procedure

1. Introduction:

There are several plug flow (tubular) reactors in the Meldrum Process Technology Laboratory and the Unit Operations Lab. Figure 1 is a photograph of one of them. The figure shows a packed-bed reactor (different reactors have different geometries and packing). Reactors like this approximate the behavior of plug-flow reactors (PFRs). The flow field in these tubular reactors may be approximated as having a plug flow profile (as in a uniform velocity profile experienced in turbulent pipe flow). There is no radial variation in the reaction rate.

Do not proceed with testing without following all safety procedures. A basic list of safety considerations is provided in Section II of this SOP.

                         

Figure 1. Plug flow reactor.

2. Safety

  • All students must wear safety glasses when working in the lab.
  • Never leave this equipment operating unattended.
  • Mix all chemicals in a fume hood.
  • All chemicals, solutions, and standards must be stored in a sealed container. The container must be labeled with the chemical(s) name (not formula) and concentration, the operator/user’s name, hazards, and the date of storage.
  • All chemical containers must be sealed when not in use.
  • All unwanted material must be placed in an appropriate container. The container must be labeled “Unwanted Material”. The label must include the chemical(s) name and concentration, the user’s name and contact information, and hazards. If you have questions regarding labeling unwanted materials, consult with the lab manager.
  • Only pure water (no additives or contaminants) can go down the drains.

 

3. Equipment Description

The tubular reactor experiment incorporates the following equipment:

  • Masterflex peristaltic pumps: These pumps have a switch on the rear panel; they must be set to external for the computer system to control the pumps (Figure 2).
  • PVC reactor tube filled with glass beads and fitted with type T thermocouples Figure 3).
  • Opto22 Control System: Data are sampled every second and stored in an Excel-compatible file on the Desktop (in a folder labeled “Data” or similar). See the section on viewing your data for more information. Save your data to a flash drive. The computer is not on the network. For more information on saving data, see the “How to View and Save Data in Excel” section.
  • Sensorex Conductivity measurement system. The conductivity range is 0 to 19.9 millisiemens with a resolution of 0.01 millisiemens.

 

Figure 2. Masterflex peristaltic pump.

Figure 3. Reactor tube and conductivity sensor.

 

4. Procedures

  1. Determine what chemicals, calibration standards are required, and measurements you will need to make.
  2. Determine the flow rates for your reactants.
  3. Refer to the section on pump specifications and tubing to help determine what tubing is appropriate for your flow rates. Be sure to use only Masterflex tubing. If you are unsure about which tubing to use, check with the lab manager. The smaller the inner diameter of the tubing the lower the flow rate.
  4. Pumps need to be first calibrated – what flow rate are you getting? The pump(s) may be calibrated using a rotameter or a graduated cylinder/calibrated bucket and a stopwatch.
  5. Install the tubing to the peristaltic pumps. By using the same size tubing in both heads of one of the dual–head pumps you can achieve two identical flow rates.
  6. Connect the reactant feed tubing to the reactor inlet.
  7. You will use conductivity to determine concentration. You will need to run a standard solution to confirm the functionality of the conductivity meter and then run a series of dilutions of your reactants to build a calibration curve.
  8. Power up all equipment:
  • Switch on the power to the pumps using the grey toggle switch located on the front panel. Switch the toggle to the right or left to control the pump direction, the center position is off.
  • The Sensorex conductivity module does not have a switch. It is always on.
  • Do not touch the opto22 control hardware located behind the computer.
  1. Using the conductivity measurement system:
  • The conductivity probe is enclosed in a tee fitting which is mounted on a ring stand next to the reactor vessel. The probe connects to the conductivity transmitter (Sensorex Model CX 100).
  • Do not adjust the position of the probe within the tee. It is set at the correct depth and angle, adjusting the probe will disrupt data collection.
  1. Calibrate the conductivity system:
  • Determine the range of conductivity you want to measure.
  • Collect the required conductivity standards.
  • Set up a pump to pump just enough conductivity standard to fill the tubing and the tee. This is typically about 200 ml.
  • Place the conductivity standard in a beaker. Then, insert a small section of tubing into the beaker and then insert the tubing through a pump head. Connect the other end of the tubing to the barbed connection at the outlet. This will allow you to pump the conductivity standard into the tee/probe assembly, filling it from the bottom. You will also use this configuration to determine the concentration-conductivity relationship.
  • This completes the pump circuit allowing you to continuously pump conductivity standard solution through the probe assembly, bypassing the packed reactor.
  • Once the CX 100 conductivity meter, as well as the corresponding conductivity reading on the computer display, are reliably displaying the value of the conductivity standard you can stop the pump and disassemble the calibration setup.
  • Do not attempt to adjust the calibration setting on the CX100 conductivity meter. Determine the amount of feedstock you will require.
  1. Mix all chemicals/feedstock dilutions in a fume hood.
  2. Place your feedstock in 8-liter Nalgene containers available in the Unit Operations Laboratory “A”) on the shelf above the chemical storage.
  3. Feed the outlet stream of the system into a different Nalgene container.
  4. Verify that the feed and drain pumps are connected.
  5. Weigh your solutions.
  6. For determining residence time, there is a syringe upstream that will allow you to inject a pulse.

 

5. How to view and save data in Excel

  • Do not try to view your data while the system is running. This will cause it to stop data collection.
  • Save data to a flash drive after each trial.
  • If you have any questions, please ask for assistance.

 

If you are running one trial:

  1. Once all your required data have been collected, exit the Opto system
  2. Open Excel. Click “Open” and navigate to the correct folder on the desktop of the computer controlling the experiment (labeled “Data” or similar).
  3. At the bottom of the Excel window, click on the drop-down window and select All Files. This will display the data files that have been collected and organized by date.
  4. Double-click on the file you wish to open. The Text Import Wizard will open.
  5. Select Delimited and then click Next. Then select Comma Delimited and click Next. Select the General Data format option and click Finish. The data should now be displayed in Excel.
  6. Save your data to the flash drive by clicking Save As and selecting your flash drive as the destination. Ensure you label your data properly and thoroughly to avoid confusion.
  7. Eject the flash drive.
  8. Follow the rest of the shutdown procedure specified in the equipment SOP (see below).

 

If you are running several trials in one day:

  1. Leave the Opto system running.
  2. Open File Explorer and navigate to the correct folder on the desktop of the computer controlling the experiment (labeled “Data” or similar).
  3. Sort by date if this has not already the case. Your data should appear at the top of the list.
  4. Right-click on your data file and “cut” the file (or press Ctrl X after clicking once on the file).
  • Note: this will effectively cut the data that were collected up to that point and put these data into a file and begin a new data collection (a new file will be created with the same name as the file you cut) as soon as it is cut
  1. Paste the file to a flash drive and rename the file with an appropriate label. Ensure you are labeling your data thoroughly to avoid confusion.
  2. Eject the flash drive and save the appropriate content to your personal device.
  3. To open in Excel on your personal device or flash drive:
  • Open Excel. Click Open and navigate to the saved data on your flash drive or device.
  • At the bottom of the Excel window, click on the drop-down window and select All Files. This will display the data files collected – organized by date.
  • Double-click on the file you wish to open. The Text Import Wizard will open.
  • Select Delimited and then click Next. Then select Comma Delimited and click Next. Select the General Data format option and click Finish. The data should now be displayed in Excel

 

6. Shutdown

  1. Drain the reactor and store any solution you wish to save in a properly labeled Nalgene container. Consult the lab manager regarding chemical storage.
  2. Flush the system with tap water for 5 minutes and then drain and dispose of the water. Confirm disposal protocols with the lab manager.
  3. Label all containers.
  4. Properly dispose of any unwanted material. Consult the lab manager for guidance.
  5. Switch off the power to the pumps. This is done with the toggle switch on the front panel, the center position is “off”.
  6. Do not attempt to switch off the Sensorex conductivity module.
  7. Exit the Opto control software. Do Not shut down the computer.
  8. Save your data to a flash drive. The computer is not on the network.