燃煤过程中微量元素砷和硒形态转化的热力学平衡模拟

Development of thermodynamic equilibrium prediction of trace arsenic and selenium speciation during coal combustion

砷和硒是煤中的易挥发有毒微量元素。由于砷和硒在燃煤烟气中的浓度极低以及实验条件的限制 ,目前化学热力学平衡分析已成为预报烟气中砷和硒等有毒元素形态分布的主要理论分析方法。本文综述了热力学平衡分析方法应用于砷和硒在燃煤过程中形态转化和平衡分布等方面的研究进展。首先用于热力学平衡分析的是只含有砷或硒一种微量元素和煤中主量元素及氯元素的简单体系 ,并假设烟气中只有理想气体组成的气相和纯凝聚相的理想模型。然而是否考虑砷和硒与其他微量、主量或次量元素的相互作用 ,砷和硒所有可能存在的反应 ,以及在熔融相砷和硒与熔融物的结合会严重地影响模型的预报结果 ,因此 ,目前热力学平衡体系已发展成为含有包括砷和硒在内的多个微量元素和煤中所有主量、次量元素 。

Arsenic and selenium are considered to be toxic and volatile trace elements in coal. A review about thermodynamic equilibrium analysis applied to arsenic and selenium speciations from coal combustion is given in this paper. Usually, only simple systems containing arsenic or selenium together with coal major elements and chlorine is considered, and in this system only gas and condensed phase exist. It is now of great interest to investigate arsenic and selenium behavior during coal combustion in a complex system where they coexist with all the coal major and minor elements and halogen, or containing not only ideal gas and condensed phase but molten phase in order to determine thermodynamic dominant species of arsenic or selenium and their elemental chemistry after considering all the possible interactions .