Development And Application Of Key Device For Dense Phase Pneumatic Conveying

In recent years, with the accelerating process of Chinese industrialization and theincreasing strengthen of people’s consciousness on environmental protection, thedense phase pneumatic conveying technology, which has many advantages,such as a highdegree of automation, clean and environmental protection, has been used more and more,most of which are used in food, power plants, building materials, chemical industry and othermanufacturing areas. In practice, the choice of equipment and the arrangement of pipelinesare important factors to decide the system performance, which are significant for the stabilityand continuity of transportation.Different kinds of supply tanks were analyzed and compared in the paper aiming at theapplication status of dense phase pneumatic conveying system. The common upwardfluidization silo pump was selected as research project. By optimal design, the experimentreached silo pump system with different geometric parameters, and then determined theoptimal geometry. Based on setting up the experiment platform, the two-phase flowexperiment was done, using air as the transmission power and using desulphurization gypsumpowder as conveying materials, and then studied the flow characteristics of silo pump systemwith different geometric structure, by which finding the optimal transport characteristics. Andthe two-phase flow field information in silo pump was studied using the numerical simulationtechniques, in order to achieving to optimize conveying silo pump.Firstly, the paper designed and developed the representative upward fluidization silopump, and got the optimal system parameters by optimized calculation, which was designedand made, based on which airtight and automated well pipeline transportation system was setup. The system mainly includes sent pump, pipeline, material receiving device and all kindsof test equipments. The experimental studies showed the system worked normally.Secondly, using the gypsum powder with different material properties as thetransportation materials, by changing the internal geometry of the silo pump, the systemoperating parameters and the system parameters. Then carried out the pneumatic conveyingexperiments, obtained the change regularity of gas-solid flow parameters. The study showed that for a stable silo pump, since considered the factors of thetransmission capacity, the pipe pressure drop and the system stability, then made experimentalanalysis, obtained the best internal geometry of the silo pump. The best internal geometry isthe height from the discharge port to fluidized bed is0.3m, the discharge port diameter is0.4m and height of fluidized bed is0.2m.In the aspects of system flow characteristics, the system’s transmission capacity and thesolid phase average speed increased with increasing superficial gas velocity. With thesolid-gas ratio increasing, the conveying capacity was gradually increased, but the solid phaseaverage speed decreased. And establish the correlation equation of conveying capacity Gsandsolid phase average speed uscombined with mathematical methods, after the comparativeanalysis, found that the error is smaller.Thirdly,it adopted numerical simulation method to research the flow information anddynamic characteristics of the conveying in silo pump, by which the changing regularity ofthe gas-solid two-phase movement was obtained in silo pump. The two-phase movement wasmore complicated during the material sending process, which could gather a large number ofmaterials easily. The two phase’s velocity vector distribution was similar and the vectordirection was complex and changing. The direction could change in the site which contactedwith two-phase and inner wall of silo pump. It could be seen that the trajectory of the particlesfrom the particle velocity flow lines, and could form whirlpool close to the inner wall of thesilo pump and form small whirlpool nearly the outlet tube easily. At last, by matching with theexperiments, then changed the internal geometry of silo pump and used the different materials,by analyzing the solid phase volume distribution, solid phase velocity vector and particlevelocity flow chart, to observe the changing of the two phase’s flow field, reaching thepurpose of design the silo pump.