Parameter Selection of Fluid Dynamic Sealing for a Submersible Slurry Pump

In the case of slurry pumps, mechanical seal is usually used. It is well known that the pump is very dangerous if any solid particle enters the seal. Nowadays, people prefer to install a fluid dynamic sealing including 1 or 2 sets of minor vanes and an auxiliary impeller rather than using high-pressure cleaning water in a slurry pump. However, if a fluid dynamic sealing is not designed properly, the mechanical seal is apt to be destroyed by the invading solid particle, and the slurry pump axes is worn seriously and rapidly. Though there are few empirical methods for designing a fluid dynamic sealing, the definite design concept is much deficiency. In the present work, the geometry selection of the fluid dynamic sealing for a submersible slurry pump is carried out so as to establish the basic principle for a fluid dynamic sealing design. The model pump is of centrifugal type, and has the specific speed of 136 m·m³/min·rpm. In order to validate the design concept, three dimensional turbulent flow in the pump was simulated. The total pump channel including inlet pipe, impeller with attached minor vane set, volute casing, and auxiliary impeller is treated as the calculation domain. The mesh grid is more than 2,000,000 nodes. The numerical simulation has been conducted by using a commercial code Fluent v6.1.2. To see the effect of minor vanes and auxiliary impeller geometrical parameters on the sealing performance, we change vane number, vane height, and radius of the minor vanes and auxiliary impeller, flow-rate of sealing water, etc. Based on the numerical results, a set of favorable geometrical parameters of the fluid dynamic sealing was selected for a submersible slurry pump. It is noted that the pump with the newly designed fluid dynamic sealing had been successfully applied for actual operation in the Yellow River sand transportation system in Shandong province, China.