Patent ID: 7832341
Filing Date: 2010-11-16
Classification: F23C,F23G

Abstract:
1. In a nozzle assembly consisting of a series of circular, cylindrical tubes assembled to provide concentric annular channels for the passage of fluids, a method of injecting, accelerating and propelling solid biomass fuel pellets, which generally have a diameter, or other maximum dimension, shape or surface characteristic that prevents passage through the nozzle, of at least 0.25 inches or other, finer, solid, biomass fuel particulate matter, together with the additional air required for complete combustion of the injected fuel, into the flame zone of a combustion chamber burning fossil fuel in a manner that provides controlled, merged combustion of the fuels, comprising the following steps: a) forming an annular nozzle-exit stream of carrier-air-conveyed solid biomass fuel consisting of pellets and/or other fine particulates; b) forming two annular, nozzle-exit streams of adjoining air, flowing at nozzle exit velocities higher than that of the biomass fuel bearing stream, but less than sonic velocity (upstream delivery pressures less than 15 psig.), adjacent to the biomass conveying stream, one on each side of it, flowing in substantially the same direction but directed so as to immediately converge with it at a small relative angle; c) forming a cylindrical stream of air that exits along the central axis of the annular nozzle at a lower velocity than the adjoining air streams, which provides a portion of the biomass combustion air, assists in the forming and controlling of the shape and length of the biomass fuel flame zone and furnishes the air for entrainment by the flow of higher velocity adjoining air that would otherwise be re-circulated back along the nozzle axis from the flame zone in the form of undesirable eddy current recirculation of combustion gases and particulates; d) forming an annular nozzle exit stream of additional combustion air, located radially outward from the outer of the two adjoining air streams, and flowing in substantially the same direction as the other streams, but directed so as to immediately converge with them in sufficient quantity to complete the biomass fuel combustion, and to assist in the forming and controlling of the shape and length of the biomass fuel flame zone; e) adjustably controlling the widths of the exit streams, the quantities flowing, the acceleration and propulsion of the solid biomass fuel and the shape and length of its flame zone to suit the physical properties of the biomass fuel.