Catalytic after-burning. A method of purifying flue gases

Abstract

The burning of hydrocarbons on alumina-supported catalysts proceeds according to a firstorder kinetic. The activation energies on one catalyst are approximately equal and, to quote an example, are ca 16 kcal for a copper chromoxide catalyst (10%), and ca 41 kcal for palladium (0.15%), per mole of reacted substance. The frequency factors can be taken as a rough guide as to whether a substance can be burned readily in the presence of a catalyst. The products of reaction in this process are carbon dioxide and water vapor. The main construction types developed for the catalytic afterburning process are those embodying the concepts of: straightforward catalytic combustion, catalytic combustion with heat exchange, and catalytic combustion with heat exchange and hot-air recycle. Implicit in the last concept, as a rule, is an improvement in the heat economy of the primary process. process. Two characteristic applications of the principle are described: o 1. The cleaning of the low-energy flue gas derived from a PVC curing oven, combined with hot-air recycling. This results in considerable running cost saving. 3. The reacting of a flue gas with a calorific value of some 100 kcal per cubic meter. The energy released in this process is utilized for steam production. The steam-production costs amount to a few D-Marks per ton.