Is it feasible to install a spray device at the inlet of a multi-stage centrifugal compressor to improve its performance in hot weather?

I have previously worked with Shengyu compressor units, which also featured an inlet section equipped with spray devices; several nozzles were installed there. The reason for this was that too much coal dust in the process gas caused blockages in the impellers, affecting the pumping capacity and leading to surging. This does not cause liquid slugging, but it increases vibration levels. As the gas temperature rises, molecular movement intensifies and the molecules expand; therefore, within a fixed volume, the molecular weight decreases. The inter-stage cooler works on the same principle. This is just my personal opinion for reference only

If it can be put into normal use, it will definitely help to lower the temperature of the process gas; however, there are two key issues that need to be resolved: 1. Liquid slugging in the compressor. Choosing a well-designed spray head is key; the better the atomization effect of the sprayed liquid, the less likely it is that the compressor will experience liquid slugging. 2. Corrode components such as impellers or gas seals. If the process gas can dissolve in water vapor to form acidic or alkaline solutions, it may cause severe corrosion to components made of special materials in the compressor, such as impellers, gas seals, sealing rings, and sealants. If not handled properly, either of these two issues can have unpredictable consequences for the unit. The first issue is actually easy to resolve and verify; one can gradually start using the spray system, then open the drain valves on the compressor cylinder to check if there is water present. If no water is detected, the process can continue; otherwise, it should be stopped ； The second question is quite tricky, as it is difficult to determine what pH level the medium will have when process gas dissolves in water vapor at a certain pressure. Even if it were possible to determine this, experimental methods would still be needed to check whether it would cause corrosion in components made of different materials in the unit. It is believed that this is difficult for companies to implement. There was once a notable case like this: a research institution calculated that making holes in the compressor cylinder could significantly reduce the compressor’s outlet temperature by allowing coolant to flow into it. A large state-owned enterprise adopted this technology, and indeed the compressor’s outlet temperature dropped considerably after its implementation. However, after a year the compressor began to vibrate, and inspections revealed that all of the impellers were severely corroded; in the end, the benefits did not outweigh the costs. Therefore, I suggest that if your compressor is a critical piece of equipment, you shouldn’t be the first to try it. But if compressors used in other enterprises under similar operating conditions and with similar media have functioned properly for several years, then you can go ahead and use them without hesitation. Or, if your production team can handle the production disruptions caused by shutdowns for maintenance, then you can certainly give it a try; after all, energy savings and efficiency improvement are eternal priorities for businesses.

There should be no problem of corrosion due to the properties of the process gas after it becomes hydrated, as this unit is essentially an air compressor and the process gas is simply air from the environment. The project site is located in the coastal area of East China, where the temperature difference between day and night is not significant most of the time, aside from a few days each year. Although the air quality isn’t excellent, it’s not that bad either. That said, corrosion can be a problematic issue; even if the misted water condenses, the amount may not be very large, but it can still cause corrosion when it adheres to the flow channels. As for whether there are any precedents of this being used in the industry, that’s exactly what we’re trying to find out by asking this question.

The increase in vibration can be attributed to several reasons. First, it corresponds to an increase in the load on the machine unit; at least the force acting on the bearings increases as the amount of air pumped increases； 2. The operating conditions for the units in this project are fairly good, with acid gas pollution not being severe.