What is Waste Heat Recovery?

”Waste heat recovery” is the process of “heat integration”, that is, reusing heat energy that would otherwise be disposed of or simply released into the atmosphere. By recovering waste heat, plants can reduce energy costs and CO2 emissions, while simultaneously increasing energy efficiency.

Typical Examples of Waste Heat Recovery

Several common consumer items recover waste heat. For example, consider turbocharged cars, which are provided by multiple car manufacturers.

In regular, non-turbocharged cars, the internal combustion gasoline engine expels hot gas through the car’s exhaust after its fuel is burned. That gas contains both heat and kinetic energy—a portion of which can be recovered. Turbocharged engines divert the hot gas to a turbine, which is used to spin an air compressor. The compressed air is routed to the engine’s combustion chamber with the vaporized gasoline, resulting in a more efficient ignition and greater power made with lower fuel consumption.

The energy benefits of industrial waste heat recovery can be similar, and some examples are

Economizer

Stack economizers, commonly used to heat water, are among the simplest type of waste heat recovery. Plant workers may be familiar with these common devices that recover waste heat. Boiler stack economizers use heat energy from the gas expelled in the heating process into the stack to heat boiler feed water and reduce the amount of energy required to make steam. According to the US Department of Energy, installation of a boiler feed water economizer can raise the thermal efficiency of a boiler and reduce fuel consumption by 5 – 10%.