碳酸钾生产中除氨新工艺实验研究

摘要

现有碳酸钾生产工艺中采用蒸发除氨,由于除氨不彻底,导致蒸发二次蒸汽中含有大量氨气和二氧化碳,使蒸发器的传热系数大大降低,从而增加了蒸发能耗;另一方面,挥发出的氨气和二氧化碳又难以集中回收,造成资源浪费,且增加原料成本费用.采用解吸法除氨,对料液温度、气液比、喷淋密度、气提时间、初始浓度等因素进行研究.实验结果表明,对于定量的处理料液,料液温度、气液比、喷淋密度、气提时间对碳酸氢铵分解影响较大,初始浓度对其影响较小.最佳工艺参数:料液温度为85℃、气液体积比为30:1、喷淋密度为55 m3/(m2·h),汽提时间为2.5 h,此时除氨率为95.48％.%The ammonia is removed by evaporation in the existing potassium carbonate production process.As the ammonia cannot be removed completely,heat transfer of evaporator is decreased when a lot of NH3 and CO2 in the secondary steam,and evaporation energy consumption is increased accordingly.On the other hand,it is difficult to collect the volatilized NH3and CO2,resulting in waste of resources and the increasing of production cost.The desorption method,a new ammonia removal process was introduced and the influence factors,such as temperature of solution,air/liquid ratio,trickle density,air-stripping time,and initial concentration,were investigated.Results showed that quantitatively,the initial temperature of solution,air/liquid ratio,trickle density,and air-stripping time has the greater influence on ammonium bicarbonate's decomposition,whereas the initial concentration does not.The optimum technological parameters were determined as follows:the initial temperature of the solution was 85 ℃,air/liquid volume ration was 30:1,trickle density was 55 m3/(m2· h),and air-stripping time was 2.5 h.Under the optimum conditions,the eliminated rate of ammonia was 95.48％.