整体煤气化联合循环系统气化岛特性模拟研究

Simulation Study on the Gasification Island in Integrated Gasification Combined Cycle System

气化岛是整体煤气化联合循环(integrated gasification combined cycle,IGCC)系统中较为复杂的关键单元,对整个系统性能有较大的影响。利用Thermoflex软件建立200MW级IGCC系统模型,从系统角度出发,对直接激冷式、除尘系统前带有气/气热交换器和取消气/气热交换器的3种IGCC系统进行比较,结果表明取消气/气热交换器的IGCC系统同样具有较高的效率,且系统更加安全可靠。对此系统中空分单元的氮气回注系数、气化炉单元的氧煤质量比,以及对流废锅出口粗合成气温度进行计算。计算结果表明:在空分系数为30%时,系统最佳氮气回注系数为70%;综合多种因素考虑,所研究煤种的最佳的氧煤质量比约为0.91;系统效率随着对流废锅(convective syngas cooler,CSC)合成气出口温度的增加而下降,当辐射废锅(radiant syngas cooler,RSC)粗合成气出口温度为700℃,对流废锅出口合成气温度取350℃,系统效率较高。

The gasification island is a key and complicate unit in integrated gasification combined cycle （IGCC） system, and it affects the whole system performance greatly. The 200 MW IGCC system model was established using Thermoflex software, from the view of system, the IGCC systems with direct chilling, with and without gas/steam heat exchanger before dust removal were compared, the conclusions were obtained. That is, the IGCC system without gas/steam heat exchanger is much safer and has high system efficiency. Then the nitrogen re-injection coefficient in the air separation unit （ASU）, the oxygen/coal ratio in gasification unit and the syngas temperature out of the convective syngas cooler （CSC） were studied based on this system. The result shows that： the best nitrogen re-injection coefficient is 70% with the air separation coefficient of 30%; with considering many elements, the best oxygen/coal ratio is about 0.91 based on the coal studied in this paper; the system efficiency decreases with the syngas temperature out of the CSC, when the syngas temperature out of radiant syngas cooler （RSC） is 700 ℃, the syngas temperature out of CSC is better to select 350 ℃ and then its system efficiency is comparatively high.