SE527375C2 - Rust and burner including such rust - Google Patents

Abstract

The invention relates to a fire grate for a burner for burning o solid fuel bodies, which fire grate (9) comprises an inside (10) with a supporting surface (11) intended for receiving fuel bodies, outlet holes (14) for combustion-supporting gas being arranged in said inside (10) in order to make possible supply of combustion-supporting gas to fuel bodies resting on the supporting surface (11). The inside (10) of the fire grate comprises two o more spaces (12), each of which being formed by a hollow (13) arranged in said inside (10) and each of which having at leas one outlet hole (14) for combustion-supporting gas arranged in the associated hollow. The invention also relates to a burne comprising such a fire grate.

Description

2 30 35 527 375 2 oats, active stirring of the hearth is required to obtain an efficient combustion of the grain. Therefore, to enable the firing of grain in a conventional pellet burner, it is usually supplemented with a mechanical stirrer which provides the required agitation of the fire hearth. A problem here is that the stirrer is subjected to very heavy wear due to the very high combustion temperature (up to about 1200 ° C) required for firing with grain, so the stirrer must be replaced at regular intervals. Another problem associated with grain burning is that when burning with grain, significantly larger amounts of ash are formed than when burning with other comparable biofuels, such as wood pellets. It often happens that the ash melts in the combustion chamber, sints and forms slag. This slag formation risks, among other things, causing clogging of the outlet holes for primary air which are arranged in the rust.

OBJECT OF THE INVENTION The object of the present invention is to create in a simple manner good possibilities for an efficient combustion of solid fuel bodies in a burner.

SUMMARY OF THE INVENTION According to the invention, said object is achieved by means of a grate having the features stated in claim 1. The grate according to the present invention has an inside which comprises two or more spaces which are each formed by a recess arranged in said inside and which each have at least one outlet hole for combustion-supporting gas arranged in the associated recess, for example in form of air. In this way, the combustion space closest to the grate is divided in a simple way into separate smaller spaces, each of which is associated with a separate supply of combustion-supporting gas, for example in the form of so-called primary air, via outlet heels in the inside of the grate. In this way, a good contact between fuel and combustion-supporting gas is obtained in the respective space, while at the same time an efficient stirring of the fuel in the respective space is made possible by the separate gas supply in the respective space. With a grate according to the present invention, it becomes possible to process the fire hearth present on the grate in smaller areas and thereby "disturb" the fire hearth in order to obtain a good firing process.

According to the invention, at least some, preferably the main part or all, of said spaces have at least one outlet hole arranged for combustion-assisting gas arranged in the associated recess which is connected to a gas duct which has its outlet directed towards the downstream end of the grate. In this way, said gas, which usually consists of primary air, helps to control the combustion and formed combustion residues such as ash in the direction of the downstream end of the grate and was sold in the direction of the outlet opening of the combustion chamber.

By suitable selection of the number of separate spaces, ie the number of individual depressions, inside the grate and suitable placement of said outlet holes and direction of the outlets of the gas ducts connected to the outlet holes, it becomes possible to achieve a stirring of fuel bodies resting on the grate and an incandescent bed that is sufficiently efficient to meet the degree of agitation required for efficient combustion of cereals, such as oats. With the aid of the grate according to the invention, it thus becomes possible to achieve a desired degree of stirring without the need for mechanical stirrers. By creating an uninterrupted active movement in the incandescent bed in this way, the incandescent bed is prevented from burning in a coherent mass, which reduces the risks of cohesive ash and sintering.

According to a preferred embodiment of the invention, each space has at least one outlet hole for combustion-assisting gas arranged in or near the deepest part of the associated depression. This ensures that said gas can be effectively caused to affect fuel bodies and combustion residues located in one of said spaces so that a good combustion is possible while at the same time ash can be prevented from accumulating in the bottom. at the respective space.

According to a further preferred embodiment of the invention, at least the inside of the grate, preferably the entire grate, is formed of ceramic material or stone material. These materials exhibit high heat resistance and high heat storage capacity. By using this type of material in the rust instead of metal material, improved possibilities are created to maintain the relatively high combustion temperature required for firing with grain.

According to a further preferred embodiment of the invention, the respective outlet hole is connected to a gas duct which extends through the grate and is integrated therein, wherein each gas duct is suitably formed by a continuous heel formed in the grate. In this way, the combustion conditions in a combustion chamber can be easily adapted by the design of the grate itself which is located in the combustion chamber, since the grate according to this embodiment also defines the gas ducts connected to the outlet holes and thus the directions of the gas ducts. By suitable selection of the number of separate spaces inside the grate and suitable placement of the outlet holes and direction of the outlet of the gas ducts connected to the outlet holes, it becomes easy to achieve desired combustion conditions in a combustion chamber provided with this grate. These combustion conditions can easily be varied if necessary, for example when a change of fuel type is to take place, by replacing a grate in a combustion chamber with a grate with a different detailed design.

Further preferred embodiments of the grate according to the invention appear from the dependent claims and the following description.

The invention also relates to a burner according to claim 13. 10 15 20 25 30 35 527 375 s BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in more detail below by means of exemplary embodiments, with reference to the accompanying drawings.

It is shown in: Fig. 1 a schematic, cut side view of a burner according to a first embodiment, Fig. 2 an exploded view of a grate according to a first embodiment, Fig. 3 a partially cut side view of the bottom plate of the grate according to Fig. 2, Fig. 4 a partially cut perspective view of a portion of a burner according to a second embodiment, Fig. 5 a cross-sectional view of a grate according to a second embodiment, Fig. 6 a cross-sectional view of a grate according to a third embodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Fig. 1 schematically illustrates an embodiment of a burner 1 according to the present invention. This burner is designed for the combustion of solid fuel bodies, for example in the form of wood pellets, grain, wood chips, peat briquettes, etc. The burner 1 comprises a combustion tank 2, a so-called combustion cup, which houses a combustion chamber 3 where the combustion of fuel bodies couple is meant to happen. In the illustrated embodiment, the combustion tank 2 is mounted inside an outer casing 4 of the burner. The combustion tank 2 has a first opening 5 for allowing the introduction of fuel bodies into the combustion chamber 3 and a second opening 6 through which flue gases and combustion residues are intended to flow out of the combustion chamber. In the illustrated embodiment, the first opening 5 is arranged in a first end of the combustion tank 2 and the second opening 6 in the opposite second end of the combustion tank. The outer casing 4 of the burner has an opening which coincides with said second opening 6 of the combustion tank. A feed line 7 for fuel bodies opens into the combustion chamber 3 via said first opening 5. In the illustrated embodiment, the feed line 7 is designed as a downcomer for allowing fuel bodies to be fed into the combustion chamber 3 by gravity. However, the burner 1 according to the invention could be provided with some type of feed means, such as a feed screw or the like, for feeding fuel bodies into the combustion chamber. The wall 2a of the combustion tank facing the feed line 7 is suitably lined on its inside with a disc 30 of ceramic material or stone material and suitably also other walls of the combustion tank 2 are internally lined with elements of ceramic material or stone material. The walls 2a, 2b of the combustion tank are suitably formed of sheet metal.

The burner 1 further comprises a device 8 for supplying combustion-supporting gas, for example in the form of air, to the combustion chamber 3. In the illustrated embodiment, this device 8 consists of a fan which is arranged to blow air into the combustion chamber to thereby support the combustion. of fuel bodies in the combustion chamber. In this case, the air is led into the space between the burner outer casing 4 and the combustion tank 2 and then into the combustion tank via openings not shown therein. The air is led into the combustion chamber 3 partly as primary air, illustrated by the arrows P1, at the lower part of the combustion chamber and partly as secondary air, illustrated by the arrows P2, at the upper part of the combustion chamber. According to the present invention, the lower part of the combustion chamber is formed by a grate 9 of a type which will be described in more detail below with reference to Figs. 2 and 3.

The upper part of the combustion chamber is formed by a gas neck 32 of a type which will be described in more detail below with reference to Fig. 4. The burner 1 may also comprise additional components of a conventional nature in addition to those described here, such as, for example, a lighter and different types of monitoring means and control means. The burner 1 according to the invention is intended to be included in a conventional boiler for supplying heat to a heating system for heating indoor air in a building, such as for instance in a residential building in the form of a villa or a multi-family house. The burner 1 is advantageously designed to replace the oil burner in a conventional villa boiler to enable the use of a fuel other than oil.

The term "rust" in this specification and the appended claims refers to the element which is intended to form the bottom and side wall portions adjoining the bottom and which is intended to accommodate solid fuel bodies during combustion thereof in said combustion chamber.

The term “gas neck” in this specification and the appended claims refers to the element which is intended to form the upper part of a combustion chamber and which contributes to guiding the flue gases formed in the desired direction. Fig. 2 illustrates a grate 9 according to an embodiment of the present invention. According to this embodiment, the grate is divided into a plurality of separate elements, which here consist of a bottom plate 9a, two side elements 9b, 9c connecting to the bottom plate, which extend along the bottom plate 9a on each side thereof, a central front element 9d connected to one end 40 of the base plate and two side-facing front elements 9e, 9f, which are connected to the end 41, 42 of each side element 9b, 9c. The front elements 9d-f form a stop which is intended to help retain in the grate 9 fuel bodies which have not yet been completely burned. Fig. 2 shows said elements 9a-f separated from each other, but they are intended to abut closely against each other to form a rust when they are arranged in a combustion chamber. By dividing the grate 9 into separate removable elements, the assembly of the grate in a combustion tank of an existing burner is facilitated, while at the same time it becomes possible to subsequently remove individual elements of the grate for cleaning, repair or removal. - byte. Because the different elements of the rust are removable, it will also be possible to replace an element with a certain configuration for an element with a different configuration in order to thereby adapt the combustion conditions depending on the type of fuel bodies which are currently intended to be used as fuel in the burner. Of course, it is also possible to design the entire grate in a single piece if this is appropriate. 'Inventive. the grate 9 comprises an inside 10 with a support surface 11 intended for receiving fuel bodies. The inside 10 of the grate comprises two or more spaces 12 which are each formed by a recess 13 arranged in said inside 10 and which each have at least one outlet hole 14 for combustion-supporting gas arranged in the associated recess. At least a part of the surface of the respective recess 13 forms a portion of said support surface 11 and consequently the respective recess 13 has such a size that the fuel bodies which are intended to be combusted are at least partially receptive therein. Said outlet holes 14 are intended to enable the supply of combustion-assisting gas to fuel bodies received in the grate. The grate 9 has a downstream end 43a via which flue gases and combustion residues formed during the combustion of fuel bodies resting on the grate are intended to be led away from the grate.

In the embodiment illustrated in Fig. 2, the inside 10 of the grate is formed by the upper surface 10a of the bottom plate 9a and by the inner surfaces 10b, 10c of the side elements 9b, 9c. All these surfaces 10a-c here have spaces 12 and outlet holes 14 of the type indicated above.

Preferably, at least the inside 10 of the grate and preferably the entire grate 9 is formed of ceramic material or stone material. In the embodiment illustrated in Fig. 2, the bottom plate 9a of the grate is provided with ten spaces 12 of said type and in this case the respective space has one or two outlet holes 14 for combustion-supporting gas. Five spaces 12 are here arranged one after the other in a first row 16a in the longitudinal direction of the bottom plate and another five spaces 12 are arranged one after the other in a second row 16b in the longitudinal direction of the bottom plate, the second row 16b of spaces extending parallel to the first row 16a of spaces. The spaces 12 in each row are mutually separated by transverse ridges 15 arranged in the inside 10 of the grate and the spaces in the first row 16a are separated from adjacent spaces in the second row 16b by longitudinal ridges 17 arranged in the inside 10 of the grate.

Of course, the grate according to the invention may be provided with both more and fewer spaces 12 of the type in question than those shown in Fig. 2, and these spaces may also have other shapes and be mutually configured in other ways than those shown in this figure.

In the embodiment illustrated in Fig. 2, longitudinal, upwardly open channels 44 are provided at the upstream end of the base plate 9a and the side elements 9b, 9c to contribute to air currents at the upstream end 43b of the grate which are favorable for combustion.

At each space 12, at least one outlet hole 14 should be arranged in or near the deepest part of the associated recess 13 so that the combustion-supporting gas flowing into a recess via said outlet hole 14 can be caused to influence such a large part. as possible of fuel bodies and combustion residues present in the depression. At least some, preferably the main part or all, of said outlet heel 14 is connected to a gas duct 18 (see Fig. 3) which has its outlet 18a directed towards the downstream end 43a of the grate. At least some, preferably each, outlet heel 14 is connected to a gas duct 18 which extends through the grate 9 and is integrated therein and which is suitably formed by a through hole formed in the grate, such as illustrated in Fig. 3.

In the embodiment illustrated in Fig. 2, longitudinal inlet ducts 45 are arranged on the outwardly facing side of the side elements 9b, 9c of the grate to guide combustion-supporting gas to the gas ducts 18 in the side elements 9b, 9c.

In the illustrated embodiments, each of said spaces 12 arranged in a row comprises a pair of walls included in the associated recess 13, consisting of: - a first wall 20a facing the downstream end 43a of the grate, and - a second wall 20b which is arranged at an angle to the first wall 20a and which is connected to the lower part of the first wall 20a via a connecting line 21 which extends substantially in the transverse direction of the grate.

In each wall pair, the first wall 20a is suitably shorter than the second wall 20b, as illustrated in Figs. 2 and 3.

The second wall 20b of the respective pair of walls is in the illustrated embodiments facing away from the downstream end of the grate, i.e. facing the upstream end 43b of the grate, and said first and second wall 20a, 20b together bridge the entire distance between the ends of the associated space 12 seen in the grate. longitudinal direction, i.e. the entire distance between two adjacent transverse axes 15. Seen in a longitudinal section through the grate 9, the respective depression 13 of the illustrated embodiments has a V-like shape, as is clear from Fig. 3, and the inside of the grate has a step-like shape. In the embodiment illustrated in Figs. 2 and 3, the first wall 20a of each pair of walls has at least one outlet hole 14 for combustion-assisting gas, which outlet hole 14 is connected to a gas duct 18 having its outlet 18a directed towards the downstream end 43a of the grate. According to a preferred embodiment of the burner 1 according to the invention, the gas neck 32 also comprises on its inside two or more spaces 33 which are each formed by a recess arranged in the inside of the gas neck and which each has at least one outlet hole 34 for combustion-assisting gas arranged in the associated recess, for example in the form of secondary air, as illustrated in Fig. bound surface structure. At least the inside of the gas neck 32, preferably the entire gas neck, is formed of ceramic material or stone material. As with the grate 9 described above, at least some, preferably the main part or all, of said outlet hole 34 is suitably connected to a gas duct 35 which has its outlet directed towards the outlet opening 6 of the combustion chamber. At least some, preferably each, outlet hole 34 is connected to a gas duct 35 which extends through the gas neck 32 and is integrated therein and which is suitably formed by a through hole formed in the gas neck, as illustrated in Fig. 4. Combustion-assisting gas, for example in the form of secondary air, is led to the respective gas duct 35 via inlet ducts 38 (schematically indicated in Fig. 4) which are arranged in the gas neck 32, for example in the form of longitudinal channels on the outside of the gas neck. In the embodiment illustrated in Fig. 4, said gas neck 32 is formed as part of a cylinder, but it can of course also have a different design depending on the shape of the combustion container. The gas neck 32 suitably forms a separately detachable part of the burner.

The transverse ridges 15 of the bottom plate 9a are suitably arranged in line with the transverse ridges 15 of the side elements 9b, 9c when the grate is mounted in the combustion tank, as illustrated in Fig. 4, so that spaces 12 are formed which each extend unbroken from the bottom plate 9a and up along one of the side elements 9b, 9c. Similarly, the ridges 15 of the side members 9b, 9c are suitably arranged in line with the transverse ridges 15 of the gas neck 32 when the grate 9 and the gas neck 32 are mounted in the combustion container, as illustrated in Fig. 4. .

In the embodiment illustrated in Fig. 4, the grate 9 and the gas neck 32 are enclosed in a metal casing 50 which forms an outer casing of the burner container 2 of the burner.

In the embodiment illustrated in Fig. 1, in front of the grate 9 there is a block 31, suitably of ceramic material or stone material, which rests on the bottom of the combustion tank and which protrudes slightly above the grate to retain in the combustion chamber 3 fuel bodies which have not yet been completely burned. In order to facilitate removal of the grate 9, this block 31 suitably forms a separate detachable part of the burner. A corresponding block 31 is also illustrated in Fig. 4 in a position separated from the grate 9.

If appropriate, an air layer or heat insulating material may be provided in the boundary layer between the metal housing 50 and the grate 9 and / or between the metal housing 50 and the gas neck 32 to limit heat dissipation via the metal housing 50. Figs. 5 and 6 illustrate two different embodiments of a grate 9 and a gas neck 32 arranged in a combustion tank 2 with a different cross-sectional shape than the combustion tank according to Fig. 4. The combustion tank 2 illustrated in Fig. 5 has a circular cross-sectional shape and the grate 9 in this case has a curved shape and is formed in one piece . The combustion container 2 illustrated in Fig. 6 has a rectangular cross-sectional shape and the grate 9 in this case consists of three separate elements, namely a bottom plate 9a and two side elements 9b, 9c.

A combustion tank of a burner of the type in question can of course be provided with a grate and gas neck of the type described above already in the manufacture of the combustion tank, but alternatively the combustion tank of an existing burner can be supplemented with such a grate and gas neck afterwards, e.g. 375 13 pelvis to adapt an existing pellet burner to the combustion of grain.

The burner according to the invention is particularly suitable for use in the combustion of cereals, but can of course also be used for the combustion of other types of fuels which consist of solid fuel bodies.

The invention is of course not in any way limited to the preferred embodiments described above, but a number of possibilities for modifications thereof should be obvious to a person skilled in the art, without this departing from the basic idea of the invention as defined. in the appended patent claims.

Claims (1)

A grate for a burner for burning solid fuel bodies, which grate (9) comprises an inside (10) with a support surface (11) intended for receiving fuel bodies, wherein: - combustion assist gas outlet holes (14) are provided in said inside (10) to enable the supply of combustion support gas to fuel bodies resting on the support surface (11), i.e. the inside (10) of the grate comprises two or more spaces (12) each formed by a recess (13) arranged in said inside (10) and each having at least one outlet hole (14) for combustion-supporting gas arranged in the associated recess, and - the grate having a downstream end (43a) via which flue gases and combustion residues formed during combustion of fuel bodies resting on the grate (9) are intended to be led away from the grate, characterized in that at least some, preferably the main part or all, of said utry The housing (12) has at least one outlet hole (14) for combustion-assisting gas arranged in the associated recess which is connected to a gas duct (18) which has its outlet (18a) directed towards the downstream end (43a) of the grate. Rust according to claim 1, characterized in that at least a part of the surface of the respective recess (13) forms a portion of said support surface (11). Rust according to Claim 1 or 2, characterized in that the respective space ('12) has at least one outlet hole (14) for combustion-assisting gas arranged in or near the deepest part of the associated depression (13). Rust according to any one of claims 1-3, characterized in that said spaces (12) are mutually separated by ridges' (15, 17) arranged in the inside (10) of the grate. 10 15 20 25 30 35 527 375 15. Rust according to one of the preceding claims, characterized in that a plurality of spaces (12) are arranged in a row in the longitudinal direction of the rust. . Rust according to claim 5, characterized in that a plurality of spaces (12) are arranged in a first row (16a) in the longitudinal direction of the grate, and that a plurality of spaces are arranged in a second row (16b) in the longitudinal direction of the grate, wherein the second row (16b) of spaces extends parallel to the first row (16a) of spaces. . Rust according to claim 5 or 6, characterized in that at least some, preferably the main part or all, of said spaces (12) arranged in a row comprise a pair of walls included in the associated recess consisting of: - a first wall (20a) which is facing the downstream end (43a) of the grate, and - a second wall (20b) arranged at an angle to the first wall (20a) and connected to the lower part of the first wall (20a) via a connecting line (21) extending substantially in the transverse direction of the rust. . Rust according to claim 7, characterized in that in at least one, preferably each, pair of walls, said first wall (20a) has at least one outlet hole (14) for combustion-assisting gas, which outlet hole (14) is connected to a gas duct (18) which has its outlet (18a) directed towards the downstream end of the grate (43a). . Rust according to claim 7 or 8, characterized in that in at least some, preferably each, pair of walls, said second wall (20b) faces away from the downstream end of the grate, said first and second wall (20a, 20b) together substantially bridging the entire distance between the ends of the associated space (12) seen in the longitudinal direction of the grate. 10. Burner 527 375 16 10. Rust according to one of the preceding claims, characterized in that at least the inside (10) of the grate, preferably the entire grate (9), is formed of ceramic material or stone material. Rust according to one of the preceding claims, in that at least one, preferably each, outlet hole (14) is connected to a gas duct (18) which extends through the grate (9) and is integrated therein. Rust according to Claim 11, characterized in that the respective gas duct (18) is formed by a through hole formed in the grate (9). Burner for combustion of solid fuel bodies, comprising a combustion chamber (3), characterized in that a grate (9) according to any one of claims 1-12 is arranged in the combustion chamber (3). according to claim 13, characterized in that the combustion chamber (3) is provided with a gas neck (32) whose inside comprises two or more spaces (33) which are each formed by a recess arranged inside and each having at least one outlet hole (34) for combustion-assisting gas arranged in the associated recess. Burner according to claim 14, characterized in that at least the inside of the gas neck, preferably the entire gas neck, is formed of ceramic material or stone material.