生物质中碱金属在煤/生物质共气化过程中的传递、分配与催化作用规律

Based on the special phenomenon that biomass alkalis (mainly K element) can transfer and accumulate to the surface of coal char during the coal/biomass co-gasification process, we put forward an idea of biomass as catalyst to be used in co-gasification with coal. The driving force of alkalis transfer, pathways and behaviors of K during co-gasification will be investigated. Furthermore, the catalytic bebaviors of biomass alkalis in co-gasification process will be studied. Based on analysis of forms and contents of K existed in solid phase, the mass balance of between K cation formed in biomass pyrolysis and gasification process, and the anion which affects the existing form of K, will be carried out in the single-stage reactor, the double-stage reactor and the wire-mesh reactor. Operation conditions (such as temperature, pressure, the gasification agents and anion concentration etc.), will be studied to evaluate how they affect the alkalis distribution during the co-gasification process. The alkalis transfer kinetics and the catalytic kinetic equation will be suggested, in which the properties of gas/solid/solid and the carbon conversion ratio act as the objective function. And the model is established to describe the conversion efficiency, energy utilization efficiency in the co-gasification process to help the co-gasfication gasifier design. A chemical technology, not only to maximize the benefit of biomass alkalis as a catalyst but also to minimize the corrosion of equipements, will be proposed to the development of employing biomass alkalis as catalyst in the catalytic coal gasification process.

以煤/生物质共气化前期研究发现"生物质中碱金属钾可在气相中向煤焦表面传递并富集"的独特现象为入手点，提出利用生物质作为煤催化气化催化剂的思想和方法。通过对生物质中碱金属钾传递的原因、方式、影响因素进行研究，明晰生物质中碱金属对煤气化催化的过程和机制。研究通过对生物质气固相的碱金属存在形态和含量进行分析；利用单段、两段和丝网反应器对生物质在热解和气化过程中气/固两相中碱金属阳离子及影响其存在形态的阴离子的质量衡算；考察影响共气化过程中碱金属分配规律的温度、压力、气化剂组成和阴离子浓度等环境因素，得到碱金属传质动力学及包含碱金属(g)/煤(s)/生物质(s)三相性质在内、以碳浓度变化规律为目标函数的催化动力学方程；构建煤/生物质共气化过程中转化效率、能量利用模型；找出可有效利用生物质中碱金属催化特点同时尽可能降低其腐蚀的方法，为生物质中碱金属作为煤催化气化催化剂的工艺开发提供依据。

生物质和煤共气化可充分利用生物质中富含的碱金属为煤气化提供廉价可弃催化剂，通过煤气化的高温环境，将生物质能量密度低产生的低温焦油和热转化效率低的问题综合解决，达到取长补短的效果。本课题利用反应区隔离技术，将共气化过程切割为制焦和气化两个阶段，研究了共转化过程中生物质碱金属的迁移路径、转化规律和催化作用机理，阐明了环境条件对生物质碱金属转移的影响方式和途径；构建了煤/生物质共气化过程中转化效率、能量利用模型；找出既可有效利用生物质中碱金属催化特点又能最大限度降低反应器腐蚀的方法，为生物质中碱金属作为煤催化气化催化剂的工艺开发提供依据。