Acoustics – Sound-modifying means – Muffler – fluid conducting type
Reexamination Certificate
2001-05-17
2003-02-18
Hsieh, Shih-Yung (Department: 2837)
Acoustics
Sound-modifying means
Muffler, fluid conducting type
C181S238000, C181S248000, C181S249000
Reexamination Certificate
active
06520287
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is in the field of pollution control, particularly in the remediation and cleaning of incomplete combustion products of carbon-containing fuels. More particularly, the present invention is in the field of the degradation and cleaning of incomplete combustion products like soot, hydrocarbons, carbon monoxide and other pollutants 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.
2. Review of the Relevant Technologies
Modem society has mastered the art of producing new goods but struggles to dispose of its wastes. One problem associated with the modem economy involves pollutants that are produced by burning carbon-containing fuels, mainly fossil fuels, such as by internal combustion engines and industrial burners. The incomplete combustion of carbon-containing fuels such as gasoline, diesel fuel, fuel oil, coal, wood, biomass and even natural gas can result in the generation of pollutants such as carbon particulates, hydrocarbons, soot, oily substances, carbon monoxide (CO) and other pollutants. Such pollutants collect in the atmosphere and can cause all manner of health problems and smog. In response to the buildup of atmospheric pollution governments have attempted to legislate strict controls on the output of pollution generated by carbon-containing fuels.
For example, in response to pollution caused by gasoline-powered internal combustion engines, catalytic converters have been developed and mandated to reduce the levels of incomplete combustion pollutants emitted into the environment by gasolinepowered vehicles. Catalytic converters are typically positioned in-line with the exhaust and muffling system of an internal combustion engine and are generally able to catalytically convert most of the unburnt hydrocarbons and CO 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 such as ceramics 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 leadbased additives (i.e., tetraethyl lead) added to some gasolines can “poison” or destroy the usefulness of the catalyst, such additives have been effectively banned in the United States.
Although modern catalytic converters can be used to convert unburnt hydrocarbons and CO into carbon dioxide (CO
2
) and water, they are generally only feasible for use with relatively clean burning systems such as gasoline-powered vehicles. They generally are not 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. Nevertheless, researchers have struggled for years to find an effective and economical way to remove pollutants from the exhaust stream of diesel engines.
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 mandating the use of conventional catalytic converters to remediate the pollution caused by diesel engines.
Researchers have also struggled to find ways to effectively and economically address the tremendous quantity of pollutants generated by industrial burners, such as those that burn coal, fuel oil, or natural gas. 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.
Finally, even assuming one could construct a perfectly effective catalytic converter for carbonaceous particulates, hydrocarbons and CO, the end result would still be the generation of equal or greater amounts of CO
2
compared to what is presently being generated. Although inert and non-polluting, CO
2
is still of concern to environmentalists due to the fear that the buildup of excessive amounts of CO
2
in the atmosphere has resulted in detectable global warming, although a minority of scientists remain skeptical, and will eventually result in catastrophic climatic changes if the world continues to generate CO
2
in high quantities. Since there does not appear to be any end in sight of the need to burn fossil fuels, the concentration of CO
2
will invariably continue to increase indefinitely.
In view of the foregoing, it would be an 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, industrial burners, and other systems that bum fossil fuels which would eliminate the need for expensive catalysts, such as palladium, platinum and other rare and expensive 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.
It would be an additional advancement if such methods and systems were able to reduce the quantity of CO
2
that is emitted into the atmosphere as a result of the burning of fossil fuels or other carbon-containing fuels.
Such methods and systems for catalytically destroying unburnt carbon particulates, soot, waste hydrocarbons, oily substances, CO and other pollutants produced by the incomplete combustion of carbon-containing fuels are disclosed and claimed herein.
SUMMARY AND OBJECTS OF THE INVENTION
The present invention relates to methods and systems for degrading and cleaning incomplete combustion products produced during the combustion of carbon-containing fuels. More particularly, the invention encompasses methods and systems that utilize a highly reactive environment generated by the complex interaction of a heated waste gas stream of incomplete combustion products, moisture, carbon dioxide, oxygen, and possibly other gaseous or fine particulate materials, with a bed of s
Harrington Alan L.
Maganas Thomas C.
Hsieh Shih-Yung
Maganas OH Radicals, Inc.
Workman & Nydegger & Seeley
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