3 replies to this topic

[iplan]

Our Refinery is having reciprocating compressor for hydrocarbon gas service to increase pressure from 280 to 550 PSIG level in the first stage. First stage is having 2 cylinders and the second and 3 rd stage is having one cylinder with Knock-out in between.

Design data of the compressor is indicated below.
C-10-01 A/B Design
1st Stage 2nd Stage 3rd Stage

Gas Compressed H2 Rich gas
Mol. Wt. 14.76 8.16
Capacity, MMSCFD 9.4 6.55 6.55
Inlet Temp. °F 110 110 110
Inlet Press. PSIA 285 505 1168
Discharge Temp. °F 220 242 230
Discharge Press. PSIA 697 1180 2525
BHP 1306
Power, KWH 974.3

In one of our Hazop reviews, it was identified that Loader valve passing / Malfunction at 1st stage cylinderresults in higher pressure at suction piping of 1st stage. It was propsed to consider installation of Check valve at each cyclinder outlets to avoid back flow and higher pressure at suction piping. Upon review it was identified that, installation of NRV result in higher discharge pressure and might exceed design limit in case of NRV flapper fall situation.

It may be noted that PSV is installed in the first stage discharge piping at the common line (after joining both individual cylinder discharge).

Please review the same and provide your valuable comments regarding the installation of check valve at individual diuscharge.

Feel free to contact for any clarification.

Attached Files

•  Doc2.doc   60.5KB   58 downloads

[JoeWong]

Engineer like sketch more than text...

Can you please provide proper sketch and indicates information at proper location for easy understanding ?

[JoeWong]

"...Upon review it was identified that, installation of NRV result in higher discharge pressure and might exceed design limit in case of NRV flapper fall situation..."

Are you saying that the flapper fall caused total blockage from either sides ?

It is normal to have dedicated PSV for individual compressor chamber as there is a risk of partial/total blockage of check valve internals...

[iplan]

"...Upon review it was identified that, installation of NRV result in higher discharge pressure and might exceed design limit in case of NRV flapper fall situation..."

Are you saying that the flapper fall caused total blockage from either sides ?

It is normal to have dedicated PSV for individual compressor chamber as there is a risk of partial/total blockage of check valve internals...

Dear Joe,
Yes, Flapper fall case will block the compressor discharge and over pressurize the chamber & compressor discharge piping (5 -10 M)