The incredible malfunctions that occurred during operation in those years, Series 3 – Switching off the primary and auxiliary oil pumps due to pressure issues

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This post was last edited by we11we11 on 2024-2-24 at 15:32. Let’s continue discussing the startup failure of this compressor unit. This time, it involves the situation where, during the commissioning of this unit and during its first start-up, the pressure in the lubricating oil main pipe dropped sharply to the low-alarm level, causing the unit to shut down. This malfunction actually occurred before Series 2 and before Series 1; in terms of chronological order, the sequence of malfunctions was Series 3 → Series 2 → Series 1. Series 2: https://bbs.hcbbs.com/thread-3238400-1-1.html Series 1: https://bbs.hcbbs.com/thread-3238295-1-1.html. Before starting up this unit, there were many problems with the installation. After finally meeting the conditions for startup and the compressor was started, it stopped operating just a few minutes later due to a low oil pressure alarm. On the DCS trend chart, at the time of startup, the pressure in the lubricating oil main line remained stable as the auxiliary oil pump was operating. Once the unit reached its rated speed, the auxiliary oil pump stopped working and the main oil pump (axial pump) took over. However, after switching to the main oil pump, the lubricating oil pressure began to drop rapidly until it reached the low-pressure alarm level. It indicates that the main oil pump is not working! The manufacturer in the United States conducted a thorough search and believed that the main oil pump was damaged. However, we checked the coupling between the main oil pump and the compressor’s spindle, and it was in good condition with no signs of damage. Since the unit is new and has been tested in the factory, the likelihood that the main oil pump is damaged is very low. Moreover, removing the main oil pump is a very difficult task; it is recommended to identify the root cause of the problem before taking any action. So neither the general contractor nor the construction team would cooperate with the American man. In his frustration, he ended up removing the main oil pump himself and carrying it down from the compressor platform, which was about 1.5 meters high; such a heavy oil pump that it left us all in awe. There was no other choice; we had to ask the construction team to replace the main oil pump that was on standby in the warehouse, and then try starting the machine again. As everyone knows, it still didn’t work – the same fault as before occurred. Another round of searching ensued; almost all the pipelines and valves connected to the main oil pump were taken apart, yet the cause was not found. Eventually, someone mentioned that it was possible there was a blockage somewhere at the inlet of the main oil pump inside the fuel tank; perhaps it would be necessary to check the interior of the fuel tank. If that didn’t work, the lubricating oil could be drained completely so as to go in and see what was going on. So they opened the fuel tank access hatch. Fortunately, the fuel tank was not large, and the inlet pipeline for the main fuel pump was located right next to the hatch. Everyone was shocked – the main fuel pump had 4 φ8mm holes distributed evenly along its inlet pipe inside the fuel tank, at the liquid surface level. Didn’t this mean that the main fuel pump was drawing in air? (Although the screw pump does have a certain self-priming ability, it’s still unable to draw in fluid due to the 4 large leaks in the inlet pipeline.) We asked the manufacturer several times what the purpose of those 4 holes was, but they refused to answer, and the matter was left unresolved. Plug these 4 holes with plug washers, start the car, and everything works fine. It’s really a strange malfunction. But there’s a story before driving, I’ll tell it next time.