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In our DHDT recycle gas compressor primary seal vent flow at non driver end side has reduced to zero while it was previously 5 Nm3/hour. Driver end side flow is running between 30 Nm3/hour. What is the possible reason behind flow reduction?
 
Answers
12/02/2010 A: Syamantak Dhar, Indian Oil corporation Limited, syamantak.dhar@aol.in
Please check the P&ID whether there is an NRV in the Driver End primary seal vent. Ideally there are two NRV(s), one each in the primary seal vent from DE and NDE and another one in the common line to flare. The NRV flapper might have got struck and restricting its flow and the common indication is that there is an increased back pressure in the primary seal vent to flare.