Hello,
This is my first post so I apologize if it is not clear ... do not hesitate and correct me if I am giving wrong statements or assumptions.
We are designing a new process Platform in the company I work for.
During a 1st phase a 3phase separation vessel will be installed to produce the surrounding wells and help reducing their WHP. Gas from the vessel will be routed to the flare. We estimate roughly 7mmscfd.
In a second phase this production gas along with gas from other platforms (through gas scrubber) will be routed to a compressor in order to provide gas lifiting.
The compressor will be designed for 28 mmscfd from 35 to 1100 psig. A 3 stage centrifugal type has been suggested, with constant speed and air cooler.
We are at a very early stage of the project meanwhile I would like to have an idea of the design of a suitable flare for both phase 1 (continuous flaring of 7 mmscfd + relieving flow from liquid outlet) and phase 2 (no continuous flaring, only relief / blowdown scenarii from 3phase vessel, compressor and slug catcher).
Thus I am wondering what would be the releiving scenarii of the centrifugal compressor... and how to arrange the compressor specifications in order not to have a full flow 28mmscfd releiving scenario since this would lead to a too big flare.
I have been told that I could disregard the case full flow by having a fully rated compressor meaning if my understanding is correct that I would need to have rouglhy 1250 - 1300 psig design pressure on the entire skid. Am I right ?
Is it to protect from anti surge HP valve failure in open position and possibility of HP gas flowing back from gas lift header to 2nd stage suction ?
But in that case only 2nd stage and 3rd stage shall be fully rated since only one single jeopardy is to occur and anti surge HP valve goes from 3rd stage discharge to 2nd stage suction. And 1st stage shall be designed to max pressure from 2nd stage discharge + extra. right ?
any other means ? since having a fully rated compressor seems quite expensive...
Besides since this is centrifugal type compressor and not reciprocating type, I would say we cannot experience pressure build up on a blocked outlet. Is that correct ? but we can experience blocked outlet case for the air cooler
thank you for your kind assistance.
Edited by julie, 07 June 2019 - 08:25 AM.