The optimization and efficient operation of air separation system are of great significance to improve the overall efficiency of IGCC power station. Based on 250 MW IGCC demonstration power station in Huaneng Tianjin IGCC company limited

with minimum separation work theory and isothermal reversible compression work theory

the influences of oxygen purity on the operation of air separation system

gasifier and power island were investigated under the pure oxygen output 41.7 km~3/h load of separation system. The results showed that the oxygen purity of air separation system decreased from 99.5% to 96.5% with the falling of outlet pressure of the air compressor from 0.525 MPa to 0.485 MPa. And the reduction of oxygen purity can significantly reduce the system power consumption. Under the experimental conditions

the power consumption of the air separation system was reduced by about 4.35%

and the power consumption of the IGCC power station was reduced by about 0.75%. By contrast

the reduced oxygen purity posed no prominent effect on the operation of gasification furnace. With the decrease of oxygen purity

the nitrogen content in the syngas increases

which can reduce the amount of steam injected into the gas turbine and improve the power generation efficiency of the unit. Finally

a new IGCC power station is suggested to further reduce the oxygen purity.