Just like the water that cools a car engine is circulated thru a radiator to remove heat the furnaces also uses a recirculating water jacket to control temperature. Cooled water is circulated throughout the furnace walls to keep the furnace from over heating after which the hot water is sent to large tanks sitting on steel structures over recovery pits. The water is cooled as it is showered from the tank into the recovery pit where it is then sent back to be recirculated into the furnace cooling jacket. The shower resembles a torrential rain but many times more dense.