Environmental conditions include atmospheric pressure, ambient temperature, atmospheric humidity, and the content of impurities such as CO₂ in the air. These conditions vary with region and climate, and will result in different performance characteristics for the same air separation unit.
1) Impact of atmospheric pressure. Atmospheric pressure fluctuates around 0.1 MPa. A decrease in atmospheric pressure will increase the compression ratio of the air compressor. A decrease of 0.01 MPa in atmospheric pressure will increase the compression ratio of the air compressor by 6%–8%, thereby increasing compression energy consumption. In addition, due to the increase in specific volume (decrease in density), the discharge capacity of the air compressor decreases, and the corresponding oxygen production will also decrease, leading to higher specific power consumption for oxygen production.
2) Impact of ambient temperature. An increase in ambient temperature will reduce the discharge capacity of the air compressor and increase shaft power. For every 3°C increase in ambient temperature, the shaft power increases by approximately 1%. In addition, an increase in ambient temperature will also raise the discharge temperature of the air compressor, increasing cold loss and requiring more refrigeration capacity to balance this cold loss, ultimately resulting in increased energy consumption.
3) Impact of air humidity. An increase in air humidity means that part of the compressor work is consumed in compressing water vapor, resulting in increased shaft power of the air compressor.
