Furnace body for a drum roaster for roasting beans, drum roaster, and operation method

Abstract

The present invention relates to a drum roaster (2) for roasting beans, comprising a housing arrangement (4) in which a roasting drum (12) for accommodating the beans is rotatably supported, a drive for rotating the roasting drum (12), and a heating device (20) for heating the beans with at least heated air, the heating device (20) comprising at least one combustion device (14) for fuel gas for heating an inlet air by a furnace body (13) in which at least one combustion flame is guided, arranged in front of the roasting drum (12) in the direction of the heated air, and a vacuum blower (18) for drawing the heated air from the roasting drum (12) and arranged behind the roasting drum (12) in the direction of the heated air, the fuel gas being a hydrogen-air mixture, and the heating device (20) comprising a fuel gas blower (16) for producing the hydrogen-air mixture. Furthermore, the present invention relates to a method of operating such a drum roaster (2) and to a furnace body (13) for such a drum roaster (2).

Description

[Technical Field]

[0001] The present invention relates to a furnace body for a drum roaster, the furnace body being part of a combustion device for fuel gas for heating the inlet air and having at least one combustion flame guided therein. Furthermore, the present invention relates to a drum roaster for roasting beans, comprising a housing arrangement in which a roasting drum for accommodating the beans is rotatably supported, a drive for rotating the roasting drum, and a heating device for heating the beans with at least heated air, the heating device having at least one combustion device for fuel gas for heating the inlet air by a furnace body in which at least one combustion flame is guided, the heating device being arranged in front of the roasting drum in the direction of flow of the heated air, and a vacuum blower arranged behind the roasting drum in the direction of flow of the heated air for sucking the heated air from the roasting drum. The present invention also relates to a method for operating such a drum roaster. [Background technology]

[0002] Drum roasters are well known from the prior art and are used in particular in relatively small roasteries, shops or cafes as so-called mini roasters, shop roasters or store roasters. An example of this is the drum roaster described in patent document 1. In this case, a combustion device for fuel gas, in this case natural gas, is provided, and heated air generated in the combustion device is sucked by a vacuum blower into the roasting drum, thereby roasting the beans therein. Rising energy prices and the shortage of fossil energy materials call for innovations in the generation of heated air and the use of alternative energy materials. It should be noted that the use of hydrogen as fuel gas is basically known from patent document 2. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] European Patent Application Publication No. 2689677 [Patent Document 2] German Patent Invention No. 102020126276 Summary of the Invention [Problem to be solved by the invention]

[0004] It is therefore an object of the present invention to provide a furnace body for a drum roaster, a drum roaster and an associated method that allows for the use of alternative energy sources in a simple and cost-effective manner. [Means for solving the problem]

[0005] This problem is solved by the present invention by providing a furnace body for use with a hydrogen-air mixture as fuel gas, comprising at least one single-walled hollow cylinder arrangement enclosing a combustion space and including a burner pad and an ignition device as a combustion device, the hollow cylinder having a first base surface in fluid communication with a fuel gas supply pipe and a second base surface open for the release of the heated air. This results in a very compact and safe combustion device integrated into the furnace body. Additionally, the furnace body is embodied with only a single wall and is therefore much simpler to construct than conventional furnace bodies also having a flame tube.

[0006] Particularly advantageously, the diameter-to-length ratio D Hz / L Hzis 0.5 to 0.9. This ensures a particularly efficient generation of heated air. If the hollow cylinder has a connecting flange with a reduced diameter for connection to the fuel gas supply pipe, a Venturi effect is generated, which results in a particularly advantageous mixing of the aspirated atmospheric charge air with the hydrogen-air mixture. In this case, it is particularly advantageous if the connecting flange at least partially accommodates the burner pad and the ignition device. In this case, the connecting flange is advantageously located at a diameter D of the hollow cylinder. Hz 0.6 to 0.9 times the diameter D Af may have:

[0007] To produce a particularly uniform heated air distribution, the hollow cylinder arrangement has a baffle arrangement in its upper half, as viewed in the direction of heated air flow, which advantageously comprises a baffle disk and a baffle ring connected to each other by a web member, such that the baffle disk is provided at a first, lower height level, as viewed in the direction of heated air flow, and the baffle ring is provided at a second, higher height level, such that the generated heated air is first directed outward toward the inner wall of the hollow cylinder before being directed back through the baffle ring to the center of the hollow cylinder.

[0008] To allow for a simple supply of intake air, an intake disk is provided in the lower region of the hollow cylinder arrangement, which surrounds the connecting flange and can be in fluid communication with it, and whose outer periphery has intake openings, resulting in a furnace body that is particularly optimized in terms of installation space.

[0009] To ensure thermal insulation of the combustion space, the hollow cylinder can be surrounded by a thermal insulator, which in this case preferably consists of foil-laminated mineral wool, which in this case can be connected to the air inlet disk in order to provide a particularly compact furnace body.

[0010] To monitor the combustion space, a sight glass and flame sensor, such as a UV cell, can be installed at the opening of the hollow cylinder. In this case, the sight glass and flame sensor are located outside the hollow cylinder and connected to the combustion space via an obliquely extending inspection cylinder. In this way, the burner pad and ignition device can be monitored in a simple and safe way.

[0011] The problem is also solved by a drum roaster in which a hydrogen-air mixture is intended as the fuel gas, and the heating device has a fuel gas blower that generates the hydrogen-air mixture, and the drum roaster is provided with such a furnace body. This allows the use of a hydrogen-air mixture as the fuel gas in a particularly simple and cost-effective manner. The roasting process does not require any special adjustments by the user compared to previously known roasting processes that use natural gas as the energy source.

[0012] Advantageously, a control device is provided at least for the heating device.

[0013] The problem is also solved by a method for operating such a drum roaster, in which the heated air and therefore the heating power is regulated in a simple manner by the rotational speed of the fuel gas blower.

[0014] An embodiment of the present invention will now be described in detail with reference to the drawings. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a partially cutaway side view of a drum roaster according to the present invention. [Figure 2] FIG. 2 is a side view, partially cut away, of the furnace body of the drum roaster of FIG. [Figure 3] FIG. 3 is a top view of the furnace body of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0016] Figure 1 shows a typical drum roaster 2 as a shop roaster. The drum roaster 2 has a housing arrangement 4 that essentially comprises a drum housing part 6 and a base housing part 8. For clarity, the base housing part 8 is shown in an open state, i.e. without a cover panel. The drum housing part 6 in this case rests on the base housing part 8, which has a collection container 10 for the roasted beans. Inside and adjacent to the drum housing part 6, in a known manner, there is a roasting drum 12, shown here partially cut away, a drive device for rotating the roasting drum 12, not further shown here, and a combustion device 14 (in this regard, see also in particular Figures 2 and 3 ) arranged in a furnace body 13 for heating the heated air present in the roasting drum 12. The furnace body 13 with the combustion device 14, together with the fuel gas blower 16 and the vacuum blower 18, in this case form a heating device 20, which ensures the supply of inlet air as heated air into the roasting drum 12 and its discharge as exhaust air through a cyclone 22 known per se and is controlled by a control device 23. A hydrogen-air mixture is generated as fuel gas by the fuel gas blower 16, which for this purpose is in fluid communication with a hydrogen source, not further shown. A display 24, arranged adjacent to the drum housing part 6, serves in this case as an input and display panel for the user.

[0017] Further shown in the figure are a bean inlet funnel 26, a sampler device 28 and a bean outlet device 30 which may also be considered part of the collecting vessel 10. Below the collecting vessel 10 there is firstly provided a mixing drive 32 for a mixing device (not shown further) rotatably supported within the collecting vessel 10 and a cooling air blower 34 for impinging cooling air on the collecting vessel 10.

[0018] As already mentioned above, for fuel gas generation, a fuel gas blower 16 is provided, which is arranged before the combustion device 14 in the flow direction of the heated air and is in fluid communication with the furnace body 13 via a fuel gas supply pipe 36.

[0019] 1, a sight glass 38 and a flame sensor 40, here designed as a UV cell, are provided in the furnace body 13 for monitoring the combustion device 14. The heating air is essentially controlled by the control device 23 via the rotation speed of the fuel gas blower 16. Furthermore, the control device 23 is in this example also connected for control purposes to the vacuum blower 18, a temperature sensor (not shown further) for determining the roasting temperature in the roasting drum 12, the combustion device 14 and the flame sensor 40.

[0020] 2 shows the furnace body 13 in a side view. The furnace body 13 has a hollow cylinder arrangement 42. In this embodiment, the hollow cylinder arrangement 42 is a single-walled hollow cylinder 44 surrounding a combustion space 43 and having, adjacent to its first base surface 45, a reduced diameter D 1 for connection to the fuel gas supply pipe 36. Af The roasting drum 12 has a hollow cylinder 44 with a connecting flange 46 having a diameter-to-length ratio D , which is the ratio of the diameter of the hollow cylinder 44 to its length. On the opposite side, a second base surface 47 of the hollow cylinder 44 is open to allow the generated heated air to be discharged into the drum housing part 6. Heat transfer to the beans takes place in this case through direct contact with the heated air by convection and via the roasting drum 12 by conduction. Hz / L Hz In this embodiment, the diameter D of the connecting flange 46 is 0.72. Af is the diameter D of the hollow cylinder 44 Hz The hollow cylinder 44 is surrounded by insulation 48 in the form of foil-laminated mineral wool (see FIG. 2).

[0021] Reference numeral 49 denotes a two-part flange element that allows connection to the drum housing. As already mentioned above, reference numeral 38 denotes a sight glass, and reference numeral 40 denotes a flame sensor for monitoring the combustion space 43. In this case, the sight glass 38 and the flame sensor 40 are arranged outside the hollow cylinder 44 and are connected to the combustion space 43 via obliquely extending inspection cylinders 50, 51 that extend through corresponding openings 52, 53 in the hollow cylinder 44. The oblique positioning of the inspection cylinders 50, 51 allows for monitoring, in particular, the combustion device 14 (see FIG. 3), which consists of a burner pad 54 and an ignition device 56. The ignition device 56 therefore appears glowing during operation, while the burner pad 54 normally contains a burning ember. The burner flame cannot be discerned during normal operation. Due to the hollow cylinder 44 having a connection flange 46 with a reduced diameter for connection to the fuel gas supply pipe 36, a Venturi effect is generated, which results in particularly advantageous mixing of the aspirated atmospheric charge with the hydrogen-air mixture.

[0022] To ensure optimal distribution of the heated air within the combustion space 43, the hollow cylinder arrangement 42 has a baffle arrangement 58 in its upper half, as viewed in the direction of the heated air flow. The baffle arrangement 58 consists of a baffle disk 60 and a baffle ring 62 connected to each other by a web member 64. As viewed in the direction of the heated air flow, the baffle disk 60 is arranged at a first, lower height level h1, and the baffle ring 62 is arranged at a second, higher height level h2. This allows the heated air to be first directed outward toward the inner wall 65 of the hollow cylinder 44 and then directed back toward the center through the baffle ring 62 to leave the combustion space 43 via the open second base surface 47.

[0023] In the lower region of the hollow cylinder arrangement 42, an air intake disk 66 is provided, surrounding the connecting flange 46 and in fluid communication with it, for supplying atmospheric air intake, the outer circumferential surface 68 of which has air intake openings 70 through which the atmospheric air intake passes into the combustion space 43 and onto the burner pad 54. The heat insulation 48 is connected to the air intake disk 66 in this embodiment.

[0024] FIG. 3 next shows a top view of the furnace body 13 of FIG. 2, in which only one flange element portion, here in particular the baffle arrangement 58 and the combustion device 14, can be clearly seen.

Claims

1. A furnace body (13) for a drum roaster (2) is part of a combustion device (14) for fuel gas for heating intake air, and at least one combustion flame is guided inside. A hydrogen-air mixture is intended as the fuel gas. The furnace body (13) includes a hollow cylinder configuration (42) having at least one single-walled hollow cylinder (44), which surrounds a combustion space (43). A burner pad (54) and an ignition device (56) are arranged inside the hollow cylinder as the combustion device (14). A first base surface (45) of the hollow cylinder is in fluid communication with a fuel gas supply pipe (36), and a second base surface (47) of the hollow cylinder is open for the discharge of the heated air.

2. The diameter-to-length ratio D of the hollow cylinder (44) is the ratio of the diameter to the length. Hz / L Hz The furnace body (13) according to claim 1, characterized in that is 0.5 to 0.

9.

3. 3. The furnace body (13) according to claim 1 or 2, characterized in that the hollow cylinder (44) is provided with a connection flange (46) having a reduced diameter for connection with the fuel gas supply pipe (36).

4. 4. The furnace body (13) according to claim 3, characterized in that the connection flange (46) at least partially accommodates the burner pad (54) and the ignition device (56).

5. The connecting flange (46) has a diameter D of the hollow cylinder (44). Hz Diameter D is 0.6 to 0.9 times the Af 4. The furnace body (13) according to claim 3, characterized in that it comprises:

6. 3. The furnace body (13) according to claim 1 or 2, characterized in that the hollow cylinder arrangement (42) has a baffle arrangement (58) in its upper half, as seen in the flow direction of the heated air.

7. 7. The furnace body (13) of claim 6, wherein the baffle arrangement (58) comprises baffle disks (60) and baffle rings (62) connected to one another by web members (64).

8. The baffle disc (60) is at a first lower height level (h 1 ), and the baffle ring (62) is disposed at a second, higher elevation level (h 2 8. The furnace body (13) according to claim 7, characterized in that the furnace body (13) is arranged on a suction pipe.

9. 3. The furnace body (13) according to claim 1 or 2, characterized in that an air inlet disk (66) is provided in the lower region of the hollow cylinder arrangement (42).

10. 10. The furnace body (13) according to claim 9, wherein the air intake disk (66) surrounds the connection flange (46) and is in fluid communication with the connection flange (46), and an outer peripheral surface (68) of the air intake disk (66) has air intake openings (70).

11. 3. The furnace body (13) according to claim 1 or 2, characterized in that the hollow cylinder (44) is surrounded by a thermal insulation material (48).

12. 3. The furnace body (13) according to claim 1 or 2, characterized in that a sight glass (38) and a flame sensor (40) are provided in the openings (52, 53) of the hollow cylinder (44).

13. 13. The furnace body (13) according to claim 12, characterized in that the sight glass (38) and the flame sensor (40) are arranged outside the hollow cylinder (44) and are connected to the combustion space (43) via obliquely extending inspection cylinders (50, 51).

14. 1. A drum roaster (2) for roasting beans, comprising: a housing arrangement (4) in which a roasting drum (12) for accommodating the beans is rotatably supported; a drive for rotating the roasting drum (12); and a heating device (20) for heating the beans with at least heated air, the heating device (20) comprising: at least one combustion device (14) for fuel gas for heating an inlet air by means of a furnace body (13) in which at least one combustion flame is guided, the combustion device (14) being arranged in front of the roasting drum (12) in the direction of the heated air; and a vacuum blower (18) for drawing the heated air from the roasting drum (12) and arranged behind the roasting drum (12) in the direction of the heated air, the vacuum blower (18) for drawing the heated air from the roasting drum (12), wherein a hydrogen-air mixture is intended as the fuel gas, and the heating device (20) comprises a fuel gas blower (16) for generating the hydrogen-air mixture, the drum roaster (2) being provided with a furnace body (13) according to claim 1 or 2.

15. 15. Drum roaster (2) according to claim 14, characterized in that a control device (23) is provided for at least the heating device (20).

16. 16. The method of operating a drum roaster (2) as claimed in claim 15, wherein the heated air is controlled through the rotational speed of the fuel gas blower (16).

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