气力输送系统设计中的放大换算技术

Scale-up Procedures for Pneumatic Conveying Design

资料研究表明,尽管实验台数据放大换算已被广泛地认为是气力输送系统设计中的一个十分重要的步骤,然而直至今日,还没有通用的方法使实验台数据能可靠而精确地按比例放大到全尺度系统,主要原因在于以前的放大换算技术并未考虑到弯管位置、数量,以及短管等对总压降的影响。试验台布置了由两长一短的直管段和两个弯管组成的简单实验管道,通过从两长直管段测得的压力来确定经验公式中的指数以预测由弯管和直管段引起的压降。研究结果表明,这些公式不但能够精确地预测不同位置直管段和弯管引起的压降,还能够精确地预测不同长度、管径、弯管数和分段的总管道压降。

A survey of literature shows that,although scaling up of test rig data is considered widely to be one of the most important stages of pneumatic conveying design,to data no general method was developed for the reliable and accurate scale-up of test rig data to full-scale installations.The main reason is that the previous procedures don't take into account the location and/or number of bends and also the relatively short straight sections of pipe that are used commonly in industry.A simple configuration of pipe is employed,compriseing two long and one short straight section of pipe and two bends.Based on the measured pressures along the two long straight sections of pipe,the exponents in the empirical formulae are determined for the prediction of pressure drop caused by bends and straight sections of pipe.The results show that these formulae are able to predict accurately not only the pressure drop caused by both bends and straight sections of pipe at different locations,but also the total pipeline air pressure drop in pipelines of different length,diameter,bend number and step.