Analyses On Distributed Variable Frequency Regulating Heating System

With the development of District Heating Systems, the heating networkbecomes large and more complicated, the structure and running modes ofsystems are various. The traditional valve-adjusting systems got behind theneeds of the networks development because of the severe energy waste andthe bad heating effect. The wide applications of variable-speed pumps makeheat system energy efficiency possible, and also have advantages in adjustprecision, security and hydraulic stability. In this dissertation, the VariableFrequency Regulating System(VFRS) in which valves are replaced byvariable-speed pumps of spur track is put forward, and studies on kinetictheories of VFRS are taken to analysis the system running rules, and furtherseek for its design and operation methods to guide the design and applicationof actual projects. Analytic derivation, simulation and engineering-practicesverification are adopted as research techniques. The kinetic model of VFRS is set up to satisfy the demands in the processof kinetic analysis. The minimum annual calculating expenses of systems isset as the goal function with accessibility, adjustability, hydraulic stabilityand security as terms of restriction, and then put forward a kind of simple andfeasible design method. First abstractly analysis several questions duringVFRS design and draw the basic rule of choice of main circulation pump andconfirmation of the point of zero pressure difference, that is the principalcontradiction of the problem. Then find the infection of changes of zeropressure difference point on system economical efficiency and the choice ofspur track pumps through the future simulation analysis, and select the bestscheme according to the goal function. The adjusting method are alsodiscussed. The results of simulation analysis indicate that the reasonable design andapplication of VFRS can realize the best economic benefits of heating systemand have significant influence on the development of heating trade. Thedesign method put forward in this paper is technically feasible andeconomically rational, it is hopeful to make enormous economic benefits andsocial benefits in actual projects.