Study On Gas Turbine Based CCHP System Multi-objective Optimal Configuration And Operation Strategy

On the background of current energy supply situation, environmental qualityrequirements, and much focus on distributed energy systems for large and medium-sizedcities, this paper attempts to study the CCHP system (Combined Cooling Heating and Power)with supplementary firing HRSG（Heat Recovery Steam Generator） and steam injected gasturbine. According to the existing research on the overall off-design characteristics of gasturbine CCHP system, using the existing off-design characteristic models of gas turbine,HRSG and LiBr absorption chiller, and considering the influence of environment temperatureand load rate on the efficiency of CCHP system components. And then, combined with theoutside cooling, heating and power load distribution and the operation mode, this systemcomponents configuration optimization and multi-objective evaluation is deeply studied. Themain research work is listed as follows:(1) In order to meet the wide range of cooling, heating and electricity load demand of thebuilding users, Considering its variability characteristics, CCHP system with supplementaryfiring HRSG and steam injected gas turbine is put forward, and its ability to satisfy therequirement of off-design characteristics on a wide range is clarified.(2) Considering the current energy situation and environmental stress of large andmedium-sized cities, and comprehensive considering the performance of energy conservation,economical efficiency and environmental protection for CCHP system，a multi-objectiveevaluation index of primary energy saving rates, operating cost savings rate, and carbondioxide emissions saving rate is established.(3) In order to make the system under the optimal operation according to characteristicsof outside load, the operation mode of FPL and FHL have been discussed. And then a optimaloperation model is established in which the multi-objective evaluation index is taken as theobjective function and the gas turbine capacity as the optimization variable. Using the hourlycooling, heating and electricity load data of a hotel building in South China as an example, theoptimal capacity configuration and its corresponding operation strategy are obtained withpattern search algorithm. In order to verify the superiority of the optimal operation strategy,different operation strategies are compared. At last, the influence of variational natural gas price and electricity price, different evaluation index weight coefficient and operationstrategies on optimize configuration of the system have been analyzed.(4) Under the optimal operation strategy, research on the feasibility of the maximumsupplementary firing of HRSG is taken. Sometimes the CCHP system will have the redundantheat, so the influence of gas turbine with superheated steam injection on the economy of theCCHP system is studied. At last, overall considering the CCHP system with supplementaryfiring HRSG and steam injected gas turbine,a technical route for optimizing configuration ofthe system is proposed.