Experimental And Numerical Simulation Study On The Airflow Distribution To Control Large Scale And Discontinuous Dust Resoure

Dust gas production of the unloader can cause serious workplace pollution in dock, affecting workers' health and holding back the development of harbor,and it has characteristics of large amount, discontinuous production time and changeable workplace.Owing to the characteristics of the unloader,and no ripe ventilation and dust remove theory, the design of the unloader depended just on experience in the past, but it often failed to achieve the expected results.Furthermore,not attaching importance enough to it, the control of dust hasn't been solved. How to choose reasonable airflow distribution to control dust diffusion, in order to reduce environment pollution? This is the paper's main content.For the equipment of the unloader and its working characteristics,this paper puts forward both sides push-pull ventilation method to control the dust diffusion of large scale and discontinuous dust resource like the unloader.The paper sets the unloader as the research object,and the conclusion of this thesis is applied to the design of ventilation and dust remove to similar equipment.It can save energy and improve the effect of controlling dust by optimizing the airflow distribution and changing airflow velocity parameters.The model set of the unloader was set up according to the theory of similarity so as to do experimental research, and simulative study on it as a secondary means.In the aspect of experimental study,the author analyzed each factor which affects capture efficiency,and did the orthogonal test from which we obtained empirical formula of capture efficiency.By smoke generator imitating contaminated gas of the unloader,empirical formula was validated on a specific work condition.By the method of specific flux,on the basis of the theory of dimensional analysis,the function of the limit specific flux about dimensionless parameters was obtained.Through the test data and empirical formula of capture efficiency,using the software of SPSS V13.0 and doing the multianalysis,the author obtained the regression relation about the limit specific flux.According to the regression expression of the limit specific flux,two situations were considered with economical flow volume, and the economical design formulas were obtained.At last,we put forward the basic design programs about the unloader.In the aspaect of numerical simulation study,the dissertation adopted the software of FLUENT to do the numerical simulation study.After comparing the numerical simulation data with the test ones,the author found that they were uniform by and large,and drawed a conclusion that the turbulent current model used is right. Two situations were considered with numerical simulation study on gas-solid flow fleld.In the numerical simulation study on solely diameter dust,we can obtain classification efficiency for solely diameter dust.The result of research shows that the bigger dust diameter is,the higher classification efficiency will be in the scope of the study.In the numerical simulation study on the diameters of dust of Rosin-Rammler,we analyzed some work conditions.The conclusion of the dissertation,specially the dimensionless multiple-factor regression expression of the limit specific flux and the economical design formulas on two conditions can applied to the design of ventilation and dust remove of the unloader.hat's more,they have important meaning for the large scale and discontinuous dust resourcelike the unloader.