US20090211565A1

US20090211565A1 - Fireplace firewood retainer assembly with air deflector, fireplace incorporating the same and method of reducing particulate emissions in a wood burning fireplace

Info

Publication number: US20090211565A1
Application number: US12/072,917
Authority: US
Inventors: Eric Dufour
Original assignee: Individual
Current assignee: Innovative Hearth Products LLC
Priority date: 2008-02-27
Filing date: 2008-02-27
Publication date: 2009-08-27

Abstract

A firewood retainer assembly and a fireplace incorporating the same are provided. The assembly includes a grate for supporting firewood at a level above a floor of a fireplace combustion chamber. The grate includes a first end opposite a second end such that a width of said grate is defined between these ends. The assembly also includes a deflector positioned adjacent the grate for deflecting air entering said combustion chamber below the level. A method of burning firewood is also provided which results in reduced particulate emissions. The method requires the deflection of air used for combustion below the firewood, heating the air with embers located below the firewood, and using the heated air for combustion.

Description

BACKGROUND OF THE INVENTION

In wood burning fireplaces, firewood, such as wood logs, are typically placed on a log retainer or grate that sits above the floor of the fireplace fire box. Grates 10 are well known in the art and typically consist of spaced apart interconnected bar members which provide a support 11 for the wood logs at a distance 13 above a combustion chamber floor 17. As combustion of the wood logs 12, 14 supported by the grate takes place, air is drawn into the fireplace combustion chamber 15 where the logs are located. Gaseous combustion products generated by the combustion of the logs are collected and exhausted via a chimney system above the combustion zone, whereas ambers 16 from log combustion remain underneath the grate and can be removed manually after the flame is extinguished.
In conventional wood burning fireplaces, as the air 18 enters the combustion chamber, it is drawn through the side of the grate, as for example shown in FIG. 1, and partially underneath the grate as also shown in FIG. 1. Most of the air enters through the grate striking the front log 12, cooling the log. Applicant has discovered that this cooling of the front log results in inefficient combustion resulting in high particulate matter emissions. In fact, a good portion of the air that enters the combustion chamber 15 is not used for combustion and just gets exhausted through the chimney along the path 20, resulting in an inefficient use of the air. Moreover, this unused air tends to have a cooling effect resulting in high particulate combustion. Consequently, a grate or grate system is desired that would improve the efficiency of the combustion and that would reduce the particulate matter emissions.

SUMMARY OF THE INVENTION

In an exemplary embodiment, a firewood retainer assembly is provided. The assembly includes a grate for supporting firewood at a level above a floor of a fireplace combustion chamber. The grate includes a first end opposite a second end. The assembly also includes a deflector positioned adjacent the grate for deflecting air entering the combustion chamber below the level. In another exemplary embodiment, the deflector extends beyond the first end in a direction away from the second end and extends beyond the second end in a direction away from the first end. In yet another exemplary embodiment, the deflector includes a first surface opposite a second surface and a thickness there between. The first surface faces away from the grate and the second surface faces the grate, and the first surface is angled relative to a vertical plane for deflecting the air entering the combustion chamber below the level. In a further exemplary embodiment, the deflector first surface includes a vertex and extends from opposite directions of the vertex and towards the grate. In yet another exemplary embodiment, the deflector first surface includes opposite end portions, such that each end portion extends in a direction opposite the other end portion and towards the grate.
In another exemplary embodiment a wood burning fireplace is provided including a combustion chamber having an opening for receiving air for combustion. The fireplace includes a grate in the combustion chamber, at least one piece of firewood supported by the grate at a level above a floor of the combustion chamber, and a deflector between the grate and the opening for deflecting air entering the opening below the level. In yet another exemplary embodiment, the deflector includes a top end opposite a bottom end, such that the top end is further from the floor than the bottom end. A height of the deflector is defined between the top and bottom ends. The at least one piece of firewood supported on the grate extends to a height level such that the top end extends to at least the same height level as the at least one piece of firewood. In yet a further exemplary embodiment, the combustion chamber includes a first side wall opposite a second side wall and the deflector includes a main portion, a first end portion extending from the main portion and a second end portion extending from the main portion opposite the first end portion, such that the first end portion extends beyond the grate toward the first side wall and the second end portion extends beyond the grate toward the second sidewall. In another exemplary embodiment, the deflector includes an outer surface opposite an inner surface and a thickness there between, such that the outer surface faces away from the grate and the inner surface faces the grate, and such that the outer surface is angled whereby the top end is further from a rear wall of the combustion chamber than the bottom end. In yet another exemplary embodiment, the outer surface includes a vertex whereby the outer surface extends from opposite directions from the vertex toward the opposite side walls and toward the rear wall. In a further exemplary embodiment, the first end portion extends at an angle relative to the main portion and in a direction toward the rear wall, and the second end portion extends at an angle relative to the main portion and in a direction toward the rear wall. In yet a further exemplary embodiment, the first end portion extends to a location adjacent to the first side wall and the second end portion extends to a location adjacent to the second side wall. In another exemplary embodiment the at least one piece of firewood includes a first end opposite a second end and a length there between, and the deflector extends beyond the at least one piece of firewood first end and away from the at least one piece of firewood and in an opposite direction beyond the at least one piece of firewood second end and away from the at least one piece of firewood. In yet another exemplary embodiment, the grate includes a first side facing the first side wall and a second side facing the second side wall, and a first space is defined having a first width bounded by the grate first side and the first side wall and a second space having a second width bounded by the grate second side and the second side wall, such that the deflector first end portion extends along a majority of the first width and the deflector second end portion extends along a majority of the second width. In another exemplary embodiment, the first end portion occupies substantially the entire first width and the second end portion occupies substantially the entire second width. In a further exemplary embodiment, the bottom end is positioned to be at a height of least 2 inches from the floor. In yet a further exemplary embodiment, the bottom end is positioned to be at a height of about 1 inch to about 4 inches from the floor.
In another exemplary embodiment a method of burning wood in a wood burning fireplace having the firewood supported on a grate in a combustion chamber having a floor and an opening is provided. The method includes burning the firewood creating a combustion, providing air through the opening, deflecting the air entering through the opening to an area above the floor and below the grate, heating said deflected air by embers located on the floor, and using the heated air in the combustion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cut away end view of a fireplace combustion chamber with a prior art log retainer assembly including logs.

FIG. 2 is a cut away end view of a fireplace combustion chamber with an exemplary embodiment retainer assembly with logs retained thereon.

FIG. 3 is a top view of an exemplary embodiment log retainer assembly with logs retained thereon.

DETAILED DESCRIPTION OF THE INVENTION

Applicant has discovered that a way to improve the burning efficiency and to reduce particulate emissions of a wood burning fireplace is to have the air entering the combustion chamber that is used for combustion be pre-heated. Applicant has discovered that this can be achieved by guiding the air entering the combustion chamber 15 beneath the firewood, e.g., the logs 12, 14 in a space 22 between the logs and the heated embers 16, as for example shown in FIG. 2. As the air moves past the heated embers, it is heated and then rises to aid in the combustion of the logs 12, 14. To achieve this effect, a baffle or deflector 24 such as for example a deflector plate is positioned in front of the grate so that air 18 a entering the combustion chamber strikes the deflector 24 and is deflected downward towards the embers, as for example along a path 26. In an exemplary embodiment, the deflector is a plate angled from the vertical plane along an angle 28. In an exemplary embodiment, the angle 28 between a vertical plane and the deflector plate 24 is 15°, such that the air striking the deflector plate is guided beneath the grate. In other exemplary embodiments, the angle 28 may be in the range from about greater than 0° to 60°.
In a further exemplary embodiment, the deflector outer surface 29 which is facing the incoming air, is angled toward the grate, as for example shown in FIG. 3. With this exemplary embodiment, the deflector outer surface 29 defines a vertex 30 which is positioned generally about the center of the grate. In an exemplary embodiment, the vertex is also formed about a center of the deflector outer surface. In an exemplary embodiment an angle 31 that the outer surface is bent on either side of the vertex is in the range of greater than 0° to about 45°. When using a plate as a deflector, this can be achieved by bending the deflector plate toward the grate. In other embodiments, the angle may be formed by machining.
In a further exemplary embodiment, opposite end portions 32 of the deflector outer surface extending from opposite sides of a main portion 33 of the deflector outer surface extend beyond either end 34 of the grate and beyond the ends 36 of the wood logs such that air attempting to reach the logs by moving around the sides of the grate will strike these ends portions 32 of the deflector and will be consequently also guided to the sides away from the logs and beneath the grate. In an exemplary embodiment, the deflector is long enough so as to extend to each opposite side wall 38 of the combustion chamber 15. In another exemplary embodiment, the deflector does not extend all the way across the combustion chamber. In a further exemplary embodiment, end portions 32 of the deflector outer surface 29 are angled in a direction towards the grate, as for example shown in FIG. 3, so as to guide the air away from the logs and underneath beneath the grate and/or logs. In an exemplary embodiment, the angle 35 that the outer surface end portions 32 are bent relative to their respective main portions is in the range of greater than 0° to 90°. In an exemplary embodiment, the outer surface portions may extend toward the firewood without extending beyond the ends of the firewood or grate. In an exemplary embodiment, the length of the deflector is at least half as long as the width 43 of the combustion chamber and may be as long as the width of the combustion chamber.
In another exemplary embodiment, the end portions 32 are not angled relative to their respective main portions toward the grate. In a further exemplary embodiment, the deflector outer surface including the end portions or the outer surface end portions individually extend across a majority of the width 40 between grate end 34 and its respective combustion chamber side wall 38 and/or a majority of the width 42 between a log end 36 and its respective side wall 38 of the combustion chamber.
Applicant has discovered that increased burning efficiency and a reduction in combustion particulates can be obtained by positioning the bottom edge 44 of the deflector to a level not higher than the lowest level 48 of the wood logs. In an exemplary embodiment, the deflector bottom edge extends to the wood log support level 11 defined by the bar members 19 of the grate. In another exemplary embodiment, the bottom edge of the deflector extends to the lower surface of the bar members 19 of the grate as for example shown in FIG. 2. In an exemplary embodiment a distance 46 of about 2¼ inches from the floor 17 the combustion chamber to the lower edge 44 of the deflector provided desired results. In another exemplary embodiments, the distance 46 is at least 2 inches. In yet another exemplary embodiment, the distance 46 is in the range of 1 inch to about 4 inches. Furthermore, Applicant has discovered that a deflector plate having a top edge 50 extending to at least the uppermost height level 52 of the logs 12, 14 will work sufficiently in deflecting an appropriate amount of the air. A deflector outer surface height 54 of about 2 to 4 inches should be sufficient for most applications so as to cover the height of the logs when resting in the grate. In other exemplary embodiments, the deflector outer surface may have a height of about 1 to about 7 inches. The deflector plate may have flat surfaces or ornamental surfaces 56 surfaces facing away from the grate. In other exemplary embodiments, the deflector plate may be perforated. In further exemplary embodiments, the perforations may be such that the air striking the plate is guided downwards through the perforations and beneath the grate.
With the deflector plate, the air entering the combustion chamber is significantly kept away from the logs and is directed beneath the grate just above the embers where it is heated. By doing so, a maximum combustion temperature is maintained as the cooler incoming air is kept away from the logs and the log extremities and is directed above the embers where it is heated prior to combustion. Furthermore, the guidance plate keeps the embers from the wood combustion to remain within a combustion zone below the firewood, thus maintaining a maximum temperature in the combustion zone. Applicant believes that bed of embers is kept hot during combustion due to the incoming air flow path created by the deflector. The air is forced to circulate right above the bed of embers as shown by arrow 18 a (FIG. 2) causing oxygen to be fed constantly underneath the firewood. This causes a higher temperature to be maintained in the combustion zone resulting in a more complete firewood combustion and lower particulate emissions.
Applicant has conducted tests with an exemplary embodiment deflector plate used in a wood burning fireplace. Tests were conducted using ASTM test methods. In a test without the use of a deflector plate, the particulate emissions exhausted from the fireplace were measured to be at 7.08 grams per kilogram of wood burned. By using a simple flat plate as the deflector plate, the emissions were reduced to 3.41 grams per kilogram of wood burned. By using a deflector plate that extended to either side wall of the combustion chamber, the particulate emissions were reduced to 3.2 grams per kilogram of wood burned. By using a deflector plate where the ends of the deflector plate were bent backward in a direction towards the grate, as for example shown in FIG. 3, the particulate emissions were further reduced to 2.69 grams per kilogram of wood burned.
Although the present invention has been described and illustrated to respect to exemplary embodiments, it is to be understood that it is not to be so limited, since changes and modifications may be made therein which are within the full intended scope of this invention as hereinafter claimed.

Claims

1. A firewood retainer assembly comprising;

a grate for supporting firewood at a level above a floor of a fireplace combustion chamber, said grate comprising a first end opposite a second end; and

a deflector positioned adjacent the grate for deflecting air entering said combustion chamber below said level.

2. The assembly as recited in claim 1 wherein said deflector extends beyond the first end in a direction away from the second end and extends beyond the second end in a direction away from the first end.

3. The assembly as recited in claim 2 wherein said deflector comprises a first surface opposite a second surface and a thickness there between, wherein the first surface faces away from said grate and said second surface faces said grate, and wherein said first surface is angled relative to a vertical plane for deflecting said air below said level.

4. The assembly as recited in claim 3 wherein said deflector first surface comprises a vertex and extends from opposite directions of said vertex in directions having a component directed toward the grate.

5. The assembly as recited in claim 4 wherein the deflector first surface comprises opposite end portions, wherein each of said end portions extends in a direction opposite the other end portion and in a direction having a component toward the grate.

6. A wood burning fireplace comprising:

a combustion chamber comprising an opening for receiving air for combustion;

a grate in the combustion chamber;

at least one piece of firewood supported by the grate a level above a floor of the combustion chamber; and

a deflector between the grate and said opening for deflecting air entering said opening below said level.

7. The fireplace as recited in claim 6 wherein the deflector comprises a top end opposite a bottom end, wherein the top end is further from the floor than the bottom end, wherein a height of said deflector is defined between said top and bottom ends, wherein said at least one piece of firewood supported on said grate extends to a height level, wherein said top end extends to at least the same height level as said piece of firewood.

8. The fireplace as recited in claim 7 wherein the combustion chamber comprises a first side wall opposite a second side wall, wherein said deflector comprises a main portion, a first end portion extending from the main portion and a second end portion extending from the main portion opposite the first end portion, wherein the first end portion extends beyond the grate toward the first side wall and wherein the second end portion extends beyond the grate toward the second sidewall.

9. The fireplace as recited in claim 8 wherein said deflector comprises an outer surface opposite an inner surface and a thickness there between, wherein the outer surface faces away from said grate and said inner surface faces said grate, wherein said combustion chamber comprises a rear wall opposite said opening and wherein the outer surface in angled whereby the top end is further from the rear wall than the bottom end.

10. The fireplace as recited in claim 9 wherein the outer surface comprises a vertex whereby the outer surface extends from opposite directions from said vertex toward the opposite side walls and toward the rear wall.

11. The fireplace as recited in claim 10 wherein said first end portion extends at an angle relative to the main portion and in a direction toward the rear wall, and wherein the second end portion extends at an angle relative to the main portion and in a direction toward the rear wall.

12. The fireplace as recited in claim 11 wherein the first end portion extends to a location adjacent the first side wall and wherein the second end portion extends to a location adjacent the second side wall.

13. The fireplace as recited in claim 11 wherein said at least one piece of firewood comprises a first end opposite a second end and a length there between, wherein said deflector extends beyond said at least one piece of firewood first end and away from said at least one piece of firewood and in an opposite direction beyond said at least one piece of firewood second end and away from said at least one piece of firewood.

14. The fireplace as recited in claim 11 wherein the grate comprises a first side facing the first side wall and a second side facing the second side wall wherein a first space is defined having a first width bounded by said grate first side and said first side wall and a second space having a second width bounded by said grate second side and said second side wall, wherein said deflector first end portion extends along a majority of said first width and wherein said deflector second end portion extends along a majority of said second width.

15. The fireplace as recited in claim 11 wherein the first end portion occupies substantially the entire first width and wherein the second end portion occupies substantially the entire second width.

16. The fireplace as recited in claim 11 wherein the bottom end is positioned to be at a height of least 2 inches from the floor.

17. The fireplace as recited in claim 11 wherein the bottom end is positioned to be at a height of about 1 inch to about 4 inches from the floor.

18. A method of burning firewood in a wood burning fireplace having the firewood supported on a grate in a combustion chamber having a floor and an opening, the method comprising:

burning said firewood creating a combustion;

providing air through the opening;

guiding using a guiding surface at least part of the air entering through the opening to an area above the floor and below the grate;

heating said guided air by embers on said floor; and

using said heated air in said combustion.

19. The method as recited in claim 18 wherein burning said firewood generates particulate emissions, and wherein said guiding comprises guiding a sufficient amount of said air for reducing said particulate emissions to levels not greater than 3.41 grams per kilogram of firewood burned.

20. The method as recited in claim 19 wherein said guiding comprises guiding a sufficient amount of said air for reducing said particulate emissions to levels not greater than 3.2 grams per kilogram of firewood burned.

21. The method as recited in claim 19 wherein said guiding comprises guiding a sufficient amount of said air for reducing said particulate emissions to levels not greater than 2.69 grams per kilogram of firewood burned.

22. The method as recited in claim 19 wherein said guiding comprises guiding a sufficient amount of said air for reducing said particulate emissions to levels in the range of 3.41 to 2.69 grams per kilogram of firewood burned.

23. The method as recited in claim 19 wherein said guiding comprises guiding a sufficient amount of said air for reducing said particulate emissions to levels less than 50% of levels without said guiding.

24. The method as recited in claim 19 wherein said guiding comprises guiding a sufficient amount of said air for reducing said particulate emissions to levels not greater than 45% of levels without said guiding.

25. The method as recited in claim 19 wherein said guiding comprises guiding a sufficient amount of said air for reducing said particulate emissions to levels not greater than 38% of levels without said guiding.

26. A firewood retainer assembly comprising;

a deflector positioned for deflecting a sufficient amount of air entering said combustion chamber below said level for limiting particulate emissions generated by burning of said firewood to a desired level.

27. The assembly as recited in claim 26 wherein said desired level is not greater than 3.41 grams per kilogram of firewood burned.

28. The assembly as recited in claim 26 wherein said desired level is not greater than 3.2 grams per kilogram of firewood burned.

29. The assembly as recited in claim 26 wherein said desired level is not greater than 2.69 grams per kilogram of firewood burned.

30. The fireplace as recited in claim 6 wherein said fireplace produce particulate emissions not greater than not greater than 3.41 grams per kilogram of firewood burned.

31. The fireplace as recited in claim 6 wherein said fireplace produce particulate emissions not greater than not greater than 3.2 grams per kilogram of firewood burned.

32. The fireplace as recited in claim 6 wherein said fireplace produce particulate emissions not greater than not greater than 2.69 grams per kilogram of firewood burned.