Dear All,
Ethylene is stored as a liquid at -100 C and transported to customers as a gas via a compressor. The ethylene tank is equipped with a Pressure Safety Valve (pilot operated) and a vaccum safety valve. The compressor takes suction from the top of the ethylene tank and operates between 50-250 mbarg suction pressure ( below 50 mbarg compressor stops and above 50 mbagr it starts to transport). A problem is accrued with a suction pressure drop that causes the compressor to trip.
To tackle this problem while running the tank's operation, the existing PSV nozzle is connected to tee with one end connected to the PSV and the other is used to lay new line tied-in to the existing compressor suction line.
My questions here are :
- Is there any restriction for this type of modification in any Code or standard ( using tank's PSV nozzle for other operations, using a tee?
- Will this modification affect the PSV operation?
- What is the criteria for upstream line pressure losses for storage tanks PSVs (Like 3 % as in API 521)?
Regards
Ahsan
Edited by Art Montemayor, 28 June 2015 - 04:15 AM.