Abstract: With the depletion of crude oil resources, a large number of highly corrosive inferior crude oils are refined in China. Among them, ammonium salt corrosion risk of cold exchange equipment is high due to strong corrosiveness of raw material and long-term extreme operating conditions of equipment. In this paper, the air cooler of the fluidized bed residue hydrogenation system was taken as the research object, and NRTL-RK model was used to construct the chemical ion-equilibrium model of the reaction effluent system under the multi-component system. Through the process correlation analysis and numerical simulation analysis, the risk of ammonium salt crystallization corrosion in the system was evaluated. The process calculation results showed that there was corrosion risk of ammonium chloride in the air cooler of the system, the crystallization temperature was 169-187 ℃, and the crystallization rate of ammonium salt increased continuously with the decrease of temperature, the limit operating condition was 0.22 kg/h. The convection heat transfer model of air cooler was constructed by component transport equation and condensation model. The numerical simulation results showed that the maximum mass transfer coefficient (1.52×10^-4 m/s) and corrosion rate (0.43 mm/a) occurred at the bottom of the outlet manifold.

Key words: hydrogenation of residue in boiling bed, air cooler, ammonium salt crystallization, sediment prediction, risk evaluation