Study on Axial Clearance Size and Leakage of Canned Motor Pump under Axial Force Self-Balance State

Canned motor pump is widely used in chemical industry. Due to the particularity of its application, it is necessary to ensure that the medium does not leak completely. If the axial force of impeller is too large, it will directly affect the performance of canned motor pump. Therefore, the floating impeller could be used in the pump to balance the axial force. In this paper, the relationship between axial clearance and leakage rate at the key part of canned motor pump is studied by means of numerical calculation and experimental verification. It is found that the fitting curve is highly consistent with the calculated value, which provided a good theoretical basis for further study of axial clearance control axial force and experimental axial force self-balance. In addition, the leakage rate increases with the increase of axial clearance. The static pressure in the axial clearance first increases and then decreases with the decrease of radius, and the maximum static pressure value is about 10.5% ∼ 15.8% near the clearance inlet. This study is of great significance to the theoretical research on the self-balance state of axial force of impeller.

Qualification of Barrier Fluidless, Sealless Seawater Canned Motor Pumps

The oil and gas industry continues to push toward subsea pumping technologies that minimize required support systems and increase system reliability. Canned motor technology has been applied successfully in other applications to achieve similar objectives including driving a subsea twin-screw pump. Applied subsea, canned motors eliminate the need for any barrier fluids within the motor, the myriad of systems and complexities necessary to store and replenish these fluids, and the mechanical shaft seals required to prevent the leaking and/or contamination of these fluids within the motors. As a direct adaptation of proven applications, see Figure 1, subsea water treatment is ideal for canned motor technology. Therefore, a development has been initiated and environment qualification testing of the first truly barrier fluidless, sealless subsea pump solution is complete. This purpose of the paper is to highlight the novel elements of this technology, review the system configuration, and document the system performance in accordance with the TRL 4 qualification initiative.

Electromagnetic Shielding Effect of a Canned Permanent Magnet Motor

Due to use of the metallic cans in the air gap, the electromagnetic shielding effect is formed, which is the prominent characteristic of the canned motor. In the flux field, eddy current induction occurs on both cans that thus affects the characteristic of the air gap flux field, and generates a loss that is the highest loss of the canned motor. In this paper, a combination method is proposed and stressed to analyze the shielding effect, based on a typical canned permanent magnet synchronous motor. First, the dq vector decomposition of the eddy current is studied. Second, the effect of the load angle on the loss distribution is studied. Finally, compared with the ordinary motor, the feature of can loss due to rotor speed and conductivity variation is shown. The three-dimensional finite element method is adopted, considering the end effect.