大型热电联产机组高背压供热改造全工况热经济分析

抽凝供热机组抽汽参数往往高于热网所需，热损失大。高背压供热机组利用排汽余热供热，增加供热能力，减少供热抽汽量。单转子运行和双转子互换是大型汽轮机高背压供热改造的2种主流方式,为研究不同方式的经济性和适用性，以某350 MW机组为例，采用Ebsilon仿真软件建立高背压供热汽轮机变工况计算模型。结合单耗理论进行不同改造方式下供热季与非供热季经济性及能耗对比。结果表明：和单转子方式相比，双转子互换方式在供热季发电量多200万 kW·h，平均发电煤耗低0.24 g/（ kW·h），最大供热量少6.48 MW，非供热季其火用效率高于单转子方式。但考虑到双转子互换方式供热季优势并不明显，且每年需要2次更换转子，因此对于大型热电联产机组高背压供热改造首选单转子方式，以降低成本。

Thermo-Economic Analysis of High Back Pressure Heating Retrofit for Large-Scale Cogeneration Unit under Full Condition

Extraction steam parameters of extraction condensate heating unit are often higher than the heating network required, which resulted in a great loss of heat. High back pressure unit makes use of exhaust heat for heating, thus increasing heating capacity and reducing heating steam extraction. There are two main methods of high back pressure heating retrofit for large steam turbine, which are single-rotor mode and double-rotor interchange mode. For the study of different forms of economy and applicability, taking a 350 MW unit as an example,this paper constructs an off-design calculation model of high back pressure heating turbine using Ebsilon simulation software. We comparatively analyze the economic efficiency and energy consumption in heating season and non-heating season under two modes based on the theory of unit fuel consumption. The results show that in heating season,the electricity output of double-rotor interchange mode is 2 000 MW·h higher, the average coal consumption rate is 0.24 g/kW·h lower and the maximum heating capacity is 6.48 MW lower compared with that of single rotor mode. In non-heating season, the exergy efficiency of double-rotor interchange mode is better than that of single-rotor mode. However,the advantage of double-rotor interchange mode in heating season is not obvious and double-rotor interchange mode requires replacing rotor twice a year. Therefore, in order to reduce cost, single-rotor mode is the first choice for high back pressure heating retrofit of large-scale cogeneration unit.