Experimental study on urea hydrolysis to ammonia for gas denitration in a continuous tank reactor

Abstract

In recent years, the risk of anhydrous and aqueous ammonia in transportation and storage has been a concern of power plants around the world, and the urea hydrolysis to ammonia using low-grade steam as heat source is gradually used for feedstock preparation in NOx reduction. In this paper, the urea hydrolysis to ammonia in a continuous tank reactor was mechanistically modeled, and a pilot plant was established to simulate the transfer process in the industrial reactor in order to obtain the scale-up rules of the process. The results of pilot test indicated that the reaction-diffusion criterion number was 0.036 when the operating temperature was 150 °C. The urea hydrolysis was a slow reaction in liquid and the ammonia production rate of reactor was dominated by kinetics. At last, the industrialized test was conducted and the ammonia production rates agreed well with the model predicted data, and the ammonia consumption of flue gas denitration in the selective catalytic reduction was satisfied. This study would provide a reference to the design and development of urea hydrolysis for gas denitration.