Furnaces – With exhaust gas treatment means – Afterburning means
Reexamination Certificate
2000-08-16
2002-04-02
Esquivel, Denise L. (Department: 3749)
Furnaces
With exhaust gas treatment means
Afterburning means
C110S235000, C110S251000, C110S203000, C110S182500, C110S302000, C110S210000, C110S211000, C110S212000
Reexamination Certificate
active
06363868
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is in the field of industrial burners, combustors and incinerators and, more particularly, relates to new industrial burners and/or combustors for combustion of either gaseous or particulate fuels including smoke.
Particulate fuels may be wet or dry sawdust and many types of varying moisture content biomass fuels including, agricultural products, wood waste, bagasse, poultry waste, and other cellulosic materials, and especially in the wood products manufacturing or processing operations. Gaseous fuels may mean (gases traditionally used as fuels or they may mean so-called off-gases, including smoke or other combustible gases produced by processes relating to such wood products and other gases, such as from kilns or primary burners, including industrial off-gases. Burners of the invention provide high efficiency. Specifically they may operate with high turndown ratios and high heat release ratios. As used herein, the term off-gases connotes gases produced not primarily as fuels but instead those produced by other processes and apparatus, including gases produced by burners whether of the present invention or other types.
2. Related Art
In the general field of burners, combustors and incinerators for industrial purposes there are myriad different configurations, wherein there has for many years been an increasing focus on efficiency and output. Thus, there have been proposals for swirling or cyclonic combustion and combustion chambers of unusual geometries, as well as many proposals for controlling the entry of air and fuel into the combustion chamber for contributing to swirling or other patterns of combustion motion. There have been various burners proposed for burning, as feed stocks, organics or biomass materials, including so-called green (high moisture content) sawdust, solid cellulosic or wood-containing waste, waste wood, and fragments of wood, and all of which may herein be referred to as wood products. And, burners of various configurations and capabilities have been proposed for combustion of off-gases.
In burners useful for burning such materials, there has been insufficient emphasis on achieving efficiency and flexibility which can result from achieving a high turndown ratio (which may for convenience be abbreviated “TDR”), which is the maximum firing rate of the burner divided by the minimum firing rate of the burner. Prior constructions have not achieved sufficiently high TDRs.
The provision of a high TDR burner, or a combustor and burner combination, capable of carrying out combustion of wood products is highly desirable, as such a burner would be capable of being operated over a great dynamic range. If, for example, in a manufacturing or materials handling operation which creates such wood products, which are to be combusted (as for heating or energy extraction for other processes or purposes), the use of a burner having a limited TDR can require that burner operation be terminated if wood product supply rates are insufficient to achieve the minimum firing rate of the burner. Or, if combustion of wood products at low feed rates is to be carried out, an auxiliary fuel such as natural gas, liquefied petroleum (LP) gas, propane, or fuel oil, may have to be fed into the burner for maintaining combustion. But, on the other hand, if the burner is designed for burning wood products at low feed rates, its output may be insufficient to handle high feed rates when wood products to be combusted are being produced at high volumes. Further, if TDR can be increased, much less auxiliary fuel will be required to initiate burner operation.
As an example, in a wood products manufacturing or processing operations, very substantial quantities of green sawdust are created during sawing, planing, shaping, etc., but the rate of production of sawdust will be dependent upon the various wood-handling processes, which vary in rate, time of operation, and volume, so that sawdust may be produced at a highly variable rate.
If the sawdust is to be combusted by a burner for the purpose of extracting heat for other uses (such as heating, boiler operation, drying, etc.), the use of a burner having a high TDR enables its operation on continuous basis or at least for longer periods of operation, as desired.
In the wood products industry, as including also the production of charcoal, there is a need also for dealing with smoke and other gases produced during operations. For example, in cooperage operations where barrels are produced for aging of beverages, such as wines or brandies, etc., some types of barrels require that they be charred, as for the aging of various kinds of whiskeys. Charring operations produce smoke which may need to be combusted. So also, in charcoal kilns, the off-gases are sources of environmental pollution, and may also need to be combusted, i.e., by oxygenation combustion.
It would be desirable to combine a burner, capable of burning wood products for the above-noted purposes, with features for combustion of off-gases in the wood products industry.
Present burners and combustors in the wood products industries have not met the needs for these kinds of combustion, and have not achieved satisfactory TDR and efficiencies for acceptable usage in the wood products industries.
As used for combustion of gases, constructions and methods of the presently claimed invention are of special utility and suitability for burning off-gases such as smoke in situations where other processes and apparatus have produced gases which are amenable to further combustion and which may be rendered less noxious or may be converted to a safer state or destroyed by being burned at relatively high temperatures.
For example, when wood products are charred as in making barrels, smoke may be released which advantageously can be burned.
As a further example, in making charcoal involving partial combustion of wood and other cellulosic or organic substances, including vegetable-based materials smoke may be released from charcoal kilns.
The present invention specifically includes improved gas combustors of high utility in wood products industries and charcoal production.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides various combustors and burner-combustor embodiments for burning particulate fuel such as so-called green (high moisture content) sawdust, various feed stocks, organics or biomass materials, including solid cellulosic or wood-containing waste, waste wood, and fragments of wood, and all of which may herein be referred to as wood products or particulate organic fuels or materials.
The invention is also concerned with such burners and combustors which are capable of combustion of gases, such as off-gases produced in the wood products industry, or other gases which are to be oxygenated or burned for conversion to a condition environmentally non-polluting.
Burners and combustors of the present invention achieve high efficiency and flexibility, particularly achieving a very high TDR.
The inventive burners and burner-combustor combinations specifically achieve a high TDR while carrying out combustion of wood products. Burners and combustors of the invention are capable of being operated over a great dynamic range.
The new burners and combustors are especially useful in wood products manufacturing or processing operations, such as stave and barrel-forming (cooperage) operations which create very substantial quantities of green sawdust.
The new burners and combustors, because of their high TDR, efficiency and dynamic range, can be used in operation on continuous basis or for longer periods of operation, and at greatly variable output different as may be desired.
The new burners and combustors disclosed are capable of combustion of a high-moisture, low-Btu value fuels not only providing high TDR but also achieving a high heat release ratio, meaning heat output per volume per unit of time. This allows a smaller size burner or combustor of the present invention than otherwise would be required in a prior art burner, and so
Boswell John J.
Eichmeyer Dale R.
Esquivel Denise L.
Gilster Peter S.
Greensfelder Hemker & Gale, P.C.
Independant Stave Co.
Rinehart K. B.
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