火电厂尿素水解工艺设计及试验研究

Crafts Design and Experimental Study of Urea Hydrolysis to Ammonia in Thermal Power Plant

尿素水解制氨工艺在火电厂SCR脱硝还原剂制备中逐渐得到应用,其操作条件和工艺路线与传统的化工行业尿素深度水解技术存在显著差别。中试试验数据表明,尿素水解制氨工艺的操作压力应选择0.6 MPa,定压运行,操作温度接近150℃。操作条件下尿素分解率大于98%,尿素水解反应的选择性为93.4%,指前因子和活化能参数分别为2.98×106 s-1和86.575 k J/mol。设计水解反应器时应在确保布置足够受热面的前提下尽量缩小反应器体积。本研究将为火电厂烟气脱硝用尿素水解系统工艺设计提供参考。

The urea hydrolysis to ammonia is applied in the SCR system of thermal power plants, and the operating conditions and process have significant differences with the depth urea hydrolysis craft in the chemical industry. The urea hydrolysis to ammonia in a continuous tank reactor was mechanistically modeled. The significances of the model were correcting the vapor and liquid non-ideality by fugacity coefficient and activity coefficient respectively, and then the experiments were conducted on a pilot plant. The experiment results show that, the operating pressure and temperature of urea hydrolysis reactor are opt to 0.6MPa and 150℃, respectively. The urea decomposition rate is greater than 98% and the selectivity of urea hydrolysis reaction, is 93.4% under operating condition. The frequency factor and activation energy of urea hydrolysis reaction are revised to 2.98 × 106 s-1 and 86.575 kJ/mol, respectively. Heat tracing of pipelines are necessary for ammonia transportation. The reactor capacity should be minimized under the premise of ensuring sufficient heat exchange area. Above all, this study will provide a reference to the crafts design of urea hydrolysis to ammonia in the thermal power plants.