Operation Optimization And Energy Efficiency Level Improvement Of Secondary Water Supply System

The secondary water supply equipment is the core component of the building pressurized water supply system,and it is also an important part that should be paid attention to in the energy saving optimization of the building mechanical and electrical equipment.Under the premise of ensuring users’water demand,applying new ideas,exploring new methods,promoting new technologies,fully tapping the energy saving potential of the secondary water supply system,and effectively improving the energy efficiency level of the secondary water supply system is a research project with social and economic benefits,and it is also of great significance for building a green and energy-saving society.This paper mainly focuses on the operation optimization of secondary water supply system in three aspects to improve its energy efficiency.First of all,analyze the energy transfer relationship of each energy consumption link in the secondary water supply system,and give the theoretical calculation formulas of the overall equipment efficiency and system comprehensive efficiency,and demonstrate the mathematical relationship between unit water supply energy consumption and system comprehensive efficiency,and calculate and compare the energy efficiency level of the actual secondary water supply project with the two indicators of unit water supply energy consumption and system comprehensive efficiency,and discuss the reasons for its low level of energy efficiency.Based on the understanding and analysis of the operation and control principle of the variable frequency constant pressure water supply equipment,the calculation method of the speed regulation ratio and shaft power during the frequency conversion operation of the pump is deduced,and the numerical solution algorithm of the cumulative operation energy consumption of the pump unit is given in particular,which lays a foundation for quantitative analysis of the full text.Secondly,aiming at the minimum running shaft power of the parallel pumps,combined with numerical solution algorithm for pump unit operation energy consumption and image properties of Q-N quadratic fitting functions,and applying the idea of combining numbers and figures and verifying it with an example,it is found that the necessary condition for energy-saving operation of parallel pumps of the same model is that the pumps are fully frequency-controlled.Then,the energy-saving advantages of the full-frequency control technology are discussed from the perspective of the unit water supply energy consumption of the equipment.Analyze the characteristic curve of parallel pumps and pump performance samples,it is proved that a single speed governing pump meeting the relationship of k₁/k₂≥4 is the premise of water supply equipment using full frequency conversion control for energy-saving operation,which provides theoretical support for the promotion and application of full frequency constant pressure water supply equipment.In addition,clarified the determination of start and stop points of small flow pumps in variable frequency water supply equipment and additive pressure water supply equipment,the influence of the reasonable determination of the precharge pressure of the pneumatic tank on the operating conditions of the water supply equipment is mainly analyzed.At last,taking the secondary water supply system in a residential area of a university as the research object,verifying the correctness of the above theoretical research and the energy-saving effects of optimization measures.Based on the water volume data module of the"Campus Energy Saving Supervision Platform",the influence of season,temperature,weekend and holidays on the monthly and daily water consumption of residents is discussed.The water supply scheme was determined and the accumulative power consumption of the maximum daily water consumption main pump was calculated,it was concluded that the pump group could save 4.20%energy when running with full frequency conversion control than with single frequency conversion control,the system comprehensive efficiencyη_S is 66.89%and 68.42%respectively under the single frequency and full frequency control modes,and the energy saving advantage of full frequency control over single frequency control in the operation of the equipment is more obvious in the period when the water output of the single variable frequency speed governing pump is less than the minimum flow of the single pump high efficiency zone.