喷淋塔内含肼碱液强化吸收气态碘的实验研究

Experimental Study on the Enhanced Absorption of Gaseous Iodine by Sodium Hydroxide Solution Containing Hydrazine

核工业乏燃料后处理过程中产生的含碘尾气排放会对生态环境和人类健康带来不可估量的危害,国际主流的技术是采用碱液湿法吸收含碘尾气,但国内缺少相关数据支撑湿法捕集技术的应用和发展。文章采用喷淋塔对含碘尾气进行吸收实验研究,考察了工艺参数,如吸收温度、碘初始浓度、气体流量、循环液气比对含碘尾气吸收效率的影响规律,分析了肼引入碱液对吸收的强化过程。实验结果表明:氢氧化钠溶液最佳温度为65℃,碱液对气态碘吸收率为96.05%,引入肼的碱液对气态碘吸收由于化学平衡的破坏,强化了气液反应和传质现象,相同条件下喷淋塔内气态碘吸收率为98.42%;碘浓度在850~1200 mg/m^(3)之间,最佳喷淋密度500 L/m^(3),在此条件下,碱液和含肼碱液吸收气态碘效率分别为97.24%和99.33%。

The emission of iodine-containing tail gas generated during the reprocessing of spent fuel in the nuclear industry can cause incalculable harm to the ecological environment and human health,and the mainstream technology in the international arena is the wet absorption of iodine-containing tail gas by alkaline solution,but the domestic lack of relevant data to support the application and development of wet capture technology.In this article,an experimental study was conducted on the absorption of iodine-containing tail gas using a spray tower to investigate the influence of process parameters,such as the temperature of the absorbing solution,the initial con⁃centration of iodine,the flow rate of the mixed gas,and the circulating liquid-gas ratio,etc.,on the efficiency of the absorption of iodine-containing tail gas,and to analyze the enhancement of the absorption process of the hydrazine introduction of alkaline solution.The experimental results showed that:the optimum temperature of NaOH solution is 65℃,the absorption rate of alkaline solution on gaseous iodine is 96.05%,the alkaline solution introduced hydrazine on gaseous iodine absorption due to the disruption of the chemical equilibrium,strengthened gas-liquid reaction and mass transfer,the absorption rate of gaseous iodine under the same conditions in the spray tower is 98.42%;the iodine concentration is higher than 850~1200 mg/m3 and the optimum spray density was 500 L/m3,the absorption efficiencies of alkaline solution and hydrazine-containing alkaline so⁃lution on gaseous iodine were 97.24%and 99.33%,respectively.