Zero-load operation of the reciprocating new hydrogen compressor
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During the startup pressure-boosting airtightness testing, airtightness testing is required at each pressure level reached. The new hydrogen compressor needs to be shut down, or all the gas exiting the new hydrogen compressor must be returned to the inlet (a small amount of hydrogen needs to be vented in order to maintain system pressure and ensure the proper operation of the compressor). Is it possible to reduce the load on the new hydrogen machine to zero? What are the hazards of operating at zero load for extended periods?
It is necessary to calculate the reverse angle to see if it is too low. A company in Sichuan has experienced multiple incidents in which the crosshead pins were damaged due to low load and an excessively small reverse angle.
Is empty-load operation mainly concerned with the reverse angle issue?
Before being put into use, the new compressor undergoes a no-load test run for a period of time, which indicates that there are no issues with the reverse angle
The forces under no-load and 0-load conditions are different; during no-load testing, the gas force is essentially 0, while during operation at 0 load there is still a gas force present. As a result, the overall force acting on the piston differs, as does the reverse angle. However, when the (piston rod diameter/piston diameter) ratio is not very large, the change in the reverse angle is not significant, and it generally remains within a reasonable range.
A reciprocating fresh hydrogen compressor of a certain unit was operated at 50% load for a long period of time, up to half a month, without any adverse issues being detected
A 50% load is within the normal operating range for the compressor, so there’s no issue; however, problems may arise at a 10% load. These can be calculated, and since the condition of each compressor varies, the calculation results also differ. If you don’t know how to calculate it, you can ask the compressor manufacturer to do the calculation; they will tell you whether there is any problem.
Your understanding is a bit off; under variable operating conditions, a small reverse angle can indeed cause the thrust bearing shells to burn out. But it’s not true that changes in operating conditions will necessarily lead to bearing wear; this is related to the change in the reverse angle. API requires that this angle be no less than 15 degrees, and typically, an experienced manufacturer will set a control value that is higher than this. The normal reverse angle of a proper compressor is close to 180 degrees. It depends on the design capability of the compressor manufacturer. The ability to maintain a specified reverse angle under any operating conditions indicates that the unit is reasonably designed. If your machine can operate at 50% capacity, it indicates that it is well-designed. Turning to the original poster’s question, if calculations show that a large steering angle can be maintained at zero load, then operating at zero load is also no problem. It’s necessary to consider things on their own merits, rather than making generalizations.