摘要
生物质作为价格低廉、来源广泛的绿色能源,具有巨大的利用潜力。但由于生物质本身碱金属(主要为钾)含量较高,在燃烧利用过程中存在如碱结渣、灰分融合、团聚、腐蚀等问题。其中,结渣存在于整个生物质利用过程中,形成极难处理的结块与沉淀,对锅炉本身及运行造成危害。因此,抗结渣生物质燃料是实现生物质高效利用的可行手段。目前可通过添加剂、共燃、化学预处理、涂层等方式改变生物质利用过程中碱金属氯化物、硫酸盐、硅酸盐的生成和转化途径,以解决生物质热转化利用过程中的结渣问题。其中利用添加剂与生物质受热反应生成新的高熔融点产物的处理方式具有较好抗结渣效果。笔者介绍了生物质中碱金属的存在形式及其热转化过程中钾的释放路径、迁移规律,概括了生物质热转化利用过程中的结渣机制,总结了铝基、钙基、磷基3种添加剂在生物质抗结渣过程中的作用机理。使用添加剂可使生物质燃料达到较好的抗结渣效果,磷基添加剂可较好地解决烟道与炉底结渣问题,钙基添加剂只能解决炉底结渣但会造成严重的烟道结渣,铝基添加剂虽能达到与磷基相近的结果,但成本较高且作用效果随温度的升高而减弱。未来抗结渣生物质燃料的研究方向可从新型添加剂出发,寻找既可固定气相中的钾,也能与灰渣中硅酸钾形成高熔融点物质的单一化合物或混合矿物质添加剂;另一方面也应考虑添加剂与生物质混合后的成型问题,开发具备高机械强度的抗结渣成型生物质。最后介绍了上海理工大学碳基燃料洁净转化实验室在抗结渣高机械强度生物质成型燃料方面的进展。以期为抗结渣生物质成型燃料的研究与开发提供一定的参考。
Biomass has great potential as a low-cost,abundant and green energy source.However,due to the high content of the alkali metal contained in biomass,there are some serious problems such as alkali slagging,ash fusion,agglomeration and corrosion during the biomass utilization process.Among those,the slagging exists in the whole process of biomass utilization and leads to the formation and growth of the agglomerates and sediments,which is extremely difficult to deal with and can bring about great harm to the boiler operation.Therefore,slagresistant biomass fuel preparation is a feasible means to achieve efficient utilization of biomass fuel.At present,in order to solve the slagging problem in the process of biomass heat conversion and utilization,the generation and conversion processes of alkali metal chlorides,sulfates,and silicates are changed by the different methods such as additives addition,co-firing,chemical pretreatment,and alloying.Among those,the high-ash-fusion-point biomass with good anti-slagging function can be produced by the mixing of additives with biomass.Here,in this paper,the existence form of alkali contained in biomass,the releasing way and the migration behavior of potassium in the process of heat conversion were introduced.Then,the mechanism of the slagging occurring during the thermal conversion of the biomas were summarized.Subsequently,the anti-slagging mechanism of the three additives including aluminum-based,calcium-based,and phosphorus-based materials during the heat conversion process of the biomass were analyzed. In general,the use of three additives have better anti-slagging performance.Among those,the phosphorus-based additive can do with the slagging occurring in the flue system and the furnace bottom of the biomass boiler.The calcium-based material can only solve the slagging occurring in the furnace bottom,but results in more serious slagging occurring in the flue system.Although the aluminum-based material can achieve similar results with that of the phosphorus-based additive,its cost is high and the performance weakens with increasing temperature.The future research of the anti-slagging biomass fuels should focus on the new additives,such as single compounds or mixed mineral additives,which can fix potassium from flue gas and react with the bottom silicate to form high ash fusion point substance.Moreover,the molding process of the biomass mixed with additives should be paid more attention to and the slag-resistant biomass briquette with high mechanical strength should be developed.Laboratory of clean carbon-based fuel conversion,USST has been engaged in the research on the high-strength slag-resistant biomass briquetteand the biomass briquette fuel with good strength and anti-slagging performance has been developed. The paper can provide some references for the research and development of the anti-slagging biomass briquette.
作者
刘宏宇
张守玉
宋晓冰
胡南
孙梦圆
常明
LIU Hongyu;ZHANG Shouyu;SONG Xiaobing;HU Nan;SUN Mengyuan;CHANG Ming(School of Energy and Power Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China;Changchun Institute of Technology,Changchun 130012,China)
出处
《洁净煤技术》
CAS
2020年第1期22-31,共10页
Clean Coal Technology
基金
上海理工大学科技发展资助项目(2019KJFZ213)
吉林省产业技术研究与开发专项资助项目(2019C056-3)。
关键词
生物质
结渣
碱金属
释放特性
添加剂
成型燃料
biomass
slagging
alkali metal
release characteristics
additives
briquette
