CaCl_2的高温稳定性试验研究

STUDY ON STABILITY OF CaCl_2 AT HIGH TEMPERATURE

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 82kJ mol和E=18 13kJ 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。

The stability of CaCl_2 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 CaCl_2 at high temperature and CaCl_2 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 1?000?℃～1?300?℃. The results will be of significance for chloride pollution control during coal combustion.