Research On Cascaded Heating System With Multi-heat Source Based On Waste Heat Utilization Of Wet Cooling Unit

Utilizing the exhausted waste heat in power plant as a new type of heat source is a key method to realize both energy-saving of thermal power and clean heat-supplying of city.To tackle the difficult issue of realizing the efficient waste heat utilization of multiple units simultaneously,this paper put forward the idea of building a cascaded heating system with muilt-heat source based on the integrated energy system.Thereafter,according to the basic theory of the last stage safety assessment and energy efficiency evaluation,this paper has done further studies on the integration and optimization of the new system.1)Study the basic theory of last stage safety assessment and energy efficiency evaluation of large unit based on waste heat utilization: on the one hand,explore the safety scope of extraction steam and exhausted steamparameters in double heat source heating conditio ns;on the other hand,introduce “heating equivalent electricity” as the evaluation index an d method of the system to evaluate the comprehensive energy utilization efficiency of syst em capacity,while the electricity quantity is unified.2)For multiple units,combine three kinds of waste heat recovery technology to construct a cascaded heating system with multi-heat source,and then analysis the characteristics of the new system,based on the typical type of wet cooling units to develop the connecting and switching method between the original cold end and the new system.Thereafter,establish the operating property analysis model in variable conditions of the new system.3)According to the characteristics of the new system integration and considering the comprehensive energy efficiency and technical economy of the system,this paper has studied the optimization method of the key parameters of the system(the ratio of extraction steam and wasted steam of the unit,the bypass water flow rate and the return water temperature of the heating network)and final presents the optimization direction of system performance.4)Taking Shijiazhuang Xibaipo Power Plant as the object of this study to carry out targeted engineering practice research.The results of theoretical research of this paper is used to guide the formulating of new system integration.Besides,the energy efficiency,technical and economic performance of the targeted system was demonstrated.The results showed that the new system presented in this paper had significant advantages in application value.