There are numerous industrial processes that require combustion systems as an indispensable part of the productive process. In many cases, exhaust gases are evacuated with high temperature into the atmosphere, dissipating thermal energy susceptible of being converted into an energy vector of higher added value, such as electricity though HRU technology.

In some cases it is necessary to reduce the temperature of these exhaust gases for subsequent treatment, through dilution processes, which represent an oversizing of the ducts and tail extraction systems, as it is necessary to convey a higher flow than initially.

Combustion gases from fusion furnaces made of different materials (steel, glass, aluminium) and thermal treatments, exhaust gases from boilers, gas turbines and internal combustion engines constitute examples of processes in which, on most occasions, the thermal energy is lost without being recovered.