| In the cold regions of our country,the cogeneration unit cannot be deeply peak-shaving because it is affected by the operating characteristic of “electric power defined by its quantity of heat produced”.The scheme of configuring the hot water storage tank for the unit is beneficial to realize the decoupling operation of power production and thermal production and improve the peaking capability.At present,although there are many studies on thermal characteristics of the operation of the tank,the methods of these are often complex and difficult to understand,and the application of these in engineering is inconvenient.Moreover,the automation of the tank system is low.Therefore,it is necessary to study thermal characteristics of the tank by using the method of simple,easy to understand and convenient for the technical staff to analyze and calculate in real time and design the DCS configuration of the tank system to improve automation.Based on the thermal power unit flexible transformation project of a power research unit,a cylindrical atmospheric hot water storage tank for a cogeneration unit in Northeast China is studied,and the control scheme of the storage tank system is preliminarily designed.These two aspects are the main content of this article:(1)Study on thermal characteristics of the tank in heat storage processFirstly,the mathematical model of the tank is established.Then,the two performance evaluation indexes of the tank are analyzed:heat storage efficiency and thermocline thickness.Finally,based on the matlab programming environment,combined with the Gauss-Seidel iterative method,the calculation program of the heat storage characteristics of the heat storage tank is compiled.Through calculation,the time of filling hot water,heat storage efficiency and the curve of outlet water temperature and thermocline thickness with time under different working conditions are obtained quickly,so as to analyze the influence of heat storage time,inlet mixing factor,inlet mass flow and temperature difference between hot and cold water on the thermal characteristics of the heat storage tank.(2)Preliminary design of DCS configuration of the heat storage tank systemIn this paper,according to the process flow,the EDPF-NT+system software developed by Beijing GuoDian ZhiShen Control Technology Co.,Ltd.is used to configure the DCS measurement point and picture of the heat storage tank system.The preliminary design of the configuration of the SCS and the MCS is completed,and the configuration design of the two kinds of storage/heat release process is completed.The virtual DPU technology is used to complete the simulation test of the control scheme,which lays a good foundation for the system operation.These works have certain reference value for the application of hot water storage tanks in the cogeneration power plant. |
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