Stoves and furnaces – Stoves – Heating
Reexamination Certificate
2000-04-10
2001-10-30
Price, Carl D. (Department: 3743)
Stoves and furnaces
Stoves
Heating
C126S28500B, C126S287000, C110S190000, C236S01500E
Reexamination Certificate
active
06308701
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a combustion system for improved combustion of solid fuels and, more particularly, to a combustion system which prevents smothering and quenching of the solid fuels during burning while providing improved performance, such as, amongst others, reducing air borne pollutants.
2. Background Description
Residential and commercial solid fuel combustion in the United States and around the world increased sharply after the oil embargoes of the 1970s. This was partly due to the decrease in oil and gas supplies at that time making it quite difficult to obtain these fuels and the simultaneous extreme price increases in such fuels. However, with the steady increase of residential and commercial solid fuel combustion came a steady increase in environmental pollutants, such as copious amounts of particulate matter. This increase in environmental pollutants was especially true with the increased usage of residential coal and wood burning combustion systems (e.g., wood burning stoves).
Due to the increase in environmental pollutants, states began to regulate wood burning stove emissions. Moreover, the United States Environmental Protection Agency (EPA) also began to regulate the emissions of wood burning stoves, and in 1988 all newly built wood burning stoves had to comply with strict EPA regulations. The EPA regulations require airtight wood burning stoves sold after 1988 to pass an emissions certification test where dimensional lumber (e.g., two by fours and four by fours) with enforced 1.5 inch spacing is burned and particulate matter (PM) emissions are measured. Once a wood burning stove passes the EPA standards, it is certified and allowed to be sold within the United States.
However, after many years of field measurements, the field performance of the EPA certified wood burning stoves leaves much room for improvement. Consumer misuse and/or inattention to proper operation, physical degradation of critical components and lack of maintenance, amongst other reasons, cause emissions to be greater than they need be. The poor field performance of many wood burning stoves is further attributed to the fact that the wood burning stoves are designed to burn clean when burning the wood of the certification test, but are generally not as effective when burning cordwood or other solid fuels at a wider range of moisture contents.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a combustion system that reduces emissions of air borne pollutants and other organic volatiles relative to emissions from current systems.
It is a further object of the present invention to prevent quenching of the burning fuel in the combustion system.
It is still a further object of the present invention to prevent smothering of the burning fuel in the combustion system.
It is also a further object of the present invention to provide a tuned air delivery in order to properly maintain air/fuel mixtures during burning of solid fuel in the combustion system.
It is another object of the present invention to provide an automatic air control system in the combustion system to improve rekindling of loaded fuel and thereby reduce air borne pollutants and other organic volatiles from discharging from the combustion system after stove reloading.
It is also another object of the present invention to provide an improved loading door that prevents smoke spillage and reduces cool air flow during solid fuel reloading in the combustion chamber.
It is yet another object of the present invention to provide an improved loading door that maintains proper air/fuel ratios within the combustion system during refueling.
It is still another object of the present invention to provide a combustion system that outperforms the EPA certification limit during field operations.
The present invention provides a combustion system comprising a primary combustion chamber divided into left and right sides by fuel-retaining standards. The fuel-retaining standards retain the solid fuel on either side of the primary combustion chamber and define a canyon (or void/space) that serves as or extends into a secondary combustion chamber, in preferred embodiments. The fuel-retaining standards create an unimpeded flow path for combustion gases from the primary combustion chamber to the secondary combustion chamber, while at the same time retaining the solid fuel on either side of the fuel-retaining standards. Thus, the canyon permits flames to travel unimpeded from the bottom of the primary combustion chamber to the top of the secondary combustion chamber.
An air delivery system generally depicted as a lower air tube is positioned within the canyon and preferably at the lower portion of the fuel-retaining standards. The lower air tube provides primary and secondary flows, where the primary flow is ejected through holes which are positioned to directly contact the solid fuel on either side of the fuel-retaining standards. The lower air tube also supplies a lower velocity secondary air ejected from holes and enables secondary combustion of the flaming combustion gases and CO produced by the primary air. In order to supply a lower velocity secondary air flow, a diffuser is provided proximate to the lower air tube which slows and redirects high velocity air ejected from the holes and causes the slower air to stay mainly within and near the canyon, rather than boring into the solid fuel where it would increase the gasification rate of the solid fuel. The air delivery system may also comprise an upper air tube which is located at the upper portion of the fuel-retaining standards and canyon, and within the secondary combustion chamber. The upper air tube provides additional secondary air and cools the catalyst so that it does not overheat and is regulated by an automatic shutter mechanism which senses temperature above or below the catalyst. Additional air delivery tubes may be located in the canyon to deliver additional primary and/or secondary air to the combustion system. A plenum is also provided which substantially eliminates back puffing.
The secondary combustion chamber includes fuel protecting baffles and a secondary combustion chamber ceiling which includes one or more openings and may extend partially over the entire length of the secondary combustion chamber. The fuel protecting baffles divide the primary combustion chamber from the secondary combustion chamber and further provide a passageway so that the canyon gases may enter into the secondary combustion chamber. The upper air tube may be centered above the opening and the canyon so that the flames and combustion gases split upon entering the secondary combustion chamber and go right and left upon reaching the upper air tube.
A loading door is positioned at the front of the combustion system so that solid fuel, such as wood, can be loaded into the primary combustion chamber. The loading door comprises a hollow frame and a window mounted in the hollow frame. The loading door further comprises holes which draw air into the hollow frame and direct the air into the primary combustion chamber.
A bypass system prevents the loading door of the combustion system from being fully closed unless the bypass is in the completely closed position. An automatic air setting mechanism is provided so that an initial higher air setting is maintained until the solid fuel becomes fully involved in the combustion process.
REFERENCES:
patent: 828411 (1906-08-01), Kirby
patent: 1131106 (1915-03-01), Beam
patent: 4207860 (1980-06-01), Schrock
patent: 4409956 (1983-10-01), Barnett
patent: 4582045 (1986-04-01), Doran et al.
patent: 6067979 (2000-05-01), Jaasma et al.
Champion Mark
Jaasma Dennis
Jaasma Dennis
McGuireWoods LLP
Price Carl D.
LandOfFree
Combustion system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Combustion system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Combustion system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2566182