火电厂尿素水解产品气输送问题分析

Problem analysis for transportation of urea hydrolysis production gas for thermal power plants

针对尿素水解产品气输送过程中存在的蒸汽回凝、氨基甲酸铵结晶析出等问题,分析了给料尿素溶液质量分数和水解反应器运行压力对产品气成分、蒸汽回凝温度和氨基甲酸铵结晶析出温度的影响。结果表明:蒸汽回凝温度和氨基甲酸铵结晶析出温度由给料尿素溶液质量分数和水解反应器运行压力决定;当运行压力0.7 MPa,给料溶液质量分数为50%时,产品气中水蒸气的回凝温度为133℃,氨基甲酸铵的结晶析出温度为85℃。并建议在设计伴热管道保温时,选用硬质或半硬质圆形保温材料,根据允许最大散热损失小于104 W/m2,计算保温层厚度。

Steam condensation,ammonium carbamate crystallization and other problems occurred during transportation of urea hydrolysis production.Thus,effects of the urea liquid mass fraction and reactor pressure on such parameters such as the compositions of the production gas,the steam condensation temperature and the ammonium carbamate crystallization temperature were investigated.The results show that,the steam condensation temperature and the ammonium carbamate crystallization temperature depended on the urea liquid mass fraction and reactor pressure.When the operation pressure was 0.7MPa and the feed mass fraction was 50%,the steam condensation temperature of the production gas was 133℃and the crystallization temperature of the ammonium carbamate was 85 ℃.Moreover,it is suggested that during the thermal insulation pipeline design,the hard or semi-hard circular thermal insulation material should be selected,and the insulation layer thickness be calculated according to the allowance maximum heat disspation rate（104 W/m2）.