Is there a minimum pressure limit for the compressor inlet pressure when the flow rate is greater than the surge flow rate?
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Is there a minimum pressure limit for the compressor inlet pressure when the flow rate is greater than the surge flow rate? Rich gas
There should be a minimum limit; otherwise, the compression ratio in the low-pressure stage will increase, causing the operating flow rate to approach the surge flow rate, which poses safety risks to the system’s operation.
There should be. If not, then too low pressure may cause air leakage.
It should be there; if not, surge is likely to occur
Yes! ! It seems to be a 3-choice-2 situation, right?
Surge in compressors occurs at low flow rates due to the rotational separation of the airflow over the blades, coupled with the back pressure in the system’s piping network; I don’t think it has much to do with the inlet pressure. As long as the flow rate under each operating condition is greater than the surge point flow rate, there will be no surge as long as the outlet isn’t under excessive pressure.
From the compressor’s surge curve, it can be seen that the operating point of the unit is determined by the pressure ratio between the inlet and outlet (represented by the coordinates) and the inlet flow rate (represented by the horizontal axis). Therefore, with all other conditions remaining constant, if the inlet pressure decreases, the pressure ratio between the inlet and outlet increases, causing the operating point of the unit to shift upward and gradually approach the unit’s surge line, which leads to surge.
The condition for surge to occur is not just the flow rate, but rather the flow rate at a certain pressure ratio; therefore, surge can still occur if only the flow rate is controlled while the compression ratio is not.
Does pressure determine the composition of the rich gas? Also, pressure is a prerequisite for controlling the reaction pressure
The surge curve of a centrifuge is drawn based on the flow rate at a certain rotational speed; when the inlet pressure and rotational speed are fixed, the surge line is determined. When the rotational speed remains constant while the inlet pressure decreases, the flow rate also decreases, and the curve shifts accordingly ； Further reduction will bring it closer to the surge line; therefore, for the compressor flow rate to remain above the surge line, the inlet pressure must be constant. If the inlet pressure drops to a certain level, surge will occur, unless the surge phenomenon is mitigated by reducing the speed or opening the return valve!
For flammable and explosive gases, a low-pressure suction interlock should be installed to prevent the suction pressure from falling below atmospheric pressure, which could lead to air leaking into the compressor and cause dangerous situations such as explosions (all three units for cracking gas, propylene, and ethylene in this facility are equipped with such low-pressure interlocks).
There should be a minimum limit; the anti-surge flow rate value for compressors generally refers to the flow rate under standard conditions (1 atmosphere pressure, 273 K temperature). The flow rate Q on the horizontal axis of the compressor’s performance curve is usually expressed in NM3/H. The flow rate at each inlet stage of the compressor is determined by taking into account the inlet temperature and pressure, to yield the standard flow rate. A lower pressure results in a lower standard flow rate; therefore, when the inlet flow rate falls below the anti-surge flow rate at that speed, the engine experiences surge.
Shenmu – Compressor sales overseas. I hope to meet more friends through Haichuan. I am in charge of selling turbine machinery, centrifugal and axial flow compressors, steam turbines, process pumps, etc., and handle the overseas market sales for Shenyang Blower Group. Over the past 15 years, Shenmu has made some progress in overseas markets and achieved certain results. However, expanding abroad is a general trend for all Chinese design institutes, engineering companies, and equipment manufacturers; therefore, I hope to meet more people here to work together for common development. Here are my contact details: Xingyu Group Import & Export Company, International Trade Department, Xiang Anding. Phone: 024-25801770, 13889350035. Email: anding.*ang@sbw-turbo.com, anding.*ang@126.com. QQ: 64735517.
For a given compressor, the characteristic curve will determine the variations in pressure and flow rate, right? The external resistance of the piping system remains constant, but it’s not clear whether mentioning a certain factor is appropriate