Problems encountered during the commissioning of the hydrogenation unit
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After graduating, I came into contact with the first hydrogenation unit that was just being put into operation, and I have a few questions I’d like to ask everyone: 1. During the nitrogen-load testing of the new hydrogen compressor, the pressure in the buffer tank at the secondary outlet of one compressor was 20 kilograms higher than the pressure in the main outlet pipe; for the other compressor, the pressure difference was very small, so there seems to be no issue with the process. 2. How should the self-acting valve used for the pilot light be calibrated? What is the typical pressure level behind this valve? 3. There are many leakage points in the wiring connectors or fittings used for the gas-tightness monitoring instruments in the reaction system. Is it acceptable to simply wrap those connections with electrical tape as a solution? 4. The turbine is about to undergo individual testing – are there any particular things to keep in mind? We really can’t afford any mistakes with this unit; we assign dedicated personnel to oversee each probe installation and take photos as proof, just to avoid any errors
1. For compressors with multi-stage compression, due to recursive control, the effect of the opening degrees of each return valve may cause this situation
2. The pressure behind the automatic valve of the constant-flame lamp should be the pressure of the gas in the system. The calibration of the automatic valve should be carried out by instrumentation personnel, including operating the on-site switches, DCS switches, and triggering interlocks
3. If there are leaks, it is necessary to contact the instrumentation staff promptly to seal them up, and then conduct a leak test using soapy water
Single-unit trial operation is necessary; any issues found should be addressed promptly. There’s no need to worry. All instrument interlock points need to be checked before starting the machine
The turbine has passed the testing, and another issue to pay attention to is the repositioning of the probe; we’ve encountered problems before where the probe’s wiring was broken, forcing us to stop production in order to replace it. Care must be taken to ensure airtightness of the dry gas seal, especially at the connections~~~~~
Well, our supervisor also said that a broken instrument cable caused the vehicle to stop, so he asked us to take photos of each connector in the junction box as proof
Attention should be paid to the oil level in the turbine oil and the operation of the lubricating systems
The compressor pressure is high; it is likely that there is a fault with the suction and exhaust valve of the next stage
1. During the nitrogen load test of the new hydrogen compressor, the pressure in the secondary outlet buffer tank of one unit was 20 kilograms higher than the pressure in the main outlet pipe; the pressure difference for the other unit was very small. Is there a total of three stages of compression? If that’s the case, it’s normal – the high outlet pressure causes the flow to return step by step. If it’s only during the testing phase and the load does not exceed the compressor’s capacity, then it’s fine if the temperature at the second-stage compressor outlet is not high; this simply indicates the required pressure in the final stage’s manifold. The other unit is different; it depends on how your compressor control system is configured. For example, this possibility exists if the flow valve is set to a very low opening. 2. How to calibrate the self-acting valve for the permanent light, and what is the typical pressure behind this valve? I don’t know that either, haha. However, for self-acting valves, the data should be available in their specifications; it seems that the pressure range is roughly around 0.01 MPag downstream of the valve, and it shouldn’t be very high ； 3. There are many leakage points in the gland fittings or couplings for the airtight instruments in the reaction system. Is it feasible to wrap duct tape around those instruments to fix the problem? It doesn’t seem like a serious issue, but I haven’t seen the installation specifications for these instruments. It seems that stainless steel pipes are required; proper compression should be sufficient, as the hardness of metal materials isn’t very high ； 4. The turbine is about to undergo a single-test run. Are there any particular things to keep in mind? We really can’t afford any mistakes with this unit; for example, we assign dedicated personnel to oversee the installation of each sensor and take photos as proof, just in case something goes wrong. That’s correct. But since it’s a test run, shouldn’t the manufacturer be involved as well? Few companies in the country are capable of producing that big thing. It is recommended to rely on the manufacturer’s support, and also search online for the guidelines regarding turbine commissioning.