高硫炼焦煤热解过程中硫的迁移行为及噻吩硫释放特性研究

The low-sulfur coking coal resource is reduced gradually in China. Besides to utilize domestic coal resources efficiently, the development and utilization of high-sulfur coal resource is also important to broaden the available coal in metallurgical coke production, and realize the green and low-cost iron making production in blast furnace .The sulfide compounds with organic thiophene structure in the raw coal is difficult to remove, and it is the restricted factor for high-sulfur coal be used as the raw material in metallurgical coke production.The present studies only showed that the thiophene sulfur is difficult to decompose and can be generated again under certain conditions, however, there is no fundamental research on the sulfur transformation microscopic mechanism and thiophene sulfur emission characteristic during coal pyrolysis. In order to study the micro influence regularity of coal physicochemical properties and pyrolysis conditions on the sulfur transformation behavior during coal devolatilization on the molecular scale, the sulfur transformation, especially the thiophene sulfur decomposition of different raw coal and different coal blending ratio during pyrolysis would be carried out research under current coking process. The decomposition and activation thermodynamic conditions of sulfur containing functional groups can be obtained, and the migration and transformation mechanism of sulfur, especially the thiophene sulfur during high-sulfur coal pyrolysis would be clarified. Then the scientific approach to thiophene sulfur removal can be found out for the high-sulfur coal, and which forms a theoretical basis for efficient utilization of high-sulfur coal.

我国低硫焦煤资源日益减少，开发利用高硫焦煤炼焦对有效利用国内煤炭资源，拓宽冶金焦炭生产可利用煤种、绿色低成本高炉炼铁具有重要意义。原煤中有机噻吩硫难于脱除是高硫煤作为冶金焦生产原料的限制性因素。现有研究仅报道了噻吩硫难于分解且在特定条件下会二次生成的现象，但未针对煤热解过程中硫的迁移微观机理及噻吩硫的释放特性进行系统的基础性研究。申请者针对现有炼焦工艺条件下，不同原煤、配煤热解过程中硫的迁移行为，特别是噻吩类有机硫化物的分解行为展开研究，从分子尺度探索原煤理化特性和热解条件对煤挥发分析出过程中硫迁移行为的微观影响规律，明确各种含硫难分解类官能团断裂、释放的热力学条件，阐明高硫煤热解过程中硫、特别是噻吩硫的迁移转化机制，获得不同高硫煤噻吩类硫脱除的科学方法，为高硫炼焦煤的高效清洁利用奠定理论基础。

冶金焦炭是高炉炼铁主要的原燃料之一，随着优质炼焦煤资源、特别是低硫炼焦煤资源的日益枯竭，拓宽冶金焦炭生产可用煤种、降低炼铁生产成本，在炼焦配煤过程中加入部分价格相对低廉的中、高硫煤具有重要意义。中高硫煤中有机噻吩硫难于脱除其作为冶金焦生产原料的限制性因素，本课题针对不同原煤热解过程中硫的迁移微观机理及噻吩硫的释放特性进行系统的基础性研究，研究结果表明：对于块状中高硫煤，热解温度的提高对其热解固相产物孔隙结构形成不利，但热解温度对于粉末状煤样热解固相产物孔隙结构形成促进作用明显。热解气氛中H2O和CO2会促进中高硫煤孔隙结构形成。热解温度提升对于粉末状和块状煤样中硫的脱除均有促进作用，但对于块状煤样，其热解固相产物中硫会有再次生成。热解气氛中H2O能有效促进中高硫煤热解过程脱硫；气氛中H2O会阻碍有机硫含量较高原煤热解过程H2S和SO2气体的释放，对无机硫含量较高原煤热解过程H2S和SO2的释放则有促进作用。热解温度较高时气氛中10%CO2利于有机硫含量较高原煤硫的脱除，对热解过程H2S和SO2的释放促进作用明显；对于无机硫含量高的原煤，热解气氛中CO2浓度越高越利于硫的脱除。对于有机硫含量较高的块状中高硫煤，N2气氛下热解温度的提升无法有效脱除噻吩硫；但对于无机硫含量较高的块状原煤，提高热解温度会促进其噻吩硫分解；热解温度增加对于粉末状中高硫煤噻吩硫的脱除作用明显。热解气氛中H2O不利于原煤中噻吩硫的分解。热解气氛中10%CO2条件下热解温度提高可有效脱除有机硫含量较高块状原煤中的噻吩硫；但热解气氛CO2的通入无法实现粉末状原煤噻吩硫的脱除，且会提高噻吩硫的相对含量。焦炉煤气气氛下高硫煤热解过程COS的逸出会增加；较高热解温度下焦炉煤气能够有效促进中高硫煤热解过程噻吩硫和硫酸盐硫的分解，释放更多的H2S和SO2；但焦炉煤气气氛对于无机硫含量较高原煤热解过程噻吩硫的分解未见明显影响。以上结论可为中、高硫煤成为冶金焦生产原料在炼焦工艺的应用和推广提供必要的依据。