CaCl2的高温稳定性试验研究
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摘要: 在燃煤造成的特殊污染物中，有关HCl等无机污染物的排放已经成为一个前沿的新热点研究领域。燃煤过程中钙基固氯剂燃烧固氯的最终产物CaCl2，其高温稳定特性对固氯效率有重要影响。本文在固定床反应器上采用气态氯化物直接吸收分析法，对CaCl2晶体粉末在干燥大气和饱和大气下的高温稳定性进行了实验研究。结果表明，在高温条件下CaCl2发生水解反应，水解反应起始温度在700 ℃左右，水解率随燃烧温度和停留时间的增加而增加，空气中水蒸气含量对水解率有显著影响。动力学计算表明在700℃～1300℃温度范围内CaCl2水解反应为二级反应，随温度变化反应机理有所不同，600℃～1000℃和1000℃～1300℃两个温度段的反应活化能分别为E=37.82 kJ/mol和E=18.13 kJ/mol。研究结果对燃煤过程中高温高效燃烧钙基固氯剂的开发有指导意义。Abstract: The stability of CaCl2 in dry and moist air at elevated temperatures were studied by direct absorption of gaseous chlorides and mercury thiocyanate measurements technique supplemented by chemical analysis (pyrohydrolysis- mercury thiocyanate method) and flame atomic absorption spectrometer (FAAS). The principal reaction is shown to be hydrolysis of CaCl2 at high temperature and CaCl2 is actually hydrolyzed appreciably at about 700 ℃ in moist atmospheres. Kinetics calculation has shown that hydrolysis is two order reaction and the activation energy for the hydrolysis is 37.82 kJ/mol and 18.13 kJ/mol, over the range 700 ℃～1 000 ℃ and 1000℃～1300℃. The results will be of significance for chloride pollution control during coal combustion.
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Key words:
- CaCl2 /
- high temperature stability /
- direct absorption /
- hydrolysis /
- kinetics
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