Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – Fluidized bed
Reexamination Certificate
1999-05-07
2001-05-22
Knode, Marian C. (Department: 1764)
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
Fluidized bed
C422S171000, C422S173000, C422S174000, C422S177000, C422S139000, C060S299000, C060S300000, C423S213200, C423S245300, C423S247000
Reexamination Certificate
active
06235247
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention is in the field of catalytic degradation of organic waste and pollutants. More particularly the present invention is in the field of methods and systems for low temperature catalytic degradation of organic matter, particularly soot and other incomplete combustion products produced by internal combustion engines, such as diesel engines, and industrial burners, such as those that burn coal, fuel oil or other carbon-containing fuels.
REVIEW OF THE RELEVANT TECHNOLOGIES
Modern society has mastered the art of producing new goods but struggles to dispose of its wastes. While recycling can reduce the overall waste stream, there is still a huge amount of waste that simply does not lend itself to be recycled. The United States generates approximately 180,000,000 pounds of municipal solid waste every year, most of which is disposed in landfills. However, landfills are becoming a scarce commodity.
Most conventional thinking regarding the destruction of industrial, medical or municipal waste has revolved around some form of combustion, incineration or other extreme temperature solution. Because of the complexities and high temperatures utilized, these systems are expensive, must be centrally located, and are operated by highly trained technicians. While combustion, burning or incineration has proven effective in reducing the overall weight and volume of many wastes, these methods have not provided a truly effective solution to our society's current waste management problems. Because of the need to centrally locate combustion, burning or incineration systems, waste materials must be picked up, delivered and then destroyed at the central site. However, just as landfills are becoming increasing difficult to open, incinerators often face greater opposition due to the perception that they are heavy polluters.
Another unfortunate problem associated with the modern economy involves pollutants that are produced by burning carbon-containing fuels, mainly fossil fuels, such as by internal combustion engines and industrial burners. In response to pollution caused by gasoline-powered internal combustion engines, catalytic converters have been developed to reduce the levels of incomplete combustion pollutants that are emitted into the environment as a result of the burning of gasoline. Catalytic converters are typically positioned in-line with the exhaust system of an internal combustion engine and are generally able to catalytically convert most of the unburnt hydrocarbons into CO
2
and water.
Conventional catalytic converters contain palladium or platinum, which are coated on top of carrier beads or pellets made of inert and heat-resistant materials in order to increase the surface area of the active catalyst and keep them from simply blowing out the exhaust pipe. Surface coating a less expensive substrate with the catalytic metal also decreases the cost of the catalyst particles since most catalytic metals tend to be quite expensive. Because lead-based additives added to some gasolines can “poison” or destroy the usefulness of the catalyst, such additives have more recently been effectively banned.
Although modern catalytic converters can be used to convert unburnt hydrocarbons to carbon dioxide (CO
2
) and water, they are generally only feasible for use with gasoline-powered vehicles. They are less suitable for use with diesel engines. Because of the nature of diesel engines, both in terms of the fuel that is burned as well as the way in which the fuel is burned, diesel engines produce substantial quantities of soot and other unburnt hydrocarbons which are too plentiful to be efficiently converted into CO
2
and water using reasonably sized and priced catalytic converters. Although they are known to generate substantial quantities of air-borne pollution, diesel engines have been largely exempted from the stringent air quality guidelines presently applied to gasoline-powered vehicles for largely economic reasons. Diesel engines are used for most long-haul shipping such as by tractor-trailers and trains and their elimination might cause dire economic problems.
More recently, however, public concern has translated into increased political pressure to strengthen emission standards for diesel engines. There is a possibility that emission guidelines will be imposed in certain states that may be difficult, if not impossible, to meet in an economically feasible manner using conventional catalytic converters. The tendency of diesel engines to produce soot and other unburnt hydrocarbons at a rate that is many times that produced by gasoline-powered engines would require the use of far greater amounts of expensive catalyst using existing technology. However, one of the reasons why diesel engines have been exempted from air pollution standards in the first play is the tremendous cost that would be incurred in fitting diesel engines with conventional catalytic converters. Such costs would undoubtedly burden the economy and possibly cause an economic recession if draconian emission standards were suddenly to be implemented without an economically feasible way to reduce the pollution produced by diesel engines.
In response to pollution controls directed to industrial burners sophisticated scrubbers and after burners have been developed in attempts to satisfy such pollution standards. However, these and other pollution reduction means can be quite expensive, both in retrofitting older industrial burners as well as in the fabrication of new ones.
In view of the foregoing, it would be an significant advancement in the art to provide methods and systems that could effectively and inexpensively eliminate, or at least substantially reduce, the quantity of unburnt or partially burnt combustion products produced by diesel engines and other internal combustion engines in an economically feasible manner.
It would be a further advancement in the art to provide methods and systems for eliminating, or at least greatly reducing, the quantity of incomplete combustion products produced by diesel engines and other systems that burn fossil fuels which could eliminate the need for expensive catalysts, such as palladium, platinum and other rare metals.
It would yet be an advancement in the art if such methods and systems could be easily adapted, such as by upscaling or downscaling, in order to catalytically degrade waste combustion products produced by virtually any system that burned carbon-containing fuels, such as diesel trucks, trains, other vehicles, power plants, metal smelters, and virtually any industrial burner.
Such methods and systems for catalytically destroying unburnt soot, waste hydrocarbons and other incomplete combustion products produced by burning carbon-containing fuels are disclosed and claimed herein.
SUMMARY AND OBJECTS OF THE INVENTION
The present invention relates to improved methods and systems for the complete and reliable degradation of soot and other unburnt organic materials found in the exhaust of internal combustion engines and from the burning of carbon-containing fuels in general. Such methods and systems are especially useful for the catalytic degradation of soot, unburnt hydrocarbons and other incomplete combustion products produced by diesel engines and industrial burners, such as coal or fuel oil fired power plants, metal smelters and the like. Rather than using expensive catalysts such as those presently used to catalyze the conversion of hydrocarbons to CO
2
and water, the present invention utilizes particles such as silica, alumina, and the like which can be made to be catalytically reactive under appropriate conditions. Such particles are believed to be capable of generating highly reactive hydroxyl and other oxidative moieties on their surface under such conditions.
Although the technology of providing a fluidized bed of inert silica and alumina to cause the pyrolysis or cracking of certain organic materials has been known, it was heretofore unknown that such particles could be made catalytically reactive unde
Harrington Alan L.
Maganas Thomas C.
Knode Marian C.
Ridley Basia
Workman & Nydegger & Seeley
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