洁净煤技术

2020, v.26;No.130(06) 168-174

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石墨热分解CaSO_4反应机理研究
Study on the reaction mechanism of thermal decomposition reaction of CaSO_4 and graphite

赵亮;
ZHAO Liang;Institute of Engineering Thermophysics,Chinese Academy of Sciences;University of Chinese Academy of Sciences;

摘要(Abstract):

碳(C)热分解硫酸钙(CaSO_4)的反应普遍发生于采用炉内脱硫的循环流化床锅炉中,深入研究其反应机理对于改善炉内固硫性能具有重要意义。基于热重质谱试验,采用等效特征图谱法(ECSA)深入探索了石墨热分解CaSO_4的反应过程;同时结合水平管式炉试验,通过表征反应后的固体产物,综合分析得出石墨热分解CaSO_4过程中各主要反应的温度区间。结果表明:基于热重质谱试验数据结合等效特征图谱法(ECSA)可以很好地解析石墨热分解CaSO_4的主要反应过程; CaSO_4自分解反应发生在1 100℃左右,石墨的加入使得CaSO_4的分解温度降低至900℃左右,同时增大其最快分解速率、缩短完全分解时间; 1 050℃左右,石墨热分解CaSO_4的速率达到最大,但最大分解速率对应的温度与石墨的添加量无关;随着石墨与CaSO_4摩尔比的增加,CaSO_4的分解速率逐渐增大,但起始分解的温度略有降低并趋于稳定;在石墨热分解CaSO_4反应过程中,生成CO_2、SO_2气体和CaO固体的反应为最主要的反应;当反应温度超过1 100℃时,石墨与CaSO_4可能发生生成CaS和CO_2的反应,但其进行程度很小。
The reaction of carbothermal decomposition of calcium sulfate( CaSO_4) generally occurs in circulating fluidized bed boilers that use furnace desulfurization. It is of great significance to in-depth study the reaction mechanism for improving the sulfur fixation performance in the furnace. Based on the experiment of thermogravimetric and mass spectrometry,the equivalent characteristic spectrum( ECSA) method was used to deeply explore the reaction process of graphite thermal decomposition of CaSO_4. Besides,combined with the horizontal tube furnace experiment,the solid product after the reaction was characterized. The temperature range of the main reactions in the decomposition of CaSO_4 was comprehensively analyzed. The results show that based on the experimental data of thermogravimetric mass spectrometry combined with ECSA,the main reaction process of graphite thermal decomposition of CaSO_4 can be well analyzed. The selfdecomposition reaction of CaSO_4 occurs at about 1 100 ℃,and the addition of graphite reduces the decomposition of CaSO_4 temperature to about 900 ℃,while increasing the fastest decomposition rate and shortening the complete weight loss time. At about 1 050 ℃,the rate of thermal decomposition of CaSO_4 by graphite is the fastest,but the temperature corresponding to the maximum decomposition rate is not correlated with the amount of graphite added. With the increase of the molar ratio of graphite and CaSO_4 increases,the fastest reaction rate of the decomposition of CaSO_4 gradually increases,and the temperature of thermal decomposition of CaSO_4 decreases slightly and tends to be stable. In the process of thermal decomposition,the reaction of CO_2,SO_2 and Ca O is the most important reaction product. When the reaction temperature is higher than 1100℃,the reaction between graphite and residual CaSO_4 will also occur to generate Ca S and CO_2,but to a small extent.

关键词(KeyWords): 硫酸钙;热分解;等效特征图谱法;热重质谱;石墨
CaSO_4;thermal decomposition;ECSA;TG-MS;graphite

Abstract:

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基金项目(Foundation): 中国科学院战略性先导科技专项资助项目(XDA21000000)

作者(Author): 赵亮;
ZHAO Liang;Institute of Engineering Thermophysics,Chinese Academy of Sciences;University of Chinese Academy of Sciences;

Email:

DOI: 10.13226/j.issn.1006-6772.19083001

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