Patent US5735681A successfully refreshed from Google Patents.
US5735681A
Expired / Lapsed
US
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Ultralean low swirl burner
Assignee: University of California
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Filing: 1993-03-19
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Granted: 1998-04-07
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Expires: 2013-03-19
Abstract
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.
Inventors
- 👤 Robert K. Cheng
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 11:17
CPC Classifications
F; F23; F23C; F23C7/00; F23C7/002; F23D; F23D14/00; F23D14/02; F23D14/46; F23D14/62; F23D23/00; F23R; F23R3/00; F23R3/02; F23R3/04; F23R3/10; F23R3/12; F23R3/14; F23D2900/00; F23D2900/14; F23D2900/14021
Claims Analysis
Total Claims: 49
Claim 1
Independent Claim
105 words
A method of burning fuel efficiently and with minimal emission of pollutants comprising, a) injecting fuel continuously into a mixing zone; b) injecting an oxygen-containing gas continuously into said mixing zone to produce a fuel and gas mixture which flows in a stream toward an exit; c) swirling the resulting fuel and gas mixture downstream of said mixing zone using swirling means with sufficient force to impart rotational motion to the periphery of, and in a plane normal to the flow of, said fuel and gas stream, but without inducing recirculation therein; d) burning said swirling mixture downstream of the mixing zone and swirling means.
Claim 2
Independent Claim
105 words
A method of burning fuel efficiently and with minimal emission of pollutants comprising, a) injecting fuel continuously into a mixing zone; b) injecting an oxygen-containing gas continuously into said mixing zone to produce a fuel and gas mixture which flows in a stream toward an exit; c) swirling the resulting fuel and gas mixture downstream of said mixing zone using swirling means with sufficient force to impart rotational motion to the periphery of, and in a plane normal to the flow of, said fuel and gas stream, but without inducing recirculation therein; d) burning said swirling mixture downstream of the mixing zone and swirling means.
Claim 3
Dependent Claim
27 words
The method of claim 1 wherein the fuel is selected or mixed from the group comprised of methane, natural gas, hydrogen gas, ethylene, propane, or gaseous hydrocarbons.
Claim 4
Dependent Claim
11 words
The method of claim 1 wherein the mixing zone is cylindrical.
Claim 5
Dependent Claim
11 words
The method of claim 1 wherein the oxygen-containing gas is air.
Claim 6
Dependent Claim
24 words
The method of claim 1 wherein said fuel and gas mixture has an equivalence ratio between about the lean flammability limit and about 2.0.
Claim 7
Dependent Claim
24 words
The method of claim 5 wherein said fuel and gas mixture has an equivalence ratio between about the lean flammability limit and about 1.0.
Claim 8
Dependent Claim
21 words
The method of claim 1 wherein the swirling is characterized by a swirl number, S, between about 0.01 and about 3.0
Claim 9
Dependent Claim
21 words
The method of claim 7 wherein the swirling is characterized by a swirl number, S, between about 0.03 and about 2.0.
Claim 10
Dependent Claim
21 words
The method of claim 8 wherein the swirling is characterized by a swirl number, S, between about 0.03 and about 1.0.
Claim 11
Dependent Claim
24 words
The method of claim 1 wherein the swirling is provided by injecting air tangential to the circumference of the mixing zone through air injectors.
Claim 12
Dependent Claim
29 words
The method of claim 1 wherein the swirling is provided by locating vanes in an annulus region immediately inside the perimeter of said fuel and gas mixture flow stream.
Claim 13
Dependent Claim
10 words
The method of claim 11 wherein the vanes are fixed.
Claim 14
Dependent Claim
10 words
The method of claim 11 wherein the vanes are movable.
Claim 15
Dependent Claim
13 words
The method of claim 11 wherein the pitch of the vanes is fixed.
Claim 16
Dependent Claim
13 words
The method of claim 11 wherein the pitch of the vanes is variable.
Claim 17
Dependent Claim
10 words
The method of claim 11 wherein the vanes are motorized.
Claim 18
Dependent Claim
24 words
The method of claim 1 wherein said swirling fuel and gas stream is expanded into an enclosed expansion zone containing the flame combustion zone.
Claim 19
Dependent Claim
26 words
The method of claim 17 wherein the heat generated by burning said fuel and gas mixture is conveyed through a heat exchanger to a heating apparatus.
Claim 20
Dependent Claim
12 words
The method of claim 1 wherein the fuel injection means generates turbulence.
Claim 21
Dependent Claim
24 words
The method of claim 19 wherein the fuel is injected in an upstream direction from a plurality of holes in a serpentine-shaped fuel line.
Claim 22
Dependent Claim
32 words
The method of claim 20 wherein the fuel is injected in an upstream direction from a plurality of holes in two orthogonally oriented serpentine shaped fuel lines which together form a grid.
Claim 23
Dependent Claim
26 words
The method of claim 21 wherein the fuel is injected in an upstream direction from a plurality of pairs of orthogonally oriented serpentine shaped fuel lines.
Claim 24
Dependent Claim
16 words
The method of claim 19 wherein the oxygen-containing gas mixture is introduced upstream of the fuel.
Claim 25
Dependent Claim
82 words
A burner comprising, a) a fuel source; b) a fuel line connected to said fuel source; c) an oxygen-containing gas source; d) an oxygen-containing gas line connected to said oxygen-containing gas source; e) a mixing zone in which said fuel line and said gas line open; f) a swirl generator for generating weak swirl in said fuel and gas mixture, located downstream of the mixing zone; and g) a combustion flame zone located in an expansion zone downstream of the mixing zone.
Claim 26
Dependent Claim
82 words
A burner comprising, a) a fuel source; b) a fuel line connected to said fuel source; c) an oxygen-containing gas source; d) an oxygen-containing gas line connected to said oxygen-containing gas source; e) a mixing zone in which said fuel line and said gas line open; f) a swirl generator for generating weak swirl in said fuel and gas mixture, located downstream of the mixing zone; and g) a combustion flame zone located in an expansion zone downstream of the mixing zone.
Claim 27
Dependent Claim
21 words
The burner of claim 24 wherein the position and shape of the fuel line located within the gas line generates turbulence.
Claim 28
Dependent Claim
20 words
The fuel line of claim 25 shaped in sepentine with a plurality of fuel holes pointing in the upstream direction.
Claim 29
Dependent Claim
27 words
The fuel line of claim 26 formed into a pair of orthogonally oriented grid-shaped fuel lines with a plurality of fuel holes pointing in the upstream direction.
Claim 30
Dependent Claim
17 words
The burner of claim 24 wherein the oxygen-containing gas line is positioned upstream of the fuel line.
Claim 31
Dependent Claim
11 words
The burner of claim 24 wherein the mixing zone is cylindrical.
Claim 32
Dependent Claim
23 words
The burner of claim 24 wherein the swirling means imparts swirl characterized by a swirl number S, between about 0.01 and about 3.0.
Claim 33
Dependent Claim
29 words
The burner of claim 24 wherein the swirling means comprise air jets positioned tangentially to a circumference of the mixing zone at the downstream end of the mixing zone.
Claim 34
Dependent Claim
31 words
The burner of claim 24 wherein the swirling means comprise vanes located in an annulus region immediately inside a perimeter of said fuel and gas mixture, downstream from the mixing zone.
Claim 35
Dependent Claim
11 words
The swirling means of claim 32 wherein the vanes are fixed.
Claim 36
Dependent Claim
11 words
The swirling means of claim 32 wherein the vanes are movable.
Claim 37
Dependent Claim
14 words
The swirling means of claim 32 wherein the pitch of the vanes is fixed.
Claim 38
Dependent Claim
14 words
The swirling means of claim 32 wherein the pitch of the vanes is variable.
Claim 39
Dependent Claim
11 words
The burner of claim 24 wherein the expansion zone is enclosed.
Claim 40
Dependent Claim
26 words
The burner of claim 24 wherein the expansion zone forms an angle with the burner body such that expansion of said fuel and gas occurs unhindered.
Claim 41
Dependent Claim
15 words
The burner of claim 37 wherein the expansion zone is attached to heat exchanger housing.
Claim 42
Dependent Claim
22 words
The burner of claim 39 wherein the heat generated from said combustion is transferred through a heat exchanger to a water heater.
Claim 43
Dependent Claim
21 words
The burner of claim 39 wherein the heat generated from said combustion is transferred through a heat exchanger to a furnace.
Claim 44
Dependent Claim
14 words
The burner of claim 37 wherein mechanical energy is derived from the combustion products.
Claim 45
Dependent Claim
15 words
The burner of claim 42 wherein the mechanical energy is used to drive a turbine.
Claim 46
Dependent Claim
18 words
The burner of claim 37 wherein the combustion zone is under pressure between atmospheric pressure and 15 atmospheres.
Claim 47
Dependent Claim
18 words
The burner of claim 44 wherein the combustion zone is under pressure between atmospheric pressure and 10 atmospheres.
Claim 48
Dependent Claim
18 words
The burner of claim 45 wherein the combustion zone is under pressure between atmospheric pressure and 5 atmospheres.
Claim 49
Dependent Claim
31 words
The burner of claim 24 wherein a safety device is attached to the mixing zone to prevent accidental ignition of the premixed fuel or of the fuel in the fuel line.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-04-06 | 2001-10-06 | 2002-04-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-04-06 | 2005-10-06 | 2006-04-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-04-06 | 2009-10-06 | 2010-04-07 | $7700.00 | Window Closed / Lapsed |