EP3306200B1

EP3306200B1 - Convection stove

Info

Publication number: EP3306200B1
Application number: EP16002137.4A
Authority: EP
Inventors: Kevin Senff; Julius RATJEN
Original assignee: Bullerjan GmbH
Current assignee: Bullerjan GmbH
Priority date: 2016-10-05
Filing date: 2016-10-05
Publication date: 2019-11-27
Anticipated expiration: 2036-10-05
Also published as: WO2018065320A1; EP3306200A1

Description

FIELD OF THE INVENTION

The present invention relates to a fireplace in the form of a convection oven which provides for low emission of carbon monoxide and particulate matter combined with effective heating by convection.

BACKGROUND OF THE INVENTION

Fireplaces such as small heating systems, also termed as small combustion systems, heating systems for single rooms such as wood-burning stoves, tile stoves, cookers and opened fireplaces which are operated with solid fuel such as wood or wood pellets may often be found in private households. Governmental regulations require reduced emissions. E.g., respective regulations of the Federal Republic of Germany specify for heating systems for single rooms an emission of carbon monoxide below 1250 mg/Nm³ (13 % O₂) and for particulate matter below 40 mg/Nm³ (13 % O₂) (1. BlmSchV II).
The heating principle of a fireplace may be based mainly on heat radiation or on convection, and/or a combination of both.
EP 0 231 424 (filing date: 03.06.1986) discloses a fireplace the heating principle thereof is in essential based on convection. This fireplace has a horizontal cylindrical body enclosing a combustion chamber, wherein the sidewalls thereof consist of curved pipes. Accordingly, the respectively formed inner surface of the combustion chamber is corrugated, thus enlarging the area of said inner surface compared to a respective smooth surface. Said curved pipes have an opening at the lower end, and an opening at the upper end, respectively. During operation, said curved pipes are heated up by the combustible burning in the combustion chamber. Due to the corrugated inner surface resulting in said comparatively enlarged surface, air being in the pipes is heated up outstandingly fast and steadily, and is also fast and steadily discharged via the upper opening, whereas colder air from the environment is aspirated via the opening at the lower end due to convection. This in turn provides for very effective recirculation of the environmental air contained e.g. in a house through said air channels, wherein the recirculating air of the environment is outstandingly fast and steadily heated up.
It is believed in the art that an essential prerequisite for the efficacy of said fireplace disclosed in this prior art is that the pipes have to be configured to form a corrugated inner surface of the combustion chamber having an enlarged area compared to a smooth surface, and have to be directly heated by the burning combustible, i.e. the pipes have to be in direct contact with fire in order to most effectively provide for said characteristic up-heating.
The fireplace known from EP 0 231 424 since the end of the 1980s was and is still very successfully in the market. Market participants have presented variations of this fireplace, however, not deviating from the above-addressed principle of up-heating the pipes in terms of the enlarged area and the direct heating by combustible. It is established believe in the art that a deviation from said principle would negatively affect the unique properties of said fireplace in terms of said outstandingly fast and steady heating up of environment.
EP 2 455 666 discloses a fireplace having a horizontal cylindrical body enclosing a combustion chamber. The outside cladding of this fireplace comprises air channels providing for convection. However, the air channels of the fireplace disclosed in EP 2 455 666 are not part of the combustion chamber, and therefore do not enlarge the heat transmitting steel surface of the combustion chamber. Moreover, the combustion chamber of this fireplace is lined with refractory fireclay. Thus, additionally to the non-enlarged area and hence reduced capacity to direct heat to the environment such as a house, the air channels cannot be directly heated up by the burning combustible. It is believed in the art that these properties are responsible for the observed less effective convection compared to the fireplace disclosed in EP 0 231 424 .
However, the fireplace disclosed in EP 2 455 666 provides for low emission. It is believed in the art that this low emission is due to a probably higher temperature which may be reached in the combustion chamber due to said lining with refractory material, which has a low thermal conductivity, compared to a combustion chamber which is free from a lining with refractory material. Accordingly, the higher temperature may support a more complete burning of combustible.
GB 723 172 discloses a heating apparatus for a building comprising a solid-fuel stove so constructed that when installed its charging and firebox doors and chimney are located external to the building, the body of the stove projecting within the building and being surrounded by a casing through which air can circulate so as to heat the interior of the building by convection. As shown the heater comprises top plate 9, side plate 5, back and front plates 8, 12, the latter being made in two parts 12a, 12b, the upper of which is provided with the necessary apertures for fuel feeding and withdrawal of combustion products and the lower of which is provided with the necessary apertures for the fitting of a pivoted ash door 39 and an air inlet regulator 42. Fitted to the apertures in the top 12a is a divided box structure 26 having a chimney outlet 29 provided with a slidable damper plate 32 and a fuel inlet shoot normally covered by a plate 27. The plates 5 and 8 are formed with air inlet and outlet holes 49, 50, whilst the top plate 9 has ribs 51 provided thereon. Attached to the inside of plate 12b is an U-shaped dished member 23 the open-ended branches of which pass down either vertical side of the ash door aperture such that combustion air which enters through the regulator 42 is guided by the member 23 downwards to discharge in a heated condition into the ash space below the grate 37. The fire-box comprises corrugated side plates 14, back plate 18 and a top plate, the side and back plates being lined with firebrick 47.

OBJECTS OF THE INVENTION

In view of the ongoing need for reducing emission of fireplaces such as small heating systems, in particular in view of the ongoing need for efforts to reduce the emission of the fireplace disclosed in EP 0 231 424 , it was the object of the invention to provide a fireplace mainly based on convection which provides for low emission without significantly negatively affecting the characteristic of a fast and steady up-heating of the pipes in order to ensure fast and comprehensive occurrence of convection.
Documents EP 2455666 A1 and GB 723172 disclose further state of the art relevant to the invention.

SUMMARY OF THE INVENTION

This object was achieved with a fireplace as defined in claim 1. Preferred embodiments are defined in the claims depending thereon.
Contrary to expectation that the reduced thermal conductivity of a refractory material might prevent the air channels from a fast and steady heating up that would ensure outstanding fast and steady occurrence of recirculation of environmental air through said air channels, the inventors unexpectedly observed that the air channels despite being at least partially lined with said refractory material, are heated up nearly as fast as the air channels in the fireplace being free from a refractory material, and reached almost the same steady heat output as the fireplace disclosed in EP 0 231 424 . Thus, with the fireplace according to the invention, still outstandingly fast and effective recirculation of the environmental air through the air channels is achieved. Contrary to expectation in view of the established believe in the art that the fireplace would lose its unique characteristic of an outstandingly fast and steady heating up of recirculating air when deviating from the addressed principle, the fireplace according to the invention maintains unique characteristics in terms of a heat output nearly as high as the heat output achieved with the fireplace disclosed in EP 0 231 424 despite an at least partial lining with a refractory material. Moreover, this effective recirculation of environmental air through said air channels is now beneficially connected with a significantly reduced emission compared to the oven disclosed in EP 0 231 424 .
Moreover, the inventors discovered that it is no longer required to necessarily provide the air channels in the form of pipes as disclosed in the prior art in order to achieve a high heat output, but that the air channels may be formed e.g. as extending recesses in the outer surface of the combustion chamber, provided the inner surface is at least partially corrugated. In one embodiment, the outer surface of the combustion chamber may be even a smooth surface, which functions as air channel, provided the inner surface is at least partially corrugated.
The construction of the fireplace according to the invention is based on a paradigm change of the hitherto long-lasting believe in the art that air channels in the form of pipeshave to be directly heated up by burning combustible in order to provide for outstandingly fast and steady occurrence of recirculation of environmental air, to the discovery that air channels forming at least partially a corrugated inner surface of a combustion chamber may at least be partially lined with a refractory material, thus reducing the area which can be contacted by burning combustible, however without significantly negatively affecting outstandingly fast and steady occurrence of recirculation of environmental air through said air channels.
This finding is connected with a beneficial reduced emission. The resulting technical effect of a reduced emission without losing a significant portion of the characteristic heat distribution benefitting from the convection effect could not be foreseen in view of the hitherto understanding as disclosed in the prior art, and the hitherto constructions of convection ovens in which air channels providing for a comparatively enlarged area of the inner surface of a combustion chamber are configured to be directly heated up by the burning combustible.
The fireplace according to the invention allows reducing the emission of carbon monoxide and particulate matter to values below 1250 mg/Nm³ (13 % O₂) carbon monoxide and 40 mg/Nm³ (13 % O₂) particulate matter.
The term "Nm³" encompasses the term "dry standard cubic meter", which term is synonymously used to the terms "normal cubic meter" or "standard cubic meter". The term "particulate matter" (all terms in quotation marks are used in the meaning of the invention) is synonymously used with the term "dust" or "fine dust". This particulate matter is generated when combustible in a fireplace is not completely combusted to gaseous products.

FIGURES

In the figures show

Fig. 1: a longitudinal section of a combustion chamber comprising a lower and an upper compartment of a preferred fireplace according to the invention;
Fig. 2: a longitudinal section of a combustion chamber of Fig. 1 including a further compartment accommodating a damper flap;
Fig. 3: a longitudinal section of a combustion chamber comprising a lower, a middle and an upper compartment of a preferred fireplace according to the invention.
Fig. 4: a longitudinal section of a combustion chamber of Fig. 3 including a further compartment accommodating a damper flap;
Fig. 5: a cross section of a combustion chamber of a fireplace according to the invention;
Fig. 6: a front view of a fireplace according to the invention;
Fig. 7: a side view of a fireplace according to the invention;
Fig. 8: a front view of a cross section of a fireplace according to the invention;
Fig. 9: a perspective view of a part of cross section of a fireplace according to the invention;
Fig. 10 to 19: a top view on a cross section along a horizontal plane of a fireplace according to the invention, respectively the combustion chamber of a fireplace according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to a fireplace at least comprising:

a combustion chamber, comprising at least two compartments which are arranged one upon the other, and
wherein the lower and the upper compartment of said at least two compartments are separated by means a baffle leaving an opening which connects the lower compartment to the upper compartment; or
wherein the lower and the upper compartment of said at least two compartments are separated by means of several baffles, which are arranged one upon the other leaving an opening, respectively, which connect the lower compartment to the upper compartment;
wherein said at least two compartments are at least partially formed by air channels, which are opened at their lower and their upper ends, respectively, and wherein the inner surface of the combustion chamber formed by said air channels is corrugated;
wherein at least a portion of said lower compartment of said combustion chamber comprises a lining with a refractory material, preferably wherein the portion of the air channels forming said lower compartment of said combustion chamber is at least partially lined with a refractory material.

The term "fireplace" encompasses an architectural structure designed to contain fire. In its broadest meaning, the term encompasses any heating system which may be operated by means of combusting a combustible. Accordingly, the term "fireplace" encompasses terms such as "oven", "furnace" or "stove". In a preferred embodiment, said fireplace encompasses a heating system that is used in a private household, preferably a small heating system. In a preferred embodiment, said heating system provides for a power of from 5 to 15 kW, preferably of from 5 to 10 kW, more preferably 6 to 8 kW. In a further embodiment, said fireplace may provide for a power up to 50 kW.
The fireplace according to the invention comprises a housing.
The term "housing" encompasses a hard or stable casing or mantle which encloses a combustion chamber.
The term "combustion chamber" encompasses the location in which the combustible is supported and combusted.
The term "combustible" encompasses any solid fuel such as wood, wood pellets, or carbon such as coal or brown coal. In a preferred embodiment, the combustible is a solid fuel comprising wood or is wood such as wood billets or wood pellets.
Said housing of the fireplace according to the invention comprises at least a front wall, which at least partially is construed as door through which said combustion chamber may be supplied with combustible, respectively through which ashes may be removed from the combustion chamber.
The term "door" encompasses the term "furnace door" or "fireplace door".
The housing of the fireplace according to the invention further comprises a rear wall.
Said housing further comprises one or more side wall/walls. The term "one or more side wall/walls" encompasses all parts of the housing which are different from the front wall and the rear wall.
According to the invention, said front wall, said one or more side wall/walls and said rear wall form the combustion chamber. Preferably, said walls forming the combustion chamber are made from cast iron or from steel.
Said door of said front wall may also consist of or may comprise cast iron or steel. In a preferred embodiment, said door of said front wall may be construed in the form of glass such that the combustion of said combustible may be monitored.
The fireplace according to the invention also comprises an outlet for smoke gas which is generated when combustible is combusted in the combustion chamber.
The term "outlet" encompasses the portion of the fireplace through which said smoke gas may exit said fireplace. Preferably, said outlet is positioned in the rear wall of said housing. However, said outlet may also be positioned in the one or more side walls (including a top wall). Preferably, said outlet is connected to a chimney.
The term "smoke gas" is synonymously used with terms such as "flue" or "exhaust" or "exhaust gas".
The term "compartment" encompasses any space or spatiality.
The term "portion of the air channels forming said lower compartment" means that the portion of the wall of the combustion chamber formed by said air channels-consists of said air channels.
The term "inner surface of the combustion chamber formed by said air channels is corrugated" encompasses any surface which is not smooth, i.e. which comprises recesses and protrusions.
In one embodiment, the invention relates to a fireplace at least comprising:

a combustion chamber configured to support and burn combustible,
wherein the combustion chamber comprises at least two compartments, which are arranged one upon the other, and
wherein the lower and the upper compartment are separated by means of a baffle leaving an opening which connects the lower compartment to the upper compartment; or
wherein the fireplace comprises three compartments which are arranged one upon the other, wherein the lower compartment and the middle compartment are separated by means of one baffle leaving one opening which connects the lower compartment to the middle compartment; and wherein the middle compartment and the upper compartment are separated by means of one further baffle leaving one further opening which connects the middle compartment to the upper compartment;
wherein said at least two compartments are at least partially formed by air channels, which are opened at their lower and their upper ends, respectively; wherein said air channels are configured to be heated up when operating the fireplace, wherein a lower opening of the air channels is configured to aspirate air from the environment of the fireplace, and wherein an upper opening of the air channels is configured to discharge the aspirated and heated air into the environment;
wherein the inner surface of the combustion chamber formed by said air channels is corrugated; and
wherein at least a portion of said lower compartment of said combustion chamber comprises a lining with a refractory material being configured to prevent said portion to be contacted by fire of the burning combustible, wherein the portion of the air channels forming said lower compartment of said combustion chamber is at least partially lined with a refractory material which is configured to prevent said portion of the air channels to be contacted by fire of the burning combustible when operating the fireplace.

Preferably, said openings are alternatedly arranged. This allows the smoke gas to pass an extended distance before it reaches the outlet. Thus, the probability of combustion of combustible in the combustion chamber being as complete as possible is increased. This further supports a reduced emission.
The upper compartment is configured to direct said formed gas to an outlet which in turn is configured to discharge said gas from said combustion chamber.
In one embodiment, the fireplace comprises a further compartment, which is connected to said upper compartment. Preferably, said further compartment accommodates a damper flap.
Accordingly, said outlet is configured to discharge said gas into said further compartment. Said further compartment is configured to direct said gas to a chimney.
In one embodiment, said further compartment is bent upwards or is straight.
In one embodiment, said further compartment is a pipe bent upwards or is a straight pipe.
In a preferred embodiment, said further compartment accommodates a damper flap. Said damper flap is configured to allow further control of the intensity of the combustion. By an appropriate opening or closing of the flap in the further compartment, the gas flow in the fireplace according to the invention may be controlled and adjusted. In an opened position, the intensity of combustion may be increased.
In turn, by means of said damper flap in the further compartment, a further reduction of emission is supported.
In one embodiment, a portion of the lower compartment or a portion of the air channels forming said lower compartment is configured to support and burn combustible, wherein said portion is not lined with a refractory material, preferably is not lined with a ceramic or a fire proof ceramic such as vermiculite.
In one embodiment, the lower compartment is lined with vermiculite, wherein the portion of the lower compartment or a portion of the air channels forming said lower compartment and which is configured to support and burn combustible, is lined with cast iron or steel.
In one embodiment, said portion of the lower compartment of the air channels forming said lower compartment which is configured to support combustible is in the form of a grid.
Said grid is configured to direct formed ashes downwards when burning combustible.
Preferably, then an ash pan is arranged under the grid. The ash pan is configured to accommodate ashes.
In one embodiment, the lower compartment is lined with a refractory material.
The term "refractory material" encompasses any material which is not destroyed when operating the fireplace, i.e. when combusting combustible. In one embodiment, said refractory material is not destroyed or negatively affected under a temperature of up to at least 700 °C. Refractory materials commonly used in fireplace technology may be used.
The term "lining with a refractory material" is used synonymously with the term "fireplace lining" or "combustion lining" as commonly used in the art.
Preferably, said refractory material is selected from the group consisting of ceramics, fire proof ceramics, chamotte (fireclay) or refractory concrete; or metal, preferably steel or cast iron; or a combination of two or more thereof; preferably wherein said refractory material is vermiculite.
In one embodiment, the corrugated inner surface of the lower compartment of combustion chamber is not in physical contact with said lining with a refractory material.
In another embodiment, at least a portion of the corrugated inner surface of the lower compartment of combustion chamber is in physical contact with said lining with a refractory material.
In a preferred embodiment, the combustion chamber is a cylindrical combustion chamber which is positioned horizontally.
Preferably, the air channels extend in a plane, respectively, which is positioned in a vertical direction or in a substantial vertical position.
The term "substantial vertical position" allows a deviation from the vertical position, i.e. the air channels may extend in a a plane which may also be arranged in an inclined position.
Further preferably, the air channels are arranged one after another.
The air channels may have any conceivable form provided they form at least a portion of the inner surface of the combustion chamber such that said inner surface is provided in a corrugated form, or wherein the inner surface is provided in a corrugated form. In one embodiment, the air channels are extending recesses of the outer wall of the combustion chamber.
Preferably, said channels are in the form of pipes. The cross section of said pipes may be in the form of a triangle, a square, a rectangle or a circle, or any shape.
In one embodiment, the invention relates to a fireplace, at least comprising:
a housing enclosing a combustion chamber, wherein said housing at least comprises:

a front wall, which at least partially is construed as door, the door being configured to allow supplying said combustion chamber with combustible, respectively allowing removing ashes from the combustion chamber;
one or more side wall/walls;
a rear wall;
at least one outlet for gas that is formed when operating the fireplace while burning a combustible in said combustion chamber, preferably wherein said outlet is located in the rear wall or the one or more side wall/walls of the housing;
wherein the one or more side wall/walls form a horizontal cylindrical body such that also the combustion chamber has a cylindrical body, wherein the combustion chamber comprises at least
a lower and an upper compartment which are arranged one upon the other, and wherein the lower and the upper compartment are separated by means of one baffle leaving one opening which connects the lower compartment to the upper compartment; or
a lower and an upper compartment which are arranged one upon the other, and wherein the lower and the upper compartment are separated by means of more than one baffle, which are arranged one upon the other leaving one opening, respectively, which connect the lower compartment to the upper compartment;
wherein the lower compartment is configured to support and burn the combustible, the at least one baffle is configured to direct gases formed in the lower compartment when operating the fireplace via said at least one opening to the upper compartment, and the upper compartment is configured to direct the gas to the outlet, the outlet being configured to discharge said gas from said combustion chamber;
preferably wherein said gas is directed via a further compartment which preferably accommodates a damper flap, wherein said further compartment is connected to said outlet;
wherein said one or more side walls consists/consist at least partially of air channels in the form of curved pipes, which are opened at their lower ends and their upper ends, respectively, and wherein the inner surface of the combustion chamber formed by said air channels is corrugated;
wherein the air channels in the form of curved pipes are configured to be heated up when operating said fireplace, wherein a lower opening of the pipes is configured to aspirate air from the environment of the fireplace, and wherein an upper opening of the pipes is configured to discharge the aspirated and heated air into the environment;
and
wherein at least a portion of said lower compartment of the combustion chamber comprises a lining with a refractory material configured to prevent said portion of the pipes to be contacted by fire of the burning combustible when operating the fireplace, preferably wherein the portion of the air channels in the form of curved pipes forming said lower compartment of said combustion chamber is at least partially lined with a refractory material configured to prevent said portion of the pipes to be contacted by fire of the burning combustible when operating the fireplace.

Further embodiments

In a further preferred embodiment, the combustion chamber comprises at least one or at least two different aerating means.
The term "means for aerating" encompasses any conceivable means or device or equipment by means of which the combustion chamber may be aerated in order to support the combusting of the combustible. By means of said aerating, air is fed into or flows into the combustion chamber. Said air may also be termed "combustion air".
In one embodiment, the rear wall of the fireplace according to the invention bears another wall that insulates the fireplace towards the environment. Preferably, said rear wall and said another wall are spaced apart from one another.
Fig. 1 shows a side view of a longitudinal section through a combustion chamber 30 of a fireplace 10 according to the invention. Combustion chamber 30 comprises a lower compartment 50 and an upper compartment 60. The compartments are separated by baffle 80 which leaves an opening 81 between the upper compartment 60 and the lower compartment 50, and which connects the two compartments. The dashed arrow shows the direction of smoke gas flowing through the combustion chamber 30 to outlet 40. The air channels are not shown.
Fig. 2 shows the combustion chamber 30 of Fig. 1 , wherein the upper compartment 60 is connected to a further compartment 65 via outlet 40. The further compartment accommodates damper flap 66 which may be switched to a closed position as shown or to an opened position. The air channels are not shown.
Fig. 3 shows a side view of a longitudinal section through a combustion chamber 30 of a fireplace 100 according to the invention. Combustion chamber 30 comprises a lower compartment 50, a middle compartment 55 and an upper compartment 60. The compartments are separated by baffles 80 which leave one opening 81 between the upper compartment 60 and the middle compartment 55, and one opening between the middle compartment 55 and the lower compartment 50. The dashed arrow shows the direction of smoke gas flowing through the combustion chamber 30 to outlet 40. The air channels are not shown.
Fig. 4 shows the combustion chamber 30 of Fig. 3 , wherein the upper compartment 60 is connected to a further compartment 65 via outlet 40. The further compartment accommodates damper flap 66. The air channels are not shown.
Fig. 5 shows a front view of a cross section through a combustion chamber 30 of a fireplace according to the invention. Baffle 80 consists of a refractory material. The side walls of the lower compartment 50 are lined with refractory material 90 such that the portion of the air channels, respectively the portion of the lower compartment which is configured to support combustible, is not lined with a refractory material 90. The air channels are not shown.
Fig. 6 shows a front view of a preferred fireplace 10 according to the invention. Fireplace 10 comprises air channels in the form of curved pipes 20 made from cast iron or steel which form the one or more side wall/walls 16 of fireplace 10. Thus, at least a portion of said side wall/walls 16 consists of said curved pipes 20. Side wall 16, front wall 11 and rear wall 15 (not shown) form a cylindrical combustion chamber 30 wherein at least a portion of the inner surface of the combustion chamber is corrugated. The combustion chamber 30 is construed as in Fig. 5 . During operation of fireplace 10, air from the environment being contained in curved pipes 20 is heated up very fastly and steadily. Heated air ascends and exits pipes 20 at the upper opening thereof. Cold air is aspirated at the lower opening of pipes 20 and is thus heated up. Consequently, the environmental air is recirculated through said pipes. Thus, heat transfer from the fireplace to the environment is effected by thermal convection.
Front wall 11 is partially construed as door 12. Combustion chamber 30 of fireplace 10 may be monitored through a glass plate 13. Front wall 11 may have a handle for closing combustion chamber 30. The handle or the front wall 11 may bear one or more openings (means for aerating 4) through which combustion air may enter combustion chamber 30 in order to support the combustion of combustible, preferably wood.
Fig. 7 shows a side view of the preferred fireplace 10 according to the invention. Curved pipes 20 form said cylindrical combustion chamber 30 (not shown). Smoke gas being formed when combusting combustible may exit outlet 40 which is located in the rear wall 15 of fireplace 10. The portion of rear wall 15 forming a part of the lower compartment 50 is lined with a refractory material.
Fig. 8 shows a front view of a cross section along rear wall 15 of the preferred fireplace 10 according to the invention. Rear wall 15 has openings which represent third means for aerating 3. From further openings in rear wall 15, second means for aerating 2 extend into the interior of combustion chamber 30. Said second means 2 extend through the refractory material 90 of the lining. Optionally, first means for aerating 1 extend from a further opening in rear wall 15 into the interior of combustion chamber 30, i.e. into the lower compartment. The air channels are not shown.
Fig. 9 shows a perspective view of a part of a cross section of a preferred fireplace 10 according to the invention as presented in Fig. 8 . The view represents a part of combustion chamber 30 which is formed by side wall 16 and rear wall 15. First means for aerating 1 and second means for aerating 2 are positioned in combustion chamber 30 in the form of pipes extending from openings in rear wall 15, respectively. First means for aerating 1 bears two rows of parallel openings through which combustion air enters combustion chamber 30 substantially vertically upwards. The first means 1 are optional means. Both second means for aerating 2 bear one row of openings through which combustion air may enter combustion chamber 30 substantially horizontally. Both second means for aerating 2 face each other. Rear wall 15 bears third means for aerating 3. Front wall 11 bears at least one fourth means for aerating 4 (front wall 11 and fourth means for aerating 4 not shown). The air channels, the upper and lower compartment including the baffle separating said lower from said upper compartment and the lining with a refractory material are not shown.
The openings of the first means for aerating 1 and second means for aerating 2 preferably have a diameter of from 1 to 10 mm, more preferred 2 to 7 mm, respectively.
Means for aerating 3 and means for aerating 4 preferably have a diameter of from 1 to 15 mm, more preferred of from 5 to 10 mm, respectively.
Preferably, the length of first means for aerating 1 and second means for aerating 2 approximately equals the distance between rear wall 15 and front wall 11, respectively.
Fig. 10 shows a top view on a cross section along a horizontal plane of a fireplace 10 according to the invention. Combustion chamber 30 is formed by curved pipes 20 having a circular diameter. The pipes form a corrugated inner surface of the combustion chamber 30. The lining with a refractory material is not shown.
Fig. 11 shows a top view on a cross section along a horizontal plane of a fireplace 10 according to the invention. Combustion chamber 30 is formed by curved pipes 20 having a circular diameter. The pipes are alternatedly arranged. The pipes form a corrugated inner surface of the combustion chamber 30. The pipes (of the lower compartment) are lined with a refractory material such that the refractory material partially is in physical contact with the lining (90).
Fig. 12 shows a top view on a cross section along a horizontal plane of a fireplace 10 according to the invention. Combustion chamber 30 is formed by air channels 20 having a cross section in the form of semicircles which are formed as recesses in the side wall/walls of combustion chamber 30. The air channels form a corrugated inner surface of the combustion chamber 30. The lining with a refractory material is not shown.
Fig. 13, 14 and 15 show a top view on a cross section of a fireplace 10 according to the invention along a horizontal plane, respectively. Combustion chamber 30 is formed by air channels 20 having a cross section in the form of semicircles ( Fig. 13 ), rectangles ( Fig. 14 ), and triangles ( Fig. 15 ). The air channels form a corrugated inner surface of the combustion chamber 30. The lining with a refractory material is not shown.
Fig. 16 shows a top view on a cross section along a horizontal plane of a fireplace 10 according to the invention. Combustion chamber 30 is formed by air channels 20 having a cross section in the form of triangles which are formed as recesses in the side wall/walls of combustion chamber 30. The air channels form a corrugated inner surface of the combustion chamber 30. The lining with a refractory material is not shown.
Fig. 17 shows a top view on a cross section along a horizontal plane of a fireplace 10 according to the invention. Combustion chamber 30 is formed by double walls which form two air channels. Fins protrude into the combustion chamber 30 in order to provide a corrugated inner surface of the combustion chamber 30. The lining with a refractory material is not shown.
Fig. 18 shows a top view on a cross section along a horizontal plane of a fireplace 10 according to the invention. Fins protrude into the combustion chamber 30 in order to provide a corrugated inner surface of the combustion chamber 30. The air channels 20 are merely formed by the side walls of the combustion chamber. The lining with a refractory material is not shown.
Fig. 19 shows a top view on a cross section along a horizontal plane of a fireplace 10 according to the invention. Combustion chamber 30 is formed by wavy air channels 20. The pipes form a corrugated inner surface of the combustion chamber 30. The lining with a refractory material is performed such that said lining is not in physical contact with the air channels.

EXAMPLES

Emissions of fireplaces having pipes allowing for recirculation of environmental air based on convection were determined according to EN13240. The fireplaces had the same construction principle except that one series contained a lining with a refractory material in the lower compartment (fireplaces according to the invention), whereas the series for comparison was free from a lining with a refractory material (fireplaces fror comparison). The fireplaces were further equipped with the further compartment in the form of a pipe bent upwards containing a damper flap, and with second, third and fourth means for aerating.
The results are summarized in the following Tables 1 to 3. The results evidence a considerable reduction of emission in terms of carbon monoxide (CO) and particulate matter (PM) for the fireplaces according to the invention. Table 1

Without lining With lining Reduction [%]

Capacity [kW] 8 6.8

CO (13 O₂) [mg/Nm³] 1,875 1,250 33

PM (13 O2) [mg/Nm³] 40 28 30

Table 2

Without lining With lining Reduction [%]

Capacity [kW] 10.4 10

CO (13 O₂) [mg/Nm³] 2,092 1,000 52

PM (13 O2) [mg/Nm³] 35.9 20 44

Table 3

Without lining With lining Reduction [%]

Capacity [kW] 13.5 14.2

CO (13 O₂) [mg/Nm³] 2,875 1,250 57

PM (13 O2) [mg/Nm³] 32 22 31

Reference numerals

10, 100: fireplace
20: air channels, e.g. in the form of curved pipes
30: combustion chamber
40: outlet
50: lower compartment
55: middle compartment
60: upper compartment
65: further compartment
66: damper flap

80: baffle for separating compartments from one another
81: opening

90: refractory material

11: front wall
12: door
13: glass plate
15: rear wall
16: side wall

1: first means for aerating
2: second means for aerating
3: third means for aerating
4: fourth means for aerating
5: fifth means for aerating

Claims

Fireplace (10, 100), at least comprising:
a combustion chamber (30), comprising at least two compartments (50, 55, 60) which are arranged one upon the other, and

wherein the lower compartment (50) and the upper compartment (60) of said at least two compartments (50, 55, 60) are separated by means of a baffle (80) leaving an opening (81) which connects the lower compartment (50) to the upper compartment (60); or

wherein the fireplace comprises three compartments (50, 55, 60) which are arranged one upon the other, wherein the lower compartment (50) and the middle compartment (55) are separated by means of one baffle (80) leaving one opening (81) which connects the lower compartment (50) to the middle compartment (55); and wherein the middle compartment (55) and the upper compartment (60) are separated by means of one further baffle (80) leaving one further opening (81) which connects the middle compartment (55) to the upper compartment (60);

characterized in that

said lower compartment (50) and at least one the middle compartment (55) and the upper compartment (60) are at least partially formed by air channels (20), which are opened at their lower and their upper ends, respectively, and wherein the inner surface of the combustion chamber formed by said air channels is corrugated;

and in that at least a portion of said lower compartment of said combustion chamber (30) comprises a lining with a refractory material (90), wherein the portion of the air channels (20) forming said lower compartment (50) of said combustion chamber (30) is at least partially lined with a refractory material (90).
Fireplace (10, 100) of claim 1, wherein the fireplace (10, 100) comprises a further compartment (65), which is connected to said upper compartment (60).
Fireplace (10, 100) of claim 2,
wherein the further compartment (65) accommodates a damper flap (66).
Fireplace (10, 100) of any one of the preceding claims, wherein the corrugated inner surface of the lower compartment (50) of combustion chamber (30) or a portion of the air channels (20) forming said lower compartment (50) is not in physical contact with said lining with a refractory material (90); or wherein at least a portion of the corrugated inner surface of the lower compartment (50) or a portion of the air channels (20) forming said lower compartment (50) of combustion chamber (30) is in physical contact with said lining with a refractory material (90).
Fireplace (10, 100) of any one of the preceding claims, wherein a portion of the lower compartment (50) or a portion of the air channels (20) forming said lower compartment (50) is configured to support combustible, wherein said portion is not lined with a refractory material (90); or
wherein the lower compartment (50) is lined with vermiculite (90), wherein the portion of the lower compartment (50) or a portion of the air channels (20) forming said lower compartment (50) and which is configured to support and burn combustible, is lined with cast iron or steel.
Fireplace (10, 100) of claim 5, wherein a portion of the lower compartment (50) or a portion of the air channels (20) forming said lower compartment (50) which is configured to support combustible is in the form of a grid; preferably wherein under the grid an ash pan is arranged.
Fireplace (10, 100) of any one of claims 1 to 6, wherein lower compartment (50) comprises a rear wall (15) which comprises a lining with a refractory material (90).
Fireplace (10, 100) of any one of the preceding claims, wherein at least a portion of upper compartment (60) comprises a lining with a refractory material (90).
Fireplace (10, 100) of any one of the preceding claims, wherein said at least one baffle (80) consists of a refractory material (90); or is lined with a refractory material (90).
Fireplace (10, 100) of any one of the preceding claims, wherein said refractory material of said lining (90) is selected from the group consisting of ceramics, fire proof ceramics, chamotte (fireclay) or refractory concrete; or metal, preferably steel or cast iron; or a combination of two or more thereof; preferably wherein said refractory material is vermiculite.
Fireplace (10, 100) of any one of claims 3 to 10, wherein said further compartment (65) is bent upwards or is straight; preferably wherein said further compartment is a pipe.
Fireplace (10, 100) of any one of the preceding claims, wherein the combustion chamber (30) comprises one aerating means (1, 2, 3, 4, 5) or comprises at least two different aerating means (1, 2, 3, 4, 5).
Fireplace (10, 100) of any one of the preceding claims, wherein the combustion chamber (30) is a cylindrical combustion chamber which is positioned horizontally.
Fireplace (10, 100) of any one of the preceding claims, wherein the air channels (20) extend in a plane, respectively, which is positioned in a vertical direction.
Fireplace (10, 100) of any one of the preceding claims, at least comprising:
a housing enclosing a combustion chamber (30), wherein said housing at least comprises:
a front wall (11), which at least partially is construed as door (12), the door (12) being configured to allow supplying said combustion chamber (30) with combustible, respectively allowing removing ashes from the combustion chamber (30);

one or more side wall/walls (16);

a rear wall (15);

at least one outlet (40) for gas that is formed when operating the fireplace while burning a combustible in said combustion chamber (30), preferably wherein said outlet (40) is located in the rear wall (15) or the one or more side wall/walls (16) of the housing;

wherein the one or more side wall/walls (16) form a horizontal cylindrical body such that also the combustion chamber (30) has a cylindrical body, wherein the combustion chamber (30) comprises at least

a lower compartment (50) and an upper compartment (60) which are arranged one upon the other, and wherein the lower compartment (50) and the upper compartment (60) are separated by means of a baffle (80) leaving an opening (81) which connects the lower compartment (50) to the upper compartment (60)

wherein the lower compartment (50) is configured to support and burn the combustible, the baffle (80) is configured to direct gases formed in the lower compartment (50) when operating the fireplace (10, 100) via said at least one opening (81) to the upper compartment (60); and the upper compartment (60) is configured to direct the gas to the outlet (40), the outlet (40) being configured to discharge said gas from said combustion chamber (30);

wherein said one or more side walls (16) consists/consist at least partially of said air channels (20) in the form of curved pipes;

wherein the air channels (20) in the form of curved pipes are configured to be heated up when operating said fireplace (10, 100), wherein a lower opening of the pipes is configured to aspirate air from the environment of the fireplace (10, 100), and wherein an upper opening of the pipes is configured to discharge the aspirated and heated air into the environment;

and

wherein said lining of at least a portion of said lower compartment (50) of combustion chamber (30) with a refractory material (90) is configured to prevent said portion of the air channels (20) in the form of curved pipes to be contacted by fire of the burning combustible when operating the fireplace (10, 100).