Hydrolysis Of Urea For Ammonia-Based Wet Flue Gas Desulfurization

Nowadays, the ammonia-based wet flue gas desulfurization technology usually gets ammonia source from liquid ammonia. The long-distance transportation and storage of liquid ammonia has a huge safety problem and uncertainty. While urea is safe to transport, using urea as ammonia source can largely increase the safety and decrease the transportation cost of resource.In this study, the effects of temperature, pressure, urea solution concentration and time on urea hydrolysis were investigated and the optimum hydrolyzing condition was estimated. It was found that when the urea solution concentration was between 20 (wt,%) and 30 (wt,%), the hydrolyzing time was extended from 2h to 4h, the conversion of urea at 140℃, 0.4MPa increased from 41.0% to 86.8%, the ammonia production increased from 9.29g to 44.20g. Moreover, when the urea solution concentration was between 20 (wt,%) and 30 (wt,%), the hydrolyzing time was 4h, the percentage of urea which took chemical reaction over the original urea at 140℃,0.4MPa was over 90%; the percentage of urea which took the reaction of hydrolysis over the urea which took chemical reaction at 140℃,0.4MPa was over 95%, which reached the requirement of industrial application.The ammonia produced under this condition was used for desulfurization experiment. The pH range was between 6.5 and 7.5. The experimental results showed that all desulfurization efficiencies at different SO2 concentrations or liquid-gas ratios exceeded 99%, which finished the practice of using ammonia from urea hydrolysis for mmonia-based wet flue gas desulfurization.This experiment provided supporting technology for the industrial application of using ammonia from urea hydrolysis for mmonia-based wet flue gas desulfurization.