EP4209708B1 - Radial nozzle solid fuel gasification heater - Google Patents

Description

The invention relates to a solid fuel gasification heater with a radial nozzle.

The concept of gasification or pyrolysis heaters for solid fuels is widespread. It is mainly used in hot water wood boilers with manual feeding and to a lesser extent in wood stoves.

Known heaters of this concept contain a gasification chamber in the upper part and a combustion chamber in the lower part. The gasification chamber almost always has a square or rectangular cross-section. In the upper part it contains a hole for filling with fuel. The gasification chamber and the combustion chamber are separated by a partition. The partition thus forms the bottom of the gasification chamber with its upper surface and the ceiling of the combustion chamber with its lower surface. The partition contains a nozzle (vent or through hole) that connects the gasification chamber and the combustion chamber. The inlet opening (slot) of the nozzle is usually located in the center of the bottom of the gasification chamber. The outlet of the nozzle is located in the wall, which usually forms the ceiling of the combustion chamber.

The bottom of the gasification chamber can be horizontal or inclined towards the nozzle. The inclined bottom of the gasification chamber thus has the shape of a four-sided pyramid with the tip at the bottom, with 4 triangular walls or a four-sided channel with a pair of opposing triangular walls and a pair of trapezoidal walls. A heating device with the features of the preamble of claim 1 is known from AT 395 905 B known.

The gasification heater works as follows: The fuel turns into gas in the gasification chamber. It flows through the inlet opening into the nozzle, where it burns. The fuel gas flows through the nozzle outlet into the combustion chamber. In the nozzle, air is usually fed into the flame, which promotes combustion. The air is usually fed through an opening in the partition wall that opens into the nozzle.

• Gasaustritt aus der Vergasungskammer, während es normalerweise wünschenswert ist, dass sich der Auslass im mittleren Teil des Bodens der Vergasungskammer befindet, wo der Energiewert (Temperatur und Heizwert) des Gases am höchsten ist.
• Entaschung vom Boden der Vergasungskammer.
• Eindämmung von unverbrannten Teilen des Brennstoffs (Kohle) in der Vergasungskammer (damit sie nicht in die Brennkammer fallen).

The nozzle of the gasification heater therefore fulfils several functions:

• Gas outlet from the gasification chamber, while it is usually desirable that the outlet be located in the middle part of the bottom of the gasification chamber, where the energy value (temperature and calorific value) of the gas is highest.
• Ash removal from the bottom of the gasification chamber.
• Containment of unburned parts of the fuel (coal) in the gasification chamber (so that they do not fall into the combustion chamber).

The nozzle is therefore an important element and its quality has a significant influence on the quality of the entire heater. From the functions of the nozzle mentioned above, it becomes clear that the requirements for the spatial arrangement of the nozzle are quite contradictory: the removal of gases and ash requires large dimensions of the nozzle, while the capture of unburned particles or mixing with air requires small dimensions of the nozzle. The ash removal requires multiple inlets in the bottom area, while gas removal requires one inlet in the middle of the bottom. During operation, the walls of the nozzle are exposed to high temperatures (up to 1100° C), gas effects (oxidation and reduction reactions, etc.), ash effects (melting, high-temperature alkaline corrosion, etc.) and mechanical stress from parts of the fuel. This places extraordinary demands on the selection of the materials used.

The walls of the nozzle can be made of heat-resistant metal alloys of iron (refractory steel and cast iron). This material is strong and allows you to create any shape (for example, a grate), but its temperature resistance is insufficient and its service life is short.

Therefore, ceramic is most often used for the walls of the nozzle. Ceramic withstands temperatures well, but is fragile. Its strength, especially in tension, is several times lower than that of metallic materials. Therefore, the ceramic parts must be solid, which imposes significant restrictions on dimensions.

From the above facts it is clear that the requirements for the dimensional arrangement of the nozzle are considerable.

Known nozzle types differ mainly in the shape and number of inlet holes. The most common nozzles are those with an inlet opening and a rectangular cross-section with a clear difference in the sides (elongated). There are also square or round nozzles. In nozzles with a single inlet opening, the nozzle vent usually follows the inlet opening. The cross-section of the vent widens downwards to prevent parts of the fuel from getting stuck. The outlet opening is therefore usually identical to the inlet opening, but slightly larger. In nozzles with a larger number of inlet holes the vents from the individual inlet holes are usually connected to a single outlet hole.

As mentioned above, the requirements for the nozzles are contradictory, so each type of nozzle has a different combination of advantages and disadvantages. For example, a square or round nozzle achieves a higher energy value of the gas (and thus the combustion quality) due to its central location in the bottom, but has the disadvantage of a large waste of fuel parts, which are then missing in the gasification chamber. This reduces the efficiency of gasification, while the fuel parts are disruptive in the combustion chamber and worsen the quality of gas combustion. On the other hand, a rectangular nozzle has the advantage (because it is significantly narrower for the same area) that parts of the fuel lose a small drop. But its disadvantage is that its ends extend into the peripheral areas of the bottom, where the energy value of the gas is lower. This reduces the overall quality of combustion. The inhomogeneity of the gas flow then worsens the correct mixing with the secondary air. This requires, for example, the need for a homogenization (mixing) chamber behind the outlet of the nozzle, which makes heating more expensive but also more complicated.

The effort to achieve the greatest possible share of the above-mentioned advantages leads to the design of nozzles with a relatively small area of the inlet opening, which increases the gas throughput and thus the pressure loss of the nozzle. For this purpose, for example, the heater must be equipped with a fan, while the fan power also increases as the pressure loss of the nozzle increases. High gas velocities locally increase the intensity of oxidation reactions, which increase the temperature due to increased formation of harmful NOX emissions (nitrogen oxides) or cause undesirable melting of ash (slag formation).

Nozzles with a larger number of inlet holes have advantageous operating characteristics. However, for reasons of strength, they do not allow the use of ceramic material, so they have to be made of metal. They therefore also have a short lifespan and have to be replaced frequently, which makes them more expensive to operate.

Some types of gasification heaters are characterized by a strongly inclined bottom of the gasification chamber towards its center - or the nozzle. The bottom thus forms the shape of a four-sided pyramid with the tip at the bottom. With a sufficient angle of fall (more than 40°), the ash slides down the bottom walls into the nozzle during operation, which is a significant advantage. However, this type of bottom also has disadvantages. For example, it limits the spatial possibilities of the nozzle, which is why heaters with a strongly inclined bottom usually have a square or round nozzle with the above-mentioned disadvantages (large drop, high gas velocities, large pressure loss). This disadvantage worsens the properties of a strongly sloping bottom to such an extent that most manufacturers of gasification furnaces prefer a horizontal or slightly sloping bottom (5 - 10°). The disadvantage of these types of bottom is that the ash does not flow through the nozzle into the combustion chamber and accumulates at the bottom of the gasification chamber. This reduces the combustion quality and places a burden on the operator (the heating must be switched off regularly and the ash removed).

In summary, existing nozzles of gasification furnaces have many defects, the extent of which varies depending on the type and size of the shape and slope (degree of slope) of the bottom. These defects are particularly pronounced in heaters with an inclined bottom.

The shortcomings of known gasification heater nozzle solutions are completely or largely eliminated by a gasification heater for solid fuels with a radial nozzle containing a gasification chamber and a combustion chamber located below the gasification chamber. The bottom of the gasification chamber is inclined towards the center of the gasification chamber by four inclined walls that form a pyramid shape form, with the tip pointing into the combustion chamber, or forming a trough. The gasification chamber and the combustion chamber are separated by a partition through which the nozzle is guided. Its inlet opening is located in the bottom of the gasification chamber and its outlet opening in the wall of the combustion chamber. The essence of the invention is that the inlet opening of the nozzle consists of a central slot in the shape of a rectangle or square and radial slots forming four rectangular openings. These are located in the edges between the inclined walls of the bottom of the gasification chamber, creating a radial pattern. The central vent of the nozzle is guided under the central slot. The radial slots are followed by channels that open into the central vent, which forms an outlet opening in the walls of the combustion chamber. The channels are located at an angle of at least 40 °, ie the angle of the bottom of the channels relative to the horizontal plane. The side walls of the channels are mutually open to their lower walls (bottom of the channels).

• Dank der radialen Form und der diagonalen Anordnung hat der Einlassbereich eine 2 - 3x größere Fläche als eine gleich breite rechteckige Düse, die traditionell im mittleren Teil des Bodens (d. h. parallel zur Seitenwand der Vergasungskammer) angeordnet ist.
• Das Austrittsloch konzentriert die Rauchgase zu einem kompakten Strom, was die Homogenität der Gase und die Qualität der Verbrennung erhöht.
• Die Geometrie der Düse erlaubt den Einsatz von Keramik (die Teile zwischen den einzelnen Balken sind ausreichend massiv).
• Der große Querschnitt der Düse reduziert den Druckverlust, was die Leistung des Ventilators reduziert und sogar den Betrieb nur mit dem natürlichen Schornsteinzug ermöglicht.
• Der Abfall eines Teils des Kraftstoffs ist deutlich kleiner als bei Düsen mit quadratischer oder kreisförmiger Eintrittsöffnung (von gleicher Fläche), die vorhandenen Heizungen mit einem deutlich abfallenden Boden haben.

The advantages of the invention are:

• Thanks to the radial shape and diagonal arrangement, the inlet area has a 2 - 3x larger area than a rectangular nozzle of the same width, which is traditionally located in the central part of the bottom (i.e. parallel to the side wall of the gasification chamber).
• The exit hole concentrates the flue gases into a compact stream, which increases the homogeneity of the gases and the quality of combustion.
• The geometry of the nozzle allows the use of ceramics (the parts between the individual beams are sufficiently solid).
• The large cross-section of the nozzle reduces the pressure loss, which reduces the power of the fan and even allows operation only with the natural chimney draft.
• The drop in a portion of the fuel is significantly smaller than in nozzles with square or circular inlet openings (of the same area), which have existing heaters with a significantly sloping bottom.

Fig. 1

ein Seitenteil eines Vergasungserhitzers mit stark geneigtem Boden mit Radialdüse,

Fig. 2

eine dimensionale Ansicht einer Vergasungskammer mit quadratischem Querschnitt und pyramidenstumpfförmigem Schrägboden,

Fig. 3

eine dimensionale Ansicht einer Düse in einem Vergaserheizer mit einer Vergasungskammer mit quadratischem Querschnitt,

Fig. 3.1

eine Draufsicht auf die Düse aus Fig. 3,

Fig. 3.2

einen Schnitt A-A orientiert an Fig. 3.1,

Fig. 3.3

eine Unteransicht der Düse aus Fig. 3,

Fig. 4

eine räumliche Darstellung der Düse und Teile der Düse aus Fig. 3,

Fig. 5

eine räumliche Darstellung der Düsenkanäle aus Fig. 3,

Fig. 6

eine räumliche Darstellung der zentralen Entlüftung der Düse aus Fig. 3,

Fig. 7

eine räumliche Darstellung der Eingangsöffnung aus Fig. 3,

Fig. 8

einen Schnitt B-B orientiert an Fig. 3.1, der die Form des Kanals zeigt,

Fig. 9

eine räumliche Darstellung des Kanals aus Fig. 3,

Fig. 10

eine dreidimensionale Ansicht einer Vergasungskammer mit rechteckigem Querschnitt und schrägem, wannenförmigem Boden,

Fig. 11

eine Raumansicht einer Düse in einem Vergaserheizer mit einer im Querschnitt rechteckigen Vergasungskammer

Fig. 11.1

eine Draufsicht auf die Düse aus Fig. 11,

Fig. 11.2

einen Schnitt A-A orientiert an Fig. 11.1,

Fig. 11.3

eine Unteransicht der Düse aus Fig. 11,

Fig. 12

eine räumliche Darstellung der Düse und Teile der Düse aus Fig. 11,

Fig. 13

eine räumliche Darstellung der Düsenkanäle aus Fig. 11,

Fig. 14

eine räumliche Darstellung der zentralen Entlüftung der Düse aus Fig. 11 und

Fig. 15

eine räumliche Darstellung der Eintrittsöffnung der Düse aus Fig. 11.

The invention is explained in more detail with reference to the attached figures. They show:

Fig.1

a side part of a gasification heater with a steeply inclined bottom with radial nozzle,

Fig. 2

a dimensional view of a gasification chamber with a square cross-section and a truncated pyramid-shaped sloping floor,

Fig. 3

a dimensional view of a nozzle in a carburetor heater with a gasification chamber with a square cross-section,

Fig. 3.1

a top view of the nozzle Fig.3 ,

Fig. 3.2

a section AA oriented to Fig. 3.1 ,

Fig. 3.3

a bottom view of the nozzle Fig.3 ,

Fig.4

a spatial representation of the nozzle and parts of the nozzle Fig.3 ,

Fig.5

a spatial representation of the nozzle channels from Fig.3 ,

Fig.6

a spatial representation of the central vent of the nozzle from Fig.3 ,

Fig.7

a spatial representation of the entrance opening Fig.3 ,

Fig.8

a cut BB based on Fig. 3.1 , which shows the shape of the channel,

Fig.9

a spatial representation of the channel Fig.3 ,

Fig.10

a three-dimensional view of a gasification chamber with a rectangular cross-section and a sloping, trough-shaped floor,

Fig. 11

a spatial view of a nozzle in a carburetor heater with a gasification chamber with a rectangular cross-section

Fig.11.1

a top view of the nozzle Fig. 11 ,

Fig. 11.2

a section AA oriented to Fig.11.1 ,

Fig.11.3

a bottom view of the nozzle Fig. 11 ,

Fig. 12

a spatial representation of the nozzle and parts of the nozzle Fig. 11 ,

Fig. 13

a spatial representation of the nozzle channels from Fig. 11 ,

Fig. 14

a spatial representation of the central vent of the nozzle from Fig. 11 and

Fig. 15

a spatial representation of the inlet opening of the nozzle Fig. 11 .

Fig.1 shows a gasification heater 100 (gasification boiler) for the manual addition of solid fuel 6, for example wood.

The gasification boiler 100 contains a gasification chamber 4 with a square or rectangular cross-section and a combustion chamber 9 arranged below the gasification chamber 4. The gasification chamber 4 and the combustion chamber 9 are separated by a partition wall 5 which forms the bottom 10 of this gasification chamber 4 on the side of the gasification chamber 4, and the combustion-side chambers 9 form the upper inner wall 7 of this combustion chamber.

A nozzle 2, consisting of an inlet opening 1 and an outlet opening 3, is guided through the partition wall 5. The floor 10 of the gasification chamber 4 is clearly inclined towards the centre of the gasification chamber 4 by four inclined walls 11. The walls 11 of the gasification chamber 4, which has a square cross-section, are inclined in the shape of a pyramid ( Fig.2 ). The inclined walls 11 of the gasification chamber 4 with rectangular cross-section are inclined in the form of a channel ( Fig.10 ).

The inlet opening 1 of the nozzle 2 at the gasification chamber 4 with square cross-section ( Fig. 3 to 9 ) includes a square central slot 13 and radial slots 14. Below the central slot 13 there is a central vent 15 which forms an outlet opening 3 in the wall 7 of the nozzles 2 of the combustion chamber 9. The central vent opening 15 has the shape of a regular prism with a square profile, the upper part of which has folded corners. The radial slots 14 are formed by rectangular openings arranged in the edges 12 of the bottom 10 of the gasification chamber 4. This creates a radial pattern which resembles a four-pointed star or a cross. The channels 8 leading to the central vent 15 are connected to the radial slots 14 through the nozzles 2. The channels 8 are inclined to the central vent 15 at an angle of at least 40°. The side walls 16 of the channels 8 are mutually open to their lower walls 17 ( Fig. 8 and 9 ).

The inlet opening 1 of the nozzle 2 on the gasification chamber 4, which has a rectangular cross-section ( Fig. 11 to 15 , 8 and 9 ) contains a central slot 13 of rectangular shape and radial slots 14. Below the opening 15, a central vent 15 is guided with central slot 13, which forms a combustion chamber wall 7, 9. The combustion chamber wall 7, 9 has an outlet opening 3 and nozzles 2. The central vent 15 has a rectangular profile of variable size. The radial slots 14 are formed by rectangular openings located in the edges 12 of the bottom 10 of the gasification chamber 4 and creating a radial pattern. The channels 8 leading to the central vent 15 are connected to the radial slots 14 by the nozzles 2. The channels 8 are inclined to the central vent 15 at an angle of at least 40°. The side walls 16 of the channels 8 are mutually open to their lower walls 17 ( Fig. 8 and 9 ).

List of reference symbols

1 -

Entrance hole

2 -

jet

3 -

Outlet hole

4 -

Gasification chamber

5 -

Bulkhead

6 -

fuel

7 -

Wall

8th -

channel

9 -

Combustion chamber

10 -

below

11 -

sloping wall

12 -

Edge

13 -

Center gap

14 -

Radial gap

15 -

central ventilation

16 -

Side wall

17 -

lower wall

100 -

Heating

Claims (1)

1. Radial nozzle solid fuel gasification heater with a jet nozzle (2), a gasification chamber (4) with a bottom (10), and a combustion chamber (9) is located below the gasification chamber (4) and the bottom (10) of the gasification chamber (4) slopes towards its centre by four inclined walls (11) which form a pyramidal shape with the apex pointing to the combustion chamber (9) or form a trough, the gasification chamber (4) and the combustion chamber (9) are separated by a partition (5), which on the side of the gasification chamber (4) forms the bottom (10) of this gasification chamber (4) and on the side of the combustion chamber (9) forms the upper inner wall (7) of this combustion chamber (9), the partition (5) being guided nozzle (2) the inlet opening (1) of which is in the bottom of the gasification chamber (4) and the outlet opening (3) is in the wall (7) of the combustion chamber (9), characterized in that the inlet opening (1) of the nozzle (2) consists of a rectangular or square central slot (13) and rectangular radial slots (14), which are formed in the edges (12) between the inclined walls (11) of the bottom (10) of the gasification chamber (4), wherein under the central slot (13) there is a central vent (15) of nozzles (2) forming a through hole, and the radial slots (14) are connected by channels (8) which go into the central vent (15) which forms in the wall (7) ) of the combustion chamber (9) outlet hole (3), wherein the channels (8) are sloped towards the central vent (15) at an angle of at least 40°, and the side walls (16) of the channels (8) are mutually opened towards their lower walls (17).

Images