Heterogeneous gas chemistry in the CPFD Eulerian–Lagrangian numerical scheme (ozone decomposition)

Heterogeneous catalytic chemistry is used throughout the chemical and petro-chemical industry. In predicting the performance of a reactor, knowing the gases and solids flow dynamics is as important as having good chemical rate expressions. This paper gives the solution of ozone decomposition in a bubbling bed using the CPFD numerical scheme which is a Eulerian–Lagrangian solution method for fluid–solid flows. The ozone decomposition can be described by a single stoichiometric equation and has a first order reaction rate. The ozone decomposition is a standard problem for chemical analysis and has been used to characterize gas–solid contacts in fluidized beds. The accuracy of predicting the ozone decomposition comes from correctly predicting the bed dynamics. The solution in this study is three-dimensional and predicts the coupled motion of both solids and gas. The chemical rate equation uses solids volume fraction, but the numerical method could calculate chemistry on the discrete catalyst, including a variation in size (surface area) if such a rate equation was available. The numerical results compare well with an analytic solution of the decomposition rate, and calculated results compare well with the experiment by Fryer and Potter [Fryer, C. and Potter, O.E, (1976), “Experimental investigation of models for fluidized bed catalytic reactors,” AIChE J., 22.].

This paper shows the use of the CPFD Eulerian-Langrangian method to calculate the heterogeneous chemistry of ozone decomposition. The ozone decomposition problem is a standard problem used to characterized gas-solid contact in fluidized beds. The calculated results are compared with the data from Fryer and Potter (AIChE J., 22, 1976). The results indicate the good agreement with the experimental data at different catalyst activities and superficial velocities indicating the suitability of the numerical method to calculate complex gas-solid flows in three dimensions.Figure optionsDownload as PowerPoint slide