WO2007040402A1

WO2007040402A1 - Feeding device

Info

Publication number: WO2007040402A1
Application number: PCT/NO2006/000304
Authority: WO
Inventors: Kurt Brun; Geir Arne Mosing
Original assignee: Bionordic As
Priority date: 2005-08-31
Filing date: 2006-08-28
Publication date: 2007-04-12
Also published as: NO20054036D0; NO323328B1; NO20054036L

Abstract

Feeding device for furnaces comprising a fuel storage (3), for adding fuel to a combustion chamber (9). The device comprises a cylinder (1) having a number of through channels (2), the device is arranged to rotate about an axis centred between an inlet (5) which is in communication with an opening in the fuel storage (3) , and an outlet (6) which is in communication with an opening (8) in the combustion chamber (9). The inlet (5) and the outlet (6) are on a different axis, and the cylinder (1) is arranged in such a way that the through channels (2) alternately corresponds with the inlet (5) and the outlet (6).

Description

Feeding device

The present patent application relates to a feeding device according to the preamble of patent claim 1.

Background

Today, there are many different systems for feeding fuel into furnaces. For all furnaces it is an advantage that temperature and effect may be supervised/controlled, and this may inter alia be achieved by supervising/controlling the air supply. Thus, it is a huge advantage that air does not come into the process with the fuel, since such an airflow will not be controllable.

US 4,915,265, US 5,538,383 and US 3,151,784 relate to different feeding devices, but have the common feature that the pellet is transferred radially, i.e. the pellets in the storage are directed into a recess in a rotating roll or the like, the roll rotates and the pellets fall out of the recess at a suitable point. All these systems and also feeding screws known from among others US 4,782,765 prevent air from coming into the system.

GB 1914,2620 relates to another device wherein fuel is transported radially in recesses on a rotating cylinder. The fuel is transported out of the recesses by means of compressed air, in such a way that air is supplied with the fuel.

Object

The object of the present invention is to develop a feeding device for a furnace having a closed combustion chamber, as the device being air tight in such a way that no air enters the combustion chamber through the device. Another object is that heat should not be transferred from the combustion chamber to the fuel storage. Yet another object is that the device should not require a lot of space, it should be cost efficient, and it should be controllable in such a way that the amount of fuel, and thereby the amount of developed heat, can be easily regulated.

The invention

The object of the invention is fulfilled with a feeding device according to the characterizing part of patent claim 1. Further advantageously features are stated in the dependent claims. The feeding device comprises a cylinder which is designed with a number of through channels, and it is rotatably arranged between a fuel storage and a combustion chamber. The device is further designed with an inlet and an outlet which, respectively, are in connection with an opening in the fuel storage and an opening in the combustion chamber. The inlet and outlet are not on the same axis, and thus there will not be a direct passage between the fuel storage and the combustion chamber even if the cylinder is in such a position that the opening of one of the through channels corresponds with the inlet or outlet. The inlet and outlet, and the openings in the fuel storage and combustion chamber, respectively, need not necessarily have the same shape and size as the opening of the channels of the cylinder.

The term "cylinder" herein means a body having a cylinder- or slice form, where a radial cross-section would be circular. The length of the cylinder may be larger or smaller than the radius, but the body will always have a length such that a through channel will have a volume. In its simplest embodiment, the cylinder has axial channels, and is mounted in such a way that its ends butt against the wall of the combustion chamber and the wall of the fuel storage, respectively. In this way, one of the openings of the through channels in the cylinder is closed by the wall of the fuel storage, while the other opening is closed by the wall of the combustion chamber. Between the cylinder and the walls there are arranged seals preventing air to get into the fuel storage and/or combustion chamber. The cylinder is further mounted in such a way that at given points of the rotation, the through channels correspond with the openings either in the fuel storage or in the combustion chamber, and in this embodiment the openings will be the same as the inlet and outlet of the device. In another preferred embodiment of the present invention, the cylinder is the same as the one described above, but it is mounted between the combustion chamber or the fuel storage, and a cover wall, or between two cover walls. A cover wall covers one end of the cylinder, and thereby the openings of the through channels in the cylinder, in such a way that the fuel stays in the channel until it corresponds with the outlet of the device. The cover wall and seals between the cover wall and the cylinder, and between the cover wall and the fuel storage or combustion chamber, ensures that air does not come into the feeding device. In cases where cover walls are used, there are openings in these constituting the inlet and/or outlet of the device, and which correspond with or are in contact with the openings of the fuel storage and of the combustion chamber. In a particularly preferred embodiment, the cylinder is mounted in such a way that it is between a wall in the fuel storage and a cover wall, and in a distance from the combustion chamber. The opening in the wall of the fuel storage will be equal to the inlet and the opening of the cover wall will be equal to the outlet of the feeding device. In this case there is arranged a supply pipe between the outlet of the device and the opening of the combustion chamber. In this way heat from the combustion chamber affecting the cylinder and fuel in the channels is avoided, when the cylinder rotates. Further, it is an advantage if the floor of the fuel storage is slanting, in such a way that the cylinder is mounted on a slant in relation to the wall of the combustion chamber. One may also consider embodiments wherein the cylinder has radial channels, and is mounted is such a way that the openings of the through channels can be closed by a surrounding housing. In such an embodiment, the housing has an inlet and an outlet on different axes, which corresponds to the opening of the fuel storage and the combustion chamber, respectively. The openings of the through channels will in such cases be closed by the material of the housing unless they correspond with the inlet or outlet, and thereby the opening into/out of the combustion chamber and fuel storage.

Concerning all embodiments of the device, when the cylinder is in such a position that one of the through channels is opened to the opening of the fuel storage, the channel is filled with fuel. Because the cylinder is tight against the wall of the combustion chamber or a cover wall, the opposite opening of the through channel will be closed. The fuel storage is preferably designed with an opening in the bottom of the storage, and moreover in such a way that the area of a cross section is always larger or equal to the area of a cross section below, so that the fuel is gathered in the bottom of the storage. Further, it is an advantage that the walls of the storage are smooth and even. In this way there will always be fuel at the opening, and due to gravity it will be shuffled into a through channel in the cylinder when the channel corresponds with the opening of the storage.

As stated above, the cylinder rotates, and when it rotates, the opening of a channel will be displaced so that it no longer corresponds with the opening of the fuel storage. The channel will be closed at both ends by the wall of the fuel storage and/or combustion chamber or a cover wall, and the fuel which was shuffled into the channel stays in the channel while the cylinder rotates. A new channel will become open towards the fuel storage and in this way all the channels in the cylinder will gradually be filled with fuel. A channel filled with fuel will at a given stage of rotation become open towards the opening of the combustion chamber and gravity will ensure that the fuel falls out and down into the combustion chamber. Since the inlet and outlet of the device are on a different axis, it will never be the same channel which opens towards the fuel storage and the combustion chamber at the same time.

In another embodiment of the invention, the filling of fuel in the through channel is enhanced, for example, by a piston or the like, pushing the fuel into the channel, and the same may be possible for emptying into the combustion chamber. The design of the through channel will also contribute to ease the filling/emptying of the channel with/for fuel, and the channel may for example be coated with a smooth surface, such as Teflon. These items may be solved in many ways, which will be obvious to a person skilled of the art, and thus, we will not discuss them any further.

The amount of fuel added to the combustion chamber will depend on the rotation speed of the cylinder, and the size or volume of the channels in the cylinder. Maximum size and/or volume of the channels will further depend on the diameter and length of the cylinder. The length and diameter of the cylinder may be varied with type of fuel, and pellet demands less volume of the channels, i.e. a less cylinder, than splinter, garbage and the similar to achieve the same heat effect at the same rotation speed. The cylinder must therefore be chosen depending on the type of fuel most likely to be used, and primarily changed only if the furnace should be rebuilt to another type of fuel. However, the speed of rotation is adjustable, in such a way that the amount of added fuel, and thereby the heat- effect from the furnace, may be adjusted by changing the speed of rotation. More speed gives more fuel into the combustion chamber and will thereby increase heat effect from the furnace.

Examples In the following the invention will be described further, with reference to the accompanying drawings in which

Figure 1 shows a cross section of a preferred feeding device according to the present invention, arranged between a fuel storage and a combustion chamber,

Figure 2 shows a radial cross section of a cylinder of the feeding device shown in Figure 1, and

Figure 3 shows an alternative embodiment of the device shown in Figure 1.

To improve the understanding of the technical principles, some components in the drawings are out of scale. In Figure 1 there is shown a cross section of a specially preferred embodiment of the present invention, where a cylinder 1 having axially through channels 2 is mounted rotatably between an opening 5 of a fuel storage 3 and an opening 6 in a cover wall 4. The opening 6 in the cover wall corresponds to a supply pipe 7 whose other end corresponds with an opening 8 of the combustion chamber 9. The opening 8 of the combustion chamber 9 is below the opening of the cover wall 4, in such a way that the supply pipe is on a slant. One end of the cylinder 1 bears against the bottom 10 of the fuel storage 3, and the other end of the cylinder 1 bears against the cover wall 4, in such a way that the through channels 2 of the cylinder 1 appear as closed cavities. The openings 5, 6 of the fuel storage 3 and the cover wall 4, respectively, are placed in such a way that they are not on the same axis.

In the embodiment of Figure 1, the fuel storage 3 has a slanting bottom 10, preferably 45° in relation to the vertical. The cylinder 1 is also arranged slanting and bears against the bottom 10, in such a way that one end of the cylinder is completely covered by the bottom 10 of the fuel storage 3.

In Figure 1, the fuel storage 3 and the combustion chamber 9 are arranged side by side, and the openings 5, 6 are placed in such a way that the fuel is brought up from the opening of the fuel storage 3 and into the slanting supply pipe 7, leading to the combustion chamber 9, when the cylinder 1 rotates. This may, of course, also be designed the opposite way. In the illustrated embodiment, the through channels 2 in the cylinder 1 have gradually increasing cross section, as the cross section at the opening towards the combustion chamber 9 is larger than the cross section at the opening towards the fuel storage 3. It is an advantage if the cross section is increased in such a way that the distance a between the surface of the cylinder and the outer part of the channel is kept constant, while the distance b between the surface of the cylinder and the inner part of the channel is increased gradually from the side facing the fuel storage and towards the side facing the combustion chamber 9. Such a design of the channels 2 will ease the removal of the fuel.

In Figure 2 there is shown a radial cross section of the cylinder 1 illustrated in Figure 1. It is designed with a number of through axial channels 2, evenly distributed along the outer edge of the cylinder 1. It is also designed with a central hole 11 which should accommodate a shaft 12 with which the cylinder should rotate.

In Figure 3 there is shown an alternative embodiment of the present invention, as the cylinder 1 is arranged horizontally and the fuel storage 3 is placed vertically above the combustion chamber 9. The cylinder 1 corresponds with the cylinder shown in Figure 1 and 2, and is rotatably arranged between a cover wall 4 and the top 13 of the combustion chamber 9. The fuel storage 3 has an opening 5 in its lower part corresponding to an opening 6 in the cover wall 4, which further corresponds with the channels 2 in the cylinde 1. The combustion chamber 9 has an opening 8 in its top 13 corresponding to the channels in the cylinder. The openings 5, 8 in the fuel storage 3 and the combustion chamber 9, respectively, are horizontally displaced in relation to each other in such a way that the sarrn channel 2 in the cylinder 1 can not correspond with both openings 5, 8 at the same time.

One might also consider embodiments corresponding to Figure 3, wherein the cylinder does not bear against the top of the combustion chamber, but is moved in a distance from this. In such a case, the lower end of the cylinder must also bear against a cover wall, and an opening in this corresponds with the opening in a supply pipe, whose other end corresponds with the opening in the top of the combustion chamber.

In the description above, only the main features of the feeding device itself are mentioned and described in detail. The combustion chamber comprises, of course, an oxygen supply-system, and the system as a whole comprises a preferably electrical engine driving the rotation of the cylinder. The mounting of the cylinder and the driving of this is also not described in detail, as this can be solved in many ways which will be obvious to a person skilled in the art. A furnace provided with a feeding device according to the present invention may further be provided with a regulation system, in such a way that the user states which temperature is desirable, and the air supply and fuel access (i.e. the rotational speed of the cylinder) among others, are regulated accordingly.

Claims

1. Feeding device for furnaces comprising a fuel storage (3), for adding fuel to a combustion chamber (9), the device comprises a cylinder (1) rotatably arranged about an axis centred between an inlet (5) in communication with an opening in the fuel storage (3) , and an outlet (6) in communication with an opening (8) in the combustion chamber (9), the inlet (5) and the outlet (6) being on a different axis, characterized in that the cylinder (1) is provided with a number of through channels (2) adapted to accommodate the fuel, and arranged in such a way that the through channels (2) alternately corresponds with the inlet (5) and the outlet (6).

2. Feeding device according to claim 1, characterized in that the through channels (2) in the cylinder (1) are axial.

3. Feeding device according to claim 1, characterized in that the ends of the cylinder (1) bear against a wall of the fuel storage (3) and a cover wall (4).

4. Feeding device according to claim 3, characterized in that an opening (6) in the cover wall (4) corresponds with an opening in a supply pipe (7), and that the other end of the supply pipe corresponds with the opening (8) of the combustion chamber (9).

5. Feeding device according to any one of the preceding claims, characterized in that the cylinder (1) is slanting in relation to the vertical.

6. Feeding device according to claim 1 or 2, characterized in that the opening (8) of the combustion chamber (9) is horizontally displaced, and below the opening of the fuel storage (3).