Stoppage due to high temperature at hydrogen compressor outlet
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Dear experts, I have a WL-type hydrogen compressor that is capable of compressing pressure from 14.5 Bar to 230 Bar. It features three stages of compression, with the first and third stages being coaxial. The current fault condition is shutdown due to a high temperature at the third-stage outlet (set value: 110 degrees). The data summary shows that the outlet pressures at stages 1 and 3 are both below the manufacturer’s design standards, but the compression ratios remain within the values provided by the manufacturer. I think since the compression ratio at level 3 is within the acceptable range, its theoretical outlet temperature should also not be high. But I checked the piston rings and cylinder liners, and replaced the valves with metal concentric valves; there were no problems. The compression clearance was 0.1 mm less than the value provided by the manufacturer. The water jacket was also chemically cleaned for 4 hours. Currently, the intake temperature at stage 3 is 35 degrees, with a pressure of 94 Bar; the exhaust temperature is 110 degrees (the maximum allowable value), and the pressure there is 187 Bar. According to the manufacturer, the compression ratio should be 197 Bar. I would appreciate your advice on this. Thanks.
It’s indeed a good post that’s worth analyzing by everyone, to learn from it! The poster believes that since the ‘three-stage compression ratio of i is within the acceptable range, its theoretical exit temperature should also not be high.’ The compression ratio has little to do with exhaust temperature; it refers to the ratio of inlet to outlet pressure. Based on what you said, first of all, there is definitely no issue with the dead-center clearance between the piston and the cylinder; in other words, the compression clearance you mentioned doesn’t need to be considered. I feel that identifying the problem should start with levels one and two, as there is a higher likelihood of issues existing at level two. The following suggestions are for reference only: 1. Check whether the circulating water pipeline is unobstructed, including the circulating water pressure. 2. Ask whether there have been any changes in the process operations; changes in production procedures or process conditions can often affect the proper operation of the compressor. For example: Liquid removal can be carried out in the secondary buffer tank to check whether there is liquid present. 3. Since it is the exhaust temperature at stage 3, what is the exhaust temperature at stage 2? If the temperature is within the normal range, then there is no problem with stage 2. Check what the intake temperature for stage 3 is If it is too high, then the cooler needs to be considered. 3. If everything else is fine, it is recommended to check the inlet filter screen of the buffer tank.
I’m initially thinking that perhaps we should first increase the outlet pressure at stage one, as that might help with the temperature at stage three.
If you think you can, go ahead and give it a try. Please continue to post replies to improve your ability to diagnose faults in on-site equipment!
I’m not sure whether it’s reciprocating or centrifugal; if it’s reciprocating, the air valve can be checked.
I’m back, with some new experiences to share: The piston rings and guide rings at stage one show wear within acceptable limits； Replace the primary rod seal ring ； Replace the first-stage oil-scraping ring ； Coaxial for level 1 and level 3; replace the air valves for level 1 and level 3 ； Replace the grade 2 piston rings, rod seal, wiper ring, and valve ； The water passages are unobstructed; there is rust present, but the water pressure is normal. The inner diameter wear of the piston cylinders at all levels is within acceptable limits. The clearance at stages 1 and 3 is normal, while the clearance at stage 2 is a bit larger – it will be adjusted next time. The exhaust temperature at level 3 is still high. I would like to ask if anyone has any other ideas that we could discuss.
Not quite sure; I’ll check on the cooler
Metal valves are generally not used these days; switch to a PEEK valve instead, as it can handle temperatures up to 120 degrees.
High exhaust temperature can be attributed to the following reasons: High intake temperature; high compression ratio; leakage in the exhaust valves, which leads to cyclic compression and prevents proper exhaust, resulting in insufficient volume of exhaust gas. Leakage in the intake valves also causes cyclic compression, and the temperature on the outside of these valves is likely to be high. Worn piston rings result in insufficient volume of exhaust gas, as does an inadequate amount of cooling water, as well as air resistance.
In fact, the simplest approach is to first check your monitoring equipment to verify its accuracy. At the same time, check whether the clearance volume of the cylinder is too large