生物质与煤混燃过程中碱金属对汞氧化影响的热力学研究  

Thermodynamics Study of Effects of Alkali Metals on Mercury Transformation During Co-combustion of Biomass With Coal

作　　者：余婉璇[1] 刁永发[1] 沈恒[1] 

机构地区：[1]东华大学环境科学与工程学院,上海市松江区201620

出　　处：《中国电机工程学报》2012年第26期96-102,153,共7页Proceedings of the CSEE

基　　金：国家高技术研究发展计划项目(863计划)(2008AA05Z305);教育部留学回国人员科研启动基金项目(201109);中央高校基本科研业务费专项基金重点项目(11D11315)~~

摘　　要：针对生物质中Cl和碱金属含量高的特点,研究生物质与煤混燃过程中Hg的氧化机制。使用化学热力学软件Chemical Equilibrium with Applications(CEA)建立C/H/O/N/S/Cl/K/Na模型,分析碱金属元素K、Na与非金属元素Cl和S的反应,发现1100K以下Cl仍然主要以HCl形式存在,SO2的含量逐渐减少,碱金属主要以碱金属硫酸盐(A2SO4)的形式存在,这对Hg的氧化反应变得更为有利,同时随着生物质的添加,这种趋势更为明显。同时使用动力学软件Chemkin4.1构建了Hg/C/H/O/N/S/Cl/K/Na的化学和气相平衡模型,进一步研究了生物质与煤混燃过程中对Hg氧化的影响。计算结果表明,生物质与煤之比越高,对Hg的氧化越有利,生物质中高含量的Cl是促进Hg氧化最主要的因素,而K、Na的存在对Hg的氧化有进一步的促进作用,这进一步证实了热力学计算结果。The oxidation mechanism of mercury during co-combustion biomass with coal was studied because of the high content of C1 and alkali metal of the biomass. C/H/O/N/S/ C1/K/Na model was established with chemical thermodynamics software CEA, and the interaction between alkali metals and chlorine or sulfur were analyzed. It is founded that below 1 100K, C1 is still mainly in the form of HC1, the content of SO2 decreases, and the alkali metals exist in the form of alkali sulfate （A2SO4）, which will contribute to the oxidation of Hg. And with the addition of biomass, this trend becomes more apparent. Hg/C/H/O/N/S/C1/Hg/K/Na chemical and phase equilibrium model was established based on previous studies with CHEMKIN 4.1, and the effect of biomass co-firing with coal on Hg oxidation was further studied. Chemical and phase equilibrium calculations results show that the more the ratio of biomass and coal is, the better the oxidation of Hg. The high content of C1 in the biomass is the most important factor to promote Hg oxidation, and the presence of K and Na will further promote Hg oxidation. The results also further confirm the thermodynamic calculations.

关 键 词：生物质与煤混燃 汞 碱金属 氧化机制 热力学 

分 类 号：TK16[动力工程及工程热物理—热能工程]