I’d like to ask everyone for advice~ The cylinder’s air volume is insufficient for some unknown reason~
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Our company has a set of six-column, seven-stage nitrogen-hydrogen gas units (M-305/314), among which stages 3 and 5 are arranged with an inverted stage difference. The process flow involves one inlet and three outlets for conversion, four inlets and four outlets for decarburization, five inlets and six outlets for alkoxylation, and seven inlets and seven outlets for synthesis. The cylinder diameter and air volume were recalculated to meet the requirement of 305 m3 at the inlet. According to the design specifications, the pressure at the primary inlet is 0.126 MPa, the pressure at the fourth-stage outlet is 2.85 MPa, the pressure at the fifth-stage inlet is 2.65 MPa, and the pressure at the fifth-stage outlet is 5.1 MPa (all values are absolute pressures). Currently, the pressure drop at the outlet of the fourth stage of the user’s decarbonization system is 2.7 MPa, while at the outlet of the fifth stage it is only 4.2 MPa; the pressure cannot be increased any further. Suspicion arose of a leak within the system; piston rings and valves were replaced successively, but with no effect. The user claims that no data has been leaked from the external system. But now, aside from the low outlet pressure at stage 5 and the high outlet temperature along with reduced pressure at stage 6, the pressures and temperatures at all the other stages were normal before. The temperature of the pipeline in the fifth-stage balance section (return to stage 2) at the cylinder flange is 76 degrees, which is also considered normal, and the pressure at the second-stage inlet is normal as well. Now neither side can find the reason. This unit is a standby unit; the pressure of the other operating unit is normal. Could everyone please help analyze what other possible causes there might be?~~~~ Thank you~~~
Check whether the pressures at each stage of the local unit are normal. The pressure at a single stage of a reciprocating compressor can reach very high levels, as long as it remains within the limits permitted by the equipment; this primarily depends on the backpressure of the system. Here is my personal analysis: (I am in charge of the equipment, so please forgive any incomplete aspects in this analysis.) Under normal circumstances, a low pressure at the fifth-stage outlet indicates that the pumping volume at that stage is low; therefore, the decarburization pressure should increase instead ； If the pressure in the first few stages is normal and the decarburization pressure is not high, it indicates that the pumping volume in stage 5 is normal; therefore, the problem may lie in a pressure leakage point at the outlet of stage 5 ； In other words, the exhaust ventilation in the fifth stage is functioning properly, but there are pressure release points in the outlet piping and similar components, which results in a low indicated pressure at the outlet of the fifth stage. It is recommended to carefully check for any issues with the air valves, the valves on the pipelines, the circuit valves, and the drain valves.
Thank you so much~ That’s exactly what we told the user as well; the user insisted that there would be no leaks in the pipeline. For now, the goal is to rule out issues with the host itself first.
It seems the problem lies in the valve on the return line; that valve is likely leaking internally, which prevents pressure from building up. This in turn leads to a higher compression ratio in the next stage, resulting in high temperatures
Well~We’ve considered this as well; although the users think there’s no problem, we’ll still ask them to check again. Thank you~