The problems existed in the original CO2 stripping process of urea production unit are analyzed,mainly including poor efficiency of gas stripping,low temperature of liquid out from the rectification column,high concentration of ammonia in ammonia water tank,and high comprehensive energy consumption per unit product.Aiming at the existing problems,an adiabatic flash distillation technique is adopted to connect the medium pressure system in series on the original CO2 stripping unit.After the transformation,the average capacity of the single-set device is increased,exceeding the original design capacity.The integrated energy consumption of the device is reduced,and the average value is 105 kg/t (converted to standard coal).The cost of production of 1 t urea product is about 17.21 yuan less than that before modification.The mass fraction of biurea in the product is lower and the product quality is improved.The mass fraction of ammonia water in the ammonia sink is maintained below 3.8％,much lower than that before modification,so that the corrosion of equipment is alleviated.The operation practice shows that the transformation of the series medium pressure system provides more convenient operating conditions for production,which increases the market competitiveness of the products.%分析了原CO2气提法尿素生产装置存在的问题,主要包括气提效率低、精馏塔出液温度低、氨水槽中氨水浓度超出设计值、单位产品综合能耗较高等.针对存在的问题,在原有CO2气提生产装置的基础上,采用绝热闪蒸技术,串联了中压系统.改造后,单套装置平均产能提高,超过原设计产能;装置综合能耗降低,平均为105 kg/t(折算成标准煤);生产1t尿素产品成本比改造前降低约17.21元;产品中缩二脲质量分数降低,产品质量提高;氨水槽的氨水质量分数维持在3.8％以下,远低于改造前,使设备腐蚀得到缓解.生产运行实践表明,串联中压系统的改造给生产提供了更便利的操作条件,增加了产品的市场竞争力.
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