Steam and Organic Ranking cycles are the most common methods of generating electricity from waste heat. They are a good choice when the temperature of the waste heat is above 140 DegC. The main draw-backs are that the temperature after the power generation module is quite low making them unsuitable for district heating, ovens or steam generation and that they suffer power loss in hotter ambients.
Hot Air Turbines are an alternative to steam and ORCs that still generate electricity, but discharge the heat at 450 DegC making them an ideal choice from any heat source with a temperature over 760 Deg C. If heat is not needed and more power is required, then an ORC can be added to almost double the amount of power generation.
In a nutshell, a hot air turbine takes in air and compresses it to 4 bar. This air is heated using energy from combustion fluegases. This hot pressurised air passes through the turbocompressor and power turbine to produce electricity. The electrical output from the turbine generator is converted into high quality grid power in a dedicated inverter.