Research On The Configuration And Operation Strategy Of District Heating System With Co-generation Based On Absorption Heat Exchange (co-ah)

One of the emphasis tasks of energy saving is to explore the energy savingpotential of co-generation and enhance the feasibility of co-generation district heating inChina. In view of the insufficient ability of co-generation heating source and poordelivery capacity of heating network, Tsinghua University proposes a new type ofdistrict heating system with cogeneration based on absorption heat exchange (Co-ahSystem). It could recycle exhaust steam waste heat of power plant and transport heatwith a larger temperature difference. This paper focuses on the configuration and theoperation strategy of Co-ah system. These research results may be of guidance fordesign and operation of Co-ah system.Because the safety and efficiency of large heating unit is affected by exhaustedheat recovery from condensers, the maximum ratio of extraction steam and condensedsteam of turbine is defined. In a safe condition, define the parameter of large extractioncondensing combination unit based on exhaust steam waste heat utilization. As evaluatethe effect of exhausted heat recovery from condensers on generate electricity, botheffective enthalpy drop and condensed steam flow of low pressure cylinder should beconsidered.For evaluate the energy efficiency, this paper puts forward three roles of exhauststeam waste heat utilization of Co-ah system. Considering the influence of exhauststeam waste heat utilization on heating and power, the definition of heating equivalentelectric is given. It is used to analyze that how quality and quantity of extraction steamand condensed steam effect the operation efficiency on the total operating period. Thusa comprehensive efficiency evaluation method of Co-ah system is completed.For the system configuration of Co-ah system, the terminal connecting formats ofair and wet cooling steam turbine and the type of absorption heat pump are sum up. Thedefinition of the ratio of extraction steam and condensed steam of Co-ah system isproposed. By analysis the matching relations of the ratio of system and turbine units, theCo-ah system performance optimization direction is clear. Some suggestions are given,namely, parameter optimization principle and method of the cogeneration unit andnetwork system; the matching relations of absorption heat exchanger unit and absorption heat pump; the rationality of improving the performance of the systemthrough adding absorption heat exchange units.For the operation control of Co-ah system, a suitable operation adjustment mode ofheating network and changing back pressure operation ideas of turbine are proposed.Based on the method of cascade utilization of energy, this paper puts forward twooptimization method: heat network water series arrangement and linking with coldterminal, to improve energy efficiency further in the operation and ease thecontradiction of exhaust steam waste heat utilization and condenser winter antifreeze inplant.To integrate theory research with project practice, the first large-scale industrialapplication demonstration project is built in Datong city. By actual test, the performanceof two kinds of absorption units is verified. In addition, based on the measurement andanalysis of head power system, reasonable operation condition and mode is determined,and the theoretical research of this paper is verified.