Effectiveness For Irregular Shape Methane Steam Reforming Catalyst

In recent years, the irregular shape methane steam reforming catalyst development progresses rapidly with the goal to increase catalyst effectiveness and reduce the pressure drop in fixed bed reactor. However present research still mainly depends upon experiment and is lack of regularity and popularization. Sufficient effectiveness data for general shape catalyst can be found in the literature to supply reference, but it is still quite difficult to accurately compute the effectiveness of irregular shape methane steam reforming catalyst.A 3D reaction-diffusion model for irregular shape methane steam reforming catalyst has been developed. Finite element method (FEM) was used to solve the model according to complexity of partial differential system of equations. FEM is simple, accurate and especially suitable for irregular geometries.Intrinsic kinetics and global kinetics experiment were carried out over seven-channel spherical and three-channel ellipsoid catalyst under a experimental condition of 570-770℃, 3. OMPa in an internal recycling gradientless reactor, and then intrinsic rate equations in power function form were derived. The global kinetics data were applied to the model to obtain the temperature and concentration profile inside thecatalyst. The simulation data are in good agreement with the experimental results. The model is proved to be reliable by comparing the computed effectiveness and experimental value.The effectiveness of seven-channel spherical catalyst is 0. 2369~ 0.3550. The average absolute deviation between the calculated effectiveness and those of experiments is 8.22%. The effectiveness of three-channel ellipsoid catalyst is 0. 2136 — 0. 3209 and the average absolute deviation is 10.71%. Temperature difference of 10-16℃ exits within seven-channel spherical catalyst. Temperature difference of 10~ 20°C exits within three-channel ellipsoid catalyst. The temperature difference is too big to be neglected. The parameters within the catalysts keep constant in a large area of central part, contrasting with the sharp change in the surface layer of the catalyst particle. A large equilibrium dead zone exists inside the steam reforming catalyst.