Study Of Pressure Loss In Cement Conveying Pipe Within The Dense Phase Vacuum System

Pneumatic conveying is a delivery method that using air flow in the pipeline to transport materials.Because of its high transmission efficiency,easy to realize automation,conducive to environmental protection,and equipment construction is simple,convenience to maintenance and management,with so much advantages,its used more and more widely in the logistics,energy,chemical,metallurgy,agriculture,environmental protection,national defense,light industry and other fields,such as the pneumatic unload-er machines used in ships at the pier.But the pneumatic conveying involves the gas-solid two-phase flow,the material movement in the pipeline is relatively complex,the design calculation,a variety of pressure loss calculation model of different material type and material movement in the pipeline,pipeline layout and shape conditions Increase the difficulty of designing.So the current application of the pneumatic conveying system design calculations on project is mostly extensive,which is bound to affect the energy using efficiency and stability and reliability of pneumatic conveying.This paper focuses on the pressure loss characteristics of pneumatic conveying system.With the aid of computer numerical simulation technology and the relevant empirical formulas,the following work is done.(1)In this paper,a brief introduction is made to the research background of the two-phase flow and the research status of the pneumatic conveying both at home and abroad.The structure and classification of the pneumatic conveying system are introduced in detail.(2)The engineering calculation method of the pressure loss of the pneumatic conveying pipeline is summarized and the calculating method and the applicable range are briefly described.At the same time,with the calculation example of pneumatic conveying,the different calculation methods are used to calculate it.By comparing the experimental data in the literature,it is found that the results of force balance method and additional pressure loss method are in good agreement with the experimental data.(3)The key design parameters of the negative dense phase pneumatic conveying system are calculated,the key equipment and pipeline arrangement of the system are analyzed andselected in order to build up the experimental system.(4)The simulation is carried out by using the Euler method under the FLUENT software platform.The pressure drop of the horizontal pipe in the single-phase flow and the two-phase flow is in good agreement with the pressure drop data in the literature.the specularity coefficient is also studied,and found that the pressure loss increase as the specularity coefficient increase,and the best specularity coefficient 0.026 gived.The mathematical model of horizontal pipe,vertical pipe and inclined pipe is established based on the relevant dimensions and initial parameters in chapter 4,simulating the pressure loss respectively,and compared it with the calculation pressure loss,found that the horizontal pipe pressure loss is closer to simulate one(to7.6%),the calculation pressure loss of vertical or inclined tube is not that accurate,When at the same pipe and working conditions,the greater the material gas ratio the larger pressure loss is,The results show that the pressure drop per unit length of the horizontal pipe is small in the short distance conveying,and the pressure drop per unit length of the vertical pipe is the biggest,the second is the inclined pipe.in the long distance conveying the vertical pipe is the smallest.the largest is the horizontal pipe.