大型机组乏汽余热利用的热电联产供热系统全工况优化

Full Operating Conditions Optimization of Cogeneration Heating System Based on Waste Heat Utilization of Exhausted Steam of Large Turbine Units

利用电厂乏汽余热构建新型热源方式,是实现火电节能和城市清洁供热的重点方向。为了同时回收多台机组全部的乏汽余热,一种新型多热源梯级供热系统,已应用于国内多座空冷电厂。文中针对该系统的全工况优化开展深入研究：以2×300MW直接空冷机组为原型建立系统供热特性计算模型,引入＂供热等效电＂作为新型热电联产供热系统的综合能效评价指标;结合热网参数和系统供热量构成的变化规律,以进一步发掘系统节能潜力为目标,提出机组背压调整的优化运行方法。经分析表明在不同设计工况下,采用优化背压运行均可以一定程度降低系统供热等效电Weq.s及单位供热量总成本ct,系统综合能效与经济性得到改善。成果用于指导大型机组乏汽余热利用系统优化运行。

Utilizing the waste heat of exhausted steam in power plant as a new type of heat source is a key direction to achieve both energy-saving and clean urban heating, In order to recycle all the exhausted steam waste heat of multiple units at the same time, the authors＇ research group proposed a new cascade heating system with multi-heat source and applied it in several power plants in China. This paper focused on the operation strategy formulating of the new system, the main study contents include： Taking two sets of 300MW direct air cooling turbine units as the example, established the calculation model of system heating characteristics and introduced the ＂equivalent electricity of heating＂ as the evaluation method of comprehensive energy efficiency of the new co-generation heating system. Then considering the change regulation of parameters of heat network and composition of heating output, put forward the optimal operation method of backpressure of units to further explore the energy saving potential of the system. The conclusions indicate that the comprehensive equivalent electric power of system heating and the total financial cost per heating output to a certain extent, which means the comprehensive energy efficiency and economy of system can be improved. Results above can be used to guide the optimized operation of exhaust steam waste heat utilization system of large-scale turbine units.