Waste heat recovery boilers are a special type of boiler that generates steam by removing the heat from a process that would have otherwise been wasted. therefore waste heat boilers are able to provide significant reductions in fuel and energy expenses, as well as reduce greenhouse gas emissions.
Waste heat recovery boilers may be horizontal or vertical shell boilers or water tube boilers. They would be designed to suit individual applications ranging through gases from furnaces, incinerators, gas turbines and diesel exhausts.
The prime requirement is that the waste gases must contain sufficient usable heat to produce steam or hot water at the condition required. Waste heat boilers may be designed for either radiant or convective heat sources.
In some cases, problems may arise due to the source of waste heat, and consideration must be taken of this, with examples being plastic content in waste being burned in incinerators, carry-over from some type of furnaces causing strongly bonded deposits and carbon from heavy oil fired engines.Some may be deal with by maintaining gas-exit temperatures at a predetermined level to prevent dew point being reached and others by soot blowing.
There is increasingly greater interest in power generation plants, including co-generation (combined heat and power) plants which incorporate waste heat recovery technologies as well trigeneration plants.