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Title:
A GRATE FOR BURNER, PREFERABLY A BIOMASS BURNER
Document Type and Number:
WIPO Patent Application WO/2018/231155
Kind Code:
A1
Abstract:
A grate for burner, preferably a biomass burner, solves the technical problem of the problem of the occurrence of an unevenly distributed fuel layer along the grate, which causes local variations in the fuel conversion rate, which further causes uneven combustion and thus unforeseeable conditions in the combustion chamber by implementing a rotating grate (2) around a vertical axis, centered substantially in the fuel supply center, wherein said fuel is brought onto said grate from below, thus achieving a homogeneous arrangement of the layer depending on the velocity profile of the fuel supply itself, and further, with the implementation of a scraper which cleans the matter from surface of said rotating grate (2), which comes into contact with it by rotating said rotating grate (2). Unlike other known burners, where the grate is rigidly clamped, the fuel supplied according to this invention is evenly distributed over said the grate and forms an uniform layer of dispersed matter, predominantly embers, this solution reflecting favorably on the quality and general control of the combustion process.

Inventors:
PART VALTER (SI)
Application Number:
SI2017/050006
Publication Date:
December 20, 2018
Filing Date:
November 29, 2017
Export Citation:
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Assignee:
PART VALTER (SI)
International Classes:
F23B40/04; F23G5/46; F23H15/00; F24B13/00
Foreign References:
US20160091198A12016-03-31
US4437452A1984-03-20
DE629015C1936-04-21
FR2961582A12011-12-23
AT10068U12008-08-15
Attorney, Agent or Firm:
MARN, Jure (2000 Maribor, SI)
Download PDF:
Claims:
PATENT CLAIMS

1. A grate for burner, preferably a biomass burner, characterized in that it comprises a rotating grate (2) said rotating grate (2) rotating about its own axis, wherein said rotating grate (2) comprises an opening (11) positioned essentially centrally to said rotating grate (2) for supplying of fuel, preferably biomass, said fuel being supplied through said opening (11) to said rotating grate (2) and arranged along said surface of said rotating grate (2), wherein said grate for burner further comprises a scraper (1), said scraper (1) positioned above said surface of said rotating grate (2), said scraper (1) adjustable in direction essentially normal to said surface of said rotating grate (2), thereby achieving a predetermined thickness of the matter disposed on said rotating grate (2) that comes into contact with the scraper (1).

2. The grate for burner according to claim 1, wherein said scraper (1) comprises a lower edge preferably parallel to said surface of said rotating grate (2), said lower edge of said scraper (1) positioned between 0 and 5 mm above said surface of said rotating grate (2), preferably between 0.5 mm and 3 mm above said surface of said rotating grate (2), even more preferably about 1 mm above said surface of said rotating grate (2), preferably parallel to said surface of said rotating grate (2).

3. The grate for burner according to any one of the preceding claims, wherein said rotating grate (2) comprises a rotating drum rotating about its axis normal to said surface of said rotating drum, and a further burner grate (7) removably attached to said surface of said rotating grate (2), preferably attached by means of screw joints.

4. The grate for burner according to any one of the preceding claims, wherein said scraper (1) is further positioned above said surface of said rotating grate (2) so as to essentially touch said surface of said rotating grate (2) and removes from said surface of said rotating grate (2) substantially predominantly, preferably all the matter that comes into contact with said scraper (1), predominantly ash.

5. The grate for burner according to any one of the preceding claims further comprising a fuel dispensing pipe (8) through which a fuel is fed to said rotating grate (2) through the fuel supply opening (11), wherein said fuel is essentially evenly distributed along said surface of said rotating grate (2) due to rotational movement of said rotating grate (2).

6. The grate for burner according to any one of the preceding claims further comprising said rotating grate (2) arranged on said rotating drum base plate (3) and provided with a form junction (13) which allows sealing despite of said movement of said rotating grate (2), said torque transmitted through the drive shaft worm (6) to the rotating drum drive shaft (5) of said rotating grate (2) by means of driving bottom sprocket of said rotating drum (10), and further transmitted from said rotating drum drive shaft (5) to said rotating grate (2) via rotating drum drive gear (4) and drum drive gear (12).

7. A solid fuel, preferably a biomass, combustion process comprising the following steps:

(a) fuel supply, preferably biomass, through the fuel supply (11) to said rotating grate (2);

(b) arranging the fuel, preferably biomass, along said surface of said rotating grate (2) for rotation thereof;

(c) combustion of fuel, preferably biomass on said rotating grate (2);

(d) purification after combustion of the residual matter, preferably ash, from said surface of said rotating grate (2) with a scraper (1).

8. The solid fuel, preferably a biomass, combustion process according to claim 7, comprising using a grate for burner according to any one of claims 1 to 6.

AMENDED CLAIMS

received by the International Bureau on 02 June 2018 (02.06.2018)

PATENT CLAIMS

1. A grate for burner, preferably a biomass burner, characterized in that it comprises a rotating grate (2) said rotating grate (2) rotating about its own axis, wherein said rotating grate (2) comprises an opening (11) positioned essentially centrally to said rotating grate (2) for supplying of fuel, preferably biomass, said fuel being supplied through said opening (11) to said rotating grate (2) and arranged along said surface of said rotating grate (2), wherein said grate for burner further comprises a scraper (1), said scraper (1) positioned above said surface of said rotating grate (2), said scraper (1) adjustable in direction essentially normal to said surface of said rotating grate (2), thereby achieving a predetermined thickness of the matter disposed on said rotating grate (2) that comes into contact with the scraper (1).

2. The grate for burner according to claim 1, wherein said scraper (1) comprises a lower edge preferably parallel to said surface of said rotating grate (2), said lower edge of said scraper (1) positioned between 0 and 5 mm above said surface of said rotating grate (2), preferably between 0.5 mm and 3 mm above said surface of said rotating grate (2), even more preferably about 1 mm above said surface of said rotating grate (2), preferably parallel to said surface of said rotating grate (2).

3. The grate for burner according to any one of the preceding claims, wherein said rotating grate (2) comprises a rotating drum rotating about its axis normal to said surface of said rotating drum, and a further burner grate (7) removably attached to said surface of said rotating grate (2), preferably attached by means of screw joints.

4. The grate for burner according to any one of the preceding claims, wherein said scraper (1) is further positioned above said surface of said rotating grate (2) so as to essentially touch said surface of said rotating grate (2) and removes from said surface of said rotating grate (2) substantially predominantly, preferably all the matter that comes into contact with said scraper (1), predominantly ash.

5. The grate for burner according to any one of the preceding claims further comprising a fuel dispensing pipe (8) through which a fuel is fed to said rotating grate (2) through the fuel supply opening (11), wherein said fuel is essentially evenly distributed along said surface of said rotating grate (2) due to rotational movement of said rotating grate (2).

6. The grate for burner according to any one of the preceding claims further comprising said rotating grate (2) arranged on said rotating drum base plate (3) and provided with a form junction (13) which allows sealing despite of said movement of said rotating grate (2), said torque transmitted through the drive shaft worm (6) to the rotating drum drive shaft (5) of said rotating grate (2) by means of driving bottom sprocket of said rotating drum (10), and further transmitted from said rotating drum drive shaft (5) to said rotating grate (2) via rotating drum drive gear (4) and drum drive gear (12).

7. A solid fuel, preferably a biomass, combustion process comprising using a grate for burner according to any one of claims 1 to 6 comprising the following steps:

(a) fuel supply, preferably biomass, through the fuel supply (11) to said rotating grate (2);

(b) arranging the fuel, preferably biomass, along said surface of said rotating grate (2) for rotation thereof;

(c) combustion of fuel, preferably biomass on said rotating grate (2);

(d) purification after combustion of the residual matter, preferably ash, from said surface of said rotating grate (2) with a scraper (1).

Description:
A grate for burner, preferably a biomass burner Field of technology

Combustion technology, combustion plants, biomass burning Technical problem

The technical problem to be solved by the present invention is the emergence of an unevenly arranged layer of fuel on a burner grate which causes local variations in the fuel conversion rate, which further causes uneven combustion and thus unforeseeable conditions in the combustion chamber. Consequently, such variations reflect in the emissions of harmful substances into the environment. Also, ash is formed, said ash after the complete transformation of fuel largely remaining on the grate itself. In order to ensure smooth operation it is necessary to provide an appropriate method of discharging the ash from the grate, otherwise, if its excessive accumulation causes negative phenomena, such as, for example, slag, sintering and coagulation.

State of the art

A common solution that allows for even distribution of fuel in the aforementioned combustion technology of biogenic fuels, usually in bulk, is: appropriately designed fuel transport system to an openings into the combustion chamber. With a suitably designed transport system and similarly designed fuel inlet conduit geometry, a homogeneously distributed fuel velocity profile is provided in said combustion chamber. When the fuel is fed evenly through the opening in the middle of the combustion chamber, then the fuel is spread evenly on all sides, which solves the problem of variation of the layer. Such a method involves the implementation of complicated forms which represents a great investment cost. Separation of ash from the grate is achieved by many technical solutions. More frequent methods include the implementation of machine parts which, by rotation, remove the ashes from the grate. Such systems use the same propulsion source as the transport system for their movement. In some places, dedicated resources are also used, which are converted into circular movements with appropriate transfers. Such a solution is presented in EP2757060 and EP2039993, but these solutions do not solve the technical problem of this invention.

Description of the new invention

A grate for burner, preferably a biomass burner, solves the technical problem described above by implementing a rotating grate (2) around a vertical axis, centered substantially in the fuel supply center, wherein said fuel is brought onto said grate from below, thus achieving a homogeneous arrangement of the layer depending on the velocity profile of the fuel supply itself, and further, with the implementation of a scraper which cleans the matter from surface of said rotating grate (2), which comes into contact with it by rotating said rotating grate (2). Unlike other known burners, where the grate is rigidly clamped, the fuel supplied according to this invention is evenly distributed over said the grate and forms an uniform layer of dispersed matter, predominantly embers, this solution reflecting favorably on the quality and general control of the combustion process.

Said rotary grate (2) may be embodied in the embodiment of this invention in such a way that it comprises a rotating drum rotating about its axis normal to said surface of the rotating drum (and a normal related to its surface), and further onto one side of the rotating drum is attached, preferably removable, burner grate (7). Said burner grate (7) can be preferably attached to said rotating drum by means of screw joints.

A scraper (1) is placed above said surface of said rotating grate (2), said scraper to provide for uniform thickness of the matter contacting said scraper (1). The scraper can be placed at a predetermined distance from said surface of said rotating grate (2) so that it can be just above said surface of said grate and essentially touches said grate, or it can be positioned at predetermined distance from said surface of said grate. Depending on said distance said scraper (1) can either remove all matter coming into contact and therefore acts as ash removal, or simply aligns height of piled matter whereby excess matter, preferably ash, falls from said surface of said rotating grate (2) either in a container or onto discharge means, such as worm for discharging of excess matter, preferably ash.

In particular embodiment the object of the invention is provided with a separation device separating from said matter which, as a consequence of contact with said scraper (1), has fallen from said rotating grate (2), fuel including partially oxidized matter, from ash.

The invention relates generally to a broader field of combustion technology that operate on solid biogenic fuels. Typical representatives of such fuels are: pellets produced from various raw materials (wood, grain biomass, waste wood, etc.), wood chips of various sizes, wood shavings, various cereals, sawdust, stones and shells of various fruits, plant products, etc.

In a narrower sense, the invention relates to a combustion technology of said fuel on a grate whereby the fuel is fed from below (also referred to as underfeed stoker burner). With the method described, the fuel is fed through the inlet opening located in the center of the grate, which often has a disc shape. The grate enables, among other things, the distribution of fuel in combustion chamber in order to provide for appropriate active surface area of the fuel, porosity of the layer, etc. The primary task of said grate is the supply of primary air into the reactive layer through the openings provided.

In the combustion of solid fuels which are stacked or piled there is a technological problem of the distribution of the fuel layer along the working surface of the burner, where the combustion air openings are located. Achieving uniformly and predictably distributed fuel layer is of great importance in small combustion plants where the operating volume of fuel is relatively low. An unevenly distributed fuel layer causes local variations in the fuel conversion rate, causing uneven combustion and thus unpredictable conditions in the combustion chamber. Consequently, such variations may result in the emissions of harmful substances into the environment.

Combustion of solid fuels is accompanied by the formation of solid products - ash. Said ash after complete conversion of fuel remains largely on the grate itself. In order to ensure smooth operation it is necessary to ensure an appropriate method of discharging of said ash from the grate otherwise its excessive accumulation causes negative phenomena, such as, for example, slag, sintering and coagulation.

This invention allows for the removal of ash from said surface of the grate by the implementation of a scraper, preferably in its stand-form. Since said rotating grate (2) is essentially in constant circular motion said scraper (1) may be mounted on the front of said rotating grate. This scraper removes the ash resulting from the flow of fuel at the outer edge of the grate. The ash falls to the bottom of the combustion chamber into a container or is by discharging means such as worm into the ash container. Using said system of cleaning of said moving burner grate there is no need to shut off the burner or switch off the device.

Said grate for burner, preferably a biomass burner is characterized in that it comprises a rotating grate (2) said rotating grate (2) rotating about its own axis, wherein said rotating grate (2) comprises opening positioned essentially centrally to rotating grate (2) for supplying of fuel preferably biomass, said fuel being supplied through said opening to said rotating grate (2) and arranged along said surface of said rotating grate (2), and further comprising a scraper (1), said scraper (1) positioned above said surface of said rotating grate (2), said scraper (1) adjustable in direction essentially normal to said surface of said rotating grate (2), thereby achieving a predetermined thickness of the matter disposed on said rotating grate (2) that comes into contact with the scraper (1).

Preferably, said scraper (1) comprises the lower edge, wherein said lower edge of said scraper (1) is positioned between 0 and 5 mm above said surface of said rotating grate (2), preferably between 0.5 mm and 3 mm above said surface of said rotating grate (2), even more preferably about 1 mm above said surface of said rotating grate (2), preferably parallel to said surface of said rotating grate (2).

The scraper according to the invention is further positioned above said surface of said rotating grate (2) so as to essentially touch said surface of said rotating grate (2) and removes from said surface of said rotating grate (2) substantially predominantly, preferably all the matter that comes into contact with said scraper (1), predominantly ash.

Below, this invention is further explained by means of figures, wherein figures form part of this patent application, and represent:

Figure 1 shows a burner with a grate, namely a scraper (1); a rotating grate (2), an arrow indicating the direction of rotation; rotating drum base plate (3); rotating drum drive gear (4); a rotating drum drive shaft (5); drive shaft worm (6); burner grate (7); fuel dispensing pipe (8); a driving bottom sprocket of said rotating drum (10).

Figure 2 shows a burner with a grate, namely a burner grate (7); fuel dispensing pipe (8); primary air inlet pipe (9); a driving bottom sprocket of a rotating drum (10).

Figure 3 shows a burner with a grate, namely a fuel supply on the grate; the arrow indicates the direction of the fuel supply through fuel supply opening (11); drum drive gear (12); form junction (13). Description below fits preferred embodiment, and represents one of possible modes for practicing this invention. Fuel is supplied through the fuel dispensing pipe (8). In this embodiment, fuel travels along the pipe and continues the path by changing the direction from essentially horizontal movement to essentially vertical one. The fuel arrives and enters the combustion chamber through the fuel supply (11) onto said rotating grate (2). As a result of the rotating movement of said rotating grate (2), the fuel is disposed along said rotating grate (2). The primary air is supplied through air inlet pipe, and then through said rotating grate (2), which allows the burning of pyrolytic charcoal. When burning, the ash is formed, which is separated from the grate using a scraper (1).

Said rotating grate (2) lies on the burner rotating drum base plate (3). The form junction (13) allows sealing despite said movement. The torque is transmitted through the drive shaft worm (6) to the rotating drum drive shaft (5) of said rotating grate (2) by means of driving bottom sprocket of said rotating drum (10). The torque is then transmitted from said rotating drum drive shaft (5) to said rotating grate (2) via rotating drum drive gear (4) and drum drive gear (12). Further, additional burner grate (7) can be detachably attached to said rotating grate (2), preferably by means of screw joints.

The primary air inlet pipe (9) serves to supply most (preferably all) of the combustion air to the area between said rotating grate (2) and the rotating drum base plate (3).

The grate for burner, preferably a biomass burner, may further comprise a fuel dispensing pipe (8) through which a fuel is fed to said rotating grate (2) through the fuel supply opening (11), wherein said fuel is essentially evenly distributed along said surface of said rotating grate (2) due to rotational movement of said rotating grate (2).

The invention further comprises said rotating grate (2) arranged on said rotating drum base plate (3) and is provided with a form junction (13) which allows sealing despite of said movement of said rotating grate (2), said torque transmitted through the drive shaft worm (6) to the rotating drum drive shaft (5) of said rotating grate (2) by means of driving bottom sprocket of said rotating drum (10), and further transmitted from said rotating drum drive shaft (5) to said rotating grate (2) via rotating drum drive gear (4) and drum drive gear (12).

The invention may further comprise a burner grate (7) removably attached to said rotating grate (2), preferably by means of screw joints.

The method of combustion of solid fuel, preferably biomass comprises the following steps:

(a) supply of fuel, preferably biomass, through a fuel supply opening (11) onto rotating grate (2);

(b) arranging of said fuel, preferably biomass, along surface of said rotating grate (2) due to its rotation;

(c) combustion of fuel, preferably biomass on said rotating grate (2);

(d) removal, after combustion ,of the residual matter, preferably ash, from said surface of said rotating grate (2) with a scraper (1).

The method of combustion of solid fuel according to this invention further comprises using a grate for burner according to this invention.