Roasting assembly for bulk plant material and method for roasting bulk plant material

Abstract

The invention relates to a roasting assembly for bulk plant material (16) comprising a housing assembly (4) having at least one roasting device (6) with an inner chamber (10), in which the bulk material (16) is to be roasted, a heating assembly (8) that enables heat transfer to the bulk material in the inner chamber (10), a waste gas cleaning unit (12) for discharging waste gas out of the roasting device (6), and a control assembly (20) for controlling a roasting process, wherein the control assembly (20) has at least one calculation program (50) specific to the roasting device (6), in which a heat transfer model (52) is calculated for the bulk material (16) to be roasted with a respective at least one heat flow rate dQ for all operating points in the roasting process (48), and same is stored, wherein the heating assembly (8) is controlled according to the at least one heat flow rate dQ. The invention also relates to a method for roasting bulk plant material (16) using a roasting assembly (2) of this type.

Description

[0001] DESCRIPTION

[0002] Roasting arrangement for bulk vegetable material and method for roasting bulk vegetable material

[0003] The invention relates to a roasting arrangement for bulk plant material, comprising a housing arrangement that includes at least one roasting device with an interior space in which the bulk material is to be roasted, a heating arrangement that enables heat transfer to the bulk material in the interior space, an exhaust gas purification device for removing exhaust gas from the roasting device, and a control arrangement for controlling a roasting process. The invention also relates to a method for roasting bulk plant material using such a roasting arrangement.

[0004] Roaster systems and methods for roasting bulk plant materials are well known in the art. Such roaster systems also include green coffee preheaters. In particular, the international publication WO 2016 / 142167 A1 describes in detail various methods for monitoring the roasting process inside the roasting device as a function of a measured variable, such as temperature, and adjusting it if necessary. To further improve the known methods, this publication proposes determining the moisture content of the coffee beans to be roasted before the start of the roasting process in order to subsequently start the actual controlled roasting process. This approach is intended to allow predefined roasting curves of roasting processes to be adhered to more precisely, thus achieving a reproducible roasting result.However, it has now been discovered that even such a process for roasting bulk materials, in this case coffee beans, leads to significant deviations in the actual roasting curve from a desired, preset roasting curve. Furthermore, energy consumption during the roasting process can still be optimized.

[0005] The object of the invention is therefore to avoid the above-mentioned disadvantages in a simple and cost-effective manner.

[0006] This object is achieved by a roaster arrangement according to the invention in that the control arrangement has at least one calculation program specific to the roasting device, in which a heat transfer model for the bulk material to be roasted, each with a heat flow coefficient dQ, is calculated and stored for all operating points in the roasting process, wherein the heating arrangement is to be controlled as a function of the at least one heat flow coefficient dQ. This inventive design of a roaster arrangement is based on the knowledge that the heating of the bulk plant material and the associated roasting process essentially depend on the heat transport to the bulk plant material. This heat transport, in turn, is significantly influenced by the respective roaster arrangement. As is known, heat transport can take place in a conductive and / or convective manner and / or through radiant heat.Depending on the type of heat transfer, different heat flow coefficients (dQ) are used, which take into account the type of specific roaster configuration with regard to the heating arrangement, the respective control elements, and the roasting device itself. This makes it particularly easy to adapt roasting curves to the specific roaster in use and, in particular, to ensure optimal energy consumption, since the heat transfer can be modeled based on the stored heat flow coefficient (dQ). In this context, the term "heating arrangement" refers to all adjustable means that ensure heating of the bulk material, such as a heating device, fans, flaps, etc.

[0007] In a particularly advantageous embodiment of the roaster arrangement according to the invention, the heating arrangement is designed as a hot gas heating arrangement, wherein the bulk material in the interior is roasted convectively and / or conductively and / or by radiant heat using heating gas. A heating device of the heating arrangement can be designed as a gas burner, oil burner, hydrogen burner or even as an electric heating element. Depending on the design of the heating arrangement, a heat flow coefficient heating gas-bulk material dQns and / or a heat flow coefficient heating gas-interior parts dQm and / or a heat flow coefficient interior parts-bulk material dQis can advantageously be calculated and stored. This makes it particularly easy to calculate the heat flows occurring and thus to store a particularly precise heat transfer model. Interior parts are understood to include, for example, the interior walls and the agitator.

[0008] In a particularly advantageous embodiment, a heat flow coefficient dQendo for endothermic reactions of the bulk material, such as liquid evaporation, can be calculated and stored. This allows the total energy flow to be calculated even more accurately.

[0009] In a further advantageous embodiment, a heat flow coefficient dQexo for the exothermic heat generation of the bulk material can be calculated and stored. This takes into account the fact that the bulk material releases energy in the form of a chemical potential, which is then released through chemical reactions (e.g., pyrolysis) during the roasting process.

[0010] The heat acting on the bulk material inside the roasting device is also largely determined by the gas mass flow or by the gas volume flow of heating gas and exhaust gas. Therefore, the calculation program particularly advantageously features a gas flow model that calculates a mass inflow rate rrm of heating gas and a mass outflow rate rriA of exhaust gas based on heating gas flow control elements of the heating system, such as fans, flaps, etc., and stores this data for all settings of the heating gas flow control elements. The gas flow model includes both a gas mass flow model and a gas volume flow model. A gas volume flow model can be calculated from a gas mass flow model by dividing the mass flow by the density of the gas at the respective temperature.Conversely, a gas mass flow model can be calculated from a gas volume flow model by multiplying the volume flow by the gas density at the respective temperature. The gas flow model is continuous and valid for all operating points or settings of the heating arrangement.

[0011] Furthermore, the calculation program can advantageously have a bulk material model that calculates and stores, among other things, but not only, the specific heat capacity of different bulk materials for all operating points of the roasting process.

[0012] In a particularly advantageous manner, the roasting device has at least one sensor element for determining a bulk material temperature, a heating gas temperature, an exhaust gas temperature and / or a bulk material color value, etc. This makes it possible, in particular, to actively control the roasting process either by the user himself, when he receives a message from the control arrangement, or automatically by the control arrangement.

[0013] The object is also achieved by a method for roasting bulk plant material by means of an aforementioned roaster arrangement, wherein a calculation program specific to the roasting device is provided in the control arrangement, wherein at least one heat transfer model for specific operating points of a roasting program with at least one heat flow coefficient dQ is calculated and stored, wherein a roasting process is started with a predefined roasting curve, wherein the heating arrangement is controlled such that at least one stored heat flow coefficient dQ is realized in the respective operating point.

[0014] In an advantageous method, the roasting device has at least one sensor element for monitoring the roasting process, wherein in the event of a deviation from the predefined roasting curve, a message is sent and / or the heating arrangement is automatically controlled and / or at least one heat transfer model is adapted.

[0015] Advantageously, when using a heating gas heating arrangement, a heat flow coefficient of heating gas bulk material ÜQHS and / or a heat flow coefficient of heating gas interior parts dQm and / or a heat flow coefficient of interior parts bulk material dQis is calculated and stored.

[0016] It can also be particularly advantageous in this case for a gas flow model to be stored in the calculation program, whereby in the roasting program a mass inflow rate rrm of heating gas and a mass outflow rate rriA of exhaust gas are set for specific operating points using heating gas flow control devices, such as fans, flaps, etc.

[0017] In a particularly advantageous manner, a bulk material model is stored in the calculation model, wherein at least the specific heat capacity of different bulk materials is stored, wherein the bulk material to be roasted is selected in the roasting program, wherein the specific heat capacity of the bulk material to be roasted is taken into account in the roasting program.

[0018] The invention is explained in more detail with reference to a drawing, which shows:

[0019] Figure 1 is a schematic representation of a roaster arrangement according to the invention, and

[0020] Figure 2 is a schematic block diagram of a calculation program of the control device.

[0021] Figure 1 shows a schematic representation of a roaster assembly 2 according to the invention, which is well known in the art. Such a roaster assembly 2 has a housing assembly 4, which contains at least one roasting device 6, a heating assembly 8 for heating an interior space 10 of the roasting device 6, an exhaust gas purification device 12 for purifying exhaust gases from the interior space 10 of the roasting device 6, and, in the present exemplary embodiment, a cooling assembly 14 for cooling a bulk plant material to be roasted, here coffee beans 16. The unroasted coffee beans 16 are fed into the interior space 10 of the roasting device 6 via a hopper inlet 18. In addition, a control assembly 20 is provided, which controls or regulates a roasting process 48 (see Figure 2) and a cooling process.In the present exemplary embodiment, the heating arrangement 8 is designed as a hot-gas heating arrangement 8 and, for this purpose, initially comprises a gas heating device 21 and a fan 22, which draws the heating gas heated by the gas heating device 21 into the interior 10, wherein an interior wall 24 and an agitator 25, as interior parts, are also heated. Heat is therefore transported to the coffee beans 16 in the present exemplary embodiment both convectively and conductively, as well as through radiant heat. Furthermore, the heating arrangement 8 comprises a heating gas flap 26 and an exhaust gas flap 28, which, together with the fan 22, determine a heating gas mass flow rriH and an exhaust gas mass flow rriA. It should be noted that, for the sake of clarity, the heating arrangement 8, with all its means 21, 22, 26, 28, is shown only as a single block in Figure 2.

[0022] In the present embodiment, the cooling arrangement 14 according to the invention consists of a cooling device 30 with a flat-bed cooler 32, onto which the coffee beans 16 are poured via an outlet opening 34 of the roasting device 6. The flat-bed cooler 32, together with a hood arrangement 36, encloses a cooling chamber 38 into which cooling air is blown by a cold air device 40. A bulk material outlet arrangement 42 and a cooling air discharge device 44 are connected to the cooling device 30 in a known manner.

[0023] In the present embodiment, the temperature of the coffee beans 16 in the interior 10 of the roasting device 6 is monitored by a contactless sensor element 46.

[0024] To ensure the most precise and reproducible roasting process 48 possible, the control system 20 has a calculation program 50 comprising a heat transfer model 52, a gas flow model 54, and a bulk material model 56. The heat transfer model is based on the heat flow coefficients dQns (heating gas - bulk material), dQm (heating gas - interior parts), dQis (interior parts - bulk material), as well as the heat flow coefficients dQendo for the liquid evaporation of the bulk material and dQexo for the exothermic heat generation of the bulk material. The gas flow model 54 is based on the mass inflow rate rrm of the heating gas and the mass outflow rate rriA of the exhaust gas. Furthermore, the specific heat capacity of different bulk materials is taken into account for the bulk material model 56.From the models 52, 54, 56, an optimal energy balance is now calculated for a specific roasting curve 48, in particular against the background of the roasting quality and an optimization of previously determined objectives, such as energy consumption, and the heating arrangement 8 is controlled accordingly.

[0025] A method according to the invention for roasting coffee beans 16 using the roaster assembly 2 according to the invention provides for a calculation program 50 specific to the roasting device 6 to be provided in the control assembly 20. In this context, it should be noted that the term "control assembly" can encompass both a single control device and a combination of various control devices, including computers. A heat transfer model 52, a gas flow model 54, and a bulk material model 56 are then stored in the calculation program, wherein the aforementioned heat flow coefficients dQns, dQm, dQis, dQendo, and dQexo, the mass inflow rate rrm, the mass outflow rate rriA, and the specific heat capacity of the coffee variety to be roasted Ks are stored. These models 52, 54, 56 already make it possible to simulate the roasting process 48.During the roasting process 48 in the roasting device 6, in the present embodiment, the temperature in the interior 10 is monitored by a non-contact sensor 46, and a warning is issued to the user if there is an excessive deviation from the roasting curve 48. If no incorrect settings of the heating arrangement 8 or other malfunctions can be detected, the models 52 and / or 54 and / or 56 are modified based on the determined deviation.

Claims

PATENT CLAIMS 1. A roasting arrangement for bulk vegetable material (16) with a housing arrangement (4) which has at least one roasting device (6) with an interior space (10) in which the bulk material (16) is to be roasted, a heating arrangement (8) which enables heat to be transferred to the bulk material in the interior space (10), an exhaust gas cleaning device (12) for removing exhaust gases from the roasting device (6), and a control arrangement (20) for controlling a roasting process, characterized in that the control arrangement (20) has at least one calculation program (50) specific to the roasting device (6), in which program a heat transfer model (52) for the bulk material (16) to be roasted is calculated and stored, each having at least one heat flow coefficient dQ for all operating points in the roasting process (48), wherein the heating arrangement (8) is to be controlled as a function of the at least one heat flow coefficient dQ.

2. Roaster arrangement according to claim 1, characterized in that the heating arrangement (8) is designed as a hot gas heating arrangement, wherein the bulk material (16) in the interior (10) is to be roasted convectively and / or conductively and / or by radiant heat by means of heating gas.

3. Roaster arrangement according to claim 2, characterized in that a heat flow coefficient of the heating gas bulk material dQns and / or a heat flow coefficient of the heating gas interior parts dQm and / or a Heat flow coefficient of interior parts-bulk material dQis is calculated and stored.

4. Roaster arrangement according to one of claims 1 - 3, characterized in that a heat flow coefficient dQendo for endothermic reactions of the bulk material (16) is calculated and stored.

5. Roaster arrangement according to one of the preceding claims, characterized in that a heat flow coefficient dQexo for the exothermic heat generation of the bulk material (16) is calculated and stored.

6. Roaster arrangement according to claims 2 - 5, characterized in that the calculation program has a gas flow model (54) which calculates a mass inflow rate rrm of heating gas and a mass outflow rate rriA of exhaust gas on the basis of heating gas flow control elements (22, 26, 28) of the heating arrangement (8), such as fans, flaps, etc., and stores it for all settings of the heating gas flow control elements (22, 26, 28).

7. Roaster arrangement according to one of the preceding claims, characterized in that the calculation program (50) has a bulk material model (56) that calculates and stores the specific heat capacity of different bulk materials (16) for all operating points of the roasting process (48).

8. Roaster arrangement according to one of the preceding claims, characterized in that the roasting device (6) has at least one sensor element (46) for determining a bulk material temperature, a heating gas temperature, an exhaust gas temperature and / or a bulk material color value, etc.

9. Method for roasting bulk vegetable material (16) by means of a roaster arrangement (2) according to one of the preceding claims, characterized in that a calculation program (50) specific for the roasting device (6) is provided in the control arrangement (20), wherein at least one heat transfer model (52) for specific operating points of a roasting program with at least one heat flow coefficient dQ is calculated and stored, wherein a roasting process is started with a predefined roasting curve, wherein the heating arrangement (8) is controlled in such a way that the at least one stored heat flow coefficient dQ is realized in the respective operating point.

10. A method for roasting bulk vegetable material (16) according to claim 9, characterized in that the roasting device (6) has at least one sensor element (46) for monitoring the roasting process, wherein in the event of a deviation from the predefined roasting curve (48) a warning signal and / or an automated control of the heating arrangement (8) is carried out and / or an adjustment of at least one heat transfer model (52) is carried out.

11. A method for roasting bulk vegetable material (16) according to claim 9 or 10, characterized in that when using a heating gas heating arrangement (8) a heat flow coefficient of the bulk heating gas dQns and / or a heat flow coefficient of the interior parts of the heating gas dQm and / or a Heat flow coefficient of interior parts-bulk material dQis is calculated and stored.

12. A method for roasting bulk vegetable material (16) according to claim 11, characterized in that a gas flow model (54) is stored in the calculation program (50), wherein in the roasting program for specific operating points a mass inflow rate rrm of heating gas and a mass outflow rate rriA of exhaust gas are set using heating gas flow control devices (22, 26, 28), such as fans, flaps, etc.

13. A method for roasting bulk vegetable material (16) according to one of claims 9 - 12, characterized in that a bulk material model (56) is stored in the calculation program (50), wherein at least the specific heat capacity of different bulk materials is stored, wherein the bulk material to be roasted is selected in the roasting program, wherein the specific heat capacity of the bulk material (16) to be roasted is taken into account in the roasting program.

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