Fluid sprinkling – spraying – and diffusing – Combining of separately supplied fluids – At or beyond outlet
Reexamination Certificate
2001-04-20
2003-09-23
Mar, Michael (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Combining of separately supplied fluids
At or beyond outlet
C239S492000, C239S552000, C239S559000, C239S560000, C239S561000
Reexamination Certificate
active
06622944
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to the combustion of fuel oil, and more particularly to the atomization of fuel oil in a combustion furnace. In particular, the present invention provides apparatus and methods for discharging atomized fuel which provide low levels of air pollution emissions, such as oxides of nitrogen (NOx), carbon monoxide (CO), particulate matter (PM) and opacity while operating at low excess oxygen levels for improved efficiency.
For environmental and economical reasons, there is an ongoing need to improve the efficiency of fuel oil atomizers which supply fuel oil to a furnace. In particular, it is well known that “heavy” fuel oil (e.g., heavy number 6 oil or “bunker” oil), which contains organically bound nitrogen and sulfur compounds and has a high asphaltene content, is difficult to combust while producing low air polluting emissions. Particulate matter (PM) in the form of ash and unburned carbon, carbon monoxide (CO) or partially oxidized carbon, oxides of nitrogen (NOx), and opacity are in particular troublesome air emissions for many furnaces burning heavy oil. It is known that the formation of NO
x
can be reduced by providing fuel-rich and fuel-lean zones in the atomizing spray pattern.
It would be advantageous to provide apparatus and methods for atomizing fuel oil which reduce NOx emissions, while also improving or maintaining CO, PM and opacity generation. It would be particularly advantageous to provide for the discharge of atomized fuel oil into a combustion chamber with effective fuel spray droplet breakup and both circumferential and radial fuel to air ratio staging in order to lower peak flame temperature and reduce NOx emissions. It would be even further advantageous to provide for the atomized fuel oil droplets discharged into the combustion chamber to be of such a sufficiently small diameter to enable rapid fuel evaporation and complete combustion for low CO emission and thorough carbon burnout with low excess oxygen levels. The methods and apparatus of the present invention provide the above-mentioned and other advantages
SUMMARY OF THE INVENTION
The present invention relates to a fuel oil atomizer and methods for discharging atomized fuel oil, e.g., into a combustion chamber of a furnace. In particular, the present invention relates to a two phase fuel oil atomizer which utilizes a secondary media such as high pressure steam or air to assist in the atomization of fuel oil, such as heavy fuel oil, while reducing NOx and other polluting emissions.
In an exemplary embodiment of the invention, a fuel oil atomizer comprises a mixing plate and a sprayer plate. The mixing plate may have a plurality of distributor openings for receiving a first material (e.g., fuel) and a plurality of central openings for receiving a second material (e.g., an atomizing media). It should be appreciated that the distributor openings can be adapted to receive either fuel or the atomizing media, with the central openings adapted to receive the other of either fuel or the atomizing media. The atomizing media may be high pressure steam or air, or any other suitable atomizing media.
The sprayer plate is adapted to engage the mixing plate in order to force the first material to mix with the second material. The sprayer plate may have an enclosed mixing chamber formed by the mixing plate and a cavity of the sprayer plate for mixing the first material traveling through the mixing plate with the second material traveling through the mixing plate. A plurality of sprayer plate openings may extend through a semi-spherical outer wall of the sprayer plate to enable atomized fuel to be expelled from the mixing chamber. The plurality of sprayer plate openings may be arranged on at least one annulus of the outer wall of the sprayer plate for expelling the atomized fuel at an at least one spray angle.
There may be at least two sets of sprayer plate openings provided. Each set of sprayer plate openings may have respective dimensions and may be arranged on respective annuli of the outer wall of the sprayer plate for expelling atomized fuel at respective spray angles. The respective dimensions of each set of openings may be successively smaller dimensions. The respective annuli may be successively smaller annuli. The respective spray angles may be successively smaller spray angles.
In an alternate embodiment, the plurality of sprayer plate openings may comprise four sets of openings. A first set of openings may have a first dimension and may be arranged on an first annulus of the outer wall of the sprayer plate for expelling atomized fuel at a first spray angle. A second set of openings may have a second dimension and may be arranged on a second annulus of the outer wall of the sprayer plate for expelling atomized fuel at a second spray angle. A third set of openings may have a third dimension and may be arranged on a third annulus of the outer wall of the sprayer plate for expelling atomized fuel at a third spray angle. A fourth set of openings may have a fourth dimension and may be arranged on a fourth annulus of the outer wall of the sprayer plate for expelling atomized fuel at a fourth spray angle.
The first dimension, second dimension, third dimension and fourth dimension may be successively smaller dimensions. The first annulus, second annulus, third annulus, and fourth annulus may be arranged on successively smaller annuli of the outer wall. The first spray angle, second spray angle, third spray angle, and fourth spray angle may be successively smaller spray angles.
In a further embodiment, the first set of openings may comprise two series of equally spaced openings, one series of openings arranged at a top portion of the first annulus and the other series of openings arranged at a bottom portion of the first annulus. The second set of openings may comprise two series of equally spaced openings, one series of openings arranged at a top portion of the second annulus and the other series of openings arranged at a bottom portion of the second annulus. The third set of openings may comprise two series of equally spaced openings, one series of openings arranged at a top portion of the third annulus and the other series of openings arranged at a bottom portion of the third annulus. The fourth set of openings may comprise two series of equally spaced openings, one series of openings arranged at a top portion of the fourth annulus and the other series of openings arranged at a bottom portion of the fourth annulus.
The first spray angle of the first set of openings may be in the range of approximately 80 to 90 degrees. The second spray angle of the second set of openings may be approximately 60 degrees. The third spray angle of the third set of openings may be approximately 40 degrees. The fourth spray angle of the fourth set of openings may be approximately 20 degrees.
Each series of openings of the first set of openings may have a first total angular separation. Each series of openings of the second set of openings may have a second total angular separation. Each series of openings of the third set of openings may have a third total angular separation. The first total angular separation may be approximately 105 degrees. The second total angular separation may be approximately 26 degrees. The third total angular separation may be approximately 36 degrees. Each series of openings of the fourth set of openings may comprise a single opening.
The first set of openings may comprise approximately 66% of total hole flow area of the sprayer plate. The second set of openings may comprise approximately 20% of the total hole flow area of the sprayer plate. The third set of openings may comprise approximately 10% of the total hole flow area of the sprayer plate. The fourth set of openings may comprise approximately 4% of the total hole flow area of the sprayer plate.
The mixing chamber may preferably have a chamber length to chamber diameter ratio in the range of about 0.75:1 to 1.25:1.
The mixing plate may further comprise a plurality of metering slots arrange
Dale John N.
Hurley John F.
Lindemann Scott H.
Combustion Components Associates, Inc.
Lipsitz Barry R.
Mar Michael
McAllister Douglas M.
Nguyen Dinh Q
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