铁矿煤球团内生还原气生产DRI工艺及估算

Technique and estimation of using reducing gas from iron ore-coal briquette to produce direct reduced iron

在高炉热风炉中用高炉煤气、垃圾制燃气、低热值煤气加热循环还原气,或用红焦、热DRI(直接还原铁)等热量加热循环还原气至1100℃,输入还原竖炉加热铁矿煤球团,生产DRI,从炉顶气中回收硫和CO2,炉顶气净化后作为还原气循环使用.球团内煤干馏形成的半焦、焦炭起到了与高炉内焦炭不同的骨架作用.利用还原反应后气体余热来预热和干馏球团,利用铁精矿粉和煤粉的高比表面积,利用煤的干馏气化促进低温下碳的一次气化反应和直接还原反应,使DRI煤耗进一步降低.设炉顶气温度降到150℃,配煤218kg,高炉煤气消耗约947m3时,工艺能耗约333kg/t煤.比高炉工艺节能约52%,减排CO2约83%.比MIDREX节能约84kg标准煤.该工艺简称为DRI-NHQ.

Recycling reducing gas was heated to 1 100 ℃ with blast furnace gas,fuel gas from garbage power,low caloric value gas or with heat from hot coke,hot direct reduced iron (DRI),or other heat in a hot-blast stove. Then,the recycling reducing gas was input to a reductive shaft kiln to heat iron ore-coal briquette to produce DRI. Sulfur and CO2 were recovered from the top gas,and the purified gas was used as the recycling reducing gas. The carbocoal and coke from coal carbonization in the briquette acted as skeleton,which was different from coke in the blast furnace. The coal consumption of DRI was reduced through using the afterheat of reducing gas to preheat and carbonize briquette,using the high surface area of iron concentrate and coal powder,and using coal carbonization and gasification to accelerate carbon gasification reaction and direct reduction reaction at low temperatures. If the temperature of the top gas drops to 150 ℃,218 kg coal is blended,and blast furnace gas of about 947 m3 is consumed,the energy consumption will be about 333 kg/t coal. Compared with the blast furnace process,this process can economize 52% energy and reduce about 83% CO2 emission;it will save about 84 kg standard coal than MIDREX process. This technical process is abbreviated to DRI-NHQ.