煤热解过程分析与工艺调控方法

通过煤热解技术获取紧缺的油气资源是低阶煤清洁利用的有效途径之一。针对煤热解工艺存在焦油产率与品质难以控制以及焦油中粉尘含量高等关键技术问题，从煤的热解反应机理出发，详细探讨了热解挥发分二次反应的种类和发生条件以及影响热解过程的主要因素，结合煤热解技术应用，总结了逆向传热与传质所导致的挥发分气相二次反应是焦油产率下降的主要原因；同时，分析了热解过程中煤颗粒破碎机理以及煤热解过程中粉尘的主要来源。在前人研究结果的基础上，提出控制热解挥发分的流动方向从高温区向低温区流动、热解耦合气化以及耦合原位的焦油提质与除尘等方法可以调控煤热解过程，抑制重质焦油生成、提高焦油中轻质组分含量以及减少焦油中的含尘量，从而实现煤的定向热解。

Analysis and control methods of coal pyrolysis process

Coal pyrolysis is an efficient route for the clean utilization of low-rank coals due to its producing scarce gas and oil resources.This paper focuses on the key technical problems of the unmanageable yield and quality of tar and the high dust content in tar.From coal pyrolysis mechanism,the types and occurrence conditions of volatile secondary reactions and the major influence factors on pyrolysis are discussed in detail.Combining the application of coal pyrolysis technology,it is summarized that gas phase secondary reactions of volatiles are responsible for the decrease of tar yield.Meanwhile,the coal particle fragmentation mechanism and the source of dust during pyrolysis are analyzed.Based on previous research results,we propose that the control methods for coal pyrolysis process,such as changing volatile flow direction from high temperature zone to low temperature zone,coupling pyrolysis with gasification and in situ tar upgrading and dust removal,which can inhibit heavy tar formation,improve light tar content and reduce dust content in tar,and thus realize oriented coal pyrolysis.