低共熔溶剂回收弛放气中NH_(3)工艺的模拟计算

Simulation calculation of NH_(3)recovery processfrom purge gas using deep eutectic solvents

合成氨厂弛放气中NH_(3)的回收对提高大气质量和资源利用具有双重意义。常用的水洗法存在吸收不完全和产生大量廉价稀氨水的缺陷,酸洗法又有解吸能耗高和氨资源浪费的不足。基于低共熔溶剂(DES)具有蒸气压低、热稳定好及气体溶解性可调的优点,因此提出了氯化胆碱和尿素摩尔比为1∶2的DES回收弛放气中NH_(3)的新工艺。基于RK-NRTL的计算方法,利用软件模拟了新工艺的过程。通过灵敏度分析关键工艺参数对结果的影响,优化确定了合理的工艺条件。计算结果表明:新工艺具有良好的吸收效果,NH_(3)回收率高达99%,净化气中氨的摩尔分数低至4.117×10^(-5),达到直排的标准;再生氨的摩尔分数为0.9744,新工艺相对离子液体[C 4mim]BF 4的吸收氨工艺节能约53.38%。新工艺的设备简单、分离过程高效且节能,具有良好的应用前景。

Ammonia recovery from the purge gas of synthetic ammonia plants have significant improvement to atmospheric quality and resource recycle.The conventional water scrubbing method suffers from incomplete absorption and generates a large amount of dilute ammonia solution.The acid scrubbing method has the shortcomings of the high energy consumption and wasted NH_(3)resources.With the advantages of deep eutectic solvents(DESs),including low vapor pressure,good thermal stability and tunable gas solubility,we presented a new process for the recovery of ammonia in purge gas by DES with a 1∶2 molar ratio of choline chloride and urea.Using RK-NRTL calculation method,conditions were simulated and optimized by analyzing the influence of several key process parameters.The results show that the present process has good absorption performance,the recovery of NH_(3)is up to 99%,the molar fraction of ammonia in purified gas is as low as 4.117×10^(-5),and the regenerated ammonia is 0.9744,which meets the standard of direct discharge.The new technology saves about 53.38%energy compared with the absorption ammonia process of ionic liquid[C 4mim]BF 4,which has the potential for practical applications because of its simple equipment,efficient and energy-saving separation.