Research On The Design Model And Method Of The Equivalent Zone Of Single Heat Source Heating Network

In the process of rapid development of urban central heating system,the reliability analysis of the heat network,which is a component with high flexibility and complexity in the heating system,is often neglected,resulting in frequent failure events.As a component that can isolate the fault area in time,the valve is often installed as a component to improve the reliability of the pipe network in the design stage.However,the reliabilitybased valve design method is not involved and the reliability problem of the pipe network is often ignored by the designer in the design system of the existing heating network.Therefore,how to optimize the reliability of pipe network more accurately and effectively is still an urgent problem that we need to think about.This paper divides the equivalent zone into valve and non-valve equivalent zone according to the different types of components.The concepts of virtual heat source and matrix traversing are introduced to divide the non-valve equivalent zone in the pipe network,so the complex heating network can be simplified into a network structure composed of several pipelines which only contain valve and non-valve equivalent zone.At the same time,the mathematical model of the probability index of failure-free operation of the single heat source branch and single heat source ring simplified pipeline is established respectively.The effects of heat load density,number of valves,fault flow parameters and heating time on the reliability of the pipeline network were analyzed.In addition,according to the different influencing factors,this paper establishes certain evaluation indexes to classify the non-valve equivalent regions in the single heat source branch and single heat source ring network.Focus on the pipeline with the non-valve equivalent zone with high importance and take the unreliable input of the pipeline as the objective function to give the optimal valve position compiling procedure for the two pipelines respectively.Then,by adjusting the position distribution of the valves in the pipeline,the unreliable input of each pipeline is reduced to improve the reliability of the entire heating pipe network.Finally,according to the number of valves,it is divided into the design of the pipeline equivalent zone of the complete valve and the fixed valve.The design steps for the single heat source branch pipe network and the single heat source ring pipe network are proposed respectively.Taking a heating pipe network in Shenyang as an example,the correctness and effectiveness of the relevant conclusions in this paper are verified.The research shows that the main influencing factors of pipe network reliability are the number and size distribution of each non-valve equivalent zone while the influence of the branch pipe network and the ring pipe network is slightly different.For the branch pipe network,the reliability decreases slowly with the number of non-valve equivalent zones,and the heat load density of each non-valve equivalent zone decreases from the heat source to the end and the trend is greater.Reliable;for a single heat source annular pipe network,the more the number of non-valve equivalent zones and the more uniform the product distribution of the equivalent heat load and the equivalent length of each nonvalve equivalent zone,the more reliable the pipe network.In addition,this paper proposes steps for the existing pipe network to calculate the non-valve equivalent zone importance—selecting the pipeline to be optimized—selected form—valve optimization—reliability calculation of the equivalent zone design method;the steps for designing the equivalent pipe for the new pipe network are to split the pipeline—calculate the number of valves—selected form—valve optimization—reliability calculation.The design method is applied to the valve setting of a heating pipe network in Shenyang City,the equivalent zone is designed based on the recommended segmental valve spacing of 1km and 1.5km respectively,and the results of the pipe network reliability greater than 0.96 are obtained,which verified the correctness and validity of the relevant conclusions of this paper.