On the (MILD) combustion of gaseous, liquid, and solid fuels in high temperature preheated air

Abstract

This paper examines the fundamental and industrial application aspects of combustion of natural gas, heavy and light fuel oils, and coal in highly preheated air. The experiments have been carried out in an experimental furnace at 0.58 MW thermal input based on fuel, and the combustion air has been preheated to 1300 °C. The fuel injectors are positioned outside of the combustion air stream. Detailed in-furnace measurements of temperature, chemistry (O 2, CO, NO x , and particulates), and heat transfer have been performed. Combustion of natural gas and light oil takes place without a visible presence of flame. Although the furnace was operated with an overall excess air of 10%, the combustion process occurs in strongly sub-stoichiometric conditions due to entrainment of large amounts of recirculated flue gases into the fuel jets before ignition. The experiments demonstrated an effective technology for efficient and environmentally friendly combustion of a wide range of fuels. The technology discussed in the main text offers the potential of high furnace efficiencies, uniform heat flux distribution, and dramatic reductions in CO 2, CO, and NO emissions. Therefore, this technology should be considered for future design of industrial furnaces.