空分系统降低氧气纯度对IGCC运行影响

Influence of reducing oxygen purity of air separation system on the operation of IGCC power station

空分系统的优化及高效运行对提高IGCC电站整体效率具有重要意义。本文基于华能(天津)煤气化发电有限公司装机容量为250 MW级IGCC示范电站的运行情况,依据最小分离功理论、等温可逆压缩功理论,在空分氧气(纯氧)产量41.7 km^3/h负荷下,研究了降低氧气纯度对空分系统、气化炉及动力岛的影响。结果表明,随空气压缩机出口压力由0.525 MPa降低至0.485 MPa,空分系统氧气纯度由99.5%降低至96.5%;氧气纯度的降低可显著降低系统功耗,实验条件下空分系统功耗降低约4.35%,IGCC厂用电率降低约0.75%;氧气纯度的降低对气化炉运行无显著影响;随着氧气纯度降低,合成气中含氮量增加,可降低燃气轮机注入蒸汽量,提高机组的发电效率。建议新建IGCC电站进一步降低氧气纯度。

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.