碘吸附器用浸渍活性炭的燃烧过程分析

Analysis of Combustion Process of the Impregnated Activated Carbon for Iodine Adsorption

浸渍活性炭用于吸附放射性气体碘,目前广泛应用于核电厂通风及应急系统中。这些活性炭在使用后被当作放射性废物暂存于废物库,需要用合适的方法对其进行减容处理。为分析对这些废浸渍活性炭进行焚烧处理的可行性,应用热重分析法研究了核用碘吸附器浸渍活性炭从室温-1100℃的热解、燃烧过程。其燃烧过程可分为干燥、热解及燃烧三个阶段,后两阶段的反应动力学原理符合一级反应方程,并可由Coats-Redfern模型求解得到活化能分别为142.4 k J/mol和48 k J/mol。浸渍活性炭比椰壳活性炭着火点、最大失重速率等特征温度点更低。对热重样品逸出气进行质谱联用分析,发现其在加热及燃烧过程中有多种副反应发生,生成乙腈(C3H3N)等含氮有害气体,在焚烧工艺设计时需考虑对这些生成物的进一步处理。

Impregnated activated carbon for the adsorption of radioactive iodine gas is widely used in the ventilation system and emergency system of nuclear power plant. The spent impregnated activated carbon was stored as radioactive waste in the temporary waste storage system in the plant. Incineration is a good treatment for reduction the volume of carbon waste. In order to analyze the feasibility of incineration for the spent impregnated activated carbon,a thermo-gravimetric analysis from 26 ℃ to1100 ℃ was studied to analyze the pyrolysis and combustion process. The combustion process can be divided into three stages：drying,pyrolysis and combustion. The kinetics of the latter two stages is in accordance with the first order reaction equation. The activation energy of pyrolysis is 48 k J/Mol and activation energy of combustion is 142. 4 k J/mol. The ignition point temperatures,maximum weight loss rate temperature of the impregnated activated carbon are lower than the non-impregnated activated carbon. It also showed that there were many side reactions in the heating and combustion process and some harmful gas（ such as acetonitrile,etc.） generated which was necessary to be treated in the further processing.