Barrel type baking oven for baking beans

Abstract

The invention relates to a drum-type baking oven (2) for baking beans, comprising a housing device (4) in which a baking drum (12) for receiving the beans is rotatably mounted, a drive device for rotating the baking drum (12) and a heating device (20) for heating the beans at least by means of hot air are provided, the heating device (20) has at least one electric heating element (14), which is located upstream of the baking cylinder (12) as viewed in the flow direction of the hot air, is arranged in the heat pipe (13) and is used for heating the input air, and a vacuum fan (18), the heating device (20) has an electrical heating element (14), which is arranged downstream of the baking cylinder (12) as viewed in the direction of flow of hot air and for drawing hot air from the baking cylinder (12), and wherein the heating device (20) has an air supply fan (16), which is arranged upstream of the electrical heating element (14) as viewed in the direction of flow of input air.

Description

[0001] The present invention relates to a cylinder roasting furnace for roasting beans, the cylinder roasting furnace comprising a housing device, a roasting cylinder for accommodating beans being rotatably supported in the housing device, wherein a drive device for rotating the roasting cylinder and a heating device for heating the beans at least by means of hot air are provided, wherein the heating device comprises at least one electric heating element and a negative pressure fan, the electric heating element being arranged in a heat pipe upstream of the roasting cylinder as viewed in the flow direction of the hot air and being used for heating the input air, and the negative pressure fan being arranged downstream of the roasting cylinder as viewed in the flow direction of the hot air and being used for sucking the hot air from the roasting cylinder.

[0002] Such cylindrical baking ovens are well known in the prior art and are used as so-called small, in-store or commercial baking ovens, especially in small bakeries or shops or cafes. A cylindrical baking oven is described in German utility model document DE 20 2017 002 951U1 as an example. An electric heating element, such as an electric hot air generator with a ceramic heating resistor, is provided here, and its hot air is sucked into the baking oven by a negative pressure fan. When an electric heating element with a negative pressure fan is used, the generation of hot air depends to a large extent on the environmental conditions. As a result, the negative pressure conditions in the baking oven may fluctuate greatly, resulting in an undesirable baking effect. It should be pointed out that in the field of household baking ovens (for example, see document EP 2 179 665 A1, baking amount 0.5kg-2kg), it is known to install a fan in front of the electric heating element so as to send hot air into the baking oven. However, in the above-mentioned embodiment, hot air is more difficult to control than a negative pressure fan.

[0003] Therefore, the technical problem to be solved by the present invention is to avoid the above-mentioned disadvantages in a simple and inexpensive manner.

[0004] The technical problem is solved according to the invention in that the heating device has an air supply fan which is arranged upstream of the electric heating element as viewed in the flow direction of the inlet air. This makes it possible to ensure a uniform entry of air into the baking oven in a particularly simple and inexpensive manner. The user can control the baking process very conveniently. In addition, reliable cooling of the electric heating element can be ensured in all operating states. The air supply fan is advantageously designed as a side channel fan.

[0005] The particularly simple and inexpensive electric heating element is designed as a thermal ceramic element, which can also be cooled in a particularly simple manner. Here, a plurality of channels are provided in the ceramic element, in which heating rods are arranged. Air flows through these channels.

[0006] A preferred embodiment provides that a control device is provided at least for the heating device, which controls at least the heating process.

[0007] A particularly advantageous embodiment is characterized in particular in that a collecting container is provided on the electric heating element for the inlet air conveyed by the supply air fan. The collecting container serves primarily to stabilize the inlet air flow. A pressure monitor is provided, which is fluidically connected to the heat pipe, thereby ensuring a minimum flow through the electric heating element.

[0008] It is particularly advantageous if a frequency converter is provided for controlling the supply air fan. Thus, energy-efficient operation and simple speed control can be achieved by a constant air flow of the supply air fan.

[0009] A temperature sensor is arranged in the heat pipe, so that a simple temperature monitoring of the electric heating element can be realized. In the case of a high temperature of the electric heating element, the electric heating element is safely shut down according to the detection result of the temperature sensor.

[0010] In a particularly advantageous embodiment, a safety temperature limiter is provided in the heat pipe, which safety temperature limiter switches off the heating element in the event of overheating and can generate an error message.

[0011] In a particularly advantageous embodiment, the electric heating element has a pulsed power supply as a first control circuit. This allows simple thermal energy regulation and thus simple control of the baking process. In order to implement the pulsed power supply, a semiconductor contactor with a PWM signal can be provided at the input, which can be determined by a PID controller, wherein a comparison of the desired temperature of the hot air in the electric heating element with the actual temperature of the hot air is carried out at the input of the PID controller.

[0012] In order to achieve recipe temperature regulation, a second control loop is provided in the automatic baking process, in which a comparison of the recipe setpoint temperature with the recipe actual temperature is carried out at the input of the PID controller. Advantageously, the baking temperature, the hot air temperature and / or the exhaust air temperature are used as recipe temperatures.

[0013] The present invention is further described with reference to the accompanying drawings, in which:

[0014] Figure 1 A partially cut-away side view of a drum baking oven according to the invention is shown,

[0015] Figure 2 A detailed view of an electric heating element and an air supply fan fluidically connected thereto are shown,

[0016] Figure 3 shows a schematic diagram of the first regulation loop, and

[0017] Figure 4A schematic diagram of a second control loop is shown.

[0018] Figure 1 A typical drum roasting oven 2 is shown as a commercial roasting oven. The drum roasting oven 2 has a housing arrangement 4, which essentially has a drum shell part 6 and a base shell part 8. For the sake of clarity, the base shell part 8 is open, i.e., without an outer cover plate. The drum shell part 6 is here mounted on the base shell part 8, wherein the base shell part 8 has a collection container 10 for roasted beans. A roasting cylinder 12 and a drive device (not shown in detail) are arranged in and on the drum shell part 6, which is shown here in a partially cutaway manner and is designed for rotating the roasting cylinder 12 and an electric heating element 14 arranged in a heat pipe 13, which is shown here only schematically and in a partially cutaway manner and is used for heating the heating air in the roasting cylinder 12 or supplied to the roasting cylinder 12, which is designed as a ceramic element. The heat pipes 13 and the electric heating elements 14 together with the air supply fan 16 and the negative pressure fan 18 form a heating device 20 which ensures that the input air is supplied to the roasting cylinder 12 as heated air and exhaust air is discharged via a cyclone 22, which is known per se, and which is controlled by a control device 23. The heat is transferred to the beans by convection through direct contact with the heated air and by conduction via the roasting cylinder 12. The display screen 24 on the drum shell part 6 serves here as an input and display panel for the user.

[0019] Furthermore, the figure shows a bean inlet hopper 26, a sample extraction device 28 and a bean outlet device 30, which also includes the collecting container 10. Below the collecting container 10, a mixing drive 32 for a mixing device (not shown) rotatably mounted in the collecting container 10 and a cooling fan 34 for supplying cooling air to the collecting container 10 are provided.

[0020] As described above, a supply air fan 16 is provided for the input air, which is located upstream of the electric heating element 14 in the flow direction of the input air. Between the supply air fan 16 and the heat pipe 13 with the electric heating element 14, a collection container 36 is also provided on the heat pipe 13, which serves to stabilize the input air flow. A pressure monitor 38 is fluidically connected to the heat pipe 13, which monitors the pressure in the heat pipe 13 and thereby ensures a minimum flow and thus reliable cooling of the electric heating element 14. The frequency converter, not shown here, used to control the supply air fan 16 allows energy-saving operation and simple speed control.

[0021] In order to monitor the temperature of the heated air in the heat pipe 13, a temperature sensor 40 is provided, which extends into the heat pipe 13 and monitors the temperature. In addition, a safety limiter 42 is provided on the heat pipe 13, which immediately shuts down the electric heating element 14 when the limit temperature is exceeded. In addition to the heating device 20, the pressure monitor 38, the temperature sensor 40 and the safety limiter 42 are also connected to the control device 23 for control technology. In order to simply adjust the heating energy of the electric heating element 14, a pulse power supply is provided, which forms a first regulating circuit 44 (see Figure 3 The second regulating circuit 46 is configured to adjust the temperature of the recipe during the automatic baking process. Figure 4 Provide explanation.

[0022] Figure 2 The heat pipe 13 is again shown in detail with the upstream collecting container 36 and the supply air fan 16 , the pressure monitor 38 , the temperature sensor 40 and the safety limiter 42 also being clearly visible here.

[0023] Figure 3 A schematic diagram of a first regulating circuit 44 for providing a pulsed power supply to the electric heating element 14 is shown, which is stored in the control device 23. The baking process stored in the control device 23 specifies a percentage value of the maximum heating power, which is converted into a set recipe temperature 50 (unit: ° C) in the block 48 and compared with the actual recipe temperature 52. The difference 53 is used as an input signal of the PID controller 54 of the electric heating element 14 and is sent to the semiconductor contactor 56 as a PWM signal. Then, a pulsed power supply is generated to supply the heating element 14, and the actual temperature of the heating element 14, that is, the actual recipe temperature 52, is monitored by the temperature sensor 40.

[0024] Figure 4 A schematic diagram of a second regulating circuit 46 is shown for setting the recipe temperature in automatic baking. The baking program stored in the control device 23 selects a target recipe temperature 60 from the recipe in a block 58 and compares it with the actual recipe temperature 62. The difference 64 serves as an input signal for a PID controller 66 for controlling the heating device 20. The actual recipe temperature 62 is also monitored by the temperature sensor 40. The baking temperature, the heating air temperature and / or the exhaust gas temperature can be used as the target recipe temperature or the actual recipe temperature.

Claims

1. A drum roasting furnace (2) for roasting beans, the drum roasting furnace comprising a housing device (4), a roasting drum (12) for accommodating beans being rotatably supported in the housing device, wherein: A drive device for rotating a roasting cylinder (12) and a heating device (20) for heating beans at least by means of hot air are provided, wherein the heating device (20) comprises at least one electric heating element (14) and a negative pressure fan (18), wherein the electric heating element is arranged in a heat pipe (13) upstream of the roasting cylinder (12) in the flow direction of the hot air and is used to heat the input air, and the negative pressure fan is arranged downstream of the roasting cylinder (12) in the flow direction of the hot air and is used to draw hot air from the roasting cylinder (12), and wherein the heating device (20) comprises an air supply fan (16) which is arranged upstream of the electric heating element (14) in the flow direction of the input air.

2. The cylindrical baking oven (2) according to claim 1, characterized in that: A control device (23) is provided at least for the heating device (20).

3. The cylindrical baking oven (2) according to claim 1 or 2, characterized in that: The electric heating element (14) is designed as a thermoceramic element.

4. The cylindrical baking oven (2) according to any one of claims 1 to 3, characterized in that A collecting container (36) for the input air delivered by the supply air fan (16) is provided on the electric heating element (14).

5. The cylindrical baking oven (2) according to any one of claims 2 to 4, characterized in that A pressure monitor (38) is provided, which is fluidically connected to the heat pipe (13).

6. The drum baking oven (2) according to one of the preceding claims, characterized in that A frequency converter is provided for controlling the air supply fan (16).

7. The cylindrical baking oven (2) according to any one of claims 2 to 6, characterized in that A temperature sensor (40) is provided in the heat pipe (13).

8. The cylindrical baking oven (2) according to any one of claims 2 to 7, characterized in that A safety temperature limiter (40) is provided in the heat pipe (13).

9. The cylindrical baking oven (2) according to any one of claims 2 to 8, characterized in that The electric heating element (14) has a pulsed power supply as a first regulating circuit (44).

10. The cylindrical baking oven (2) according to claim 9, characterized in that: To realize a pulsed power supply, a semiconductor contactor with a PWM signal is provided at the input, which PWM signal can be determined by a PID controller, wherein a comparison of the desired temperature of the hot air in the electric heating element with the actual temperature of the hot air is carried out at the input of the PID controller.

11. The cylindrical baking oven (2) according to claim 7 or 8, characterized in that: In order to achieve recipe temperature control, a second control loop (46) is provided in the case of automatic baking, in which a comparison of the recipe setpoint temperature with the recipe actual temperature is carried out at the input of the PID controller.

12. The cylindrical baking oven (2) according to claim 9, characterized in that: Baking temperature, hot air temperature and / or exhaust gas temperature are considered as recipe temperature.

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