Research On Hydraulic Balance Adjustment Of Heating Pipe Network Based On Butterfly Valve

With the rapid development of my country’s economy,the scale of urban central heating has become larger and larger.The heating system often encounters hydraulic imbalance during operation,and the hydraulic balance of the pipe network has become more and more important.In this paper,based on the principle of network graph theory for the secondary heating pipe network with butterfly valves,a mathematical model of the hydraulic conditions of the heating pipe network is established,a calculation program is compiled,and the pipe network is adjusted for hydraulic balance.First,the resistance performance of the butterfly valve was studied by experiment and simulation.Set up a valve resistance performance test bench to test the resistance performance of butterfly valves with DN70 and DN80 pipe diameters.By adjusting the opening of the butterfly valve,measuring the pipe flow and the pressure difference before and after the valve at different openings,the corresponding relationship between the opening of the butterfly valve and the resistance characteristic of the butterfly valve is calculated.At the same time,the physical model and mathematical model of the butterfly valve are established,and the relationship between the opening degree of the DN70 and DN80 butterfly valve and the resistance characteristic number is obtained by the numerical simulation method.And compared with the experimental data,the results show that the simulated data is basically consistent with the experimental data,and the model can simulate the resistance characteristics of the actual butterfly valve.Based on the above conclusions,the model is used to calculate the resistance characteristics of butterfly valves with other pipe diameters of DN50～DN150,and according to the simulation results,the opening degree-resistance characteristic number function of butterfly valves under different pipe diameters is obtained,and six pipe diameters are analyzed.The best adjustment range of the butterfly valve.This conclusion provides a basis for the subsequent adjustment of the hydraulic balance of the pipe network.The article establishes a mathematical model of the hydraulic conditions of the branched heating pipe network,compiles a program to solve the model,and calculates the ideal distribution of resistance of the heating pipe network according to the prescribed flow rate of the heat user,and calculates the equilibrium state of the pipe network.The number of ideal resistance characteristics of the user.Measure the flow rate and typical pressure nodes of each user of the actual pipe network on site,and calculate the actual resistance characteristic number of each user under the actual state of the pipe network.According to the user’s ideal resistance characteristic number and actual resistance characteristic number,calculate the resistance characteristic value that the user to be adjusted needs to increase,and then substitute the opening degree of the butterfly valve under different pipe diameters into the function of resistance characteristic number according to the different pipe diameters of the user.The opening degree to which the inlet valve of the user to be adjusted needs to be adjusted is adjusted at one time on site.Applying the whole set of theory to engineering practice,in the heating season of 2020,the external heating network of a residential district in Dingzhou city was adjusted in hydraulic balance,and the flow rate of each user and the pressure value of the end user were measured.Using the compiled program combined with the researched butterfly valve resistance characteristic function,the hydraulic balance adjustment scheme of the pipe network is proposed.The actual adjustment results of the pipe network show that the hydraulic imbalance of the pipe network has been improved through the adjustment,and the hydraulic imbalance of each user after the adjustment can be controlled within ±15%.