高炉风口喷吹焦炉煤气的减排能力分析

Analysis on carbon emission reduction ability of blast furnace tuyere with COG injection

为了探讨高炉喷入焦炉煤气降低钢铁行业碳消耗和碳排放的潜力,本文对风口喷吹焦炉煤气在高炉内各个区域的还原行为进行研究。从风口吹入的焦炉煤气被加热后,通过裂解、气化形成富H2、CO煤气,其标态体积约为原始焦炉煤气体积的1.5倍。在1373 K以上温度区域,风口区产生的富氢煤气将热量传给固态或熔态物料,并作为催化剂加速焦炭与多价态氧化铁间的还原反应。富氢煤气中的CO在1373 K以下与氧化铁发生还原反应,焦炭的气化反应随着温度降低而减弱。1273 K至水煤气变换反应平衡转变温度段,富氢煤气中的氢气还原各种价态氧化铁,当温度低于水煤气变换反应平衡转变温度时,富氢煤气中的氢气继续还原氧化铁,同时还促进CO和各种价态氧化铁物料的还原反应,起到了催化剂的作用。高炉风口喷吹焦炉煤气,虽然在风口区增加了能量吸收,但上部间接还原度的增加,降低了高温段的直接还原度,且富氢煤气也将热量传递给高温区炉料,可实现高温区能量收支平衡,降低焦碳的使用量。喷吹的焦炉煤气量与减少高炉固态碳使用量的关系近似表达为ΔC_(1)=-0.046+0.324V。最终碳减排量与喷吹焦炉煤气量的关系为ΔC_(2)=-0.047+0.110V。

In order to discuss the potential of COG injection into blast furnace to reduce carbon consumption and carbon emission in iron and steel industry,the reduction behavior of COG injected into blast furnace is studied.After being heated in the tuyere area of blast furnace,COG is formed by cracking and gasification to be rich in H2 and CO gas,and its standard volume is about 1.5 times of the volume of original COG.The hydrogen rich gas produced at tuyere area above 1373 K transfers heat to solid or molten materials,and acts as a catalyst to accelerate the reduction reaction between carbon and polyvalent iron oxide.The CO in hydrogen-rich gas reacts with iron oxide below 1373 K,and the gasification reaction of coke decreases with the decrease of temperature.From 1273 K to the equilibrium transition temperature of water gas shift reaction,hydrogen in hydrogen-rich gas reduces iron oxides of various valences.When the temperature is lower than the equilibrium transition temperature of water gas shift reaction,hydrogen in hydrogen-rich gas continues to reduce iron oxide,and also acts as a catalyst to promote the reduction of CO and various valence iron oxides.Although the energy absorption is increased when COG is injected into the tuyere of blast furnace,the direct reduction degree of high temperature section is reduced with the increase of indirect reduction degree in the upper part and the hydrogen rich gas also transfers heat to the charge which brings heat into the high temperature zone again,thus energy balance can be realized in the high temperature zone and the use of carbon can be reduced.The relationship between the amount of COG injected and the reduction in the amount of solid carbon used in the blast furnace is approximately expressed asΔC_(1)=-0.046+0.324V.The amount of final carbon reduction and the amount of COG injected isΔC_(2)=-0.047+0.110V.