The issue of compression ratio
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Dear experts, I would like to ask what the compression ratio is for piston oxygen generators and centrifugal air compressors
The pressure before and after the compressor, as well as the number of compression stages, are not specified, so it’s difficult to answer~~
As mentioned above, you haven’t provided the pressure parameters, so it’s difficult to give an answer; the pressure ratio is a specific numerical value
The oxygen compressor has 3 stages of compression: 0.24 for stage 1 and 0.82 for stage 2. Grade 3 design, model 30, zw56/30
What the poster is referring to is a piston machine; generally, centrifugal oxygen compressors are divided into high-pressure and low-pressure cylinders. Taking the model 3TYS85+2TYS68 as an example, it features 8 stages of compression, with 4 stages in each of the high-pressure and low-pressure sections. These 8 stages of compression are further divided into 4 segments, for which 4 water-cooled units are used. The exhaust pressure in stage 1 is 0.33 Mpa, in stage 2 it is 0.9 Mpa, in stage 3 it is 1.82 Mpa, and in stage 4 it is 3.0 Mpa. As for the pressure ratio, the original poster can calculate it themselves~~
Under isothermal compression conditions, the compression ratio of piston compressors in the industry generally does not exceed 3, while that of centrifuges does not exceed 2. For reference only!
Sir, could you please explain how the values for these three levels of compression are determined? If I’m using a screw compressor with an outlet pressure of 0.8 MPa and it has two stages of compression, how should the ratios be set? What should be the pressure after the first stage of compression? ? Thank you
For different types of compressors, their design pressure ratios vary depending on factors such as exhaust temperature and efficiency. As for screw compressors, it depends on whether they are oil-injected or dry-type; the single-stage pressure ratio for oil-injected ones can reach 10. The compression ratio of a dry single-stage compressor is generally 1.5 to 3.5, while that of a two-stage compressor can reach 8 to 10. . .
Where did these experts get this information from? We manufacture oil-injected screw compressors, and we often produce models with a single stage that operate at an exhaust pressure of 1.3 MPa. Currently, we are working on a two-stage compressor with an exhaust pressure of 0.8 MPa. I saw that in their design, the exhaust pressure for the first stage is 0.3 MPa, while it’s 0.8 MPa for the second stage. I don’t understand why the first stage has a pressure of 0.3 MPa. As you mentioned, the compression ratio set for each stage differs from mine. Is there some formula or reference material that explains this? Thank you
You might want to take a look at the book “Screw Compressors: Theoretical Design and Applications”~~