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[goggles]

Hello, I am looking for a method to control a pressure swing adsorber. The outlet stream of the adsorber connects to a series of compressors with interstage cooling before it enters a reactor. This stream is also controlled by a ratio controller because I would like to maintain the ratios of reactants entering the reactor.

 

I have been searching online and found a control system by Linde. In this patent, they describe the use of inlet valve 18a to control the inlet flowrate based on the signal obtained from the composition analyzer at the outlet stream. According to the patent and referring to figure 2 of the patent,

 

"As will become clear later herein, if the amount of oxygen in the produced nitrogen is above a preselected level then comparator-controller 114 generates an output signal thereof which causes the size of the opening in valve 18a to decrease so as to reduce the air flow rate into chambers 38 and 40. This in turn allows for greater adsorption of oxygen from the air that enters chambers 38 or 40. Accordingly, the nitrogen product which reaches tank 44 has a smaller amount of oxygen contained therein. Conversely, if the amount of oxygen in the product nitrogen is below the preselected level then comparator-controller 114 generates an output signal which causes the size of the opening in valve 18a to increase so as to increase the air flow into chambers 38 and 40."

 

The thing is since I already have a control valve on the outlet stream, I'm not sure if it would "fight" with this inlet control valve. I realize that there is a buffer tank at the outlet of the pressure swing adsorber for product storage. Would this buffer tank prevent such a scenario?

 

I'm not sure how to represent the control for the pressurization time measuring device in a proper P&ID:

"Referring now to FIG. 3, there is shown a Pressure Swing Adsorption (PSA) system 1000 which includes essentially all of the components of system 100 of FIG. 2 and in addition comprises within dashed line rectangle 1002 (denotes as control system 1002) a pressurization time measuring device (means) 1004, and a comparator-controller 1006. Components 1004 and 1006 permit system 1000 to control the air flow into chamber 38 or 40 during the pressurization portion of the cycle of operation so as to control the time needed to cause either of chambers 38 or 40 to reach a pressure of Vref2. It has been found that it is desirable to control the time in which chamber 38 or 40 is pressurized to a preselected pressure to insure that there is sufficient residence time in the chamber to allow adequate oxygen adsorption before product gas is released"

 

I would also like to represent the programmable logic controllers in a P&ID: https://www.google.c...gbeXhUImVoIDlM:

 

Would it be correct to represent the PLC and pressurization time control systems as rectangles?