Research On Balance Adjustment And Optimal Operation Of The Secondary Network In Centralized Heating System

China has a vast territory with a large north-south span.Because of the long winter,the centralized heating systems are used to ensure indoor thermal comfort in China northern region.With the implementation of energy saving and emission reduction policies,reducing the energy consumption of the centralized heating systems has gradually attracted attention.The centralized heating system is divided into two parts,the primary network and the secondary network.Because the secondary heating network system has the characteristics of wide distribution and large number,there is a great potential for energy saving.This article studies on the initial adjustment and operation adjustment of the centralized heating system,and focuses on reducing the energy consumption of the secondary network.This paper is used the method of the secondary network balance adjustment based on pipe network impedance identification.The purpose of thermal balance of the pipe network is achieved by adjusting the hydraulic balance of the pipe network.For branched pipe networks with static balance valves,according to the adjustment characteristics of the static balance valves,two sets of different operating conditions data are obtained by adjusting the opening of the balance valve once.The inherent impedance of the pipe network is completed according to these data.Then calculate the ideal opening degree of all static balance valves in the pipe network according to the identification result of the inherent impedance.According to the calculation results of the opening degree,the valves of the actual pipe network are directly adjusted,and the hydraulic leveling of the heating secondary network is completed at one time,thereby achieving the hydraulic and thermal balance of the pipe network.For the operation adjustment part,this article first analyzes the variable flow characteristics of the heating network and the variable-frequency water pump from the principle,and obtains the flow adjustment range for different heating network and the high-efficiency operation range of the pump.Then uses the result as one of the constraints to base research on the optimal operating conditions of the secondary network.Based on nonlinear programming,taking the ratio of power consumption and heat transmission as the objective function,by setting reasonable constraint conditions,the optimal configuration of heating operating parameters at each outdoor temperature is realized.Using the calculated operating conditions for heating can improve the efficiency of energy utilization,reduce the power consumption of the unit pumps throughout the heating season,and achieve the purpose of energy saving.Finally,this article combines the actual project,and applies the initial adjustment and operation adjustment model of the heating system proposed in this article to this actual project.The correctness of the two adjustment models in this paper is verified through actual engineering application data.At the same time,the actual project operation data also proved the energy-saving characteristics of the two adjustments.Reasonable initial adjustment and operation adjustment of the pipe network can greatly reduce the energy consumption of the unit and achieve the purpose of energy saving.