大型联合钢铁企业低中热值煤气发电综合利用的优化分析

Optimization of power generation with low or medium calorific gas in large integrated iron and steel works

大型联合钢企的副产品低、中热值煤气不是洁净高能燃料,由此建成的煤气蒸汽联合循环机组要比天然气机组效率低8%-10%,排放特性与BTG型机组类似,且有较高投入、较高维护成本、较低可用率及不能适应变负荷运行等,难以满足电网AGC的要求。分析了可燃用低中热值的各种常规容量下的BTG类型与GTCC类型发电机组的经济特性与技术特性,根据东南沿海燃料价格高昂的实际情况,认为对低热值煤气BFG,以350 MW以上大型混烧BTG方式发电是较优的,高炉煤气放散可以接近零、安全可靠、成本较低、排放较少、对各种波动的煤气流量适应性更强,有利于投资方与当地电网。对COREX工艺大型联合钢企,以GTCC为主力是较好的方案。对天然气价格较低、COG/LDG富余较多的地方,结果不同。建议大型联合钢企副产品低、中热值煤气发电,要因地置宜,要根据煤气富余量、燃料价格、用电需求、环境与气候、投资与维护、综合实际供电成本等诸方面综合论证,以得出理性的优化方案。

Low or medium calorific gas,a kind of by-product of large integrated iron and steel works,is not a clean and high energy fuel.Based on the fuel gas,a gas-turbine combine cycle（GTCC） power unit could be built.It is 8%-10% less efficient than the natural gas unit（NG-GTCC）.Its emission characteristic is similar to that of the boiler-turbine-generator（BTG） type unit and it needs higher investment,higher maintenance cost and has lower availability.It is for the variable load operation and difficult to meet the grid AGC requirement.This paper analyzes the technical and economic properties of various BTG type and GTCC type power units with a conventional capacity,burning low or medium calorific gas.According to the situation of the southeast coast area of China where the fossil fuel price is higher,a BTG type power unit,with a capacity of 350 MW or above,burning coal mixed low calorific BFG,is a better choice.The BFG bleeding can be reduced to zero.It is safer and more reliable,featuring lower cost and less emission.It is suitable to those with fluctuated gas flow and in favour of investors and the local power grid.For those integrated large iron and steel works with COREX process,taking GTCC as their main unit has better effect.In some places where the natural gas price is low,and COG/LDG is surplus,the result will be certainly different.The paper also suggested that those large integrated iron and steel works with low or medium calorific gas as their by-product should consider the following aspects,such as their locations,amount of surplus gas,fuel price,demand for electricity,environment and climate,investment and maintenance,actual cost of supplying electricity and other factors,so as to obtain a rational optimization solution.