EP0445437B1 - Burner arrangement - Google Patents

Abstract

2.1. Known burner arrangements are designed for oil and gas burning operation. Burner arrangements for solid-fuel operation are as is generally known prefurnaces which operate with a poor degree of efficiency. 2.2. The invention proposes in particular a solid-fuel forced-draught burner which has a chute (11) for solid fuel to be burned, a soild fuel supply device (9) connected preferably on the underside to the chute, a turbulence chanber (12) arranged downstream of the chute (11) and a lateral burning-out pipe (13) following the turbulence chamber, it being possible additionally to provide a blower (14) for the controlled supply of lower air (1), secondary air (2), upper air (3) and outgoing air (4). <IMAGE>

Description

The invention relates to a burner arrangement with a combustion pipe, in the pre-arrangement of a boiler for the purpose of heating it, with a filling shaft for solids to be burned, which extends horizontally behind the filling shaft in the transverse direction and the diameter of the swirl chamber is larger than the diameter of the burnout pipe, and the swirl chamber has a jacket opening with a tangential wall area connection to the filling shaft.

Known oil and gas burners, so-called "blue burners", have a burner nozzle and a combustion chamber which can soot and may not ensure optimal, low-pollutant combustion with good efficiency. Of course, oil and gas burners are not suitable for solid matter combustion, especially industrial wood chips and chips.

In order to burn solids, the prior art provides so-called preliminary furnaces in a preliminary arrangement of boilers which are operated in the manner of a burner arrangement. In operation, the supplied solid material is burned in the forehearth, the flame of which is directed through a combustion tube onto the combustion chamber of a downstream boiler. The result is an undefined flame with a comparatively low temperature, combined with a high dust emission, ie with a comparatively high proportion of unburned parts. A pre-furnace operation is therefore associated with a comparatively low efficiency. Pollution, soot and environmental pollution are great.

The known preliminary furnaces have a solids supply which does not allow pressure sealing on the inlet side. In accordance with the external atmospheric pressure, practically only constant pressure operation with reduced draft ratios of primary and secondary air is possible in the forehearth. Fan connections are not provided and would also be ineffective due to the constant pressure operation.

The object of the invention is to provide a burner arrangement with a combustion tube of the type mentioned at the outset, which is simple in construction and nevertheless has good heating efficiency with low-pollutant flue gas combustion and can also be used in a variety of ways.

The object on which the invention is based is achieved by the means specified in the characterizing part of claim 1.

The subject of the invention is advantageously further developed by the features of subclaims 2 to 12.

The swirl chamber is therefore designed as a hollow tube closed on one side, the concentric burnout tube adjoining the open end of the tube, which is located to the side of the jacket opening of the swirl chamber, and the jacket opening has the width of the filling shaft. As a result, practically the entire width of the filling shaft is used for the tangential entry of the gases into the swirling chamber, which has a correspondingly long design and thus ensures an optimally defined swirling. Characterized in that the burnout tube connects laterally to the swirl chamber, an axial flow component is also created during operation of the burner arrangement, which leads to a high-quality flame. This flame can then be fed into the downstream boiler at the desired location will. The separation of the burnout tube is easy because there is an opening flange opposite the flame outlet, so that the swirl chamber and the burnout tube can be easily seen.

DE-U-8 809 659 discloses a burner arrangement with a burner tube of the type mentioned at the outset. However, the known inflow geometry into the afterburning area is fundamentally different and, as a result, the gas behavior during combustion is different. The known combustion chamber cannot be separated from the main degassing room. Functionally, in the known arrangement, even after a short period of operation, deposits and consequently cross-sectional constrictions in the channels can occur. The design-related temperature build-up conditions also lead to very high combustion gas temperatures, which significantly increases nitrogen oxide production. The known arrangement is designed for a so-called "lower edge".

In a further development of the invention, the solid material is pressed into the combustion chamber of the filling shaft designed as a gasification chamber by means of a screw conveyor or the like, and a so-called “upper edge” is therefore set up.

In an advantageous development of the invention, baffles are provided in the swirling chamber, which are arranged helically on the inner circumference (with the exception of the pipe jacket opening), the screw pitch being directed in the direction of the entrance of the burnout pipe. In this way, flue gases conducted from the filling shaft through the swirling chamber to the burnout pipe are subjected not only to increased swirling but also to an increased axial force in the direction of the burnout pipe axis.

It is particularly expedient if the burnout tube has a plurality of parallel individual combustion tubes, three equally distributed individual combustion tubes being provided on the circumference.

Since the solids supply device is connected directly to the filling shaft, it is particularly expedient to provide a blower with a metering device for the controlled supply of air. The solids feed device preferably comprises a cellular wheel sluice or a solids screw conveyor, which opens at the bottom of the filling shaft and extends to the grate of the filling shaft. Here, an upward curved ramp is preferably provided at the end of the screw conveyor, which extends to the grate. There is an (electrical) ignition device under the ramp.

Due to the screw conveyor, which is cold during operation, no burn-back to the free solid material on the inlet side is possible, and perfect "overpressure operation" in the filling shaft or gasification chamber is possible, which has good draft conditions, particularly due to the blower.

The fan is expediently connected to an air distribution chamber located in the interior of the burner arrangement, which feeds sub-air or primary air via a first air duct to the underside of the filling duct below the grate and secondary air via a second air duct close above the grate of the filling duct. Here, a section of the second air duct runs directly past the filling shaft wall, as a result of which the secondary air warms up optimally before entering the filling shaft.

The air distribution chamber has a connection for a third air duct, via which so-called upper air is fed to the top of the filling shaft clearly above the grate. The inlet opening of the upper air into the filling shaft is located on the side and supports the passage of the combustion air to the downstream swirling chamber in such a way that a defined swirling occurs in the swirling chamber and the flue gas is likewise fed through the swirl chamber to a downstream burnout pipe.

In a particularly advantageous development of the invention, the air distribution chamber has a further fourth air duct, which feeds so-called comparatively cool outlet air directly to the entrance of the burnout tube. The supply line for the abovementioned outlet air cools the high-quality flame which is subjected to a rotary movement (swirl) in the burnout tube, from a flame temperature of approximately 1100 ° C. to a flame temperature of 800 ° C. This means that the flames emerging from the burner arrangement have less NO _x , since the NO _x formation only takes place at 600 ° C. This last-mentioned measure clearly shows an environmentally friendly, low-pollution combustion.

All of the aforementioned air channels for the supply of lower, secondary, upper and outlet air are at least partially provided with adjusting screws in order to meter the supply air manually or automatically.

The burner arrangement has in particular cube or box shape of compact cut. The basic housing can have steel walls, in particular an outer heat insulation jacket being provided. Behind it is an all-round water jacket, which is connected to the downstream boiler.

The burner arrangement according to the invention enables, in particular, the automatic firing of wood chips and chips (carpenter material). The basic housing is designed so that a different installation technique is possible.

Overall, the water flow of the basic housing is designed so that radiation loss from the burner arrangement is prevented. The burner can be regulated quickly and is controlled via the boiler temperature. It has great flexibility with regard to the types of loading. In addition to underfeed loading, one is also possible Fall loading of the filling shaft from above through a feed opening with a closure arranged there. The advantages and disadvantages of the different types of feed depend to a large extent on the fuel. If underfeed loading is provided, the grate in the feed area is recessed to accommodate the end of the aforementioned ramp. The firing material is pushed up here. Extending the material transport shaft beyond the grate provides optimal predrying and better loosening of the fired goods. Overall, the design of the grate depends on the ash content and the degree of slagging of the fuel.

The function of the burner arrangement is described below.

When the burner arrangement is started up, the screw conveyor is in operation, which is driven by a motor which in turn is controlled by the boiler temperature. Similarly, the electrical ignition device is in operation for about 10 minutes. The forwarded wood chips or chips begin to smolder and are pushed further on the ramp into the filling shaft or pre-carburetor room. There, the combustion air supplied causes combustion of primary air and secondary air via the blower. A level indicator or sensor in the form of a swivel lever is installed in the combustion chamber or filling shaft, which actuates a level switch to switch off the screw conveyor. The burner arrangement works independently like an oil burner, and every boiler output can be heated even in the smallest low-load operation. This prevents the temperature from falling below the dew point, as well as the formation of wood vinegar on the boiler walls, whereby there is no premature corrosion. The aforementioned Solid-fuel blowpipe can be operated fully automatically without supervisory personnel. Due to the upstream rotary valve or the like, there is a large backfire protection. The practically obtained exhaust gas values are significantly below the prescribed values of the Federal Immission Control Ordinance.

The advantage of the pre-swirling chamber lies in particular in the start-up phase of the burner arrangement, since a good burn-out can already be achieved in the start-up phase. The fresh air / gas mixture is then optimally prepared for the burnout section.

Fig. 1

in schematischer perspektivischer aufgebrochener Ansicht eine Brenneranordnung,

Fig. 2

die Anordnung nach Fig. 1 in schematischer aufgebrochener Draufsicht,

Fig. 3

die Anordnung nach Fig. 1 in einem Schnitt A-A der Fig. 2,

Fig. 4

die Anordnung nach Fig. 1 in einem Schnitt B-B der Fig. 2,

Fig. 5

eine Einzelheit in Bereich des Eingangs des Ausbrennrohrs ähnlich der Schnittansicht der Fig.3,

Fig. 6

einen Schnitt C-C der Fig. 5, und

Fig. 7

eine perspektivische aufgebrochene Gesamtansicht der Brenneranordnung ähnlich Fig.1 in größerer Einzelheit.

The invention is explained in more detail using an exemplary embodiment with reference to the accompanying drawings; show it:

Fig. 1

a schematic perspective broken view of a burner arrangement,

Fig. 2

1 in a schematic broken top view,

Fig. 3

1 in a section AA of FIG. 2,

Fig. 4

1 in a section BB of FIG. 2,

Fig. 5

a detail in the area of the entrance of the burnout tube similar to the sectional view of Figure 3,

Fig. 6

a section CC of Fig. 5, and

Fig. 7

a broken perspective overall view of the burner assembly similar to Figure 1 in greater detail.

According to the drawing, a burner arrangement 10 is provided for automatically burning industrial wood chips and chips (carpenter material).

The basic housing is designed so that a different installation technique is possible.

The burner arrangement 10 essentially comprises a filling shaft 11 for solids to be burned, a solids supply device connected to the filling shaft 11, a swirling chamber 12 arranged downstream of the filling shaft and a side burnout tube 13 following the swirling chamber.

Furthermore, a blower 14 with a metering device is provided for the controlled supply of combustion air.

The blower 14 is connected to an air distribution chamber 15 located in the interior of the burner arrangement, which supplies sub-air 1 through a first air duct to the underside of the filling shaft and secondary air 2 through a second air duct close above the grate 18 to the filling shaft, a section 17 of the second air duct passes directly past the vertical inner filling shaft wall 18 in order to set up optimal preheating of the secondary air.

The air distribution chamber 15 is also connected to a third air duct, which supplies the upper air 3 to the upper side of the filling duct 11 clearly above the grate 18 in a manner as will be described below. Dosing devices are located in the individual air channels for lower air 1, secondary air 2 and upper air 3 in the form of adjusting screws 6, which allow quantity regulation by rotation. Thus, in operation, metering air 5 flowing into the air distribution chamber 15 flows through the fan 14 in a controlled manner to the individual areas of the filling shaft 11 for the purpose of optimizing the combustion and flow.

The blower 14 ensures a so-called “overpressure operation” of the combustion chamber in particular because the filling shaft 11 is tightly connected to the solids supply device 9 on the inlet side.

The solids feed device 9 is designed according to the embodiment of the drawing as a so-called underfeed feed and provides for an automatic feed of the solid to be burned, industrial wood chips, chips or the like. A screw conveyor 26 which is motor-driven and controlled by the boiler temperature. The screw conveyor 26 is essentially in horizontal extension on the front side and extends below the grate 16 into the burner arrangement 10, closely followed by an upwardly curved ramp 27 which is guided up to a recess in the grate 16. The material is pushed through the screw up to the top of the filling shaft, an electric ignition device 28 being provided under the ramp 27 being in operation in the start-up phase of the burner arrangement for approx. 10 minutes, so that the chips supplied, wood chips or the like. begins to smolder and is brought to the combustion in the filling shaft or pre-carburetor through the fan 14 supplied primary and secondary air for combustion.

In the filling chamber 11 there are a central level sensor 8 with a swivel lever 29 which is on the side of the filling shaft is articulated in a burner arrangement. The free end of the pivot lever 29 is designed as a so-called solid float 30 such that the float moves upward when the level is increased and the pivot lever 29 is therefore pivoted. When the swivel lever 29 swivels upwards, the swivel lever 29 engages with a level switch 7, which switches off the screw conveyor 26. If the filling level in the filling shaft 11 falls, the screw conveyor 26 is put into operation again.

The level switch 7 is adjustable in height in order to set up different fill levels. The height of the level transmitter 8 can also be adjusted accordingly. Of course, the screw conveyor 28 is only put into operation when the boiler temperature has dropped accordingly.

In addition to the above-mentioned underfeed loading, however, it is also possible for the filling shaft 11 to be loaded from above, since in principle an access opening 31 is provided on the top of the filling shaft, which extends in a dome shape upwards. The upper access opening 31 has an upper closure which has an insulating layer on the underside (which is not illustrated in the drawing).

The burner assembly is constructed in a cube or box shape in a compact manner and has an outer heat insulation jacket 32, which is followed on the inside by a circumferential water jacket 33, which is connected via a connection 34 to a boiler (not shown). The swirl chamber 12, which is designed in the form of a tube whose one axial side is closed, is located behind the filling shaft 11 in a horizontal transverse arrangement. The other axial side of the tube is open and is connected to the inlet 19 of the coaxial burnout tube 13, the three circumferentially equally distributed individual combustion tubes 25 of which are directed towards the combustion chamber of the boiler, not shown. The individual fuel tubes 25 are made of silicon carbide and have a small wall thickness, which reaches a high ignition temperature early on when being put into operation. Silicon carbide tolerates temperature changes and withstands aggressive gases. The component is also easy to replace.

The inlet 19 of the burnout tube 13 has an annular channel 23, which is illustrated in greater detail in FIGS. 5 and 6. The annular duct 23 is connected on the input side to a fourth air duct, which is connected to the aforementioned air distribution chamber 15 or to the aforementioned fan 14 in order to convey comparatively cool exhaust air 4 to the inlet 19 of the burnout tube 13 during operation, namely through axially parallel outlet openings 24 which set up a passage from the ring channel 23 to the entrance 19 of the burnout tube 13. The outlet air 4 is pressed out of the ring channel 23 on the outer edge of the individual fuel tubes against the flow of the fuel gas and is only active in the individual fuel tubes in such a way that the flame temperature is staggered from approx. 1100 ° C. to 800 ° C., which reduces the NO Mixing is influenced favorably, ie essentially reduces the formation of NO _x .

The swirling chamber has a tubular casing opening 21 in the direction of the filling chute 11 approximately in the width of the filling chute, the upper horizontal edge 35 of the tubular casing opening 21 allowing tangential inlet of the fuel gas from the filling chute 11 into the swirling chamber 12.

The upper horizontal edge 35 lies approximately in an extension of the upper side of the vertical filling shaft wall 18.

During operation, a defined rotary movement or a swirl of the fuel gas is generated in the swirling chamber 12, which continues up to the individual combustion tubes 25 of the combustion tube 13 and there ensures a high-quality defined flame flow, which even after exiting the combustion tube 13 in a targeted manner can be directed to the combustion chamber of the downstream boiler.

The inlet 20 of the upper air 3 to the filling shaft 11 is located on the side of the burner arrangement 10 opposite the inlet 19 of the burnout tube 13, so that the upper air 3 supports the axial flow of the fuel gas in the swirling chamber towards the burnout tube 13.

On the inside of the jacket of the swirling chamber 12, swirling baffles 22 can be provided, which are arranged helically. The screw pitch runs in the direction of the burnout tube 13 for the purpose of establishing an axial delivery component for the fuel gases flowing through.

It is therefore created in particular by the invention, a solid-fuel forced-air burner which has a chute to be loaded from below or from above. The outer basic unit is water-bearing, the outer jacket has a cube shape. The fuel gas is injected into the swirl chamber tangentially with an effective swirl effect. By supplying the outlet air 4, a gradual burnout in the individual combustion tubes is possible. The individual combustion pipes or the burnout pipe are arranged in a lateral arrangement in a coaxial extension of the Swirling chamber behind the filling shaft 11 or degassing shaft. The combustion air supply is achieved with the aid of a blower 14, the air being able to be optimally fed to the individual burner arrangement points via an air distribution chamber 15, in particular in that each air point is provided with a metering throttle.

Claims (12)

1. Burner arrangement with burner tube mounted before a boiler for the purposes of heating it, with a filler shaft (11) for the solid fuels to be burned, a solid fuel feed device (9) connected to the filler shaft (11), a cylindrical swirl chamber (12) mounted after the filler shaft and a burner tube (13) connected to the swirl chamber (12), whereby the swirl chamber extends substantially horizontally and transversely behind the filler shaft (11) and the diameter of the swirl chamber is greater than the diameter of the burner tube, and the swirl chamber (12) has a sleeve aperture (21) with tangential wall region connection to the filler shaft (11),
   characterized in that
   the swirl chamber (12) has the form of a tube the one axial end of which is closed and the other end is arranged concentrically to the subsequent burner tube (13) and is connected to this, with the inlet (19) of the burner tube (13) being located at the level of one axial side of the sleeve aperture (21), which has the same width as the filler shaft (11).
2. Burner arrangement in accordance with claim 1,
   characterized in that
   the swirl chamber (12) has swirl baffle plates (22) which are arranged helically on the inner circumference of the swirl chamber (12) (with the exception of the sleeve aperture) and the helix pitch is aligned in the direction of the inlet (19) to the burner tube (13).
3. Burner arrangement in accordance with one of the claims 1 or 2,
   characterized in that
   the burner tube (13) has a number of individual burner tubes (25) distributed equally around the circumference (3) and with parallel axes.
4. Burner arrangement in accordance with one of the claims 1 to 3,
   characterized in that
   a blower (14) is located on the side of the burner arrangement opposed to the burner tube (13).
5. Burner arrangement in accordance with claim 4,
   characterized in that
   the blower (14) has a dosing device for the controlled supply of air.
6. Burner arrangement in accordance with claim 4 or 5,
   characterized in that
   the blower (14) is connected to an air distribution chamber (15), which supplies bottom air (1) through a first air duct to the underside of the filler shaft (11) below the grid (16) and secondary air (2) through a second air duct just above the grid (16) to the filler shaft (11), whereby the second air duct is skirted tightly by one wall of the filler shaft (18) in one section (17), in that the air distribution chamber (15) connected with the blower (14) feeds into a third air duct, which supplies top air (3) to the top of the filler shaft and has a fourth air duct which supplies exit air (4) to the inlet (19) of the burner tube (13), with the inlet (20) of the top air (3) to the filler shaft (11) being arranged in opposition to the inlet (19) of the burner tube (13).
7. Burner arrangement in accordance with one of the claims 5 or 6,
   characterized in that
   the air ducts supplying bottom air (1), secondary air (2), top air (3) and exit air (4) are at least partially equipped with adjustment screws (6) for the purposes of dosing the supply air.
8. Burner arrangement in accordance with one of the claims 6 or 7,
   characterized in that
   the fourth air duct has a ring duct (23) surrounding the burner tube (13) in the region of the inlet (19) to the burner tube (13), said ring duct for its part having a number of axially parallel exit apertures (24) around the inlet (19) to the burner tube (13).
9. Burner arrangement in accordance with one of the claims 1 to 8,
   characterized in that
   the solid fuel feed device is constructed as an underfeed loader of the filler shaft (11) and has a motor-driven solid material conveyor screw (26) or bucket wheel device, and that a boiler temperature-dependent controller device is provided for the drive to the solid material feed device (9).
10. Burner arrangement in accordance with claim 9,
    characterized in that
    the screw conveyor (26) is mounted substantially horizontally in the transverse direction to the swirl chamber (12) and to the burner tube (13), in that a curved ramp (27) at the delivery end of the screw conveyor (26) extends as far as the filler shaft grid (16) and a solid fuel ignition device (28) is provided and in that a boiler temperature-dependent controller is provided for the ignition of the ignition device (28).
11. Burner arrangement in accordance with one of the claims 1 to 10,
    characterized in that
    a height-adjustable level indicator (8) and a height-adjustable level detector or level switch (7) are mounted in or by the filler shaft (11) to limit the fill level or solid fuel, with the level indicator (8) having a hinged lever (29) the free end of which takes the form of a solid material float (30) and is located within the filler shaft (11), with it being possible to bring the hinged lever (29) in mesh with the level switch (7).
12. Burner arrangement in accordance with one of the claims 1 to 11,
    characterized in that
    the arrangement substantially has a box form and has an external thermal insulation jacket (32) and that an enclosing water jacket (33) connected to a boiler is constructed in the inner side of the thermal insulation jacket (32).

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