一种基于壅塞原理的多路气粉两相流等流量控制方法

Uniform Mass Flowrate Control of Multi-pipeline Gas–Powder Flows Based on Choking Phenomena

在诸如高炉喷吹煤粉等粉状物料气力输送的场合,常有将粉料经过多条不同长度和布置的路径,按相同的质量流量连续输送到多个目的地的工艺要求.本研究将纯气流的壅塞现象推广到气粉两相流中,对基于气粉两相流壅塞原理的多路气粉两相流等流量控制方法进行了实验验证.实验结果表明,若在各支管路入口之前加入一组具有相同尺寸的壅塞喷管,并满足相应的压力条件时,可使流过各壅塞喷管的多路气粉两相流的速度在其喉口处同时达到音速,且该速度不会因后续管路的长短和布置而改变,进而可以起到均衡流经各支管路的气粉两相流质量流量的作用.通过对发生壅塞现象时,煤粉的质量流量和进口压强的关系以及临界压强比等参数的实验确定,给出了壅塞喷管的选择依据和使用条件.

It is often demanded in multi-pipeline pneumatic conveying,such as PCI into BF,that the mass flowrates of powders passing through different pipelines are uniformly controlled to their destinations.Applying the concept of choking phenomenon in aerodynamics to gas–powder two-phase flow,the uniform mass flowrate control of PCI into BF tuyeres was experimentally studied in the present work.The experimental results confirmed that,as long as choking of the gas–particle flow was developed at the nozzles of the same orifice on the pipeline between the distributor and tuyeres,the gas–powder flow would attain its apparent sonic velocity,and uniform mass flowrate of powder into each tuyere can then be obtained.The critical pressure ratio for attaining the choking state was also determined for various powder/gas ratios of the two-phase flow,and thereby the rules were established for the selection of orifice and carrier gas pressure.