Abstract: The present invention provides a new heat exchanger element comprising a premix burner with an outward curved or ridged burner surface. The heat exchanger element further comprises a combustion chamber. The combustion chamber is bound on one side by the burner and is further made up of water cooled metal walls which, starting from the burner and in downstream direction, first widen and thereafter narrow down to the width of a customary heat exchanger element. This creates enough space for a proper combustion, avoiding dead angles and recirculation or too early ending of the combustion reaction, thereby reaching low emissions of NOx and CO.

Abstract: An improved two-stage combustion chamber for burning waste hydrocarbons such as crank case oil, spent motor oil, transmission fluid, lubrication dopes, and heavy bodied gear lubes. The combustion chamber is formed from a plurality of spaced apart, stacked annular rings that form a flame containment housing having superheated surfaces. The flame containment housing contains the flame of an atomizing oil burner suitable for burning the variable viscosity waste hydrocarbons. The annular rings include outer walls and inwardly extending flanges that intercept unburned fuel droplets and combustion byproducts, vaporizing the droplets and/or stimulating secondary combustion. The annular rings are removable and replaceable, and are supported in spaced-apart relation by spacers on a plurality of support rods.

Abstract: The invention relates to a method and apparatus for combusting a dirty and/or difficult to burn fuel in a fluidized bed combustor. The fluidized bed and freeboard zone of the combustor are cooled by a non-intrusive counterflow cooling system which controls combustion temperatures and produces a clean, hot gas. The combustor is operated with many combinations of features including: low, in bed fuel injection; use of finely divided fuel; slug flow fluidization; and injection of lime or limestone to effect desulferization or raise the ash melting temperature, if desired.