Research On Extended Design Of Distributed Heating System

With the rapid development of the economy,the people's demand for quality of life gradually increased,and the pace of urbanization in China is also accelerating.However,the urban heat supply planning is lagging and imperfect for urban development,which makes the urban heating system facing the expansion requirements.In this paper,we mainly study the extended design of the distributed heating system,and propose a new heating system to solve the problem of the expansion of the heating network.For the variable frequency pump,the concept of the allowing maximum raise high ratio is proposed to reflect the pump working capacity and its influential factors are determined through theoretical analysis and establishing mathematical model.Based on the sample analysis of pump,the working ability of the two types of pumps which are flat type and steep drop type,is quantitatively determined.Proposing a method to select the variable frequency pump to ensure that the pump's maximum working capacity is utilized.Through the establishment of the thermal network model and the control variable method,the hydraulic regime before and after the system expansion are simulated.At the same time,making a qualitative analysis of the influence of the difference of zero pressure point and the position of heat load access on the hydraulic condition before and after the expansion of distributed heating system is according to factor analysis.The paper gives the evaluation index of the scale of the heating system,and a maximal scale of expansion is obtained according to the analysis of different distributed hating systems.A type of heating system is proposed,which named as the multi-stage distributed heating system,and the system form is briefly described.At the same time,the method of system's power consumption calculation is analyzed from the theoretical level.The qualitative and quantitative analysis of the energy efficiency of the system,the scale of the grade and the feasibility of the system expansion and transformation is made by simulation.The extended design strategy of distributed transmission and distribution system is proposed according to research conclusions.Taking a heating network project in Liaoning province as an example,the calculation and analysis of pump head lift ratio of the heating system's thermal station are carried out before and after the reconstruction of the system expansion to prove the feasibility of the reconstruction method.