基于吸收式换热机组的热电厂乏汽余热利用供热系统研究

Research on waste heat utilization heating system of thermal power plant based on absorption heat exchanger

通过分析目前热电联产集中供热系统存在问题,基于吸收式换热系统运行原理,一方面提出在部分二级换热站安装吸收式换热机组,使得在不改变一次网供水温度、二次网供回水温度的前提下,显著降低一次网回水温度,一次网供回水温差增加可有效提高管网输送能力;另一方面提出在电厂安装吸收式换热机组,以汽轮机采暖抽汽作为驱动热源回收汽轮机乏汽余热,用于梯级加热一次网回水。由于一次热网低温回水与汽轮机乏汽能级匹配,使得改造后的供热系统处于极佳效率工作区间。经过此次改造后提高了热源供热能力,增加了管网输送能力及电厂发电量,同时大幅提高电厂热效率,该方案的实施可有效缓解北方城市热电联产集中供热面临的矛盾。

By the analysis of the existing problems in the cogeneration central heating system,based on the operation principle of absorption heat exchange system,it is proposed to install absorption heat exchange units in some secondary heat exchange stations,so as to significantly reduce the return water temperature of the primary network,increase the temperature difference between the supply and return water of the primary network and effectively improve the transmission capacity of the pipe network without changing the water supply temperature of the primary network and the return water temperature of the secondary network.At the same time,it is proposed to install absorption heat exchange unit in power plant,using steam turbine heating extraction as the driving heat source to recover the waste heat of steam turbine exhaust steam for the return water of cascade heating primary network.Because the low temperature return water of primary heating network matches with the exhaust steam level of steam turbine,the reformed heating system is in the working range of excellent efficiency.After the transformation,the heating capacity of the heat source is improved,the transmission capacity of the pipe network and the power generation capacity of the power plant are increased,and the thermal efficiency of the power plant is greatly improved,which can effectively alleviate the contradiction faced by the central heating of cogeneration in northern cities.