Dear gents,
What is the most common sizing criterion to design a centrifugal compressor suction throttling valve? On one hand, I can allow in the STV a DP equivalent to some percentage of the system dynamic pressure drop of the suction side (some 20-25%). On the other hand, some people...
Dear colleagues,
A colleague and I have been tasked with coming up with a procedure to drain some 500 m of a 10 inch pipe initially totally full of LNG. We must empty the line into a vessel which is elevated by some 8 m, and the line is on the ground. Unfortunately there are a couple of...
Hello,
Annex E "Guidelines for Anti-surge Control Systems" in the latest revision of API 617 9th Ed includes some recommendations (i.e. the annex is marked as "informative) on the design of anti-surge control systems for axial and centrifugal compressors. Section E.2.5 "Trapped Volumes"...
Gents:
When starting up a centrifugal compressor, do you normally allow the discharge isolation valve to open before or after the discharge pressure of the compressor matches the discharge header pressure?
For instance, consider a single stage centrifugal compressor driven by a fixed...
Gents,
What are the requirements of the suction line of a centrifugal/reciprocating compressor? I have been having a discussion with a colleague about this and we would appreciate if someone could shed some light on the issue.
From his point of view, no pockets + free draining towards...
Gents:
I am currently involved in the analysis of the results/findings of a dynamic simulation of the ESD of a gas compressor. This is a fairly large unit compressing some 300 MMSCFD of natural gas between 350 and 1000 psig. The results provided by the third party in charge of this...
Gents,
I am wondering if based on your experience the ESD trip of a centrifugal compressor needs to be investigated by the Stress analysis engineers.
I am a Process Engineer who is working on the dynamic analysis of a compressor. One of the scenarios we are studying is the ESD trip of...
Dear all,
When compressor Vendors state the moment of inertia of their machines/drivers they normally state the MOI and a reference speed. I have never fully understood why: I assumed that the moment of inertia of a rotating element is constant irrespective of its speed.
Aspentech...
Dear all,
I am currently working on a NGL recovery plant with a patented Ortloff's RSV process. The overhead of the Demethanizer (99% C1 i.e. very lean gas) is routed to the suction of a recompressor (of course coupled to a turboexpander) and then it is compressed to around 1000 psig by a...
Gents,
Disclaimer: Process Eng background here with only superficial knowledge of intimate details of valve design: be gentle! ;)
It seems to be common practice amongst my Process Eng colleagues that a full bore, ball on/off valve shall not be open before ensuring that the differential...
Gents,
I have seen a few gas compressors driven by a fixed speed electric motor controlled by suction throttling where the inlet throttling valve has a mechanical stop, or some other means to prevent the valve from fully closing. I've enquired a couple senior process engineers at my company...
Dear colleagues,
I am currently working on a natural gas compression plant, and the dynamic simulation study carried out by a third party contractor concluded that most of the compressors shall be furnished with a Cold Gas Bypass loop (i.e. an additional on/off valve bypassing the antisurge...
Dear colleagues,
I am currently working on a natural gas compression plant, and the dynamic simulation study carried out by a third party contractor concluded that most of the compressors shall be furnished with a Cold Gas Bypass loop (i.e. an additional on/off valve bypassing the antisurge...
Gents,
It seems to be common practice amongst my colleagues that a full bore, ball on/off valve shall not be open before ensuring that the differential pressure between the upstream and downstream side is lower than 15-30 psi. Some colleagues argue that this holds for liquid, but some of...
