Fuel consumption in the COREX-3000 process run in Baosteel is currently higher than the design index.Therefore,mass and heat balance equations for the COREX process were established using the basic principles included in the Rist operating diagram for blast furnace(BF)as a reference.Thermodynamic calculations were then used to modify the Rist operating diagram so that it was suitable for the COREX process.The modified Rist operating diagram was then applied for the evaluation of metallization rate(MR)and fuel structure to reduce the energy consumption in the COREX process.The modified Rist operating diagram for the shaft furnace(SF)provided a nearly ideal value for the restriction point W when the metallization rate was increased,while the point Pon the operating line for the melter gasifier(MG)moved upward due to reduction in the heat required in hearth.The feasibility of reducing the energy consumption during the COREX process by changing the fuel structure was also demonstrated.
The theoretical flame temperature(TFT)before tuyere,always highly concerned by blast furnace(BF)operators,is one of the most important parameters for evaluating the thermal state of hearth.However,some influencing parameters,for example,the SiO2 reduction by carbon,were always neglected or inaccurate when calculating the TFT.According to the definition of TFT,the temperature of coke into raceway and the reduction rate of SiO2 in ash of coke and pulverized coal were obtained by analyzing the samples before tuyere in blast furnace.Taking full account of different factors,a modified model for calculating the TFT in blast furnace was established.The effects of the oxygen enrichment rate,the reduction rate of SiO2 in raceway,the ash content in coke and pulverized coal and the pulverized coal injection(PCI)rate on TFT were determined quantitatively.The modified model was applied to selecting the used coal for PCI in blast furnace.Considering the different SiO2 contents of mixed coal,the calculated TFT remained a stable level.This showed that the selected coal could be suitable for PCI in blast furnace.
Li ZHUKeng WUEr-hua ZHANGYuan SHEWen-long ZHANQi-hang LIU
块煤的高温粉化是限制CCREX高效生产的主要因素之一,采用试验和理论结果分析了块煤在熔融气化炉内的高温粉化规律及关键控制因素。通过块煤的高温模拟成焦和热重试验,分析了块煤高温强度的演变与气化动力学规律,在建立传热与块煤性质、粉化行为关系的基础上,提出了抑制块煤高温粉化的方法。研究结果表明,在块煤平均温度达到700℃之前,总吸热比例已达到80%,而煤焦转化率仅增加了30%,此时高温强度小于30%,起始气化温度和气化活化能很低,属于快速粉化阶段。后期吸热量每增加10%,转化率可增加20.4%,其反应性及裂变强度分别降低8.36%和增加7.75%,气化活化能大于230 k J/mol,属于慢速粉化阶段。因此,前期传热是COREX炉内块煤粉化的限制性因素。
