蒸汽汽提尿素水解制氨试验研究

Experimental Study on Urea Hydrolysis for Ammonia With Steam Stripping

在高浓度尿素水解制氨工艺中,为减少中间产物甲铵对设备的腐蚀,提出一种蒸汽汽提工艺来促进水解液中甲铵的分解。文中通过建立蒸汽汽提工艺的机理模型,并结合中试装置开展试验研究,分析了蒸汽汽提对尿素水解制氨过程的影响。试验结果表明,汽提蒸汽改变了水解反应体系的气液相平衡,促进了液相中甲铵的分解。水解产氨速率由动力学控制,蒸汽汽提工况下表观动力学参数和产氨速率均保持不变。汽提蒸汽中仅有部分显热被利用,增加汽提蒸汽流量会增大产氨蒸汽耗量。当给料尿素溶液浓度为60%,汽提蒸汽量准则数?增加到29%时,水解反应液中尿素及其衍生物的质量分数降低20.1个百分点,单位产氨蒸汽耗量增加23%。

The process of urea hydrolysis with steam stripping was proposed in order to reduce the corrosion of ammonium carbamate on the reactor in the urea hydrolysis with higher feed concentration.In this paper the mechanism model of steam stripping'process was established firstly,and then the pilot tests were conducted.The results show that,the gas-liquid equilibrium in the reactor is re-established by the stripping steam,and the ammonium carbamate in the solution is decomposed.The ammonia production rate is dominated by kinetics and the apparent kinetic parameters remain unchanged at the steam stripping conditions,Because only part of the sensible heat in the stripping steam is utilized,the energy consumption of ammonia production is increased with the increasingflow ofstrippingsteam.Whenthefeed concentration is60%and the criteria number of stripping steam flow is increased from0%to29%,the mass fraction of urea and its derivatives in the reaction solution is reduced by20.1%, and the steam consumption for unit ammonia production is decreased by23%.