Study On Power Loss Of Canned Motor Pump

The canned motor pump is an electromechanical integral product. The fundamental difference with the general pump is that the electric engine and the pump are combined together. It is convenient to transport some liquid that is deleterious to human health (such as noxious and radioactive liquid ), inflammable and explosive, costliness and mordant. It has the advantages of absolutely seal, small bulk, light weight, high dependability and economical efficiency etc.Canned motor pump has not the same shaft sealing structure as the common chemical pump, which results in a series of problems to be resolved. Because of the housing, gap between the stator and the rotor increases; There is eddy current loss in the housing; Meanwhile, the rotor rotates in the medium and frictional resistance increases , which results in the lower efficiency of canned motor than that of common motor. In addition, the blade wheel gap of canned motor is bigger than that of the common chemical pump and some fluid supplys circulating cooling for canned motor, so the volumetric efficiency is low. In a word, the unit efficiency of canned motor pump is lower than that of the common chemical pump with the same parameters.The PZA chemical engineering canned motor pump recently developed by Jiangsu University is taken for example. The calculating formula of normal housing total loss which is common used in project and the calculating formula of frictional loss of liquid are referred to. Particularity several kinds of factors that affect the power loss of canned motor pump are analyzed and the inner magnetic field are simulated using finite element software ANSYS. And these design parameters are optimized, which provides theoretical basement for the later design of canned motor pump.In the analytical calculation of cooling and lubricating loop, we provide a new type of calculating method , viz. predigesting several resistance components to a series-parallel connection loop, then using the similar way used in calculating serial-parallel connection loop of electrocircuit to calculate the resistance drop and the total head of delivery of each resistance component. The PZA chemical engineering canned motor pump recently developed by Jiangsu University is taken for example and the calculating results are compared with the survey result, and the predigest method is proved to be feasible . It can be known that the efficiency of the canned motor is lower than that of the common asynchronous motor with the same parameters through theoretical analysis. Based on the no-loading experimental datas of the canned motor and the common asynchronous motor with the same rated power in the paper, the reason that the canned motor has low efficiency is analyed. The power loss caculation formulas of the common asynchronous motor are added to caculation of the power loss of the canned motor. The power loss caculation formulas of the canned motor are gotten and the formulas are proved to be right based on the no-loading experiment.