Energy-Saving Design of Large-Capacity Compressed Air Systems

This case study examines the energy-saving design methods for large air compressor stations in thermal power plants, where the air production exceeds 300 m³/min. It proposes a system that separates high and low pressure, with the low-pressure system utilising low-pressure centrifugal compressors with lower specific power consumption. The study also presents an implementation case with significant energy optimisation results.

The optimised design separates the system into high and low pressure components. The high-pressure section uses oil-injected screw compressors, while the low-pressure section employs a combination of low-pressure centrifugal and screw compressors. Calculations indicate that the low-pressure compressor outlet pressure should be set at 0.55 MPa. Post-treatment equipment includes zero air consumption hot air dryers and zero air consumption compressed air dryers. After flow correction calculations, the Free Air Delivery (FAD) of the compressors is reduced.

In this case, the optimised system reduced the specific power consumption to 1.73 kW/(m³/min), saving 2.7 million RMB (CN¥2,700,000, approximately US$380,281) in annual operating electricity costs (about 28% of the original design’s annual operating electricity costs). The optimisation results are significant.