空気による粒体プラグの輸送

Abstract

This paper describes behaviour of solid plugs pneumatically conveyed in a horizontal and vertical pipe whose purpose is to establish a basis for design of shch a conveying system, in which it is required to estimate the minimum air velocity, the velocity of the solid plug and the pressure loss of air. On the assumption that ideal flow of alternate solid plugs and air takes place, the minimum air velocity is obtained from force balance on the solid plug, and the plug velocity is also obtained from comparison of energy of air with that of the solid plug. The Ergun equation is adopted to compute the pressure loss of air passing through the solid plug. Computed results are favourably compared with results obtained from plug phase conveying for some polyethylene pellets. The particle diameter and its density, the voidage of the solid plug, the angle of internal friction and the frictional angle between the particle and the pipe wall are important. In this conveying system, there is an optimum air velocity at which the maximum power coefficient is reached, and the horizontal conveying is superior in power consumption to the vertical one.