Particles from Combustion with Infrared Obscuration Potential.

Four particle types formed during combustion have been studied: Soot A smoke generator has been designed and built which is capable of producing soot particles about 1.5microm in size - approximately 1000 times larger than those formed in conventional flames. Mass extinction measurements have been taken, typical a values being 1. 3 m2 /gram in the infrared wavelength region 2. 5 to 12microm. Carbon cenospheres Using this smoke generator, carbon cenospheres have been produced from the specialised fuel Orimulson. The size requirements for good obscuration in the infrared spectral window can be achieved with such fuels. Ash cenospheres The formation of spherical ash particles from the combustion of coal has been investigated. The type of ash sphere produced has been linked to the behaviour of the coal during devolatilisation - swelling coals tend to form cenospheres, non swelling coals tend to form plerospheres. It is concluded that the thermal degradation of clays is responsible for inflating the spheres. Buckminstefullerene The recently discovered third allotrope of carbon, buckminsterfullerene, has been synthesized from a turbulent diffusion flame at atmospheric pressure for the first time. The implications for commercial production from such a route appear promising. Buckminsterfullerene has also been detected within the soot structure. This observation may provide an insight into soot formation generally