Zeitliche Darstellung des Alterungsverhaltens eines Oxidationskatalysators in einem Biogas-BHKW

The emissions released during the burning of biogas are subject to legal limits. In order to comply with these limits, exhaust aftertreatment is required by oxidation catalyst. Over time, decreasing pollutant conversion occur due to aging of the catalyst. Therefore, after only 1.5 years working time, compliance with the formaldehyde limit is no longer possible with certainty. The main reason is the deposition of inorganic compounds called oil ashes. These flue gas components from biogas engines block the catalytic active species and plugs pores.     

Stand der Simulation von heterogen‐gaskatalytischen Reaktionsabläufen in Festbettrohrreaktoren — Teil 1

This contribution analyses the state of the art in two parts. Based on general quasi‐homogeneous and heterogeneous reactor models, their benefits and disadvantages as well as simplification options are discussed, taking into consideration catalyst deactivation. Further on, the article focuses on the issue of model trimming for industrial applications. A distinction is made between process rationalisation and the development of new processes. In process rationalisation, models can be tested/adjusted on the basis of meas ured values from industrial reactors. This is not feasible when developing new processes. Thus, the major factors influencing the reliability of prediction, such as model assumptions, initial and boundary conditions, mathematical and computation restrictions, chemical kinetics, thermal and mass transport as well as flow distribution, are analysed first. Eventually, this contribution proposes ways of model trimming and resolving problems of scale transfer.