Water injection into screw compressors
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The last edit to this post was made by blued simple life on 2022-7-19 at 17:11. By looking at the company’s process diagram, it was found that one of the screw compressors has a water injection stream (water is injected into the gas inlet as shown in the PFD)； In a PID system, water is atomized and then injected into the compressor through the machine body; usually, centrifugal compressors are used, and it is not allowed for any liquid to enter the compressor. So it seemed a bit strange. After asking the technical staff, I was told that the presence of atomized liquid in a screw compressor has little impact on the compressor. I wonder if this view is correct? Please give me your advice
This post was last edited by Lao Wu Set on 2022-7-20 at 18:13. Screw compressors come in spray-type (briefly mentioned) and water spray-type; water is used for inter-stage lubrication, sealing between units, and cooling the compressed medium, playing a key role in this process. It is generally isolated from the lubricating oil system using a nitrogen seal.
In the case of dry screw compressors, water is sprayed to increase the pressure ratio, which is a common practice in industrial processes
Are water spraying and oil spraying related to the compressed medium?
Thank you; water is sprayed into the inlet gas phase medium, and there is indeed temperature control at the compressor outlet.
The principle remains the same; different operating conditions and media require different choices
Screw compressors can tolerate a slight amount of liquid presence, and they have excellent process adaptability. Whether it is oil injection or water injection, both can be used to cool and lubricate the screw section; cooling also serves as an effective way to increase the processing capacity of the screw compressor.
The water injected serves as an auxiliary sealing fluid for the screw machine, which reduces the requirements for the manufacturing precision of the male and female rotors, and lowers the risk of seizure caused by excessive tight fitting of these rotors due to compression temperature rises. It improves the operational efficiency and processing capacity of screw compressors, while also facilitating lubrication, reducing compression temperature rise, and minimizing the number of stages required in series. However, in operating conditions where the gas dissolves significantly in water, it is not advisable to use a water-cooled oil-free screw compressor.
I’ve learned it, thank you. That last “but” makes me see the issue from another perspective.