碱金属迁移转化对生物质灰沾污结渣的影响研究进展

Research progress of the influence of alkali metal migration and transformation on biomass ash fouling and slagging

生物质热化学转化利用过程会产生大量的生物质灰,其钾、钠等碱金属元素的含量高,导致其熔融温度低,在高温下极易熔融或挥发,进而对锅炉、管道或设备受热面造成沾污结渣、腐蚀等危害。为系统了解碱金属迁移转化对生物质灰沾污结渣影响的研究并预测其发展趋势,首先,归纳生物质热化学转化过程中由碱金属迁移转化引发的安全问题及危害;其次,回顾和总结近年来国内外生物质灰沾污结渣机理方面的研究进展,主要包括不同热化学转化来源生物质灰沾污结渣演变规律和碱金属迁移转化特性研究等;最后,预测生物质灰沾污结渣防治研究的发展趋势。研究结果显示:生物质热化学转化过程中碱金属的赋存形式和演化特征是影响灰熔融和沾污结渣特性的重要因素,不同热化学转化来源生物质灰的熔融和烧结规律是灰沾污结渣防治研究的关键。以往针对碱金属迁移转化特性的研究,大多只考虑生物质自身的燃料性质、矿物组成等,对不同热化学转化过程中碱金属迁移转化对生物质灰沾污结渣和熔融烧结的影响以及不同形式碱金属成分的影响研究仍不够深入和系统,尚未形成完善的理论体系,这将成为以后的重点研究方向。

The thermal conversion and utilization process of biomass produces a large amount of biomass ash,in which the contents of alkali metal elements such as potassium and sodium are high,resulting in low melting temperature,easy to melt or volatilize at high temperatures,causing fouling,slagging,corrosion and other hazards to boiler,pipeline or equipment heating surface.To systematically understand the research results of the influence of the migration and transformation of alkali metal on the fouling and slagging behaviors of biomass ash and predict its development trend,this paper first summarized the safety problems and hazards caused by alkali metal migration and transformation in biomass thermal transformation process.Secondly,the research progress on the fouling and slagging mechanism of biomass ash at home and abroad in recent years was reviewed,including the evolution law of fouling and slagging behaviors of biomass ash from different thermal conversion sources,alkali metal migration and transformation characteristics,ash melting and sintering law,etc.Finally,the development trend of biomass ash fouling and slagging control in the future was prospected.The results indicate that the occurrence form and evolution characteristics of alkali metals are important factors affecting the characteristics of ash melting and slagging,and the melting and sintering law of biomass ash from different thermal conversion sources is the key to the prevention and control of ash slagging.Most previous studies of alkali metal migration characteristics only focused on biomass fuel properties,mineral composition,etc.The influence of alkali metal migration on biomass ash fouling and melting as well as the influence of different forms of alkaline compounds during the thermal conversion process is still insufficiently thorough and systematic,and a perfect theory system has not been formed,which will become the focus of future research.