WO1998033015A1

WO1998033015A1 - Combustion apparatus

Info

Publication number: WO1998033015A1
Application number: PCT/SE1998/000112
Authority: WO
Inventors: Ove FÄNGSTRÖM
Original assignee: Pelletsbrännaren Junsele Ab
Priority date: 1997-01-27
Filing date: 1998-01-27
Publication date: 1998-07-30
Also published as: SE9700220D0; SE9700220L; AU5788798A; SE519557C2

Abstract

This invention relates to an apparatus for combustion of biofuels, preferably pellets, comprising a container for the fuel, which is connected with a combustion furnace via a feeder device for the fuel, a pipe part being connected to the combustion furnace and projecting out from this one so that when coupling together the apparatus with a boiler the pipe part projects into the boiler, and an ignition pipe or the like being positioned in that way in the apparatus that it is possible to ignite the fuel in the combustion furnace from the outside, whereafter the combustion is maintained by supply of fuel and combustion air. According to the invention the apparatus is characterized by the fact that the feeder means is designed in that way that the fuel by its own weight is removed from the container (1) to the combustion furnace (2), and that the feeder means comprises two straight, concentric pipes (5, 6), the lower part of the outer pipe (5) being connected to the roof portion of the combustion furnace and surrounds a lower hole (8) there, whereas the upper part of the pipe (5) is connected to the lower part of the container and surrounds an upper hole (9) there, and the inner pipe (6) being intended to be able to go through at least the mentioned lower hole (8) and being displaceably arranged in relation to the outer pipe, so that the size of the fuel stack of the combustion furnace can be varied by the displacement of the inner pipe.

Description

Combustion apparatus

This invention relates to an apparatus for combustion of biofuels, preferably pellets, comprising a container for the fuel, which is connected with a combustion furnace via a feeder device for the fuel, a pipe part being connected to the combustion furnace and projecting out from this one so that when coupling together the apparatus with a boiler the pipe part projects into the boiler, and an ignition pipe or the like being positioned in that way in the apparatus that it is possible to ignite the fuel in the combustion furnace from the outside.

Such apparatuses are previously known but has as a rule an expensive and complicated electronic control system for its function. Known apparatuses, for instance, have a feeder screw for feeding in the fuel, which requires the expensive electronic system for its function.

The purpose of this invention is to provide an apparatus for biofuels, which is very simple regarding its construction, and which, due to that fact, becomes very reliable and safe to operate. This has been achieved by the fact that the apparatus has the features mentioned in the accompanying claims.

A preferred embodiment of the invention shall be described more closely with reference to the accompanying drawings, where Fig. 1 shows a side view of a complete apparatus, standing on a removable frame, Fig. 2 shows a cross-section through the apparatus according to Fig. 1, without frame, and Fig. 3 shows a section taken along the line II-II of

Fig. 2 and seen in the direction of the arrows.

The new apparatus for biofuels comprises a container 1, which is connected to a combustion furnace 2 via a feeder means 3 by which the fuel, which preferably comprises pellets, is fed down to the bottom plate 4 of the combustion furnace 2, which plate is essentially horizontally directed and consists of a ceramic plate. The combustion furnace 2 is oblong and made of steel plate and its transverse section has the shape of a half-circle with its dome directed upwards.

The feeder means 3 comprises two straight, concentric pipes 5, 6, which are preferably made of steel, and between which there is arranged a sealing 7, the sealing being fastened to the inner portion of the outer pipe 5. The outer pipe 5 is fastened, preferably by welding, with its upper part to the lower portion of the container 1 and surrounds a hole there, whereas the pipe is fastened with its lower part to the top of the dome-shaped roof portion of the combustion furnace 2. Inside the pipe 5 on the mentioned roof portion is also made a hole 9, which is accordingly surrounded by the pipe 5, and into this hole the lower part of the inner pipe 6 is intended to be inserted. The inner pipe 6 is preferably also intended to go through the upper hole 8, the sealing means 10 being arranged at the upper part of the outer pipe 5 for preventing the fuel from permeating down between the two pipes. The upper part of the mentioned pipe is articulately connected to the lower part of a rod 1 1 , the upper part of which penetrates a lid 12 of the container 1 and is so arranged at the lid that by turning a knob 13 of the rod 11, this one can be moved upwards or downwards.

This turning movement has the consequence that also the inner pipe 6 is displaced upwards or downwards, the pipe 6 sliding against the stationary sealing means 7.

When feeding the fuel down to combustion furnace 2, the fuel falls by its own weight from the container 1 via the inner pipe 6 down onto the ceramic plate 4, where it forms a stack of a certain size. If there is a desire that this fuel stack shall be larger, which means that the combustion becomes stronger and by that the heating effect higher, the inner pipe 6 is drawn up by the rod 11. Thus, the control of the heating effect is made very simply by means of the rod 11. Of course, the turning of the rod 11 could be made by means of an electric stepping motor instead of manual turning.

The combustion air is generated by an electrically driven fan means 14, which spurts air into a space 15 outside the combustion furnace 2 via a duct 16. From this space the air penetrates into the combustion furnace 2 via a large number of small holes, of which certain 17 are arranged along the long sides of the furnace and are positioned close to the ceramic plate 4, whereas other holes 18 are arranged in the backwall 19 of the combustion furnace.

The combustion furnace 2 and the surrounding space 15 are enclosed by a cover 20, which has the shape of a parallelepiped with a square or rectangular cross-section and comprises an inner 21 and an outer 22 plate, which are separated by a heat-resistant isolation 23. In a suitable hole in the front wall of the cover 20 is a pipe part 24 fastened, which is in a direct connection with the combustion furnace 2 and projects a small distance outside the front wall of the cover. This pipe part 24 is intended to project into the heating space of the boiler when coupling together this one with the apparatus according to the invention, the front wall of the cover/combustion furnace being in contact with the front wall of the boiler. When burning the fuel in the furnace, the created flames of fire will accordingly be thrown into the boiler via the pipe part 24 and heat up the boiler water.

The ignition of the fuel is made by a match or the like, which is pushed in to the fuel via an ignition pipe 25. An essential part of this invention is an air duct 26, which leads from the fan duct 16 to a side surface 27 of the container 1 , and which accordingly receives air from the fan means 14. Due to that fact two advantages are achieved: Firstly, smoke and fire are prevented from being spread upwards via the inner pipe 6 to the container 1 , because the air that is spurted into the container creates an oveφressure there. Secondly, the oveφressure-air of the container makes possible that there is created an airstream downwards through the inneφipe 6 to the fuel stack. This airstream, hitting the top portion of the fuel stack, functions as complementary combustion air and contributes together with the dome-shape of the combustion furnace to the fact that the entire fuel stack is simultaneously burning, which makes the combustion of the fuel very effective.

In Fig. 1 the apparatus according to the invention is shown in a position on a movable frame 28. Due to that fact the apparatus can simply be removed from the boiler when making a technical overhaul.

The invention is of course not limited to the mentioned embodiment but can be modified within the scope of the following claims.

Claims

1. Apparatus for combustion of biofuels, preferably pellets, comprising a container for the fuel, which is connected with a combustion furnace via a feeder device for the fuel, a pipe part being connected to the combustion furnace and projecting out from this one so that when coupling together the apparatus with a boiler the pipe part projects into the boiler, and an ignition pipe or the like being positioned in that way in the apparatus that it is possible to ignite fuel in the combustion furnace from the outside, whereafter the combustion is maintained by supply of fuel and combustion air, c h a r a c t e r i z e d by the combination of the following features: - The feeder means is designed in that way that the fuel by its own weight is removed from the container (1) to the combustion furnace (2);

- The feeder means comprises two straight, concentric pipes (5, 6), the lower part of the outer pipe (5) being connected to the roof portion of the combustion furnace and surrounds a lower hole (8) there, whereas the upper part of the pipe (5) is connected to the lower part of the container and surrounds an upper hole (9) there;

- The inner pipe (6) is intended to be able to go through at least the mentioned second hole (8) and is displaceably arranged in relation to the outer pipe, so that the size of the fuel stack of the combustion furnace can be varied by the displacement of the inner pipe;

- An air duct (26) is connected to the container (1) for leading air into the same, whereby there is created an ove╧åressure in the same.

2. An apparatus according to claim 1, c h a r a c t e r i z e d in that the combustion air is generated by an electrically driven fan means (14), which spurts air into a space (15) outside the combustion furnace (2) via a duct (16), and that the combustion air further permeates into the combustion furnace (2) via a large number of small holes, of which certain ones (17) are arranged along the long sides of the furnace and are positioned close to the bottom portion (4) of the furnace, whereas other holes (18) are arranged in the backwall (19) of the combustion furnace (2).

3. An apparatus according to claim 2, c h a r a c t e r i z e d in that the combustion furnace (2) and the surrounding space (15) are enclosed by a cover (20), which has the shape of a parallelepiped with a square or rectangular cross-section and comprises an inner (21) and an outer plate (22), which are separated by a heat-resistant isolation (23).

4. An apparatus according to claim 2 or 3, c h a r a c t e r i z e d in that the air duct (26) for leading air into the container (1) is connected to the fan duct (16).

5. An apparatus according to any one of the preceding claims, characterized in that the upper part of the inner pipe (6) is articulately connected to the lower part of a rod (11), the upper part of which penetrates a lid (12) of the container (1), and which is arranged at the lid in that way that by turning a knob (13) or the like of the rod (11), this one can be forced upwards or downwards, which means that the inner pipe (6) is displaced upwards or downwards in relation to the outer pipe (5).

6. An apparatus according to any one of the preceding claims, characterized in that the combustion furnace (2) is oblong and made of steelplate, its transverse cross- section having the shape of a half-circle with its dome directed upwards, and that the bottom plate of the combustion furnace (2) is made of ceramic.