Abstract
Fluidized-bed technology is compared against fixed-bed technology for the production of methanol from synthesis gas. The two-phase theory of fluidization is used to model and simulate the fluidized bed. The model takes into consideration the change in the number of moles accompanying the reaction. An industrial modern quench type fixed-bed methanol synthesis converter is used as a basis for comparison. The fluidized bed resulted in a 30% improvement in the methanol production rate. The efficiency of the fluidized bed is due to the elimination of diffusional limitations, giving rise to an effectiveness factor very close to unity, and also because of the shift of equilibrium to more favorable conditions, which is due to the removal of products of reaction by diffusion from the dense phase to the bubble phase. Simulation of a fluidized-bed case with minimized effect of back-mixing shows a 51.1% improvement in production rate over the industrial fixed-bed reactor.