For a two-stage compression piston compressor, there is already an outlet buffer tank and a separation tank at the first stage – why is a buffer tank needed at the inlet of the second stage as well?
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I’m not in the compressor business, nor do I understand compressors; if my questions are rather amateurish, please don’t laugh at me. I recently saw a schematic of a piston compressor using natural gas as the medium, and the flow rate isn’t very high. I took a look; after the first stage of compression, there is a buffer tank, a cooler, and a separation tank at the outlet, and nothing seems to be wrong with those. But why is there another buffer tank at the inlet of the second stage? I think with all these tanks in place, the airflow should already be quite stable. I’ve seen some piston compressors in which the buffer tank and cooler are integrated together; the fluid flows through the tube side, and by making the pipe ends larger, a buffering effect is achieved at the outlet. There is also no buffer tank at the inlet of the second stage.
Both the suction and exhaust of a reciprocating compressor experience pulsation. .
A normal reciprocating machine requires a buffer tank; the primary outlet you described already has a buffer tank, a cooler, and a separation tank. Logically, there is no longer a need for a buffer tank. Maybe it was added by the equipment to better buffer gas fluctuations? Another possibility is that this buffer tank has a secondary outlet and a secondary inlet, along with a non-pressure line or some additional pressure supply line; that’s probably why this buffer tank was installed It’s just my personal guess; the original poster needs to analyze it.
Reply to 3# zhiyuan1100: My compressor doesn’t have a 2-back 2 configuration; it only has a 2-back 1 configuration. There is a buffer tank at the inlet of the first stage, so there’s no problem. I’d also like to ask how exactly the size of the buffer tank is determined; I always think it’s set at a too small value. . .
Reply to 4# hangzhuozyh: Roughly speaking, it’s 10 to 12 times the cylinder volume
Buffering effect to prevent the compressor from shutting down due to low pressure at startup!
Maintain stable inlet airflow and eliminate the effects of pulsation
Reply to 6# Kankan198411: Actually, I’m wondering why a buffer tank is still needed at the secondary inlet when there are already so many tanks – can this tank be omitted?
The airflow in reciprocating compressors is pulsating and discontinuous; to ensure that the next stage of cylinders receives a stable, continuous, and sufficient supply of air, a buffer tank is generally installed at the inlet of each cylinder stage (the same principle applies even if a large buffer volume is provided on the cooler you mentioned), thereby preventing fluctuations in the airflow. It cannot be skipped.
Reply to 8# hangzhuozyh: The buffer tank cannot be removed; the closer it is to the inlet and outlet of the cylinder, the better the effect. If it is removed, the section from the 1st stage outlet to the 2nd stage inlet will vibrate due to the suction pulse of the 2nd stage
Without a buffer tank, gas fluctuations can cause shocks to the pipeline, leading to vibrations in it.