转底炉还原炼钢含锌粉尘球团的数值模拟

针对某钢铁厂处理含锌粉尘的转底炉直接还原工艺，建立了描述炉膛气体流动、燃烧和传热过程及炉内含碳球团理化反应和传热过程的数学模型，采用实际生产用球团在高温硅钼炉内进行还原实验验证模型的可靠性，得到转底炉炉膛内温度场、流场、压力场及球团内部的温度和组分分布，分析了转底炉主要操控参数对产品铁金属化和脱锌指标的影响. 结果表明，炉气流速沿流动方向逐渐增大，炉温最高点出现在还原二段(接近1350℃)，球团还原20 min出炉后铁金属化率和脱锌率分别达77.9%和92.7%；要使产品铁金属化率达70%，生球碳氧摩尔比不得低于0.9，而配碳量对脱锌率影响不大；煤气供给减少1%将使产品铁金属化率和脱锌率分别降低0.8%和1.3%，二次风欠供20%时二者分别下降14%和24%；球团中锌还原脱除后在炉气中再次氧化，可通过转底炉烟气除尘系统将富锌粉尘回收并用于有色行业炼锌.

Numerical Simulation on Reduction of Zinc-containing Steel-making Dust Pellets in a Rotary Hearth Furnace

Based on zinc-containing dust treatment by direct reduction process in a rotary hearth furnace (RHF) in a steel plant, mathematical models of thermal process with gas flow, combustion and heat transfer in furnace and heat transfer process with physical-chemical reactions inside carbon-based pellets are established. Direct reduction experiment of the pellets used in actual production is performed by an Si-Mo heating furnace to validate the models. Distributions of temperature, flow and pressure of furnace gas, pellets temperature and composition are obtained. Influences of major operating parameters of RHF on product index are also analyzed. The results show that flow velocity of furnace gas increases along flow direction, and the highest furnace temperature (nearly 1350℃) appears in the reduction section II. After reduction for 20 min, metallization degree of iron and zinc removal rate of pellets will reach 77.9% and 92.7%, respectively. And, if iron metallization target reaches 70%, C/O molar ratio of green pellets should be below 0.9, however, zinc removal index is slightly affected by carbon content. When coal gas supply is reduced by 1%, final metallization degree of iron and zinc removal will fall 0.8% and 1.3%, respectively, and metallization degree of iron and zinc removal will also decline 14% and 24% when secondary air supply is less 20% than needed. Reduced zinc vapor, after diffusing out of pellets, is re-oxidized in furnace gas, and zinc-enriched dust collected during flue gas treatment can be sent to nonferrous industry.