摘要
面对碳达峰、碳中和的减排压力,生物质由于其来源广泛、储量丰富、排放清洁低碳等优点而备受关注。生物质种类繁多,包括农业秸秆、林业废弃物、禽畜粪便、生活垃圾及废弃油脂,燃煤电站掺烧生物质可有效降低CO_(2)排放量,增强锅炉侧燃料灵活性。介绍了生物质燃料特点,概述了其与煤混燃的燃烧特性、结渣特性以及污染物排放特性。对煤粉锅炉掺烧生物质的技术路线及其改造成本进行总结与比较,最后讨论了煤粉炉掺烧生物质的技术壁垒及解决方案。农林类生物质挥发分较高,反应活性较好,掺烧该生物质可改善燃料燃烧性能,增加炉内燃烧稳定性。但该类生物质中碱金属含量高,掺烧时易结渣,灰熔融温度及燃料中碱金属含量是预测锅炉结渣的重要指标。农林类生物质硫含量、氮含量、灰分及重金属含量均较低,掺烧可减少SO_(x)、NO_(x)、烟尘及重金属等污染物排放。污泥类生物质水分高、重金属含量高、热值低,燃烧特性不如煤,掺烧污泥易对锅炉燃烧及污染物排放产生不利影响,但质量比10%以下的污泥直接掺烧对机组影响不大。禽畜粪便、生活垃圾及废弃油脂气化后的生物质气用于煤粉炉掺烧可起到稳燃作用,减少锅炉SO_(x)、NO_(x)、烟尘及重金属等污染物排放。生物质与煤耦合发电技术中直接耦合方案较适合农林类生物质掺烧,间接耦合适用于禽畜粪便、生活垃圾及废弃油脂的掺烧,而污泥宜干化后掺烧。生物质经压缩成型后的成型燃料抗压强度及能量密度有较大提升,该技术可一定程度解决生物质储藏及运输等供应链问题;燃料预处理及抗结渣添加剂可降低燃料碱金属含量,提高灰熔融温度,降低锅炉结渣风险;烘焙处理可提高生物质可磨性,增加生物质掺烧比例,提高锅炉制粉系统对掺烧生物质的适应性;对锅炉燃烧器进行改造,合理配风可提高燃烧系统对掺烧生物质的适应性。农林类生物质原料的收购成本高于煤,且生物质发电量无法精确计量暂不能获得财政支持,经济性较差。掺烧生物质的经济性是现阶段阻碍生物质大规模掺烧的主要原因,较低成本的生物质来源及生物质发电量的计量难题亟待解决。
Under the pressure of carbon peak and carbon neutralization emission reduction,biomass has attracted much attention due to its characteristics of wide source,abundant reserves,clean and low-carbon emissions.There are many kinds of biomass,including straw,forestry waste,livestock manure,domestic waste and waste oil.Biomass blending in coal-fired power plants can effectively reduce carbon dioxide emissions and strengthen the flexibility transformation of boiler fuel side.The characteristics of biomass were introduced,and the characteristics of combustion,slagging and pollutant emissions of biomass blending in pulverized were summarized.The technical routes and transformation cost of biomass blending in pulverized coal boiler were summarized and compared.Lastly,the technical barriers and so⁃lutions to co-combustion of biomass in pulverized coal boiler were discussed.Agroforestry biomass has high volatiles and good reactivity.Blending this kind of biomass can improve the fuel combustion performance and increase the combustion stability of the boiler.However,the alkali metal content in biomass is high,and it is easy to cause serious slagging when blending.The ash melting temperature and alka⁃li metal content in fuel are important indicators for predicting boiler slagging.The sulfur content,nitrogen content,ash content and heavy metal content of agricultural and forestry biomass are low.The combustion of blending biomass can reduce SO_(x),NO_(x),soot and heavy metal emission.Sludge biomass has high moisture content,high heavy metal content,low calorific value,and less combustion charac⁃teristics than coal,so it is usually to have a bad influence on combustion and pollutant emission,but the direct blending sludge below 10%(mass ratio)has little effect on the unit.The biomass gas generated from the gasification of livestock manure,domestic waste and waste oil can play a role in stabilizing combustion in pulverized coal furnace and reduce SO_(x),NO_(x),soot and heavy metal emissions.The direct coupling scheme of biomass and coal coupling power generation technology is more suitable for the co-combustion of agricultural and forestry waste.The indirect coupling co-combustion is more suitable for the co-combustion of livestock manure and domestic waste,while sludge co-combustion needs to be dried.It is believed that the compressive strength and energy density of molded fuel made of biomass af⁃ter compression molding are greatly improved,and this technology can solve the supply chain problems such as biomass storage and trans⁃portation.Fuel pretreatment and anti-slagging additives can reduce alkali metal content of biomass,improve ash melting temperature and reduce the risk of boiler slagging.Baking treatment can improve the grindability of biomass,increase the proportion of biomass blending,and improve the adaptability of boiler pulverizing system to biomass blending.The modification of boiler burners and reasonable air distri⁃bution can improve the adaptability of combustion system to mixed burning biomass.The acquisition cost of agricultural and forestry bio⁃mass raw materials is higher than that of coal,and inaccurate measurement of biomass power generation can not get financial support,the economy is poor.The economy of co-firing biomass is the main reason that hinders the large-scale co-firing of biomass.The measurement of low-cost biomass sources and biomass power generation needs to be solved urgently.
作者
周义
张守玉
郎森
刘思梦
杨济凡
马达夫
胡南
吴玉新
ZHOU Yi;ZHANG Shouyu;LANG Sen;LIU Simeng;YANG Jifan;MA Dafu;HU Nan;WU Yuxin(School of Energy and Power Engineering,University of Shanghai for Science and Technology,Shanghai200093,China;Changchun Institute of Technology,Changchun130103,China;Department of Thermal Engineering,Tsinghua University,Beijing100084,China)
出处
《洁净煤技术》
CAS
北大核心
2022年第6期26-34,共9页
Clean Coal Technology
基金
国家自然科学基金重点国际(地区)合作研究资助项目(51761125011)。
关键词
煤粉炉
生物质
掺烧
燃煤污染物
低碳
燃煤发电
pulverized coal fired boiler
biomass
blending combustion
pollutant from coal combustion
low carbon emission
coal-fired power generation
