DIRECT OBSERVATION OF ALKALI VAPOR RELEASE DURING BIOMASS COMBUSTION AND GASIFICATION .1. APPLICATION OF MOLECULAR-BEAM MASS-SPECTROMETRY TO SWITCHGRASS COMBUSTION
DIRECT OBSERVATION OF ALKALI VAPOR RELEASE DURING BIOMASS COMBUSTION AND GASIFICATION .1. APPLICATION OF MOLECULAR-BEAM MASS-SPECTROMETRY TO SWITCHGRASS COMBUSTION
复制标题
DOI：
10.1021/ef00053a018
复制
发表时间：
1995-09-01
期刊：
影响因子：
5.3
通讯作者：
MILNE, TA
中科院分区：
文献类型：
--
作者：
DAYTON, DC;FRENCH, RJ;MILNE, TA
生物质和生物质衍生燃料发电已成为一种有吸引力和可行的替代能源。生物质燃烧过程中的碱金属释放会导致锅炉传热表面严重结垢和结渣，从而降低效率，在最坏的情况下，导致工厂意外停机。未来的生物质发电设施将受益于通过整合气化联合循环系统来提高效率，该系统使用生物质燃烧气体直接驱动航改涡轮机。这些系统对于碱蒸汽释放具有甚至更低的公差，因为涡轮机叶片的加速侵蚀和腐蚀导致更短的涡轮机寿命。结垢和结渣问题的一个解决方案是开发热气净化方法，以将碱蒸汽的量减少到可接受的水平。对生物质燃烧过程中碱金属释放机理的深入了解，以及对含碱金属蒸汽的识别，以及这些蒸汽如何导致结垢和结渣的研究，将对热气净化技术的发展大有裨益。本文演示了分子束/质谱法的应用研究碱金属的形态和释放柳枝稷燃烧。我们已经成功地使用这种实验技术，以确定碱金属的柳枝稷燃烧过程中释放的物种在四个不同的条件：1100摄氏度的He/O-2（20%），800摄氏度的He/O-2（20%），1100摄氏度的He/O-2（5%），和1100摄氏度的He/O-2（10%）/蒸汽（20%）。选择这些条件来研究温度、氧浓度和过量蒸汽对碱金属释放和形态的影响。初始原料组成是影响生物质燃烧过程中碱金属释放量和种类的最重要因素。本研究筛选的柳枝稷样品碱金属（钾）和氯含量都很高。因此，柳枝稷燃烧过程中释放的主要含碱金属物质是氯化钾。改变燃烧条件对碱金属释放量的影响为2倍或更小。向燃烧环境中加入过量的蒸汽往往会使碱金属的释放形式从碱金属氯化物转变为氢氧化物。
Electricity from biomass and biomass-derived fuels has become an attractive and viable alternative energy source. Alkali metal release during biomass combustion can cause significant problems in terms of severe fouling and slagging of heat transfer surfaces in boilers thus reducing efficiency, and in the worst case, leading to unscheduled plant shutdown. Future biomass to electricity facilities will benefit from increased efficiencies by incorporating integrated gasification combined cycle systems that use biomass combustion gases to directly drive an aeroderivative turbine. These systems will have even lower tolerances for alkali vapor release because accelerated erosion and corrosion of turbine blades results in shorter turbine lifetimes. One solution to the fouling and slagging problem is to develop methods of hot gas cleanup to reduce the amount of alkali vapor to acceptable levels. A detailed understanding of the mechanisms of alkali metal release during biomass combustion as well as identifying alkali metal containing vapors and how the vapors lead to fouling and slagging could greatly benefit the development of hot gas cleanup technology. This paper demonstrates the application of molecular beam/mass spectrometry to the study of alkali metal speciation and release during switchgrass combustion. We have successfully used this experimental technique to identify alkali metal containing species released during the combustion of switchgrass at four different conditions: 1100 degrees C in He/O-2(20%), 800 degrees C in He/O-2(20%), 1100 degrees C in He/O-2(5%), and 1100 degrees C in He/O-2(10%)/steam(20%). These conditions were chosen to study the effect of temperature, oxygen concentration, and excess steam on alkali metal release and speciation. Initial feedstock composition is the most significant factor which affects the amount and species of alkali metal released during biomass combustion. The switchgrass sample screened in the present study is high in both alkali metal (potassium) and chlorine. As a result, the predominant alkali metal containing species released during switchgrass combustion is potassium chloride. Varying the combustion condition affects the amount of alkali metal released by a factor of 2 or less. Adding excess steam to the combustion environment tends to shift the form of alkali metal release from the alkali chloride to the hydroxide.