FI74340B - ANORDNING FOER FOERBRAENNING AV GRANULAERT MATERIAL. - Google Patents

Description

1 74340

TECHNICAL FIELD The present invention relates to an apparatus for burning granular material, for example wood powder pellets, wood chips and the like, comprising a substantially horizontal combustion chamber, outlets for primary air and secondary air, and at least one pipeline outlet to feed fuel for combustion gases 10 to transfer heat to, for example, water-cooled surfaces, the combustion chamber being rotatable and provided with first outlet openings for air in or near the combustion chamber jacket, the at least one second and is adapted to be connected to said boiler section, in addition to which the combustion chamber is provided with means for raising and mixing the fuel, in addition to which 20 common first rotating tubes are arranged for said two air supplies opening into the combustion chamber. The fuels in question are relatively gas-rich fuels with a small particle size, such as wood powder pellets, wood chips and the like.

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State of the art

Rotary combustion chamber burners are known, for example, from U.S. Pat. Nos. 4,060,042, 3,547,056, 3,357,382, 3,380,407, 3,098,458, 30,455,257, 3,808,989, and German Patent 2,356,294. These patents describe having a rotating combustion chamber, usually in the form of a relatively large rotating cylinder. This rotating cylinder is in most cases provided with grippers to effect fuel mixing.

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From the point of view of combustion, these known devices with a rotating combustion chamber have the disadvantage, for example with respect to combustion in the grate, that the primary air does not penetrate from below through the fuel. In a prior art rotary combustion chamber, the primary air comes into primary contact with the present surface of the fuel mass. However, in part, this drawback is eliminated by mixing the fuel through fixed grippers inside the rotary combustion chamber. The described 10 way of conducting the primary air further causes the disadvantage that the exact dosing of the primary air becomes very difficult, almost impossible to perform.

In commonly known rotary combustion chambers, the air supply is arranged so that the primary and secondary air are led together in such a way that the air passes over the fuel mass. In this case, the combustion air that has not been used as primary air or secondary air is used.

It is clear from the above that the secondary-20 air supply cannot be adjusted with high accuracy either.

Rotary combustion chambers made according to the prior art thus have the disadvantage that the deficient supply of primary air and the difficult-to-adjust supply of secondary air do not provide efficient utilization of the calorific value of the fuel from a fuel economy point of view.

German application 1 952 243 also discloses a combustion device with a rotary combustion chamber in which air is directed against the direction of flow of the fuel.

30 German patent publication 2 343 206 discloses an incinerator which, however, does not have a central secondary air supply. It also has no means for raising and mixing the fuel.

Swedish publication 3 225 092 describes 35 devices in which secondary air is blown onto the top of a rotary kiln.

U.S. Patent No. 3,734,340 discloses an apparatus with a fixed combustion chamber. Fuel is supplied by a rotating screw. The air flows against the direction of fuel flow and all the air is led to the combustion chamber.

U.S. Pat. No. 3,827,379 discloses an apparatus with a rotary oven and a centralized air supply.

In the device of U.S. Patent No. 1,340,274, secondary air is supplied to a fixed cylinder.

Disclosure of the Invention It is an object of the present invention to provide a device in which the above-mentioned drawbacks and limitations have been eliminated. The combustor with a rotating combustion chamber according to the present invention is then characterized in that said conduit 15 for secondary air has a common axis of rotation with the combustion chamber and also the axis of symmetry of the tube coincides with the common axis of symmetry and rotation of the combustion chamber. The secondary air duct has an opening associated with the combustion chamber outlet through which 20 secondary air is conducted to the combustible gases released in the combustion chamber.

Inside the combustion chamber, the combustion air is distributed in such a way that a well-defined amount of air is introduced into the fuel in the form of primary air and the remaining amount of air, which is also quantitatively well-defined, is passed through a rotating combustion chamber to an opening.

When the second outlet for the secondary air is in the region of the outlet of the combustion chamber, the final combustion is effected with a free flame similar to that of the oil burners. Thus, an oil-fired boiler can be easily converted to be heated with solid fuel by connecting a device according to the invention. In the device according to the invention, an axial supply of both fuel and ash is provided in the direction of primary and secondary air.

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Highly efficient combustion is made possible by the fact that the conical opening of the combustion chamber towards the boiler is ceramic-insulated and allows the gases to burn at a temperature of 1300 ° C. By controlling the air supply, the temperature in the primary region can be adjusted to avoid slag formation. At the same time, the temperature level in the secondary combustion zone can be maintained, which results in a high combustion efficiency.

Other features and advantages of the invention will be apparent from the following description and the appended claims.

Brief description of the drawings

In the following description, reference will be made to the accompanying drawings, in which Figure 1 shows a longitudinal central section of the combustion chamber, Figure 2 shows details of pipelines for supplying primary air, Figure 3 shows a longitudinal section of a load-bearing pipe and a valve plate dividing primary air into different ducts; the function of the combined organs for mixing and supplying the primary air.

25 Description of a preferred embodiment

The device for combustion shown in the figures is placed in the outer space 2, which is horizontal and cylindrical, and placed in connection with the heating boiler. In the outer space 2 there is a rotating combustion chamber 1, a downcomer 20 for the supply of fuel 30, an axially moving pipe 5 for supplying secondary air, a rotating and supporting pipe 4, two bearings 3 supporting the pipe 4 and a rear, non-rotating, tubular unit 14. The tube 4 is provided with an inner, concentric tube 35 7. This tube 7 is held in a concentric position with respect to the tube 4 by means of eight partitions 9 located in a plane comprising the axis of symmetry and rotation of the tube 4 and evenly distributed in the tube 4. along the inner wall. Thus, the jacket space between the tube 4 and the tube 7 becomes divided into eight channels 10. Each channel 10 communicates with one of the eight arms 8 via an opening 23.

Figure 2 shows a valve plate 12 rotating about an axis which coincides with the axis of rotation of the pipe 4.

The rotating combustion chamber 1 is provided internally with eight tubular arms 8 which are fixedly connected to the rotating tube 4. The arms 8 are also fixed relative to the combustion chamber 1, which supports the arms 8. At the end of the rotating combustion chamber 1 leading to the heating boiler there is a circular opening 11. This conical opening of the combustion chamber is provided with ceramic insulation 27.

Also at the opposite end of the combustion chamber is a circular opening associated with a fixed, non-rotating, cylindrical second unit 14 provided with a rear slide plate 18 supporting a sealing device 15 which seals the passage of the rotating tube 4 through the rear slide plate 18. The rear conical jacket surface 17, which is fixedly connected to the combustion chamber 1 by means of a flange connection 26, seals the cylinder 14 against a circular sealing surface.

The arms 8 are attached to the rotating tube 4 at a point where the rotating tube 4 has a number of openings 23. These openings 23 form an extension of the interior of the tubular arms 8. The openings 23 thus allow the supply of primary air through the ducts 10 to the tubular arms 8.

By rotating the valve plate 12, the primary air can be distributed so that only certain ducts 10 and thus only certain arms 8 receive primary air. Primary air is fed to the arms 8 mainly only when they move upwards. With the valve plate 12 in the normal 6 74340 adjustment position and the eight arms 8 in the combustion chamber, primary air is supplied, for example, to the lowest position arm 8 and in addition to the three arms moving upwards. No air is supplied to the other four arms.

The air duct 6 forms a connection between the inner tube 7 and the front tube 5. This air duct 6 can be enlarged or reduced so that the tube 5 is moved in the axial direction. If the pipe 5 is moved so that it approaches the pipe 4, the air duct 6, through which the combustion air is led to the pipe 5 from the pipe 7, decreases.

At the outer end of the outer space 2 are placed two plate-like ends which support two bearings 3, which in turn support a rotating tube 4.

At the front end of the axially displaceable tube 5 there is an opening 15 19 through which the secondary air is led from the tube 5 to the unburned fuel molecules, which are led to the furnace space through the opening 11 in the rotating combustion chamber. At the front end of the pipe 5, a device 16 is placed, i.e. flanges placed at an angle, which are intended to give turbulence to the secondary air 20.

Figure 4 shows how the arms 8, which may be provided with flanges, mix and lift the fuel. The openings 13 of the arms 8 are directed inwards so that air is blown out in a direction corresponding to the direction of rotation of the combustion chamber 1. Thus, the primary air is blown out in the direction indicated by the arrow 22. In this way, the primary air is given the opportunity to penetrate through the fuel mass. However, in certain cases, especially in large installations, it may be appropriate to blow 30 primary air in both directions.

In addition to conducting primary air to the fuel during the primary combustion stage, the tubular arms 8 have the function of mechanically modifying the fuel and raising it with it by about 1/3 of a turn and then blowing 35 fuel with an obliquely upward air flow from the holes 13.

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As a result of the mechanical modification, the ash is released from the fuel and, as a result of the primary air being added from below, the light ash rises towards the center of the chamber as the fuel falls down. The air stream 5 from the holes 13 then takes the ash with it from the combustion chamber and the primary combustion becomes efficient without obstructing the ash on or around the fuel surface.

The combustion air thus enters the burner from the fan through a rotating pipe 4. The primary air is led through the ducts 10 and the openings 23 in the pipe 4 to the arms 8 and the openings 13. Thus, the primary air is led to the combustion chamber 1 in the vicinity of its inner jacket surface and from there the primary air penetrates through the fuel mass towards the combustion chamber 1. In connection with the primary combustion 15 in the combustion chamber 1, combustible gases are formed which are led out of the combustion chamber 1 through an opening 1, to which secondary air is introduced to burn these gases.

Secondary air is led to the pipe 5 through the slots 6. The supply of secondary air can be adjusted by axial displacement of the pipe 5. The supply of primary air is regulated, for example, by a flap device of a quality known per se. The devices for axial transfer of the tube 5 are also of a quality known per se. Said known devices are not shown in the figures of the drawings in order to improve their clarity.

The structure of the dosing unit 19 and the downcomer 20 prevents the formation of a uniform fuel flow from the storage to the combustion chamber and the risk of backfire.

The figures show a device with eight arms 8.

For different types of fuels and for different sizes of furnace and combustion chamber 1, the number of arms can be suitably either larger or smaller. Thus, the combustion chamber 1 can be provided with, for example, five or nine arms.

It has been mentioned above that the arms 8 can be provided with a la-35 for mixing the fuel. However, for certain types of fuels and in particular for certain grain sizes 8 74340, it may be suitable to provide separate devices for supplying primary air, which may, for example, be located between flanges fixed directly to the inner surface of the inner jacket surface of the combustion chamber 1.

5 In the drawings, the combustion chamber 1 is shown as a rotationally symmetrical structure. However, the combustion chamber 1 may be made so that its cross section has a polygonal shape. In the case of such a structure, the design of the combustion chamber 1 already provides a certain mixing during the rotation of the combustion chamber 1 10.

Other modifications of the combustion chamber 1 or its components are also possible without departing from the spirit of the invention, as defined in the following claims.

Claims (3)

74340 An apparatus for burning granular material, for example wood powder pellets, wood chips and the like, comprising a substantially horizontal combustion chamber (1), outflow openings (13) for primary air and secondary air (19), at least one pipeline (20) for supplying fuel and an outlet (11) opening in the boiler part for combustion gases to transfer heat to, for example, water-cooled surfaces, the combustion chamber (1) being rotatable and provided with 10 first outlets (13) for air in or near the combustion chamber (1) jacket, at least one second 19) for air is arranged in connection with the combustion chamber (1), which second outlet opening (19) opens into the end part (27) of the combustion chamber, which is located in the axial direction of the combustion chamber and is adapted to be connected to said boiler part; raising and mixing, in addition to which a common prim said rotating tube (4) is arranged for said two air supplies opening into the combustion chamber 20, characterized in that the rotating second tube (5) forming an extension of the first tube (4) passes axially through the combustion chamber and has a second outlet (19) for air in the region of the axial outlet (11) of the combustion chamber (1). Device according to claim 1, characterized in that said rotatable second tube (5) is arranged to move in the axial direction and is provided with a valve-like member (6) which, in the axial displacement of said tube (5), allows air supply to said to the second outlet. Device according to claim 1 or 2, characterized by means (16) which provide turbulence of air to the current coming out of said second tube 35 (5) in the region of the axial outlet (11) of the combustion chamber.