| Parallel centrifugal pump systems are widely used in municipal water supply and chemical production.A certain design margin will be reserved when the pump group is selected,which also leads to the deviation of the optimal working condition of the pump group from the actual production demand,and the problem of deviating working condition.Off-design operation not only brings energy loss,but also reduces equipment reliability.From the perspective of reducing the whole life cycle cost of the pump group,the commonly used single-objective control models such as maximum efficiency,minimum power and minimum flow deviation only pay attention to the efficiency optimization of operation cost,ignored the hidden maintenance cost caused by the reliability reduction,and their control strategies are relatively single,unable to adjust operation strategy according to real-time state pump group.In order to solve the problem that single-objective control model cannot adjust the operation strategy according to the real-time state of the pump group,a multi-objective control model of parallel pump group that integrates the energy efficiency and reliability of the pump group is proposed.Objective deviation rate,specific energy consumption and impeller load were used as evaluation indexes for the economic benefit,technical operation and safety reliability of the pumping system.Operation strategy is determined by adjusting the weight of each indicator in multi-objective control model,and the operation condition of pump group is adjusted to match its real-time state by which high energy efficiency(low target deviation and specific energy consumption)and high reliability(low impeller load)in the low wear stage of the pump group can be achieved,so do the reduction of the cost of the whole life cycle of the pump group.The main content includes the following aspects:(a)The basic parameters and monitoring methods of centrifugal pump are analyzed and studied.The accuracy and cost of different monitoring methods are compared through experiments to obtain the monitoring method of pump group with low cost and guaranteed accuracy,and the determination of the parallel operation point of pump group is analyzed.(b)Based on the proportion of operation and maintenance cost in the whole life cycle cost of the centrifugal pump,the distribution and variation trend of efficiency and specific energy consumption in the working area of the centrifugal pump are studied from the perspective of operation cost.The load distribution,the minimum reliable flow rate and the cavitation reliability distribution of centrifugal pump impeller are calculated by analyzing the mechanical and hydraulic reliability from the maintenance cost.The recommended working area was obtained based on efficiency,specific energy consumption,impeller load and hydraulic reliability.(c)Combined with the recommended working area of the main indexes and the characteristics of the control modes of the centrifugal pump,a control structure matching the requirements of the multi-objective model is constructed.From the perspective of economic benefit,technical operation and safety reliability,the target deviation rate,specific energy consumption of centrifugal pump and impeller load were selected as evaluation indexes,and the three indexes were taken as objective functions of the ideal point model.The distribution of solutions under different weights is analyzed,and the influence of the weight of Pareto solution set obtained by multi-objective particle swarm optimization algorithm is compared to improve the ergodic property of solutions and the diversity of control strategies.(d)The control models of different parallel systems is studied and a simplified modeling method is proposed.Combined with Pareto solution set,the flow distribution characteristics and optimal solution distribution of centrifugal pumps in different parallel systems are analyzed at the same time,and the control structure of pump group is improved according to the system characteristics.In this paper,a multi-objective control model of parallel pump group is proposed,which integrates the energy efficiency and reliability of the system and adjusts the operation strategy according to the real-time status of the pump group.The efficiency and reliability of the pump group under different targets and strategies are verified.The results show that by introducing the real-time status of the pump group into the decision-making and using the weight change control strategy,the high energy efficiency and high reliability of the pump group in the low wear stage and the high wear stage can be realized,and the cost of the whole life cycle of the pump group can be effectively reduced. |
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