Today in 1989, US Patent 4836097 A was issued, an invention of Hans Tretter, assigned to Anton Steinecker Maschinenfabrik Gmbh, for his “Whirlpool for Coarse Sludge Separation in Brewing Of Beer.” Here’s the Abstract:

The present invention refers to a whirlpool for coarse sludge separation from the wort in brewing of beer, said whirlpool being being constructed as a circular receptacle provided with a base on which the sludge deposits and with a heating means for heating the wort.

For providing a possibility of treating the wort in a space-saving manner and without any special insulating measures in the wort heating process, the invention is characterized by the features that a rotationally symmetrical inner boiler is provided as a heating means, said inner boiler being arranged in the interior of the receptacle such that it is concentric with the longitudinal center axis of the receptacle and such that its lower side extends in spaced relationship with the base of the receptacle.