Riley Stoker Corporation

Daniel C Itse

Craig A Penterson

A new and improved burner for pulverized coal comprises a tubular nozzle for containing a primary, flowing stream of coal/air mixture having an outlet for discharging the stream into a combustion zone of a furnace. A venturi is mounted in the nozzle having a convergent section, a throat, and divergent flow section adjacent the outlet. The convergent section concentrates the pulverized coal toward a central portion of the flowing stream in the throat of the venturi. A conical flow spreader is mounted in the divergent section and includes a hollow, open outer end. The spreader cone and the divergent flow section of the venturi form an annular, expanding, flow pattern of coal/air mixture for discharge into the combustion zone and a plurality of swirl vanes between the spreader cone and wall of the divergent section impart swirl to stabilize an annular discharge of the primary coal/air stream from the nozzle to form a high temperature reducing zone wherein a portion of the hot combustion products are recirculated back toward the open end of the flow spreader so that volatiles in the coal are driven off rapidly and burned in a fuel-rich, reducing atmosphere, minimizing the formation of NO.sub.x . A stream of secondary air is introduced by vanes to swirl around the primary coal/air stream discharged from the outlet forming a long stable flame pattern providing a relatively slow combustion rate.

Venturi burner nozzle for pulverized coal

A method of burning pulverized coal and other fuels comprises the steps of containing a primary flowing stream of coal/air mixture received adjacent an inlet end of a tubular nozzle for discharge at an outlet end into a combustion zone of a furnace for burning. The stream is accelerated in a convergent venturi section upstream of the outlet to distribute and concentrate the coal particles toward a central portion of the venturi in a minimum area throat, followed by decelerating the flow downstream of the venturi throat in a convergent flow section while forming a shallow, annular, conically shaped flow pattern around a hollow spreader cone mounted in the convergent section. The annular flow is caused to swirl around the axis of the cone by vanes outwardly thereof within the convergent flow section of the venturi, thus forming a stable, annularly-shaped, swirling flow pattern for discharge into the combustion zone, wherein the coal is burned in an elongated flame pattern extending along the stabilized conical flow pattern. A zone of high temperature and reducing atmosphere is formed adjacent the hollow outer end of the cone due to recirculation of combustion products into the rich fuel/air mixture wherein the volatiles in the coal are driven off early in the combustion process and are rapidly burned in a continuing process reducing the formation of oxides of nitrogen.

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Worcester, MA, United States of America

Daniel C Itse