A reduced model for the evaporation and decomposition of urea–water solution droplets

Theoretical study of the gas-phase thermal decomposition of urea

“…Figure 6 presents the pyrolysis of pure urea at 1 atm, in a constant pressure and temperature homogeneous batch reactor. The simulations are performed for a residence time of 10 s, which corresponds to the same order of magnitude that the induction time for gas phase chemistry (between 773 K and 873 K) reported by Stein et al [3] in their decomposition model of urea-water solution droplets.…”

“…Stein et al showed that the evaporation and decomposition of a droplet of urea-water solution occurs in three main phases: water evaporation, urea decomposition and reactions in the gas phase [3]. Thus, there is a need to understand the mechanism of urea thermal decomposition and the formation routes of the pyrolysis products.…”

“…It will help in the interpretation of the literature data by allowing the decoupling of the intricate gazliquid-solid data. In SCR and SNCR processes, it is a droplet of liquid urea that is subjected to pyrolysis [3]. The proposed gas-phase kinetic mechanism will be able to serve as a starting point in the development of a liquid phase kinetic model for the thermal decomposition of urea.…”

A Review of Urea Pyrolysis to Produce NH3 Used for NOx Removal

“…HNCO was an important intermediate product, as its hydrolysis reaction (12) played an important role in NH 3 production [16][17][18]. e HNCO formed from urea decomposition is quite stable in the gas phase, so its hydrolysis reaction does not proceed as a homogeneous reaction.…”

“…Its production, transportation, storage, application, and handling require strict safety and environmental regulations, which immensely restricts the convenience of its utilization [14,15]. On this account, as a substitution, urea (NH 2 CONH 2 ) has been suggested as the reducing agent nowadays because of its nontoxicity, innocuousness, impossibility of explosion, and capacity to be carried on board [16][17][18].…”