Abnormal noises in twin-screw pumps
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This is our crude oil storage and transportation area, where there are two twin-screw pumps with a capacity of 600 m3/h each. During production operations, we noticed that after operating for extended periods of time, these pumps produced unusual noises coming from their gearboxes, and the noise level was quite high. Checks show that pressures and temperatures are normal everywhere. At the same time, during production, the output volume was significantly insufficient. In such cases, the abnormal noise is, in my opinion, caused by the pump shaft; the low output volume may be due to the high viscosity of the oil’s physicochemical properties or to the pump being under vacuum. I kindly ask everyone to help discuss this.
The sound of the pump being evacuated comes from the pump itself; unusual noises coming from the gearbox are likely due to problems with the gears or bearings. The sounds are distinctly different from each other, and any change in the sound emitted by mechanical equipment requires prompt attention.
Cavitation in positive-displacement pumps can also produce impact-like abnormal noises. When the oil temperature is high, and the oil contains water and other light components, these substances vaporize as they are drawn in by the pump; then, due to the high pressure at the outlet, they liquefy again. Moments of low pressure occur, which results in a knocking sound similar to that caused by liquid slugging. It is recommended to consider checking the oil composition.
No abnormal pressure, but clearly insufficient volume? It seems a bit contradictory – gear noise should not affect the measurement. It’s better to proceed with a step-by-step investigation, first checking whether there is any blockage.
Insufficient output volume indicates air blockage, while gear noise is caused by unstable flow and pulsations in the screw pump, leading to abnormal gear sounds; it is necessary to release air promptly and check the process. Over time, this can result in gear wear and screw impact