Closed Loop Air System Pressure Drop Problem

[Runaround]

Looking for assistance with closed loop inert gas process system blower requirements. In an open system discharging to atmosphere the calculated system pressure drop (PD) would be "X". Now,
same system in a closed loop arrangement returning the process gas to the system inlet, we have an actual PD of approx. 2X with regen blower maxed out. The excessive PD in the closed loop introduces air leak issues into the system along with excessive energy consumption and most of all, unstable blower performance. I have found that with insufficient gas volume within the closed loop system, the blower will operate off of its design curve (beyond designed PD). When you add volume to the system by adding an inline vessel or tank you will lower the PD and get a performance from the blower as if it were in a standard open system. It is as if the blower is starved for air.

I need to show that we can eliminate the high PD problem by adding gas volume to the system and I need to know how to calculate how much volume would be required for a blower to perform as if or almost as if it were in an open system. Any ideas or experience sharing would be greatly appreciated. This is the second time dealing with the same trouble in a closed loop system.
Thanks
Mike

 

[gerhardl]

Have you solved the problem yet?

Seems you need to add som details (sketch?) to get an answer.

Generally flow and pressure un-balances can occur if you regulate both in and output and the components are not proper adjusted and working 'against' each other.

If you compare with liquid fluid, the same problem as often found might be present here: the pump (fan) is not selected/dimensioned or run at correct speed.

Is your case a practical problem, or just different from calculated?

looking forward to your answer. Best Luck!

 

[HCBFlash]

I'm sorry if this produces a string of posts; apparently my Chrome browser and the website aren't playing nicely together lately.

Adding additional gas beyond your added capacity will of course produce a higher system pressure and also change the compression curve on your inert gas. This will also give you additional stability. It is unclear what your load is and how your blower is being controlled as well as how your system pressure is being controlled. The cycling you describe indicates that your integral control of your blower or system pressure has not yet been tuned properly and your controlled elements or sensed values may well be out of your range. Once you do determine the integral the type of surging and load you apparently have will certainly benefit from derivative aspects of system element control as well. I don't know if you are familiar with true PID control but it will achieve the stability that you desire and probably require.

Still, I think you need more gas in your system

.

(Me,,,wrong? ...aw, just fine-tuning my sarcasm!)