Optimization Of The System Combined Cooling,Heating And Power

The development of the CCHP technology can not only realize the cascade efficient utilization of energy,but also enhance the protection of the environment.Therefore,it is of great practical significance to strengthen the research and development of CCHP technology,and it is imperative to promote and implement the technology.Although there have been studies on the optimization of the integration scheme and operation strategy based on the CCHP technology,there are different optimal integration schemes and operation strategies for different projects.Therefore,this paper carries out integrated scheme design and operation strategy optimization according to the engineering requirements studied.This paper firstly analyzes the advantages and disadvantages of different equipments in the power generation system,heating system and cooling system.The system integration scheme is designed according to the actual engineering requirements.The new system integration scheme is designed as follows: Gas-steam turbine combined cycle + refuel type dual pressure waste heat boiler + lithium bromide absorption refrigeration unit,it uses steam extraction in the waste heat boiler to achieve a simple peak adjustment.Then,the system was calculated using the Aspen Plus platform,and exergy loss analysis was performed based on the calculation results.It was concluded that exergy loss in the system mainly came from the residual heat of gas turbine and flue gas,and exergy loss in the combustion room accounted for about 75% of the total exergy loss in the system.According to the analysis results,the structure of the system is optimized,and the traditional air compressor is changed to primary cooling and secondary compression,and the residual heat of flue gas is used to heat the fuel.The evaluation indexes of heat efficiency,exergy efficiency and unit energy consumption return were used to compare and analyze the integrated schemes before and after optimization from the perspectives of the first law of thermodynamics,the second law of thermodynamics and economy,respectively.It was found that after optimization,the heat efficiency of the system would be improved by about 4%-6%,the exergy efficiency would be improved by about 2%,and unit energy consumption return would be increased by about 0.3 yuan /GJ,proving that the optimization is feasible.In the process of comparison,it was found that the heat efficiency,exergy efficiency and unit energy consumption return of the system would change with the changes of interstage pressure,outlet pressure and interstage cooling temperature.Through sensitivity analysis,it is concluded that the heat efficiency,exergy efficiency and unit energy consumption return of the system will decrease with the increase of interstage pressure.They increases with the increase of the outlet pressure,but when the pressure ratio of the compressed part of the high pressure increases to about 8,they will start to decrease instead.In addition,it also decreases with the increase of interstage cooling temperature.However,when the pressure of the high-pressure parts is relatively small,about lower than 8.5,they will increase first and then decrease.Finally,the paper analyzes the climate and load characteristics of the project area,and optimizes the operation strategy scheme of the CCHP system based on the three aspects of energy conservation,economy and environmental protection.It is concluded that: in this region,only from noon to evening in summer is based on the operation strategy of "heat fixed power",and the rest of the time period and other seasons are based on the operation strategy of "power fixed heat".