COREX流程中块煤/半焦性质与粉化关系探讨

Discussion of lump coal/char properties with its disintegration in COREX process

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。

The disintegration of lump coal is one of the most crucial limiting factor for COREX production. The law and the key control factors for lump coal disintegration in melting gasifier were analyzed by experiment and theoretical results. Coking and TG experiment were conducted to determine the evolution of lump coal＇s high temperature strength and gasification kinetics,then the method to avoid the pulverization of lump coal was proposed based on the establishment of the relationship between heat transfer and lump coal＇s disintegration. According to the results,the heat absorption ratio of lump coal accounted for 80% before the average temperature of lump coal reached 700 ℃,and the coal/char conversion only increased by 30%. Then the fast generation of lump coal fines at this stage appeared due to the low strength less than 30%,as well as the low initial gasification temperature and activation energy. At later coking stage,the coal/char conversion could increase by 20.4% with the heat absorption increased by every 10%,and the reactivity decreased by 8.36% and the fission strength increased by 7.75%. What＇s more,the gasification activation energy was more than 230 k J/mol which could be considered as the low disintegration of lump coal. As the results,the heat transfer at early stage is the limiting factor for the pulverization of lump coal in COREX.