水浸出对生物质秸秆碱金属-诱导结渣特性的影响

• 作 者: 刘延静 颜婷珪 安燕 张为 董阳
• 机 构: 贵州大学化学与化工学院,贵州贵阳550025;贵州师范大学喀斯特生态文明研究中心,贵州贵阳550025
• 出 处: 燃料化学学报
• 发表日期: 2021年12期
• 关键词: biomass alkali metal deposition and slagging leaching low temperature ash

由碱金属矿物引起的沉积、结渣问题是在燃烧和气化装置中利用生物质燃料的主要障碍之一.论文主要研究了水浸出对玉米秸秆和水稻秸秆碱诱导结渣特性的影响.通过比较水浸前后生物质低温灰的成分,探究了生物质秸秆中碱金属的原始矿物存在形式.结合高温生物质灰的矿物晶体分析和消解样品的化学成分,分析了生物质秸秆在不同温度下碱金属化合物的释放和转化规律.结果表明,玉米和稻草中的钾主要以KNO3、KClO4、K2SO4和KAlSi3O8的形式存在,其中KNO3、K2SO4和KClO4大部分可通过水浸去除.水浸后生物质灰的熔融温度升高,尤其是碱性化合物以含钾化合物为主的典型样品—稻草灰.原玉米和稻草中钾含量随温度降低的原因是含钾矿物质在25-1000℃时分解逸出.水浸后玉米和稻草在400-800℃钾的释放量显著减少,但在800℃以上钾含量仍会下降.玉米中镁含量随温度升高而降低,是由于氧化镁在碳还原作用下挥发所致.对于水浸后碱金属含量高的燃料,残留的碱金属仍会逸出,尤其是在800℃以上容易发生碱金属引发的沉积或结渣.“,”Deposition or slagging problem caused by the alkali metal species is one of the major obstacles to utilize biomass fuel in combustion and gasification plant.The paper mainly studies the effect of water leaching on alkali-induced slagging properties of corn straw and rice straw.The original mineral form of alkali elements in biomass straw was studied with comparison of low temperature ash of biomass before and after water leaching.The release and transformation of alkali compounds in biomass straw at different temperatures during heating were analyzed with combination of the XRD result of the heated biomass and the chemical composition of the digested samples.The result shows that the potassium in corn and rice straw mainly exists in the form of KNO3,KClO4,K2SO4 and KAlSi3O8,in which KNO3,K2SO4 and KClO4 is mostly removed in water leaching.The fusion temperatures increased after water leaching,especially for rice straw ash,which is a typical sample that the basic compounds are mainly potassium-containing compounds.The decrease of potassium content with temperature in the original corn and rice was because the potassium-containing minerals decomposed and escaped at 25-1000℃.The release of potassium in the range of 400-800℃significantly reduced for corn and rice straw after water leaching,but the potassium content will still decrease above 800℃.The decrease of magnesium content in corn with increasing temperature may be due to the volatilization of magnesium oxide under the action of carbon reduction.For fuels with high alkali metal content after water leaching,the residual alkali metal will still escape and cause deposition or slagging in the furnace,especially in the temperature range above 800℃.