Heating – With means diluting – purifying or burning exhaust gases
Reexamination Certificate
2000-04-28
2001-07-17
Lu, Jiping (Department: 3749)
Heating
With means diluting, purifying or burning exhaust gases
C432S120000, C110S203000, C110S204000, C110S205000, C110S206000, C110S210000, C110S211000, C110S254000
Reexamination Certificate
active
06261090
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to improvements of the apparatus and methods of the present inventors set forth in provisional patent application Ser. No. 60/095,054 filed Aug. 3, 1998, entitled COMBUSTORS AND BURNERS WITH HIGH TURNDOWN RATIO, incorporated herein by reference, continued preservation of which is requested.
FIELD OF THE INVENTION
The invention is in the field of industrial burners, combustors and incinerators and, more particularly, relates to a new combustor and combustor system for combustion of smoke and other combustible off-gases and other emissions produced in the operation of charcoal kilns and other processes, as in wood products manufacturing or processing operations.
Charcoal is made by both continuous and batch processes which carry out partial combustion of wood, e.g., hardwood and/or wood waste, sawdust, agricultural products, bagasse, biomass, poultry waste, and other mixtures of various carbonaceous or cellulosic materials. A well-known example of batch process for charcoal manufacture involves the use of kilns, or arrays of kilns to which products are charged, combusted and then retrieved as charcoal lumps and/or fines.
Charcoal production from wood involves the thermal degradation of wood in a starved-air atmosphere. In a kiln, pyrolysis and combustion both occur in self-sustaining reaction. Heat required for pyrolysis is supplied from the combustion reactions which are exothermic. Kilns of this type are not subjected to or pressure control or to precise temperature control. These batch process kilns operate discontinously. They have typical charcoal yields generally only 20-30%, and accordingly much mass and heat are lost by combustion and with accordingly high liberation and emission of smoke, gas and constituents.
Such kilns can emit pollutants in the form of smoke and hot gas emissions including particulate matter (PM), volatile organic compounds (VOC) and possibly toxic compounds such as certain polyaromatic hydrocarbons (PAHs) in the form of combustible off gases and other emission products. Among the possible emission products of carbonaceous combustion occurring in such kilns is carbon monoxide, a pervasive atmospheric contaminant.
For pollution prevention, it is desired to provide further burning combustible off-gases and other emission products, including VOCs, PAHs and particulate matter, to prevent potential atmospheric contaminants and other untreated emission products produced in kiln operation by treating them before they are allowed to be released to the atmosphere.
Other combustion processes and devices used in processing of wood products similar may produce smoke, combustible gases particulates, VOCs, PAHs and particulate matter and other emission products. These include primary burners and incinerators, and may also include various processes and devices which release industrial off-gases. For example in the wood products industry, as also the production of charcoal, there is a need also for dealing with smoke and other gases and other potential contaminants and other emission products which might be 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.
All such kiln emissions and other gaseous products, including without limitation kiln smoke and other gaseous products and off-gases and other emissions or emission products from combustion processes, will herein be referred to for convenience as “emissions” or “emission products.” As used for convenience herein, the term emission or emission product also connotes, without limitation, gases and gaseous products and off-gases produced not primarily as fuels but instead emitted, liberated or created by other processes and apparatus, including smoke and other gases as well as VOCs, PAHs and particulate matter and other emission products produced by kilns, burners and other apparatus in which partial or contaminant-producing combustion occurs under conditions producing smoke or other gases or other emissions.
Such emissions as may be sources of environmental pollution can advantageously be combusted, i.e., by oxygenation combustion. Such emissions (including their related products and reaction products) are in the typical usages described above capable of further combustion before release to the atmosphere.
Combustion apparatus of the present invention, hereinafter referred to for convenience simply as “combustor” or “combustors” or “combustor system” is intended to provide high temperature oxygenation combustion of emissions. Specifically combustors and combustor systems of the invention operate with high turndown ratios and high heat release ratios.
RELATED ART
With regard generally to reactions occurring in charcoal production, the following papers are generally relevant to of reactions and compositions released during the manufacture of charcoal but are not believed relevant to constructions presently disclosed and claimed.
Di Blasi, C., 1993, Analysis of Convection and Secondary Reaction Effects within Porous Solid Fuels undergoing Pyrolysis. Combust. Sci. Technology 90, 315-339.
Hajaligol, M. R., Howard, J. B., Longwell, J. P., Peters, W. A., 1982, Product Compositions and Kinetics for Rapid Pyrolysis of Cellulose. Ind. Eng. Chem. Process Des. Dev. 21, 457-465.
Shafizadeh, F. and Chin, P. P. S., 1977, Thermal deterioration of wood. ACS Symp. Ser. 43, 57-81.
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 emissions.
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 for a combustor capable of carrying out combustion of emissions and their related constituents is highly desirable, as such a combustor would be capable of being operated over a very substantial dynamic range. If the use of a burner having a limited TDR requires that burner operation be terminated if off-gas supply rates are insufficient to achieve the minimum firing rate of the burner, utility of the burner will be undesirably limited. Or, combustion of emissions at low feed rates is to be carried out, may require use of an auxiliary fuel such as natural gas, liquefied petroleum (LP) gas, propane, or fuel oil for maintaining combustion. But, on the other hand, if a burner is designed for burning emissions 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.
Present burners 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.
In connection with use of the present combustor and combustor system with charcoal production, batch-type cha
Boswell John J.
Eichmeyer Dale R.
Gilster Peter S.
Greensfelder Hemker & Gale, P.C.
Independent Stave Company
Lu Jiping
LandOfFree
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