Dear All,
Please kindly help me with one question regarding provision of thermal expansion.
According to API 521, 5th edition, part 5.14.1, one of the causes of thermal expansion is “an exchanger is blocked in on the cold side with flow in the hot side”. I understand that thermal expansion is only considered when there is a case that exchanger is not operated and cold side is blocked in.
When I study one TRV from our previous PJ (please kindly refer to attached sketch for more details), it is found out that:
Case 1: TRV was provided for cold side (process flow) of reboiler.
Case 2: TRV was provided for cold side (utility flow) of cooler.
I don’t understand why TRV should be provided for these cases because the exchanger is always on flow. Please kindly tell me what point I am wrong.
Thank you very much.