Cyclic hydrogen compressor

In my opinion, if there is really no compression, then it is not necessary to include an anti-surge line. From the principles of surge, it can be seen that surge occurs when the flow rate at the compressor inlet decreases to a certain level, causing the gas in the pipeline system to flow back into the compressor; once the pressure at the compressor outlet exceeds that in the pipeline system, the compressor starts to discharge gas again, resulting in periodic oscillations of the gas flow within the system. Surge does not occur if there is no compression. I hope experts can give some guidance

I went to DCS today to take a look, and it’s still compressed (0.24Mpa-0.43Mpa)

Is the recycle hydrogen compressor in the original poster’s facility a reciprocating piston compressor? It is important to understand what surge means; it is primarily related to centrifugal compressors (those with high flow rates), and surge can occur when there is not enough air intake ； On the other hand, reciprocating compressors do not experience surge. Additionally, in order to maintain normal circulation (playing a role similar to the heart in a hydrogenation unit, with circulating hydrogen acting like blood in the human body), hydrogen circulation compressors must have a pressure ratio.

Centrifuges are equipped to prevent surge, while reciprocating machines are not

It is a centrifugal circulating hydrogen compressor, but it indeed does not have an anti-surge valve

I won’t go into detail about the principle of surge; what was said above explains it clearly. The essence of the surge line is a return path from the outlet back to the inlet, used to supplement the flow at the inlet; theoretically, this path should be designed to protect the compressor. However, in practice, this line is not included in some processes for the following two reasons: 1. Essentially, from the perspective of anti-surge protection, the recycle hydrogen compressor together with its inlet and outlet process lines already forms a return line; adding another return line would be redundant since both serve the same purpose. 2. The operating curve of the recycle hydrogen compressor is far away from the surge point, providing sufficient margin so that surge generally does not occur. Yet, from the standpoint of protecting the unit, it is still necessary to include such a line

I seem to understand a bit now; if there is severe leakage in the intermediate pipeline for circulating hydrogen, is it theoretically easy to experience surge?

In my personal view, the addition of anti-surge lines is used sometimes to protect the unit in such extreme situations. For example, a severe leak that reduces the amount of air entering the system (although in such cases, interlocks are usually triggered to shut down the unit already), or blockages in the inlet pipelines that prevent sufficient air flow from reaching the unit. Since these situations cannot be ruled out, and the manufacturer of the unit isn’t sure whether the process design takes into account the possibility of such extreme conditions triggering unit interlocks, manufacturers recommend adding anti-surge devices as a precaution

See this post: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1896279