Peak-shaving Ability And Economic Performance Analysis Of The Solar Aided Cogeneration Unit

With the economic development of human society,the consumption of fossil energy is increasing day by day,and the environmental problems arising from the utilization of fossil energy are becoming increasingly serious,which has a non-negligible impact on human survival and development.As a large country consuming energy mainly from coal,China urgently needs to increase the proportion of renewable and clean energy in the energy structure.In this paper,the technology of solar thermal utilization is introduced into the heating unit,and the solar aided cogeneration unit integrated by solar energy collector system,heat storage system and heating unit is proposed.During non-heating period,the heat gain from heat gathering field is used to replace the high-pressure steam extraction of some steam turbines;during heating period,the heat gained from the heat collecting field is preferentially stored in the heat storage system.After the heat storage is completed,the heat of the collector field is directly supplied to the heat user,and the heat in the heat storage system is timely supplied to the heat user according to the operation needs.For this integrated system,the main work and the key conclusions of this paper are as follows:Firstly,the model of solar aided cogeneration unit is built,and the mathematical models of the main equipments in the system are established,including trough collector field model,steam turbine model,heat storage heater model,etc.The program of the solar aided cogeneration unit under variable operating conditions is completed by using MATLAB,and the thermodynamic parameters of the unit are obtained.It provides a basis for the following research on peak shaving performance and economy of solar aided cogeneration unit.Secondly,the peak-shaving range of the heating unit is modeled,the peak-shaving range curve of the unit is obtained,and the operation strategy of the heat storage system is formulated.Based on this,the peak-shaving performance of the solar aided cogeneration unit is studied.The results show that the peak shaving performance of solar aided cogeneration units with the same installed capacity is significantly enhanced compared with traditional heating units.Under the rated extraction condition,that is;when the heat load is 251.72 MW,the peak-shaving range of the solar aided cogeneration unit is 228.48 MW-299.06MW,while that of the traditional heating unit is 191.54 MW-313.32 MW,and the peak-shaving capacity has increased by 72.54%.In full period of a typical day,according to the operation strategy of heat storage system,solar energy resources can not only increase the peak-shaving capacity of the unit during the peak period of day,but also stabilize the heat release through the heat storage system at night,so as to reduce the minimum power output of the unit.The solar aided cogeneration unit realizes the rational and efficient utilization of solar energy resources and has good peak shaving performance.Finally,according to the structure theory of thermoeconomics,the economic analysis model of the unit is established to analyze the economic performance of the system.In the economic analysis of 330 MW traditional heating units and solar aided cogeneration units,the following conclusions are drawn:on typical days of heating period,the cost of generating and heating of solar aided cogeneration units is 0.260 yuan/degree and 62.811 yuan/GJ,lower than traditional heating units of 0.262 yuan/degrees,72.813 yuan/GJ,in which the cost of heating decreases significantly.Obviously,it has good economy.