What is a method for sizing a surge vessel for compressible fluids?

[chemebabak]

What is a method for sizing a surge vessel for compressible fluids? That is, how can a pulsation dampener, surge drum, suction or discharge bottle or any other drum be sized to maintain steady flow of a compressible fluid?

Our process requires X SCFM flow of gas at temperature T and pressure P. Due to the actual conditions of the process, X flow rate varies by ~25% and P by ~10%. The downstream conditions of the gas require steady flow rate.

Actual volume can be calculated by converting from SCFM compensating for compressiblity, temperature and pressure. Does the procedure for calculating surge volume require calculating a volume for the excess gas flow? That is, the actual flow for normal flow conditions is NC ACFM. The actual flow for conditions 1 and 2 is C1 and C2, respectively. Would the surge volume be calculated as
A. SV = C2 - C1;
B. SV = maximum ( absolute(C2-NC), absolute(C1-NC) ); or
C. SV = absolute( maximum(C1, C2) - NC )?

 

[chemebabak]

Engineers, does anyone have an answer for this?

Our process has a variable flow rate and downstream the requirements are that the flow rate is steady. We plan on installing an empty vessel to provide surge volume with a flow control valve on the discharge.

 

[25362]

Being no expert on the subject I can only direct you to Ludwig's Applied process design for chemical and petrochemical plants Volume 3, GULF; Chapter 13: Compressor surge drums.
It contains examples.
Hoping it will be of help.

 

[25362]

BTW, visiting

thread378-126517,

may also be helpful.

 

[maddocks]

One of the best ways to deal with this is to contact a local compression vendor. You can check with any of the main compressor shops and they may share their pulsation info. I can't drop names inside eng-tips, but there are some pulsation engineering firms out there (Calgary, Houston, etc) that make a living doing this work on behalf of the packagers.

 

[Fzob]

Try this vendor. I have had good success using their products

http://www.flexicraft.com/Hydropad_Accumulator/