Wood stove equipped with a recirculation duct for combustion gases

Abstract

A wood stove 1 is equipped with a combustion chamber 3, the wall 5 of which is equipped with a number of air supply openings 7 and 9 and exhaust openings 11 and 13 for combustion gases 14, as well as two wood supply openings 15 for logs 17. The wood stove 1 also has two storage ducts 19 and 21 for logs 17, which are connected to the wood supply openings 15 and extend upwards from the combustion chamber 3 and are closed at the upper end by covers 22. The wood stove 1 also has two exhaust ducts 23 and 25 for combustion gases 14, which are connected to the exhaust openings 11 and 13. One of the exhaust ducts for combustion gases forms a recirculation duct 23 which extends upwards from the combustion chamber 3 and is connected to the ducts near the top of the storage ducts 19 and 21 to prevent the combustion gases from rising from the combustion chamber 3 into the storage ducts 19 and 21.

Description

[0001] Wood stove equipped with a recirculation duct for combustion gases

[0002] DESCRIPTION:

[0003] Technical field of the invention

[0004] The invention relates to a wood stove comprising: a combustion chamber, the wall of which is provided with a number of air supply openings and exhaust openings for combustion gases, as well as at least one wood supply opening for logs, at least one storage duct for logs that is connected to the wood supply opening and extends upwards from the combustion chamber and is closed at the upper end by a lid, and two exhaust ducts for combustion gases that are connected to the exhaust openings.

[0005] Thanks to these storage ducts, you do not have to throw wood into the stove every time, but the wood stove can bum for a relatively long time on the wood in the storage ducts. As the logs present in the combustion chamber burn more, the logs present above it slowly sink down. This results in an automatic supply of logs, which means that a new log does not have to be manually inserted every time a log has burned out.

[0006] Background of the invention

[0007] Such a wood stove is known from EP 2 597 371 A. The disadvantage of this known wood stove is that combustion gases and / or gases released from the wood during heating rise in the storage tube and cause tar deposits on the inside of the storage tube in the cooler, higher parts of the storage tube. In the known wood stove, one of the exhaust tubes extends partly along the storage tube, with a thermally insulated partition wall between the exhaust tube and the storage tube.

[0008] Summary of the invention An object of the invention is to provide a wood stove of the type described in the preamble in which no or less tar deposits occur in the storage tube. To this end, the wood stove according to the invention is characterised in that one of the exhaust ducts for combustion gases forms a recirculation duct that extends upwards from the combustion chamber and is connected to the storage duct near the top of the storage duct. By returning part of the combustion gases to the top of the storage duct, a downward flow is created in the storage duct that prevents the rise of incompletely burned combustion gases and gases escaping from the wood as a result of heating the lower logs and directs the flames towards the exhaust ducts. As a result, no deposit of tar can occur on the inside of the storage ducts.

[0009] An embodiment of the wood stove according to the invention is characterised in that the exhaust ducts from the combustion chamber are insulated from the outside environment over a length, whereby this length and the insulation are configured in such a way that the temperature of the combustion gases in these parts of the exhaust ducts remains sufficiently high to allow complete afterburning of the combustion gases to take place. Preferably, the distance from the combustion chamber where the temperature in the exhaust ducts is sufficiently high for afterburning is large enough to achieve complete combustion of the gases so that the combustion gases are clean and cannot cause any deposits of tar in the storage duct.

[0010] A further embodiment of the wood stove according to the invention is characterised in that at and / or near the exhaust opening to which the recirculation duct is connected and / or in the recirculation duct, a number of air supply openings are present, which are directed away from the combustion chamber into the recirculation duct and / or are directed upwards in the recirculation duct, in order to promote the flow of combustion gases in the recirculation duct. When starting up the wood stove, the combustion gases will be more likely to rise in the storage duct because little or no recirculation occurs at that time. In order to promote recirculation, especially during start-up, a number of the air supply openings are located near the exhaust opening, for example in the lower edge of the recirculation duct, or in the recirculation duct, and the openings are such that they stimulate the flow of combustion gases from the firebox into the recirculation duct and / or flow in the recirculation cylinder upwards.

[0011] A further embodiment of the wood stove according to the invention is characterised in that a casing is present over the entire or part of the circumference of the storage duct over the entire or almost entire height of the storage duct at a distance from the storage duct, whereby a convection channel is formed between the casing and the storage duct and whereby the lower and upper ends of the convection channel are open. During use of the wood stove, a natural flow of air will take place in the convection channel, whereby relatively cold air flows into the bottom of the convection channel, is heated in the convection channel by the heat in the storage tube near the firebox, causing the warm air to rise in the convection channel and is heated in the upper part of the storage tube, so that the storage tube obtains a more even temperature over the entire height and less combustion and / or gasification of wood takes place at the bottom of the storage tube.

[0012] It should be noted that the use of a convection channel around a storage tube for wood for a wood-burning stove can also be used for other wood-burning stoves where no recirculation of combustion gases takes place and has the same favourable effect on reducing combustion and gasification at the bottom of the storage tube.

[0013] Brief description of the drawings

[0014] The invention will be explained in more detail below using an exemplary embodiment of the wood-burning stove according to the invention shown in the drawings. In the drawings:

[0015] Figure 1 shows the wood-burning stove in vertical section;

[0016] Figure 2 shows an enlarged detail of the wood-burning stove; and Figure 3 shows the wood stove in horizontal section.

[0017] Detailed description of the drawings

[0018] Figure 1 shows an embodiment of the wood stove according to the invention in vertical section. The wood stove 1 is provided with a combustion chamber 3, the wall 5 of which is provided with a number of air supply openings 7 and discharge openings 11 and 13 for combustion gases 14, to which two discharge ducts 23 and 25 for combustion gases 14 are connected.

[0019] The wall 5 of the combustion chamber 3 is further provided with two wood supply openings 15, to which two storage ducts 19 and 21 for logs 17 are connected. These storage ducts extend upwards from the combustion chamber 3 and are closed at the upper end by covers 22. One of the exhaust ducts for combustion gases 14 forms a recirculation duct 23 which extends upwards from the combustion chamber 3 and is connected to the storage ducts near the top of the storage ducts 19 and 21. Via this recirculation duct 23, combustion gases 14 flow at the top in the storage ducts 19 and 21 in the direction of the combustion chamber 3 and combustion gases are prevented from rising from the combustion chamber 3 into the storage ducts 19 and 21.

[0020] Pipes 8 are connected to two of the air supply openings 7 and are provided with further air supply openings 9. In figure 2, a detail of the wood stove 1 at the location of these pipes 8 is shown enlarged. The tubes 8 extend along two opposite lower edges of the recirculation duct 19. The further air inlet openings 9 are directed in the recirculation duct 19 to promote the flow of combustion gases 14 from the combustion chamber 3 into the recirculation duct 19. This is particularly important during starting up of the wood stove to stimulate the flow in the recirculation duct 19 so that less or no rise of combustion gases 14 takes place in the storage ducts 19 and 21.

[0021] In order to achieve complete combustion in the combustion gases 14, afterburning of the combustion gases 14 must take place. To this end, the combustion gases 14 must not be cooled down too much. This is achieved by insulating the exhaust ducts 23 and 25 from the outside environment over a length L from the combustion chamber 3. This length L and the insulation 27 are configured in such a way that the temperature of the combustion gases 14 in these parts of the exhaust ducts 23 and 25 remains sufficiently high to allow complete afterburning of the combustion gases 14 to take place.

[0022] In addition to the two storage ducts 19 and 21, there is also a third empty duct 20 so that the three ducts together have a rectangular cross-section. This is clearly visible in figure 3, which shows a horizontal cross-section of the wood stove 1 at the location of the connection of the recirculation duct 19 to the storage ducts 19 and 21. A casing 29 is present over the circumference and over the height of these ducts 19-21. This casing 29 is present at a distance from the ducts, whereby a convection channel 31 is formed between the casing 29 and the ducts 19-21. The convection channel 31 is open at the lower and upper ends 31a and 31b to create a natural air flow through the convection channel 31. This air flow cools the lower parts of the storage ducts 19 and 21 and heats the upper parts of the storage ducts. This results in a more even temperature over the height of the storage ducts, so that no combustion or gasification of the logs takes place at the bottom of the storage ducts 19 and 21. In addition, this results in less cooling of the combustion gases flowing above in the storage ducts 19 and 21 and flowing downwards in the storage ducts, so that the temperature of the firebox is less affected by the combustion gases flowing into the combustion chamber.

[0023] Although the present invention is elucidated above on the basis of the given drawings, it should be noted that this invention is not limited whatsoever to the embodiments shown in the drawings. The invention also extends to all embodiments deviating from the embodiments shown in the drawings within the scope of the invention defined by the appended claims.

Claims

CLAIMS:

1. Wood stove (1) comprising: a combustion chamber (3) the wall (5) of which is provided with a number of air supply openings (7, 9) and exhaust openings (11, 13) for combustion gases (14), as well as at least one wood supply opening (15) for logs (17), at least one storage duct (19, 21) for logs (17) which is connected to the wood supply opening (15) and extends upwards from the combustion chamber (3) and is closed at the upper end by a cover (22), and two exhaust ducts (23, 25) for combustion gases (14) which are connected to the exhaust openings (11, 13), characterized in that one of the exhaust ducts for combustion gases forms a recirculation duct (23) which extends upwards from the combustion chamber (3) and is connected to the storage duct (19, 21) near the top of the storage duct (19, 21).

2. Wood stove (1) according to claim 1, characterised in that the exhaust ducts (23, 25) are insulated from the outside environment over a length (L) from the combustion chamber, this length (L) and the insulation (27) being configured in such a way that the temperature of the combustion gases in these parts of the exhaust ducts (23, 25) remains sufficiently high to allow complete afterburning of the combustion gases to take place.

3. Wood stove (1) according to claim 1 or 2, characterised in that at and / or near the exhaust opening (11) to which the recirculation duct (23) is connected and / or in the recirculation duct (23) a number of air supply openings (9) are present, which are directed away from the combustion chamber into the recirculation duct (23) and / or are directed upwards in the recirculation duct (23), in order to promote the flow of combustion gases in the recirculation duct (23).

4. Wood stove (1) according to claim 1, 2 or 3, characterised in that a casing (29) is present over the entire or part of the circumference of the storage tube (19, 21) over the entire or almost entire height of the storage tube (19, 21) at a distance from the storage tube (19, 21), whereby a convection channel (31) is formed between the casing (29) and the storage tube (19, 21) and whereby the lower and upper ends (31a, 31b) of the convection channel (31) are open.

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