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

Abstract

The invention relates to a drum roaster (2) for roasting beans, comprising a housing assembly (4) in which a roasting drum (12) for receiving the beans is rotatably mounted. A drive device for rotating the roasting drum (12) and a heating assembly (20) for heating the beans at least by means of hot air are provided, wherein the heating assembly (20) has at least one combustion assembly (14), which is arranged upstream of the roasting drum (12) when viewed in the flow direction of the hot air, for a combustion gas for heating supply air, said combustion assembly comprising a furnace body (13) in which at least the combustion flame is guided, and the heating assembly also has at least one vacuum fan (18), which is arranged downstream of the roasting drum (12) when viewed in the flow direction of the hot air, for suctioning the hot air out of the roasting drum (12). A hydrogen-air mixture is provided as the combustion gas, and the heating assembly (20) has a combustion gas fan (16) which generates the hydrogen-air mixture. The invention additionally relates to a method for operating such a drum roaster (2) and to a furnace body (13) for such a drum roaster (2).

Description

[0001] DESCRIPTION

[0002] Oven body for a drum roaster for roasting beans as well as drum roaster and method for operating

[0003] The invention relates to a furnace body for a drum roaster which is part of a combustion arrangement for a fuel gas for heating supply air and in which at least one combustion flame is guided. Furthermore, the invention relates to a drum roaster for roasting beans, comprising a housing arrangement in which a roasting drum for receiving the beans is rotatably mounted, wherein a drive device for rotating the roasting drum and a heating arrangement for heating the beans at least by means of heating air are provided, wherein the heating arrangement has at least one combustion arrangement for a fuel gas for heating supply air, arranged upstream of the roasting drum as seen in the flow direction of the heating air, with a furnace body in which at least one combustion flame is guided, and at least one vacuum fan arranged downstream of the roasting drum as seen in the flow direction of the heating air for extracting the heating air from the roasting drum.The invention also relates to a method for operating such a drum roaster.

[0004] Drum roasters are well known in the art and are used primarily as so-called small, shop, or store roasters in smaller roasteries, shops, or cafes. An example of this is the drum roaster described in European patent application EP 2 689 677 A1. This involves a combustion arrangement for a fuel gas, in this case natural gas, whose generated hot air is drawn into the roasting drum by a vacuum blower, thereby roasting the beans in the roasting drum. Rising energy prices and the shortage of fossil fuels require a rethink in the generation of hot air and the use of alternative fuels. It should be noted that the use of hydrogen as a fuel gas is generally known from DE 10 2020 126 276 B3.

[0005] The object of the invention is therefore to provide a furnace body for a drum roaster, a drum roaster and an associated method which enable the use of alternative energy sources in a simple and cost-effective manner.

[0006] This object is achieved according to the invention in that a furnace body is provided in which a hydrogen-air mixture is provided as the fuel gas, wherein a hollow cylinder arrangement is provided which has at least one single-walled hollow cylinder which encloses a combustion chamber and in which a burner pad and an ignition device are arranged as a combustion arrangement and whose first base surface is fluidically connected to a fuel gas supply and whose second base surface is open for the discharge of the heating air. This creates a very compact and safe combustion arrangement integrated in the furnace body. In addition, the furnace body has only a single wall and is therefore considerably simpler in construction than conventional furnace bodies which also have a flame tube.

[0007] Particularly advantageously, the diameter-to-length ratio DHZ / LHZ of the diameter to the length of the hollow cylinder is between 0.5 and 0.9. This ensures particularly efficient heating air generation. The fact that the hollow cylinder has a connecting flange with a reduced diameter for connection to the fuel gas supply creates a Venturi effect, resulting in particularly advantageous mixing of the drawn-in, atmospheric supply air with the hydrogen-air mixture. It is particularly advantageous if the connecting flange at least partially accommodates the burner pad and the ignition device. The connecting flange can advantageously have a diameter DAF that is between 0.6 x DHZ and 0.9 x DHZ of the diameter DHZ of the hollow cylinder.

[0008] To achieve a particularly even distribution of the heated air, the hollow cylinder arrangement has a baffle arrangement in its upper half, as seen in the direction of flow of the heated air. The baffle arrangement advantageously comprises a baffle plate and a baffle ring, which are connected to one another by web elements. Because the baffle plate is arranged at a first, lower height level, as seen in the direction of flow of the heated air, and the baffle ring is arranged at a second, higher height level, the generated heated air is initially directed outwards toward an inner wall of the hollow cylinder, before being guided back to the center of the hollow cylinder by the baffle ring.

[0009] To facilitate the supply of fresh air, an air supply disc is provided in the lower section of the hollow cylinder assembly. The air supply disc can enclose the connecting flange and be fluidly connected to it, with one outer surface of the air supply disc featuring air supply openings. This creates a furnace body that is particularly space-optimized.

[0010] To ensure insulation of the combustion chamber, the hollow cylinder can be enclosed in an insulating material. The insulating material is advantageously made of aluminum-coated mineral wool. The insulating material can be connected to the air supply panel to create a particularly compact furnace body. To monitor the combustion chamber, a sight glass and a flame sensor, such as a UV cell, can be provided in openings in the hollow cylinder. The sight glass and flame sensor are located outside the hollow cylinder and connected to the combustion chamber via angled test cylinders. This allows the burner pad and ignition device to be monitored simply and safely.

[0011] The object is also achieved according to the invention by a drum roaster in which a hydrogen-air mixture is provided as the fuel gas, wherein the heating arrangement has a fuel gas blower that generates the hydrogen-air mixture, and such a furnace body is provided. This allows a hydrogen-air mixture to be used as the fuel gas in a particularly simple and cost-effective manner. The roasting process does not require any special adjustment for the user compared to the conventional roasting process using natural gas as the energy source.

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

[0013] The problem is also solved by a method for operating such a drum roaster, in which the heating air and thus the heating power are regulated in a simple manner by the speed of the combustion gas fan.

[0014] An embodiment of the invention is explained in more detail with reference to a drawing, in which:

[0015] Figure 1 is a partially sectioned side view of a drum roaster according to the invention, Figure 2 is a partially sectioned side view of a furnace body of the drum roaster from Figure 1, and

[0016] Figure 3 is a plan view of the furnace body from Figure 2.

[0017] Figure 1 shows a typical drum roaster 2 as a shop roaster. The drum roaster 2 has a housing assembly 4, which essentially comprises a drum housing part 6 and a base housing part 8. For the sake of clarity, the base housing part 8 is shown open, i.e., without any cladding panels. The drum housing part 6 is placed on the base housing part 8, with the base housing part 8 having a collecting container 10 for roasted beans. In and on the drum housing part 6, in a known manner, are a roasting drum 12, which is shown partially in section here, as well as a drive device (not shown) for rotating the roasting drum 12 and a combustion assembly 14 arranged in a furnace body 13 for heating the hot air in the roasting drum 12 (see in particular Figures 2 and 3).The furnace body 13 with the combustion arrangement 14, together with a fuel gas blower 16 and a vacuum blower 18, forms a heating arrangement 20, which ensures the supply of supply air as heating air into the roasting drum 12 and the removal as exhaust air through a conventional cyclone 22 and is controlled by a control device 23. A hydrogen-air mixture is generated as fuel gas by the fuel gas blower 16, with the fuel gas blower 16 being fluidly connected to a hydrogen source (not shown). A display 24 arranged on the drum housing part 6 serves as an input and display panel for the user.

[0018] Furthermore, the view shows a bean inlet hopper 26, a sampler assembly 28, and a bean outlet assembly 30, which also includes the collecting container 10. Below the collecting container 10, there is a mixing drive device 32 for a mixing device (not shown) rotatably mounted in the collecting container 10, and a cooling air blower 34 for supplying cooling air to the collecting container 10.

[0019] As already noted above, the fuel gas blower 16 is provided for generating fuel gas, which is arranged in front of the combustion arrangement 14, seen in the flow direction of the heating air, and is fluidly connected to the furnace body 13 via a fuel gas supply 36.

[0020] As only schematically indicated in Figure 1, a sight glass 38 and a flame sensor 40, which is designed here as a UV cell, are provided in the furnace body 13 for monitoring the combustion assembly 14. The heating air is essentially controlled by the speed of the fuel gas fan 16 by means of the control device 23. Furthermore, in the present embodiment, the control device 23 is also connected for control purposes to the vacuum fan 18, a temperature sensor (not shown) for determining a roasting temperature in the roasting drum 12, the combustion assembly 14, and the flame sensor 40.

[0021] Figure 2 now shows a side view of the furnace body 13. The furnace body 13 has a hollow cylinder arrangement 42. In the present exemplary embodiment, the hollow cylinder arrangement 42 has a single-walled hollow cylinder 44 enclosing a combustion chamber 43 and having a connecting flange 46 with a reduced diameter DAF adjoining the first base surface 45 of the hollow cylinder for connection to the fuel gas supply 36. On the opposite side, the second base surface 47 of the hollow cylinder 44 is open to allow the generated heating air to be released into the drum housing part 6. The heat is transferred to the beans through direct contact with the heating air by convection and via the roasting drum 12 by conduction. A diameter-to-length ratio DHZ / LHZ of the diameter to the length of the hollow cylinder 44 is 0.72 in the present exemplary embodiment.The diameter DAF of the connecting flange 46 is 0.86 x DHZ of the diameter of the hollow cylinder 44. The hollow cylinder 44 is surrounded by an insulating material 48 in the form of an aluminum-coated mineral wool (see Figure 2).

[0022] Reference numeral 49 represents a two-part flange element that enables connection to the drum housing. As already explained above, reference numeral 38 designates the sight glass, and reference numeral 40 designates the flame sensor for monitoring the combustion chamber 43. The sight glass 38 and the flame sensor 40 are arranged outside the hollow cylinder 44 and are connected to the combustion chamber 43 via angled test cylinders 50, 51 that extend through corresponding openings 52, 53 in the hollow cylinder 44. The angled positioning of the test cylinders 50, 51 enables, in particular, monitoring of the combustion arrangement 14, consisting of a burner pad 54 and an ignition device 56 (see Figure 3). Thus, the ignition device 56 appears red-hot during operation, and the burner pad 54 exhibits embers in the normal state. The burner flame cannot be seen during normal operation.Because the hollow cylinder 44 has a connecting flange 46 with a reduced diameter for connection to the fuel gas supply 36, a Venturi effect is generated, which results in a particularly advantageous mixing of sucked-in atmospheric supply air with the hydrogen-air mixture.

[0023] To ensure optimal distribution of the hot air in the combustion chamber 43, the hollow cylinder arrangement 42 has a baffle arrangement 58 in its upper half, viewed in the direction of flow of the hot air. The baffle arrangement 58 consists of a baffle plate 60 and a baffle ring 62, which are connected to one another by web members 64. The baffle plate 60 is arranged at a first, lower height level hi, viewed in the direction of flow of the hot air, and the baffle ring 62 is arranged at a second, higher height level h2. As a result, the hot air is initially guided outwards to an inner wall 65 of the hollow cylinder 44 and then guided back through the baffle ring 62 to the center, before subsequently leaving the combustion chamber 43 via the open second base area 47.

[0024] In the lower region of the hollow cylinder assembly 42, an air supply disc 66 is provided for supplying atmospheric air, which surrounds the connecting flange 46 and is fluidly connected to the connecting flange 46. A peripheral surface 68 of the air supply disc 66 has air supply openings 70 through which the atmospheric air enters the combustion chamber 43 and the burner pad 54. In the present embodiment, the insulating material 48 adjoins the air supply disc 66.

[0025] Figure 3 now shows a plan view of the furnace body 13 from Figure 2, wherein only one flange element part is clearly visible, here in particular the baffle wall arrangement 58 and the combustion arrangement 14.

Claims

PATENT CLAIMS Furnace body (13) for a drum roaster (2) which is part of a Combustion arrangement (14) for a fuel gas for heating supply air and in which at least one combustion flame is guided, characterized in that a hydrogen-air mixture is provided as the fuel gas, wherein a hollow cylinder arrangement (42) is provided which has at least one single-walled hollow cylinder (44) which encloses a combustion chamber (43) and in which a burner pad (54) and an ignition device (56) as Combustion arrangement (14) are arranged and whose first base surface (45) is fluidically connected to a fuel gas supply (36) and whose second base surface (47) is open for the discharge of the heating air. Furnace body (13) according to claim 1, characterized in that the diameter-length ratio DHZ / LHZ of the diameter to the length of the hollow cylinder (44) is between 0.5 and 0.

9. Furnace body (13) according to claim 1 or 2, characterized in that the hollow cylinder (44) has a connecting flange (46) with a reduced diameter for connection to the fuel gas supply (36). Furnace body (13) according to claim 3, characterized in that the connecting flange (46) at least partially accommodates the burner pad (54) and the ignition device (56). Furnace body (13) according to claim 3 or 4, characterized in that the connecting flange (46) has a diameter DAF that is between 0.6 x DHZ and 0.9 x DHZ of the diameter DHZ of the hollow cylinder (44). Furnace body (13) according to one of the preceding claims, characterized in that the hollow cylinder arrangement (42), viewed in the flow direction of the heating air, has a baffle arrangement (58) in its upper half. Furnace body (13) according to claim 6, characterized in that the baffle arrangement (58) has a baffle plate (60) and a baffle ring (62) that are connected to one another by web members (64). Furnace body (13) according to claim 7, characterized in that the baffle plate (60) is provided at a first, lower height level (hi), viewed in the flow direction of the heating air, and the baffle ring (62) is provided at a second, higher height level (h2).Furnace body (13) according to one of the preceding claims, characterized in that an air supply disc (66) is provided in the lower region of the hollow cylinder arrangement (42). Furnace body according to claim 9, characterized in that the air supply disc (66) surrounds the connecting flange (46) and is fluidically connected to the connecting flange (46), wherein a lateral surface (68) of the air supply disc (66) has air supply openings (70). Furnace body (13) according to one of the preceding claims, characterized in that the hollow cylinder (44) is enclosed by an insulating material (48). Furnace body (13) according to one of the preceding claims, characterized in that a sight glass (38) and a flame sensor (40) are provided in openings (52, 53) of the hollow cylinder (44). 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 chamber (43) via angled test cylinders (50, 51).Drum roaster (2) for roasting beans, with a housing arrangement (4) in which a roasting drum (12) for receiving the beans is rotatably mounted, wherein a drive device for rotating the roasting drum (12) and a heating arrangement (20) for heating the beans at least by means of heating air are provided, wherein the heating arrangement (20) has at least one combustion arrangement (14) arranged in front of the roasting drum (12) as seen in the flow direction of the heating air for a fuel gas for heating supply air with a furnace body (13) in which at least one combustion flame is guided, and at least one vacuum blower (18) arranged behind the roasting drum (12) as seen in the flow direction of the heating air for sucking the heating air out of the roasting drum (12), characterized in that a hydrogen-air mixture is provided as the fuel gas, wherein the heating arrangement (20) has a fuel gas blower (16) which. the hydrogen-air mixture is generated, wherein a furnace body (13) according to one of the preceding claims is provided. Drum roaster (2) according to claim 14, characterized in that at least for the heating arrangement (20) a A control device (23) is provided. A method for operating a drum roaster according to claim 15, characterized in that the heating air is regulated by the speed of the fuel gas fan (16).

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