How can the compression ratios of the left and right columns in a reciprocating compressor be made different?
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The combined compressor for supplemental hydrogen and backblast hydrogen in the S-ZORB unit is of a two-column, symmetrically balanced design; the left column is used for backblast hydrogen, with pressure rising from 2.61 MPa to 6.63 MPa, while the right column is used for supplemental hydrogen, with pressure rising from 2.1 MPa to 3.75 MPa. The cylinders in the backblast hydrogen section are longer but narrower than those in the supplemental hydrogen section. How can it be achieved that the pressure ratio in the backblast hydrogen section is higher than that in the supplemental hydrogen section? Is it due to the air valve?
The pressure ratio is selected as needed, specifically determined by the opening pressure of the outlet valve. The outlet pressure is determined based on the pressure ratio, and then the cross-sectional area and length of the cylinder are designed based on the force balance of the compressor crankshaft.
Adjust according to the cylinder diameter, piston stroke, and the size and quantity of valves
Reciprocating compressors belong to the category of positive-displacement compressors; as long as the strength of the compressor body is sufficient, the pressure can increase indefinitely. In other words, its compression ratio can be very high, as long as your equipment and drivers meet the requirements. The high backpressure in the reverse-blow hydrogen system, as you mentioned, is what results in a high compression ratio; this high backpressure in turn leads to a higher opening pressure for the gas valves. So, there is a saying that the outlet pressure of a positive-displacement compressor is determined by the back pressure.
So how does its back pressure increase? It’s also pumped in by a compressor, right? I think it was still the pressure valve that played a key role
As the compression ratio increases, the exhaust temperature also rises, and gas valves have temperature limits for operation.
Back pressure is indeed achieved by the compressor applying pressure, but it is accomplished through valve control to maintain that pressure. For example, with your compressor, does the gas sent out in each stage need to wait until the pressure rises to the required level for the next stage before it is released?