Development and application of mathematical models of pilot-scale catalytic combustors fueled by gasified biomasses

The mathematical modeling of the catalyst section of an atmospheric pilot-s cale combustor fueled by gasified biomasses is addressed. The development o f distributed three-dimensional (3D) and two-dimensional (2D) models of the single channel of the monolith catalyst; is first described. The results o f models derived under different assumptions are then compared in order to identify the simplest accurate mathematical description. According to this procedure, a 2D model for circular channel geometry, which includes axial c onduction in the solid walls, can be regarded as the most suitable model fo r parametric investigations requiring a large number of simulations. Such a model is finally applied to the analysis of the results obtained in an exp erimental 30 kW pilot facility. A reasonable fitting of the experimental da ta is achieved, and the key role of high-temperature homogeneous and cataly tic kinetics in determining the combustor performances is pointed out. In p articular, evidence is provided in favor of temperature self-control of the palladium catalyst because of a drop of CH4 combustion activity associated with thermal decomposition of PdO.