MILD Combustion
Moderate or Intense Low Oxygen Dilution (MILD) Combustion Technology.
MILD Combustion of Brown Coal in Furnace
Combustion technologies are expected to continue providing society with energy needs for a variety of sectors in the foreseeable future. In particular, combustion will still be needed for transport, industrial processes and high temperature applications.
Hence, there is a need for the evolution and advancement of the combustion technology to reduce green houses and pollutant emissions.
MILD combustion technology is one such promising technology that can increase thermal efficiency leading to a reduction in greenhouse gas emissions while minimising the emission of other pollutants.
About the technology
Moderate or Intense Low oxygen Dilution (MILD) combustion technology uses recirculated heat and exhaust gases to achieve stable volumetric combustion at moderate temperatures. These operating mode can reduce the amount of pollutants produced, particularly nitrogen oxides, and increase thermal efficiency.
MILD combustion can be readily adapted to different fuel types – a major advantage for incorporating MILD combustion into industrial systems. The research team of Associate Professor Paul Medwell, Professor Bassam Dally, Dr Alfonso Chinnici and Dr Michael Evans have investigated the combustion of gaseous, liquid and solid fuels under MILD conditions. Experimental and computational research have helped deepen our understanding, increase the applicability and the adaptation of MILD combustion. They applied advanced laser based techniques and CFD models to understand the detailed structure of flames stabilised on a Jet in Hot Coflow, JHC, burner. They have also investigated the impact of the mixing pattern, fuel type and dilution on combustion stability and emission from a MILD Combustion furnace.
Applications
MILD combustion could be readily used in furnaces within the ceramic, glass and chemical industries as well as increasing the industrial use of non-conventional fuel types.
Computed Velocity Contours inside a MILD Combustion Furnace
MILD combustion can be used with non-conventional fuels like biomass and bio-derived fuels (e.g. biogas and bioliquids) which are traditionally more difficult to combust – this could reduce our dependence on fossil fuels.
Brown coal is another non-conventional fuel type that could be used with MILD combustion. While it is not often used because of its high water content and high pollutant rate compared to other fuel types, using brown coal could be more feasible if it's burnt under MILD conditions.
What’s happening now?
The team is continuing to work towards a better understanding of fuel performance under MILD conditions. Their current research focuses on how MILD flames are sustained under pressure and liquid fuels, including biofuels.