Robert H Cheng

US Patent:

57356815, Apr 7, 1998

Filed:

Mar 19, 1993

Appl. No.:

8/033878

Inventors:

Robert K. Cheng - Kensington CA

Assignee:

The Regents, University of California - Oakland CA

International Classification:

F23M 304

US Classification:

431 10

Abstract:

A novel burner and burner method has been invented which burns an ultra lean premixed fuel-air mixture with a stable flame. The inventive burning method results in efficient burning and much lower emissions of pollutants such as oxides of nitrogen than previous burners and burning methods. The inventive method imparts weak swirl (swirl numbers of between about 0. 01 to 3. 0) on a fuel-air flow stream. The swirl, too small to cause recirculation, causes an annulus region immediately inside the perimeter of the fuel-air flow to rotate in a plane normal to the axial flow. The rotation in turn causes the diameter of the fuel-air flow to increase with concomitant decrease in axial flow velocity. The flame stabilizes where the fuel-air mixture velocity equals the rate of burning resulting in a stable, turbulent flame.

US Patent:

55162800, May 14, 1996

Filed:

Nov 3, 1993

Appl. No.:

8/147380

Inventors:

Larry W. Kostiuk - Edmonton, CA
Robert K. Cheng - Kensington CA

Assignee:

The Regents, University of California - Berkeley CA

International Classification:

F23D 1446

US Classification:

431350

Abstract:

An apparatus for enabling a burner to stably burn a lean fuel/air mixture. The burner directs the lean fuel/air mixture in a stream. The apparatus comprises an annular flame stabilizer; and a device for mounting the flame stabilizer in the fuel/air mixture stream. The burner may include a body having an internal bore, in which case, the annular flame stabilizer is shaped to conform to the cross-sectional shape of the bore, is spaced from the bore by a distance greater than about 0. 5 mm, and the mounting device mounts the flame stabilizer in the bore. An apparatus for burning a gaseous fuel with low NOx emissions comprises a device for premixing air with the fuel to provide a lean fuel/air mixture; a nozzle having an internal bore through which the lean fuel/air mixture passes in a stream; and a flame stabilizer mounted in the stream of the lean fuel/air mixture. The flame stabilizer may be mounted in the internal bore, in which case, it is shaped and is spaced from the bore as just described. In a method of burning a lean fuel/air mixture, a lean fuel/air mixture is provided, and is directed in a stream; an annular eddy is created in the stream of the lean fuel/air mixture; and the lean fuel/air mixture is ignited at the eddy.

US Patent:

58791485, Mar 9, 1999

Filed:

Apr 16, 1997

Appl. No.:

8/837377

Inventors:

Robert K. Cheng - Kensington CA
Derek T. Yegian - Berkeley CA

Assignee:

The Regents of the University of California - Oakland CA

International Classification:

F23D 1462

US Classification:

431 9

Abstract:

Disclosed is a mechanical swirler for generating diverging flow in lean premixed fuel burners. The swirler of the present invention includes a central passage with an entrance for accepting a feed gas, a flow balancing insert that introduces additional pressure drop beyond that occurring in the central passage in the absence of the flow balancing insert, and an exit aligned to direct the feed gas into a combustor. The swirler also has an annular passage about the central passage and including one or more vanes oriented to impart angular momentum to feed gas exiting the annular passage. The diverging flow generated by the swirler stabilizes lean combustion thus allowing for lower production of pollutants, particularly oxides of nitrogen.

US Patent:

20140230701, Aug 21, 2014

Filed:

Apr 6, 2012

Appl. No.:

14/111161

Inventors:

Robert K. Cheng - Kensington CA, US
David Littlejohn - Oakland CA, US

Assignee:

THE REGENTS OF THE UNIVERSITY OF CALIFORNIA - Oakland CA

International Classification:

F23D 14/08
F23B 30/00

US Classification:

110207, 239316, 431354

Abstract:

A new design for a low swirl burner is disclosed in which natural draft rather than a motorized pump is used to move a fuel-air mixture through the burner. This new design enables the burn off of gas at refineries in an environment where electric motors cannot be used because of the potential for sparks, which could trigger explosions. Additional modifications to the burner, including the introduction of flue gas to the burner allows for the reduction of NOx gas to meet current emission control targets, without the need for further post combustion emission control systems.