碱金属催化对高炉焦炭非均匀劣化特征的影响分析

Analysis of influence of alkali metal catalysis on non-uniform deterioration characteristics of blast furnace coke

随着高炉中低质原料的加入,碱金属的富集量也随之增大,本工作考察了碱金属催化对焦炭非均匀溶损劣化特征的影响。结果表明,溶损过程中,焦炭多孔结构内部会产生明显的反应梯度即非均匀性,其非均匀性与焦炭的基质反应活性和孔扩散特性密切相关,而孔扩散系数会随着焦炭孔隙结构的随机演化而变化。因此,通过分段分析法研究碱金属对焦炭不同反应阶段孔结构与扩散系数的影响,并以焦炭劣化的基本特征即化学反应速率和孔扩散速率的相对大小为基础,进一步优化了焦炭非均匀劣化参数(k_(v)/D_(eff))^(1/2),使其更为准确地描述焦炭在高炉中的非均匀劣化行为。碱金属催化对焦炭的失碳过程有显著的动力学作用,即能显著提高焦炭的(k_(v)/D_(eff))^(1/2),导致焦炭的多孔结构内部形成更大的反应梯度,即降低焦炭的劣化均匀性。这将使焦炭在高炉劣化后粒度分布更加不均匀,从而大大降低高炉的渗透性。非均匀劣化参数可为进一步构建高炉焦炭溶损行为的数学关系提供有效参考,为今后的高炉生产提供借鉴。

With the addition of various lowquality raw materials in the blast furnace,the enrichment of alkali metals increases.And in the context of carbon peaking and carbon neutrality,the reduction in coke usage makes its quality more and more important.In order to elucidate the effect of alkali metal catalysis on the non-uniform dissolution and deterioration characteristics of coke,the relationship between matrix and porosity of alkali metal at different reaction stages of coke was studied by coke powder and block coke dissolution experiments and segmented analysis method.Based on the relative size of the chemical reaction rate and the stomatal diffusion rate of the basic characteristics of coke deterioration,the non-uniform deterioration parameter(k_(v)/D_(eff))^(1/2)of coke was further improved and optimized to more accurately describe the non-uniform deterioration behavior of coke in the blast furnace.The results showed that during the dissolution process,there was an obvious reaction gradient in the porous structure of coke,that was non-uniformity.Its size was closely related to the matrix reactivity and pore diffusion characteristics of coke,and alkali metals played a positive catalytic role in matrix reactivity,while the pore diffusion coefficient changed with the random evolution of coke pore structure,and the direct relationship with alkali metals was small.Alkali metal catalysis had a significant kinetic effect on the carbon loss process of coke,it can significantly increase the(k_(v)/D_(eff))^(1/2),resulting in the formation of a larger reaction gradient inside the porous structure of coke,reducing the deterioration uniformity of coke.This made the particle size distribution of the coke more uneven after the deterioration of the blast furnace,thus greatly reducing the permeability of the blast furnace.The non-uniform deterioration parameters can provide an effective reference for further constructing the mathematical relationship of the dissolution behavior of blast furnace coke,and provide a reference for future blast furnace production.