摘要
作为煤化工的源头技术,煤气化是实现煤炭清洁高效利用的重要途径。但煤气化过程产生大量气化灰渣,资源化利用难度较大。目前,气化灰渣的处理主要以堆存为主,引起严重的环境和土壤污染问题,成为制约煤化工行业发展的短板。因此,亟需开发煤气化灰渣的规模化利用技术。聚焦流化床煤气化细灰和气流床煤气化细渣的热处理技术,综述各热处理技术的处置原理、处置能力和研究阶段。流化床气化细灰的处置方法包括水蒸气活化、燃烧、气化和熔融。为充分利用气化灰渣发达的孔隙结构、丰富的无定形炭结构和活性位点,确定了水蒸气活化制备活性炭的方案;料腿给料延长炉内停留时间的强化预热燃烧技术对气化细灰燃烧效率均超过98%,基于循环流化床的预热燃烧技术在实现气化细灰稳定脱碳的基础上还可控制NO x排放;流化床与气流床耦合再气化则通过提高气化细灰的气化反应温度来弥补其较差的反应活性;流化-熔融气化工艺利用循环流化床对煤气化细灰进行流态化改性,改性产物与二次气化剂同时给入熔融气化单元,再对改性飞灰进行高温熔融气化,实现了气化飞灰单一燃料常压再气化制取合成气。气流床气化细渣的热处理方法有掺烧和流化熔融燃烧。掺烧物料主要为原煤和生物质,但掺烧比例低,且气化灰渣大量灰对输灰系统等部件提出新的挑战;流化熔融燃烧采用气化细渣热改性-高效焚烧与矿相重构-熔渣高值化利用相结合的技术路线,实现煤气化细渣有机组分碳和无机组分灰的分质利用。目前,煤气化灰渣的热处理技术主要针对其中有机组分碳的脱除和利用,而其中的无机组分灰经热处理后仍为固体废弃物,未真正实现煤气化灰渣的无害化处置和资源化利用。因此,为实现流化床煤气化细灰的规模化处理和资源化利用,须根据热处理后无机矿物组分的特性研发对应的高值化利用技术,这将是未来主要研究方向。
Coal gasification,as the leading technology in coal chemical industry,is an important pathway to achieve clean and efficient utilization of coal.However,the gasification process generates a large amount of gasification ash and slag,which is difficult to achieve resource utilization.Currently,the treatment of gasification ash mainly relies on storage,causing serious environmental and soil pollution issues,which becomes a bottleneck in the development of the coal chemical industry.Therefore,it is urgent to develop large-scale utilization technologies for gasification ash and slag.The thermal treatment technologies for fluidized bed coal gasification fine ash and entrained flow coal gasification fine slag were highlighted,and the disposal principles,disposal capabilities,and research stages of various thermal treatment technologies were summarized.The disposal methods for fluidized bed coal gasification fine ash include steam activation,combustion,gasification,and melting.In order to fully utilize the developed porous structure,abundant amorphous carbon structure,and active sites of gasification ash,a scheme for steam activation to produce activated carbon was determined.The enhanced preheating combustion technology,which prolongs the residence time of gasification ash in the furnace through material leg feeding,achieves a combustion efficiency of over 98%for gasification fine ash.The preheating combustion technology based on circulating fluidized bed can not only achieve stable decarbonization of gasification ash,but also control the emission of NO x.The coupled regasification of fluidized bed and entrained bed makes up for its poor reactivity by increasing the gasification reaction temperature.The fluidized-melting gasification process utilizes a circulating fluidized bed to fluidize and modify the coal gasification ash,and the modified product and secondary gasifying agent are simultaneously fed into the melting gasification unit to achieve high-temperature melting gasification of the modified fly ash,thereby obtaining synthesis gas from gasification fly ash as a single fuel under atmospheric pressure.The thermal treatment methods for entrained flow gasification fine slag are blending combustion and fluidized-melting combustion.The blending combustion materials mainly consist of raw coal and biomass,but the blending ratio is low,and the large amount of ash in the gasification fine slag presents new challenges to ash conveying systems and other components.The fluidized-melting combustion adopts a technical route of combining thermal modification and high-efficiency incineration of gasification slag,as well as mineral phase reconstruction and high-value utilization of slag,to achieve the separate utilization of organic carbon and inorganic ash components in coal gasification slag.Currently,the thermal treatment technologies for coal gasification ash slag mainly focus on the removal and utilization of organic carbon,while the inorganic ash components,after thermal treatment,still remain as solid waste,without achieving the harmless disposal and resource utilization of coal gasification ash.Therefore,in order to truly achieve large-scale treatment and resource utilization of coal gasification ash and slag,the corresponding high-value utilization technologies must be developed based on the characteristics of inorganic mineral components after thermal treatment,which will be the main research direction in the future.
作者
周丽
梁晨
齐晓宾
李伟
任强强
ZHOU Li;LIANG Chen;QI Xiaobin;LI Wei;REN Qiangqiang(Institute of Engineering Thermophysics,Chinese Academy of Sciences,Beijing 100190,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《洁净煤技术》
CAS
CSCD
北大核心
2023年第7期65-77,共13页
Clean Coal Technology
基金
中国科学院A类战略性先导科技专项资助项目(XDA21040602)
中国科学院青年创新促进会资助项目(Y201932)。
关键词
煤气化灰渣
热处理
活化
燃烧
气化
熔融
coal gasification fine ash and slag
thermal treatment
activate
combustion
gasification
melting
