Most industrial plants have a potential to save money through heat recovery.
Automotive plants, in particular, use huge volumes of heated liquids daily.
Unfortunately, once these liquids are used, they are usually discharged down a
drain or sewer.
Much of the heated liquid is hot water used in washing and rinsing parts - often heated with boiler steam. By combining waste heat and heat consumers, significant energy and water can be saved.
Reduced maintenance may also occur since equipment normally cooled with open-circuit cooling tower water would normally need periodic shutdown due to fouling of the heat exchange surface.
The combination of heat exchange and heat pump concepts may also eliminate the need for a large cooling tower. Two major benefits may be possible: the closed, inhibited water loop may eliminate open-loop contamination problems that commonly affect a plant's quench tanks and annealing furnaces, and waste heat formerly dissipated through the tower is conserved and used in another process.
Elimination of the cooling tower is an important benefit of the heat pumps, since water treatment problems and fan horsepower costs are eliminated. Adding that to elimination of the makeup water requirements associated with cooling towers results in significant savings.
In addition, phosphatizing solutions are often extremely temperature-sensitive. If a large temperature differential exists between the solution and the heating medium, the solution will foul, or "plate-out," on the heat transfer surfaces of the heat exchanger. By using hot water instead of steam to heat these solutions, this temperature differential is decreased, and fouling is reduced.
