料液中盐对气态膜法脱氨过程的影响

摘要

系统研究了气态膜法脱氨操作过程中无机盐种类和浓度对氨传质性能的影响,并初步探讨了温度对盐效应的影响.实验结果表明,盐效应和盐溶液的黏度变化均影响氨的传质.盐对氨的盐析效果越强,氨的膜相传质系数kM越大,而盐溶液的黏度越大,氨的液相传质系数kL越小,总传质系数K的变化是kM和kL变化的综合结果.在几种常见的无机盐中,氯化钠、硫酸钠、硫酸铵对氨具有不同程度的盐析效应,可促进氨在体系中的传质；而氯化铵和氯化钙对氨具有盐溶效应,其中氯化钙的盐溶效应最为明显.温度对盐效应和体系的传质性能有显著影响,硫酸铵和氯化钙的盐效应均随着温度的升高而减弱.%The experiments were carried out to investigate the effect of salts on the mass transfer performance and the effect of temperature on the salt-effect in the removal of ammonia from aqueous solutions by gas-membrane-based stripping-absorption process. The experimental results show that the mass transfer of ammonia is affected by the salt-effect and the viscosity of salt solutions. The stronger the salting-out effect is, the higher the membrane transfer coefficient (￡m) is; and the higher the viscosity of the feed is, the lower the liquid transfer coefficient (kL) is. The change of the overall transfer coefficient depends on the change of kM and kL. Sodium chloride, sodium sulfate and ammonium sulfate exhibit a salting-out effect on ammonia and prompt the mass transfer. Although the viscosity of feed containing ammonium chloride becomes slightly smaller with the increase of the concentration, ammonium chloride exhibits a salting-in effect on ammonia, so the overall transfer coefficient changes little. Calcium chloride shows a significant salting-in effect on the gas-membrane-based ammonia stripping process. The temperature affects the salt-effect and the mass transfer performance dramatically. With the increase of temperature, the salt-effect of ammonium sulfate and calcium chloride becomes weaker and the overall transfer coefficient increases significantly.