Study On The Design Of Long-distance Pipeline And Optimization Of Primary Heating Network In Urban Central Heating System

Heat supply is an important part of the development of national life.In the course of heating development,urban central heating system has been playing a decisive role in the efficient and rational use of energy for a long time.The demand for heating is no longer limited to the gradual expansion of the scale,and at the same time,the reliability,economy and rationality of the heating system are required at a higher level.In this paper,typical engineering projects are designed and studied in two parts.The first part is the feasibility study on the long-distance heat transfer pipe network of the urban central heating pipe network of a power plant in Shanxi Province.The second part is the optimization design study on the layout and diameter of the first-level heating pipe network in the urban area.In the first part,the feasibility analysis of 23 km long-distance heat supply pipeline proposed by a power plant in Shanxi Province to Jincheng city is carried out.This paper studies the heating scheme of long distance central heating network under high altitude difference,the setting conditions of relay pump station and the theoretical setting range of relay pump station in the main heating line.According to the heating load and the pipeline lines in the long-distance heating transmission section,four kinds of heating pipe network projects are proposed: the first stage pressurization in the first station,the multi-stage pressurization in the relay pump station,the heat exchange in the isolation pump station,the combination of the relay pump station and the isolation pump station.Through the analysis of water pressure diagram,the scheme combining relay pump station with isolation station is the most suitable.Some energy-saving measures for heating engineering are put forward.In the second part,for the locations of energy stations and heat exchange stations that have been determined in the urban area,the layout of heating pipe network is expressed in matrix form through the method of graph theory,and the hydraulic calculation mathematical model of pipe network is established based on the knowledge of fluid mechanics,which can be used as a hydraulic calculation tool in the layout of first-grade heating pipe network and the optimization design of pipe diameter.Economy as evaluation index,the heating pipe network construction cost,depreciation,maintenance cost,annual operation cost and costs of heat loss calculation integration this four parts,based on equivalent annual cost as the objective function of the heating pipe network optimization design mathematical model,as the level of heating pipe network layout and pipe diameter optimization objective function of optimization design.With the ideas of the analytic hierarchy process,make the heating pipe network layout and pipe diameter optimization design problem is divided into three layers: the first layer for heating pipe network layout optimization,hydraulic calculation by hydraulic calculation mathematical model,with equivalent annual cost as objective function,using the binary genetic algorithm to urban level of heating pipe network layout optimization,get some reasonable set of heating pipe network layout scheme;The second floor for heating pipe diameter optimization,that is,in the first level of heating pipe network layout scheme,on the basis of hydraulic calculation by hydraulic calculation mathematical model,with equivalent annual cost as objective function,apply a layer of integer genetic algorithm to get each layout scheme of pipe diameter optimization respectively,for each of the pipe diameter combination and its network under a layout in reduced cost;In the third layer,the annual converted cost of each scheme was compared to find out the heating pipe network layout scheme corresponding to the minimum annual converted cost of the pipe network,that is,the final optimal heating pipe network.The corresponding layout was the optimal pipe network layout,and the corresponding pipe diameter combination was the optimal pipe diameter combination.