On the vibration of the hollow shaft

There are many reasons for vibration in the shaft of a compressor. Issues such as rotor imbalance, excessive motor vibration, misalignment of couplings, problems with lubricating oil pressure, oil temperature, or oil quality, bearing problems, gear problems, gas pulsations, eddy currents, and even surge can all cause compressor vibration. Based on what you’ve described, I suspect it might be a bearing problem. I wonder if the temperature of the compressor’s bearings has increased; bearing wear, excessive clearance, or large backlash can all lead to compressor vibration. It could also be an issue with the inter-stage seals, which may result in leakage from the high-pressure side to the low-pressure side and thus cause excessive vibration on the low-pressure side. However, I wasn’t at the scene and am not familiar with the situation; this is just my speculation for reference only. However, there’s still something I don’t understand. Your compressors are single-axis; the vibration on the low-pressure side is already at 50, while it’s only 8 on the high-pressure side. Moreover, the shaft displacement is normal – this really doesn’t make any sense! ! ! :L

There are definitely problems. There are also many possible reasons, as mentioned above. But there’s always a but, haha; it’s difficult to determine the issue when there’s only one value. It has been running for 8 months; it’s only recently that the price started to rise, right? Has there been any fluctuation in the amplitude? A steady increase in amplitude is generally a sign of an equilibrium condition; if there are no fluctuations, the system can be monitored without any major issues arising.

It is recommended to use a handheld vibration meter to check the vibrations on the high-pressure and low-pressure sides, to see if there are any significant issues with the measurements. Then, focus on checking the issues on the low-pressure side, such as the tightness of the foundation (by measuring vibration at the fastening points) and the condition of the bearings on the low-pressure side. You can take a look at the lubricant wear debris analysis. This phenomenon is gradual and is likely related to the bearings. However, the direct cause could also be things like rotor scaling leading to excessive bearing wear.

Additionally, check whether the foundation bolts are loose； It is necessary to disassemble and check whether the impeller is scaled and its dynamic balance has been disrupted ； Are the gaps of the bearing shells and bearing shell gland plates too large? ； Conduct inspections early to prevent accidents.

Check the primary water cooler? Generally, the pressure in the exhaust gas stream is lower than that of the water pressure. If there is a leak when it gets cold, circulating water will enter the gas pipeline; since the pressure of the gas is higher than that of the water, the water turns into a mist, which leads to an increase in secondary load. However, there is no sound associated with the entrainment of water vapor. This causes vibration in the low-pressure bearing; since the secondary cooler is functioning properly, water does not enter the third stage, and therefore the bearing in that stage does not vibrate. Note: During regular inspections of the compressor, it is necessary to drain water from the gas phase of the water cooler periodically, as water is released as a result of gas compression.

Keep the oil temperature at around 25 degrees to increase the viscosity of the lubricant and monitor its operation.

1 Keep the oil temperature between 35 and 38 degrees during operation； 2 There is a parking space to check the rear bearing ； 3. Inspect the rear bearing vibration probe, instrument wires, preamplifier, and other components ； Check the drainage condition of 4 pairs of secondary coolers ； 5. There is a parking space to check for leaks in the primary cooler ； Inspect the cylinder fasteners such as the foundation bolts of the 6 sets of units ；