Today in 1989, US Patent 4801462 A was issued, an invention of Arthur Tonna, assigned to The Stroh Brewery Company, for his “Copper Heat Exchange Tubes.” Here’s the Abstract:

Wort, heated to boiling in a brew kettle, is continuously withdrawn from the brew kettle and passed through a copper heat exchange coil in an external heat exchanger. Hot combustion gases are discharged at high velocity into direct contact with the heat exchange coil to thereby heat the wort flowing through the coil to a temperature in the range of 220° to 240° F. The heated wort is then returned to the brew kettle and discharged at a location beneath the level of the wort in the kettle. The direct firing of the wort in the copper heat exchange coil provides improved flavor characteristics for the beer.