Roasting system for bulk vegetable material and method for roasting bulk vegetable material

Abstract

A roasting system for vegetable bulk material (16) having a housing arrangement (4), the housing arrangement (4) comprising at least one roasting apparatus (6) having an interior space (10) in which the bulk material (16) can be roasted, a heating system (8) enabling heat transfer to the bulk material in the interior space (10), an exhaust gas cleaning device (12) for exhaust gas discharge from the roasting apparatus (6), and a control system (20) for controlling the roasting process, the control system (20) having at least one calculation program (50) specific to the roasting apparatus (6), in which a heat transfer model (52) for the bulk material (16) to be roasted is calculated and stored, the heat transfer model having at least one heat flow coefficient dQ for each of all operating points in the roasting process (48), and the heating system (8) can be adjusted depending on the at least one heat flow coefficient dQ. Likewise, the present invention relates to a method for roasting bulk vegetable material (16) using such a roasting system (2).

Description

[Technical Field]

[0001] The present invention relates to a roasting system for bulk vegetable material, the housing comprising at least one roasting apparatus having an interior space in which the bulk material can be roasted, a heating system enabling heat transfer to the bulk material in the interior space, an exhaust gas cleaning apparatus for exhausting exhaust gases from the roasting apparatus, and a control system for controlling the roasting process. The present invention also relates to a method for roasting bulk vegetable material using such a roasting system. [Background technology]

[0002] Roasting systems and methods for roasting bulk plant materials are well known in the prior art. Green coffee bean preheaters are also included in such roasting systems. Patent Document 1, in particular, describes in detail various methods for monitoring and, if necessary, adapting the roasting process in the interior space of a roasting apparatus, depending on measured quantities such as temperature. To further improve known methods, the present application proposes determining the moisture content of the coffee beans to be roasted before the start of the roasting process, with the aim of subsequently initiating the actual, controlled roasting process. It is intended that, through such an approach, the predetermined roasting curve of the roasting process can be more accurately adhered to in order to obtain reproducible roasting results. However, it has been found that even such roasting methods for bulk materials, in this case coffee beans, result in significant deviations of the realized roasting curve from the desired, preset roasting curve. Additionally, energy consumption in the roasting process can be further optimized. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 142167 Summary of the Invention [Problem to be solved by the invention]

[0004] The object of the present invention is therefore to avoid the above-mentioned drawbacks in a simple and cost-effective manner. [Means for solving the problem]

[0005] This problem is solved by the roasting system according to the present invention in that the control system comprises at least one calculation program specific to the roasting device, in which a heat transfer model for the bulk material to be roasted, with a respective heat flow coefficient dQ, is calculated and stored for every operating point in the roasting process, and the heating system can be adjusted depending on the at least one heat flow coefficient dQ. The design of the roasting system according to the present invention is based on the knowledge that the heating of the plant-based bulk material and the associated roasting process essentially depends on the heat transfer to the plant-based bulk material. This heat transfer, in turn, is significantly influenced by the respective roasting system. As is known, heat transfer can occur conductively and / or convectively and / or by radiation. Depending on the type of heat transfer, different heat flow coefficients dQ are used, which take into account the type of specific roasting system, the heating system with its respective adjustment mechanism, and the roasting device itself. This therefore makes it particularly easy to adapt the roast curve taking into account the roaster to be used and thus to plan a particularly optimal energy consumption, since the heat transport can be modeled on the basis of the stored heat flow coefficient dQ. In this context, heating system is understood to mean all adjustable means that ensure the heating of the bulk material, such as, for example, heaters and fans, flaps, etc.

[0006] In a particularly advantageous embodiment of the roasting system according to the invention, the heating system is designed as a hot gas heating system, and the bulk material in the interior space can be roasted by the heating gas convectively and / or conductively and / or by radiant heat. In this case, the heating devices of the heating system can be embodied as gas burners, oil burners, hydrogen burners or even electric heating elements. Depending on the design of the heating system, it is advantageous to have a heating gas-bulk material heat flow coefficient dQ HS , and / or the heat flow coefficient dQ of the heated gas-internal space portion HI , and / or the heat flow coefficient dQ of the internal space portion-bulk material IS can be calculated and stored. This makes it particularly easy to calculate the heat flow that occurs and thus store a particularly accurate heat transfer model. The interior space is understood to be, for example, the interior space wall and the stirrer.

[0007] In a particularly advantageous embodiment, the heat flow coefficient dQ for an endothermic reaction of the bulk material, such as liquid evaporation, endo can be calculated and stored, which allows for a more accurate calculation of the total energy flow.

[0008] In a further advantageous embodiment, the heat flow coefficient dQ for the heat generation of the bulk material exo can be calculated and stored, taking into account that the bulk material has energy in the form of chemical potential that is then released through chemical reactions (e.g., pyrolysis) during the torrefaction process.

[0009] The heat acting on the bulk material in the interior space of the roasting device is additionally determined substantially by the gas mass flow rate or by the gas volume flow rate of the heating gas and the exhaust gas. Therefore, it is particularly advantageous that the calculation program has a gas flow model, which is based on the heating gas flow regulation mechanisms of the heating system, such as fans, flaps, etc., and determines the mass inflow rate of the heating gas m_dot H and mass outflow rate of exhaust gas m_dot Aand stores it for all settings of the heating gas flow regulating mechanism. In this case, the gas flow model includes both a gas mass flow model and a gas volumetric flow model. The gas volumetric flow model can be calculated from the gas mass flow model by dividing the mass flow rate by the density of the gas at the respective temperature. Conversely, the gas mass flow model can be calculated from the gas volumetric flow model by multiplying the volumetric flow rate by the gas density at the respective temperature. In this case, the gas flow model is continuous and valid for all operating points or settings of the medium in the heating system.

[0010] Furthermore, advantageously, the calculation program may comprise a bulk material model, which calculates and stores, among other things, the specific heat capacities of the different bulk materials for all operating points of the roasting process.

[0011] Particularly advantageously, the roasting device comprises at least one sensor mechanism for determining the bulk material temperature, the heating gas temperature, the exhaust gas temperature and / or the bulk material color value, etc. This makes it possible, in particular, to actively regulate the roasting process either by the user himself when he receives a message from the control system, or automatically by the control system.

[0012] The problem is also solved by a method for roasting bulk vegetable material using the roasting system described above, wherein a calculation program specific to the roasting apparatus is provided in the control system, at least one heat transfer model for specific operating points of the roasting program having at least one heat flow coefficient dQ is calculated and stored, a roasting process having a predefined roasting curve is started, and the heating system is controlled in such a way that the at least one stored heat flow coefficient is realized at each of the operating points.

[0013] In an advantageous manner, the roasting device comprises at least one sensor mechanism for monitoring the roasting process, and in the event of deviations from a predefined roasting curve, a message and / or automatic control of the heating system and / or adaptation of at least one heat transfer model is triggered.

[0014] Advantageously, when using the heating gas heating system, the heating gas-bulk material heat flow coefficient dQ HS , and / or the heat flow coefficient dQ of the heated gas-internal space portion HI , and / or the heat flow coefficient dQ of the internal space portion-bulk material IS can be calculated and stored.

[0015] In this case, a gas flow model is stored in the calculation program, and the mass inflow rate of the heating gas m_dot is calculated for a specific operating point in the roasting program based on the heating gas flow regulation mechanism, e.g., fan, flap, etc. H and mass outflow rate of exhaust gas m_dot A It may be advantageous to set

[0016] Particularly advantageously, a bulk material model is stored in the calculation model, at least the specific heat capacities of different bulk materials are stored, and the bulk material to be roasted in the roasting program is selected and the specific heat capacities of the bulk material to be roasted are taken into account in the roasting program.

[0017] The present invention will now be described in detail with reference to the drawings. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram of a roasting system according to the present invention; [Figure 2] FIG. 10 is a schematic block diagram of a calculation program for a control device. DETAILED DESCRIPTION OF THE INVENTION

[0019] Figure 1 shows in a schematic diagram a roasting system 2 according to the invention, which is known per se from the prior art. Such a roasting system 2 comprises a housing arrangement 4 having at least one roasting apparatus 6, a heating system 8 for heating the interior space 10 of the roasting apparatus 6, an exhaust gas cleaning device 12 for cleaning exhaust gases from the interior space 10 of the roasting apparatus 6, and a cooling system 14 for cooling the plant bulk material to be roasted, which in this embodiment are coffee beans 16. In this case, unroasted coffee beans 16 are fed to the interior space 10 of the roasting apparatus 6 via a funnel inlet 18. In addition, a control system 20 is provided for controlling or regulating the roasting process 48 (see Figure 2) and the cooling process.

[0020] The heating system 8 is designed as a hot gas heating system 8 in this embodiment and for this purpose comprises firstly a gas heating device 21 and a fan 22 for drawing the heating gas heated by the gas heating device 21 into the interior space 10, whereby the interior space wall 24 and the stirrer 25 as part of the interior space are also heated. Heat transfer to the coffee beans 16 is carried out in this embodiment by convection, conduction and radiation. In addition, the heating system 8 comprises a heating gas flap 26 and an exhaust gas flap 28, which together with the fan 22 regulate the heating gas mass flow m_dot H and exhaust gas mass flow m_dot A It should be noted that the heating system 8 with all of its means 21, 22, 26, 28 is shown only as one block in FIG. 2 for the sake of clarity.

[0021] The cooling system 14 according to the invention consists in this example of a cooling device 30 having a flat-bed cooler 32 onto which the coffee beans 16 are poured via an outlet opening 34 of the roaster 6. In this case, the flat-bed cooler 32, together with a hood arrangement 36, encloses a cooling space 38 into which cooling air is blown by a cooling 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.

[0022] The temperature of the coffee beans 16 within the interior space 10 of the roasting apparatus 6 is monitored in this embodiment by a non-contact sensor mechanism 46.

[0023] To ensure the roasting process 48 is as accurate and reproducible as possible, the control system 20 comprises a calculation program 50 provided with a heat transfer model 52, a gas flow model 54 and a bulk material model 56. The basis of the heat transfer model is the heat flow coefficient dQ HS (heated gas-bulk material), dQ HI (heated gas - internal space), dQ IS (internal space portion - bulk material), and the heat flow coefficient dQ for liquid evaporation of the bulk material endo and dQ for heat generation in bulk materials exo The basis of the gas flow model 54 is the mass inflow rate of the heated gas m_dot H and mass outflow rate of exhaust gas m_dot A Additionally, the specific heat capacities of different bulk materials are taken into account for the bulk material model 56. From the models 52, 54, 56, an optimal energy balance is calculated for a specific roast curve 48, taking into account in particular the roast quality and the optimization of predetermined objectives, such as energy consumption, and the heating system 8 is controlled accordingly.

[0024] The method according to the invention for roasting coffee beans 16 using a roasting system 2 according to the invention now contemplates that a calculation program 50 specific to the roaster 6 is provided in the control system 20. It should be noted that in this context the term control system can include both a single control device and a combination of various control devices, which may also include a computer. The calculation program then stores a heat transfer model 52, a gas flow model 54 and a bulk material model 56, and calculates the heat flow coefficient dQ as mentioned above. HS , dQ HI , dQ IS , dQ endo , dQ exo , mass inflow rate m_dot H , mass flux m_dot A, and the coffee species K to be roasted S are stored. With these models 52, 54, 56 it is already possible to simulate the roasting process 48 itself. During the roasting process 48 in the roaster 6, in this embodiment the temperature of the interior space 10 is monitored by a non-contact sensor mechanism 46, and in case of excessive deviation from the roasting curve 48, a warning is issued to the user. If an incorrect setting of the heating system 8 or another malfunction cannot be reproduced, the models 52 and / or 54 and / or 56 are modified based on the determined deviation.

Claims

1. 1. A roasting system for vegetable bulk material (16) having a housing arrangement (4), the housing arrangement (4) comprising at least one roasting apparatus (6) having an interior space (10) in which the bulk material (16) can be roasted, a heating system (8) enabling heat transfer to the bulk material in the interior space (10), an exhaust gas cleaning device (12) for exhaust gas discharge from the roasting apparatus (6), and a control system (20) for controlling the roasting process, the control system (20) having at least one calculation program (50) specific to the roasting apparatus (6), wherein a heat transfer model (52) for the bulk material (16) to be roasted is calculated and stored in the calculation program (50), the heat transfer model having at least one heat flow coefficient dQ for each of all operating points in the roasting process (48), and the heating system (8) can be adjusted depending on the at least one heat flow coefficient dQ.

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

3. Heat flow coefficient dQ between heated gas and bulk material HS , and / or the heat flow coefficient dQ of the heated gas-internal space portion HI , and / or the heat flow coefficient dQ of the internal space portion-bulk material IS 3. The roasting system of claim 2, wherein the ρ is calculated and stored.

4. The heat flow coefficient dQ for the endothermic reaction of the bulk material (16) endo 4. The roasting system according to claim 1, wherein the calculated value is calculated and stored.

5. The heat flow coefficient dQ for heat generation in the bulk material (16) exo 4. The roasting system according to claim 1, wherein the calculated value is calculated and stored.

6. The calculation program has a gas flow model (54), which calculates the mass inflow rate m_dot of the heating gas based on the heating gas flow regulating mechanisms (22, 26, 28) of the heating system (8), such as fans, flaps, etc. H and mass outflow rate of exhaust gas m_dot A 4. A roasting system according to claim 2 or 3, characterized in that: ##EQU1## is calculated and stored for all settings of the heating gas flow regulating mechanisms (22, 26, 28).

7. 4. The roasting system according to claim 1, wherein the calculation program (50) comprises a bulk material model (56) that calculates and stores specific heat capacities of different bulk materials (16) for all operating points of the roasting process (48).

8. 4. Roasting system according to any one of claims 1 to 3, characterized in that the roasting device (6) comprises at least one sensor mechanism (46) for determining bulk material temperature, heating gas temperature, exhaust gas temperature and / or bulk material color value, etc.

9. 4. A method for roasting vegetable bulk material (16) using a roasting system (2) according to any one of claims 1 to 3, characterized in that a calculation program (50) specific to the roasting apparatus (6) is provided in the control system (20), at least one heat transfer model (52) for specific operating points of the roasting program having at least one heat flow coefficient dQ is calculated and stored, a roasting process having a predefined roasting curve is started, and the heating system (8) is controlled in such a way that the stored at least one heat flow coefficient dQ is realized at each of the operating points.

10. 10. The method for roasting vegetable bulk materials (16) according to claim 9, characterized in that the roasting device (6) comprises at least one sensor mechanism (46) for monitoring the roasting process, and in the event of deviation from the predefined roasting curve (48), an alarm and / or automatic control of the heating system (8) and / or adaptation of at least one heat transfer model (52) is triggered.

11. When using the heating gas-heating system (8), the heating gas-bulk material heat flow coefficient dQ HS , and / or the heat flow coefficient dQ of the heated gas-internal space portion HI , and / or the heat flow coefficient dQ of the internal space portion-bulk material IS 10. The method for roasting vegetable bulk material (16) according to claim 9, characterized in that:

12. A gas flow model (54) is stored in the calculation program (50) and is used to calculate the mass inflow rate of the heating gas m_dot for a particular operating point in the roasting program based on the heating gas flow regulating mechanisms (22, 26, 28), e.g., fans, flaps, etc. H and mass outflow rate of exhaust gas m_dot A 12. The method for roasting vegetable bulk materials (16) according to claim 11, characterized in that:

13. 10. The method for roasting vegetable bulk materials (16) according to claim 9, characterized in that a bulk material model (56) is stored in the calculation program (50), and the specific heat capacities of at least different bulk materials are stored, and the bulk material to be roasted is selected in the roasting program, and the specific heat capacity of the bulk material to be roasted (16) is taken into account in the roasting program.

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