高背压供热机组供热温度特性与[火用]分析

Heating temperature characteristics and exergy analysis for high back pressure heating unit

高背压供热具有大幅减少冷源损失及扩大机组供热能力的优势,而针对高背压供热机组供热温度特性及[火用]分析未见报道。本文采用自主研发的热力系统集成优化软件,搭建热力系统仿真模型,建立了热电联产机组[火用]分析模型,研究了不同供热期高背压机组供热温度特性。为了避免低供热负荷对机组供电负荷的限制,提出了高背压凝汽器供热-新风加热方法。结果表明:采用高背压凝汽器供热-新风加热方法,解决了低供热负荷对机组供电负荷的限制,实现了供热初末期热电解耦;相同主蒸汽流量工况,热电厂总[火用]效率大小顺序为严寒期>寒冷期>次寒期。本文研究结果可为热电联产运行优化提供借鉴。

High back pressure heating technology is widely used in heating retrofitting of large-scale cogeneration units because of its advantages of greatly reducing the loss of cold source and expanding the heating capacity of the units.However,there is no report on heating temperature characteristics and exergy analysis of the high back pressure heating unit.By using the self-developed thermal power integration scheme(TPIS)software,this paper builds up the simulation model of thermal power system and establishes the exergy analysis model of cogeneration units to study he heating temperature characteristics of high back pressure units in different heating supply periods.In order to avoid the restriction of low heating load on the unit power supply load,a method of high back pressure condenser heating-fresh air heating is proposed.The results show that,adopting the high back pressure condenser heating-fresh air heating method can break the limitation of low heating load on the unit supply power load and realize thermo-electric decoupling at the early and last period of heating.Under conditions with the same main steam flow,the total exergy efficiency of thermal power plant is ranked as follows:big-freeze period>cold period>secondary cold period.The result provides a reference for operation optimization of the cogeneration.