The Automatic Control Of The Distributed Pump System Keeping The Critical Zero-Pressure State

The development of China has been greatly restricted by the energy shortage and environment pollution, where buildings are consuming a large portion of energy. With the development of the district heating facilities, people realized that the traditional district heating systems are energy-wasting, inefficient and ill-regulated. As a result, the distributed pumps system installing booster pumps rather than regulating valves in users'circuit is proposed to improve the condition. Through the analysis of various structures, terminals and regulating models of the distributed pump systems, this paper proposes the most energy efficient and practical regulating mode of the distributed pump system– keeping the critical zero-pressure state.This paper analyzed the variable speed intervals of the circulating pump and booster pump, in which the pumps are working in the highest operating efficiency. While the heating source is regulated in the mode of improved variable flow strategy, the regulating and control strategy of keeping the critical zero-pressure state in the distributed heating system are proposed. Simulation is applied to better analyze the hydraulic condition of the distributed pump heating system. First, the effect of the circulating pump on the heating station is simulated. Then the effect of the booster pump on the heating station is added, by which the hydraulic condition of the distributed heating system is figured out.To reach better control of the heating system, the thermal performance under the state and dynamic state need to be studied. The water temperature change along the pipe and the lag time of the primary loop in variable flow condition is calculated with models. In the end, the pumps'energy consumption in the distributed system combining the traditional heating system, the valves and the booster pumps are computed through analog to analyze the energy efficient effect.The distributed pumps system working under the critical zero-pressure sate are applied in the demonstration project and showed the advantages of being energy-efficient and adjustable. But the energy conservation effect doesn't meet with the theoretical analysis. The next step of research would be analyzing the affecting factors of the distributed heating system by combining the physical situation to achieve better application effect in practice.