1993: European Patent no. 0374649B1 was granted

“Method and an apparatus for impregnating or coating object”

“The method according to the invention for impregnating and/or coating objects in a drip-, and/or dipping roller installation by passing the objects through a preheating zone, at least one drip-, dipping roller- and or coating zone, an after baking zone, and possibly at least one intermediate baking zone is characterised in that the outgoing air from the drip-, dipping roller-, intermediate baking- and/or after baking zone ist passed as crude gas to a post-combustion installation, wherein the crude gas is heated by indirect heat exchange with the clean post-combustion gas, that the clean post-combustion gas is returned at least partly to the preheating zone, and that the energy content of the clean gas which is returned to the preheating zone is adjusted in such a way that the energy requirement of the preheating zone is basically just met.”