Simulation of an industrial turbulent fluidized bed reactor for n-butane partial oxidation to maleic anhydride

A fluid-dynamic and chemical model of an industrial-scale turbulent fluidized-bed reactor, which performs n-butane partial oxidation to maleic anhydride (MA) catalyzed by (VO)2P2O7 solid particles, is proposed. Main assumptions are: gas plug-flow in the dense bed because gas back-mixing is minimized by internals; perfectly mixed particulate phase in the dense bed due to high recirculation rate of entrained particles at the bottom of the reactor, after separation by cyclones; plug-flow of both gas and solids in the freeboard. Literature kinetic models are considered to simulate reactions, slightly modified to allow careful prediction of industrial performance. The model is organized in ordinary differential and algebraic equations describing mass and energy balances and constitutive expressions for reaction rates, heat and mass transport phenomena, and implemented in MATLAB®. Numerical results simulate accurately temperature along the reactor, MA yield and by-products selectivity in the outlet stream, and allow to estimate the solid circulation rate. Inlet gas flow rate and n-butane/air feeding ratio are varied within a ±10% range around industrial operating conditions, to test the parametric sensitivity of the model: corresponding dense bed height, n-butane conversion, products selectivity in the outlet stream vary within ±5% of the experimental performances, depicting stable conditions.