| Low unloading effect and large heavy maintenance workload are two disadvantages to alumina powder tank truck for railway. Through investigating existing tank trucks, the design for fluidization unloading unit of alumina powder tank truck for railway is improved, and its use on the job site proves that application of fluidization principle to railway truck is successful and provides theoretical basis for wide and deep application in the future.The paper finds out that complicated structure of air sparger and space between air sparger and bottom of tank lead to above-mentioned problems. Alumina powder damages air sparger, then goes into interlining space and permanently retains there, which results in bad fluidization for alumina powder; and design of sliding plate and breathing rod doesn' t accord with fluidization principle , increasing truck deadweight and reducing effective volume of tank.Improving theory and designing method for fluidization unloading unit verified by calculation of dense phase convey speed are described. 200 new tank trucks purchased by Zhongzhou Branch from 2003 to 2004 are modified according to improved design and they are working very well; breathing rods of three old tank trucks are changed and get a good unloading effect.The paper indicates that design theory of unloading unit is based on fluidization principle; fluidization process of alumina powder in tank includes three related stages, the first stage is fluidization in tank; the second stage is fluidization in outlet pipe and the third one is air convey in feeding pipe. The fluidization in tank is the base of fluidization in outlet pipe, both of them provide possibility with highly effective dense convey of tank truck, which enhances form of better fluidization; structure of air sparger can be largely simplified , and powder blower, sliding plate and breathing rod can be cancelled to completely resolve problems of bad unloading effect and large maintenance workload. |
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