利用壅塞原理均匀分配高炉各风口的喷煤量

应用纯气体的壅塞原理,对由空气和煤粉组成的气粉两相流的壅塞现象进行了理论和实验研究,提出了一种基于壅塞原理的可均匀分配高炉喷吹煤粉流量的新方法.结果表明,在现有高炉喷煤系统的各输送支管前安装一组具有相同几何尺寸的“喉形喷管”并满足适当压力条件时,两相流将在各喷管内发生壅塞流动.此时,其流速和流量将保持一致且不受后续管路条件不同的影响,从而可起到均化喷煤量的作用.实验测定了质量流量与出口压强的关系,定义了临界压强比可作为判定壅塞发生与否的依据,并找出了临界压强比与固气比之间的变化规律,给出了实用喷管的选择依据和使用条件.

Uniformly Distributed Mass Flow Rate of PCI into BF Tuyeres on Formation Principle of Choking

Considering aerodynamically the choking phenomenon as that it is formed by a "pure gas flow",an experimental investigation and theoretical analysis are made to the choking phenomenon formed by a two-phase flow consisting of air and pulverized coal,thus providing an approach to distributing uniformly the mass flow rate of PCI(pulverized coal injection) into BF(blast furnace) tuyeres.The experimental results showed that the air-coal flow will become choking flow in all jet pipes if connecting a set of venturis to all branch tuyere pipes of the same size in the existing PCI system of BF and the required pressure can be met.Then,the flow speed is in line with flow rate and kept on without being affected by subsequent pipes,thus distributing uniformly the pulverized coal injected.Measuring the mass flow rate in relation to outlet pressure,the critical pressure ratio is defined as the criterion for whether the choking phenomenon takes place.The relationship between critical pressure ratio and solid/gas ratio is thus found to provide a reference for choosing appropriate jet pipes and conditions for their applications.