Uniform mass flowrate control of multi-pipeline gas-powder flows based on choking phenomena

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.