Variable exit high velocity burner

Details Variable exit high velocity burner Variable exit high velocity burner

2000-06-01

2001-04-24

Price, Carl D. (Department: 3743)

Combustion

Process of combustion or burner operation

Flame shaping, or distributing components in combustion zone

C431S012000, C431S158000, C431S159000, C431S189000, C432S159000, C239S265190, C060S242000, C060S279000

Reexamination Certificate

active

06220852

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a high velocity burner, and more particularly, a variable exit high velocity burner. The variable exit provides a mechanism for controlling the actual flame exit velocity over a wide range of burner operation variables.
2. Description of Related Art
High velocity burners are a heating source preferred for most industrial furnaces and kilns. In these types of burners, such as those described in U.S. Pat. Nos. 5,570,679 and 5,263,849, fuel and combustion air are mixed with and ignited in a high-heat-resistant combustion chamber. The resultant hot combustion gases flow at high velocity through a nozzle-shaped outlet into the heating chamber, which is formed either by the furnace chamber itself or by some other device. The outlet of the combustion chamber can be constricted in nozzle-like fashion or formed by a nozzle ring. The mechanical energy of the gas stream or jet emerging from the combustion chamber, which derives predominantly from the fuel and nozzle shape, serves to mix and circulate the gases in the heating chamber, which in turn promotes the temperature equalization in a desired manner. Exit flame velocity for this type of burner is in excess of 25,000 ft/min when then burner is at high fire. The high velocity promotes good flue gas circulation in the furnace or kiln resulting in good temperature uniformity.
In high velocity burners, however, the burners cannot always be operated at their maximum firing rate. The flame exit velocity decreases as the burner firing rate is decreased. Actual flame exit velocity is a function of flow rate, pressure drop, combustor exit area and flame temperature. Accordingly, it would be advantageous to control the flame exit velocity in a high velocity burner to account for these variables.
There are several types of known flow control devices for conventional burners. For example, U.S. Pat. No. 2,565,039 shows a burner having a nozzle member as a part of a mixing valve. A needle having a tapered end cooperates with an aperture to increase or decrease the area between the outer size of the tapered end of the needle. The area of the opening of the burner is adjusted by rotating a head on the threaded stud to obtain the desired opening for best performance.
U.S. Pat. No. 3,663,153 shows an LTG burner in which a central rod is provided with a cone-shaped downstream end to vary the width of the primary air supply opening. A similar arrangement is shown in the acid gas burner of U.S. Pat. No. 3,782,884.
Other movable plug arrangements are seen in U.S. Pat. No. 4,902,222 in which a conical valve body cooperates with a valve seat. The valve rod is moved in a predetermined manner to decrease air flowing through the bypass conduit and allowing more air to flow into the mixing cup and the combustion chamber. U.S. Pat. No. 5,292,244 also shows that the use of Venturi mixer formed by a movable hollow body to vary the fuel/air mixture introduced into a combustion chamber is well known. However, these devices are used primarily to control the flow of combustible material in or around the combustion chamber, and not at the flame exit area of the burner.
What is desired is an adjustable velocity exit area for a high velocity burner to adjust the flame exit velocity or to maintain a constant velocity over a range of modulated firing rates. Such an adjustment would allow the flame exit velocity to be optimized over a wide range of operating conditions once the burner is installed in a furnace or kiln.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a high velocity burner having an adjustable flame exit orifice. The adjustability of the exit orifice allows the flame to be maintained at a constant velocity over a range of modulated firing rates.
To obtain these and other advantages, one aspect of the present is an adjustable velocity burner having variable flame exit. The burner includes burner combustor chamber having a fluid accelerating nozzle and a burner combustor exhaust port. Fuel is delivered to the burner combustor through a fuel inlet. An ignitor is provided to initiate combustion of the fuel. An adjusting device is provided to vary the flame exit area of the burner. The adjusting device includes an adjusting rod which preferably extends through the burner ignition chamber to the burner combustion exit port. In a currently preferred embodiment, a plug is attached to the end of the adjusting rod and is tapered in a direction decreasing toward the burner combustion exit port, and preferable includes fins attached around a periphery of the plug.
In one embodiment of the invention, the adjusting rod has a hand-manipulated operating device. However, the adjusting rod can have a computer controlled, machine manipulated operating device.
Another aspect of the present invention is a flame adjusting plug for a burner combustion assembly. The plug includes a conical tapered plug, having a first end of a first diameter and a second end of a second diameter, the second diameter being less than the first diameter. Preferably, the plug includes a plurality of fins arranged the periphery of the plug.
A further embodiment of the present invention is a method for adjusting the velocity of a flame at the exit of a burner assembly. The method includes the steps of delivering fuel to a combustion chamber of the burner and igniting the fuel in the combustion chamber. The method includes a further step of adjustable positioning a tapered burner plug in an exit opening of a burner combustion chamber and axially adjusting the position of the burner plug within the burner combustion exit port to vary the size of the burner combustion exit port opening.
These, together with other objects of the invention and along with the various features of novelty which characterize the invention, are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated currently preferred embodiments of the invention.


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