Study On Optimal Design Of The District Heat-supply Network

Heat-supply network plays a very important role in modern city centralized heat-supply system. It needs huge financial investment and many laying methods. It impacts huge when accident or failure happens.This work focuses on the design of heat-supply network for Tianjin Freightage Transport District. The design is based on analyzing and comparing different laying methods with respect to their environment and financial requirements and heating requirements of buildings during winter.This work first discusses overhead, directly burying, trench and utility tunnel methods. Then it focuses on directly burying method, compares its technical specifications and cost with compensatory directly buried method, directly buffed cold installation without expansion joint, installation method of non-compensating preheating. Regarding long straight pipes, the design replaces elastic analysis with stress analysis and uses directly buffed cold installation and preheating installation without expansion joint to replace compensatory directly buried method and cancels most compensators and anchor blocks trying to reduce construction cost and duration. This work focuses on analyzing the method of directly buffed cold installation without expansion joint, makes detailed analysis on its technical feasibility and economic benefits and compares different laying methods for various pipe diameters. It also emphasizes the protection of weak pipe areas, e.g., it increases wall thickness and adds compensator and anchor block to elbow, T joint and valves. It chooses installation method, pipe diameter; pump lift and develops economical operation process based on the calculation of stress, wall thickness, insulation thickness and hydraulic calculation of the heat-supply network. This design provides theoretic background for operating the network in various conditions, including incidents. It also helps maintaining reasonable budget to the project.This work designs heat-supply network system by analyzing geo and social environment, comparing and analyzing different laying methods and considering domestic and international cutting-edge technologies.