Changes in the molecular weight of rich gas cause unit surging

http://bbs.hcbbs.com/thread-338438-1-1.html Research on Compressor Surge Problems. I searched for it, and it was this article that helped solve many of my problems related to surge; I hope it will be useful to you as well!

The effect of the lighter medium gas in the compressor is that there is a orifice plate differential pressure gauge at the compressor inlet; its function is to affect the corrected output value of the flow rate at the inlet, thereby influencing the flow rate reading at that point. There are mainly three factors that affect the differential pressure measurement of orifice plates: the temperature and pressure of the gas at the inlet, as well as the density of the gas. The reduction in weight you mentioned is related to the gas density of the medium. As the density decreases (in other words, the gas in the medium becomes less dense), the pressure difference created before and after the orifice plate is reduced, and as a result the flow rate correction output value is also lower. According to the compressor performance curve, the lower the flow rate, the more likely surging will occur. I hope this explanation helps you.

Personally, I think it can be understood in this way: the compressor is a centrifuge that uses centrifugal force to increase the pressure of the rich gas. When the rich gas becomes less dense, the centrifugal force at the same rotational speed decreases. If the back pressure is not reduced in time, surge can occur easily. The fundamental solution to surge is to increase the speed.