A Technique Improvement On Mechanical Seal In Reactor Of Sodium Aluminum Hydride

Mechanical seal, which can prevent the leakage of the material from the equipment effectively, is used in industry field extensively. During the operation, the differential pressure between the inside and the outside of the mechanical equipment is quite high.Under this situation, the engineers devote themselves to stopping the leakage of the material from the gap between the shaft and the shell. In the process of poly silicon production, when the sodium aluminum hydride is compounded, the pressure of the reactor is 15 MPa higher than the atmosphere. In order to harvest the qualified production,it is needed to mix the raw material by the agitator. Because of the failure of the mechanical seal of the agitator rotating shaft, the production is stopped frequently.This paper analysis the theory of the failure of the mechanical seal, aiming at the alternative high pressure operation situation. This paper points out that improving the structure, material, flushing system, adding the element for detecting temperature and flow, keeping the steady differential pressure between the inner and the outer by interlock adjustment of electro-magnetic proportional over-flow valve and so on can meet the requirement of the system operation and prolong the life of the mechanical seal.Changing the fixed frequency direct starting to variable-frequency starting that can start the mechanical gradually and avoid the shocking damage.As the results of the proposed improvements, the life of the mechanical seal, the failure frequency and the operating cost of the factory are getting better. The fluctuation of the production quality caused by sudden interruption, the impact on the up and down stream, the possibility of leakage of dangerous material and the economic losses are getting lower. The factory can get considerable benefits of economy and safety The thought and measures of improving and researching in this paper can be generalized when improving the mechanical seal with large-diameter shaft under high temperature,high pressure situation, especially to solve the failure of mechanical seal under the alternative pressure operating situation.