The outlet pressure of the hydrogen compressor is sufficient, but the flow rate is not enough
Thread Content
It is a single-cylinder, 2-stage hydrogen compressor; during maintenance, the intermediate packing (that is located between the oil scrapper ring and the piston rod packing) was replaced. Both the intake and exhaust valves were removed, but only the valve gaskets were replaced – the valves themselves were not replaced. After starting up this time, it was found that the flow meter on the nitrogen pipeline used for packing purging had no flow. The compressor outlet pressure is sufficient (inlet pressure of 2 MPa, exhaust pressure of 5 MPa); the inlet temperature is around 44°C, while the exhaust temperatures are 100°C at the first stage and 124°C at the second stage. However, the flow rate is insufficient (the process engineers said that a portion of it was lost), and when using a 4-in-1 device for measurement around the compressor, combustible gas alarms were detected (up to 4%) as well as CO alarms (up to 90 ppm). Have any experts encountered this situation? Is the exhaust valve damaged? Or isn’t the valve gasket installed properly?
If the air valve is damaged, pressure cannot be built up. The most likely location of external leakage is the packing seal; a large amount of the leaking gas goes into the seal air discharge pipe, while only a small amount leaks at the site； This results in high pressure at the packing seal, preventing the protective nitrogen from being introduced, thus resulting in no flow. It can be confirmed that the inspection can be carried out using a four-in-one portable detector or a hydrogen detector at the outer perimeter of the packing seal; if the concentration of combustible gases is highest here, this serves as proof. It is recommended to switch to a backup unit or first implement local forced ventilation measures to reduce the concentration of flammable gases around the compressor, as the local area may already have reached the explosive limit.
Leaks do exist, but not to that extent. It seems that the air valve still needs to be checked; the valve gasket is too thick, resulting in insufficient airflow
Well, the leak location has been found. But for some reason, the flow rate of the medium-body purging is so low
The leak source has been found; it’s a leak in the valve of the compressor pipeline. I would like to ask everyone why the purge gas flow rate in the Zhongti box is low, and also why the temperature of the gas valve is 3-4 degrees higher than the rated temperature℃
The outlet pressure of the reciprocating machine has nothing to do with the compressor; it is determined by the system pressure downstream of the compressor. Based on the symptoms you described, it seems that there is air leakage in the inlet and outlet valves of the compressor. To diagnose the issue, one can measure the temperature at the valve covers and listen for sounds produced by the needle pressing against the screws on the valve cover. In fact, the machine has already been shut down; it is recommended to take out all the valves for inspection. The nitrogen flow rate in the system is insufficient; it seems that there is excessive hydrogen leakage at the packing area, which is preventing the nitrogen from flowing properly.
Thank you for your advice. In the case of air leakage during import and export, does the temperature of the air valve usually increase significantly? The temperature of the valve didn’t rise significantly either when it was in operation. Then the middle gasket was replaced, but the gasket at the cylinder wasn’t changed.
The secondary exhaust temperature has exceeded the limit; check the secondary intake and exhaust valves first. The air valve must be faulty