Roasting equipment

Abstract

To provide a roasting device that employs a hot air system and is capable of roasting several kg of coffee beans at a time. [Solution] A roasting apparatus comprising: a cylindrical body made of a carbon material constituting a roasting chamber for roasting coffee beans; a blower that supplies airflow from the bottom of the roasting chamber to raise the coffee beans; a first heater that heats the air from the blower; and a second heater that heats the peripheral wall of the cylindrical body, wherein the cylindrical body is fixed in an upright position, and the cross-sectional area (S1) of the upper part of the roasting chamber is larger than the area (S2) of the bottom face. The roasting chamber may have an inclined inner wall surface so that the cross-sectional area increases in the height direction from the bottom face, or may be configured by a combination of a tapered section whose inner diameter increases in the height direction from the bottom face and a cylindrical section that is fixed at the maximum inner diameter of the tapered section.

Description

[Technical Field]

[0001] The present invention relates to a hot air roaster for coffee beans. [Background technology]

[0002] Small-scale coffee roasters for home or cafe use typically use small roasters in which coffee beans are agitated in hot air. These roasters incorporate a hot air fluidized bed chamber, where heated air is forced through the fluidized bed chamber with enough force to lift the coffee beans. As the beans tumble and circulate within the fluidized bed, heat is transferred to the beans, resulting in roasting.

[0003] For example, Patent No. 4847622 (Patent Document 1) proposes such a roasting device, which uses a combination of a blower and an electric heater as a hot air generating means, and sprays the generated hot air into a roasting chamber (roasting container) through a nozzle. In this document, the roasting chamber is fixed, and the beans inside the roasting chamber are circulated by a hot air flow. By constructing the roasting chamber from heat-resistant glass, it is possible to observe the state of the beans inside the roasting chamber.

[0004] In addition, Patent No. 6679302 (Patent Document 2) proposes placing an infrared sensor outside a glass roasting container to receive infrared rays from the object to be roasted, thereby detecting the temperature of the object itself and controlling the temperature of the heating means (heater).

[0005] Furthermore, JP 2022-537527 A (Patent Document 3) proposes a roasting apparatus comprising a chamber, an air flow driver, and an electric heater arranged below the bottom opening of the chamber, the roasting apparatus further comprising a conduit for driving a hot air flow from the heater to the bottom opening of the roasting chamber, the conduit having a local transverse constriction that reduces the cross section of the conduit to its minimum cross section, and at least one temperature probe arranged at the minimum cross section of the conduit. Here, the air driver is a fan driven by a motor, and the generated airflow is configured to heat the beans and lift them while stirring them. The heater is operable to heat the airflow generated by the airflow driver. In a specific embodiment, the heater is disposed between the fan and the bottom opening of the chamber, and heats the airflow before it enters the chamber, causing it to lift the beans. (

[0044] ) The constriction forces the different, non-homogeneous flows to mix, so that the airflow at every other cross-section of the constriction has the same temperature. As a result, the constriction homogenizes the airflow, and the airflow and temperature measured by the probe at the constriction accurately reflect the temperature of the hot airflow supplied to the bottom of the chamber, and can be reliably used in a heating control feedback loop (

[0051] ). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4847622 [Patent Document 2] Patent No. 6679302 [Patent Document 3] Special table number 2022-537527 [Patent Document 4] Patent Publication No. 2025-036818 Summary of the Invention [Problem to be solved by the invention]

[0007] The hot air heating methods proposed in Patent Documents 1 to 3 control the temperature inside the roasting chamber by controlling the heater temperature. The roasting chamber is made of a glass container with low thermal conductivity, and the beans are stirred by a heated air flow. Therefore, in terms of the energy cost required to generate enough hot air for heating and stirring, this method is limited to roasters used in homes or cafes that roast enough beans for a few cups.

[0008] The present invention was made in consideration of the above circumstances, and its purpose is to provide technology that can be applied to a roaster that uses a hot air system and is capable of roasting several kilograms of coffee beans at a time. [Means for solving the problem]

[0009] The present inventors have conducted various studies on a roasting device that can heat and stir coffee beans using hot air. When trying to scale up a conventional hot air roaster, which blows hot air into the bottom of the roasting chamber, the air flow does not sufficiently agitate the beans, resulting in a decrease in the homogeneity of the roasted beans. The inventors discovered that a tornado flow can be generated by blowing hot air from the bottom and air from the side, allowing the coffee beans to be stirred, and filed a patent application (Patent Document 4). However, a large amount of energy is required to generate a tornado flow sufficient for stirring, posing a problem in terms of energy costs.

[0010] The inventors of the present invention have conducted further studies and arrived at the present invention. That is, the roasting device of the present invention has the following features. [1] A cylindrical body made of a carbon material that constitutes a roasting chamber for roasting coffee beans; A roasting apparatus comprising: a blower that supplies air from the bottom of the roasting chamber to cause the coffee beans to rise; a first heater that heats the air from the blower; and a second heater that heats the peripheral wall of the cylindrical body, The cylindrical body is fixed upright, and the cross-sectional area (S1) of the upper part of the roasting chamber is larger than the area (S2) of the bottom surface.

[0011] [2] The roasting apparatus according to aspect 1, wherein the inner wall surface of the roasting chamber is inclined so that the cross-sectional area of ​​the roasting chamber increases in the height direction from the bottom surface. [3] The roasting device according to aspect 1, wherein the roasting chamber is configured by a combination of a tapered section whose inner diameter increases from the bottom surface upward in the height direction and a cylindrical section fixed at the maximum inner diameter of the tapered section.

[0012] [4] The roasting device according to aspect 1 or 2, wherein the second heater is attached to the peripheral wall of the cylindrical body. [5] The roasting device according to aspect 4, wherein the second heater is a stick-type heater and is housed in the peripheral wall of the roasting chamber along the height direction of the roasting chamber. [6] The roasting apparatus according to any one of aspects 1 to 5, wherein an upper end of the roasting chamber is provided with a powder separating means for separating dust from the coffee beans generated by roasting. [7] The roasting device according to aspect 1, wherein the second heater is a band heater installed so as to cover the outer circumferential surface of the cylindrical body. [8] The roasting device according to aspect 1, wherein the normal airflow rate of the blower can be controlled to decrease gradually from the early stage of roasting to the later stage of roasting. [Effects of the Invention]

[0013] According to the roasting device of the present invention, when the cross-sectional area at the top of the roasting chamber through which the hot air passes increases, the pressure of the hot air that lifts the coffee beans decreases, causing a lateral flow and circulating the coffee beans. Moreover, because the peripheral wall of the roasting chamber is made of a carbon material with excellent thermal conductivity, the beans come into contact with the peripheral wall as they move from top to bottom, allowing them to be exposed to far-infrared rays. The combination of far-infrared exposure and hot air allows for efficient roasting, and because the far-infrared rays can directly heat the interior of the coffee beans, which have a multi-layered structure, there is little variation in the degree of roasting between the same batch, even when roasting a large amount of coffee beans weighing more than 1 kg. [Brief explanation of the drawings]

[0014] [Figure 1] 1A and 1B are schematic diagrams showing the configuration of one embodiment (Embodiment 1) of a roasting chamber used in the roasting apparatus of the present invention, where (A) is a top view and (B) is a cross-sectional view. [Figure 2] 1A and 1B are schematic diagrams showing the configuration of another embodiment of the roasting chamber used in the roasting device of the present invention, in which (A) is a top view and (B) is a cross-sectional view. [Figure 3]1A and 1B are schematic diagrams showing the configuration of another embodiment of the roasting chamber used in the roasting device of the present invention, in which (A) is a top view and (B) is a cross-sectional view. [Figure 4] FIG. 1 is a schematic diagram showing the configuration of an embodiment of a cartridge-type heater. [Figure 5] FIG. 2 is a block diagram showing the configuration of an embodiment of a roasting device including the roasting section of the embodiment shown in FIG. 1. [Figure 6] FIG. 1 is a schematic diagram showing the configuration of roasting chambers No. 1 to No. 4 evaluated in the examples. [Figure 7] 1A and 1B are a schematic top view and a schematic cross-sectional view, respectively, showing the configuration of roasting chamber No. 5 used in the examples. [Figure 8] FIG. 10 is a vertical cross-sectional view schematically showing the configuration of a second embodiment. [Figure 9] 4 is a graph showing the changes over time in the heating temperatures of the first and second heaters and the temperatures of the cylindrical body and coffee beans in the first embodiment. [Figure 10] 10 is a graph showing the changes over time in the heating temperatures of the first and second heaters and the temperatures of the cylindrical body and coffee beans in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] The roasting apparatus of the present invention is a roasting apparatus comprising: a cylindrical body made of a carbon material that forms a roasting chamber in which coffee beans are roasted; a blower that supplies an ascending air current from the bottom of the roasting chamber to raise the coffee beans; a first heater that heats the air from the blower; and a second heater that heats the peripheral wall of the cylindrical body, wherein the cylindrical body is fixed upright, and the cross-sectional area (S1) of the upper part of the roasting chamber is larger than the cross-sectional area (S2) of the bottom part.

[0016] (Embodiment 1) First, the roasting chamber, which is the main part of the roasting device of the present invention, will be described with reference to Figs. 1 to 3.

[0017] The roasting chamber used in the roasting device of the present invention is a cylinder made of a carbon material, fixed in place in an upright position in the vertical direction of the cylinder, and the interior of the cylinder serves as the roasting chamber. Airflow from a blower is blown into the bottom of the cylinder, creating an ascending air current that circulates the coffee beans inside the roasting chamber.

[0018] The type of carbon material that constitutes the cylindrical body is not particularly limited, but it should have a bulk density of 1.2 to 2.2 g / cm 3 and preferably 1.3 to 2.0 g / cm 3 , more preferably 1.5 to 1.9 g / cm 3 The thermal conductivity at 25°C is preferably 60 W / m K or more, preferably 80 W / m K or more, and more preferably 100 W / m K or more, and the upper limit is usually preferably 200 W / m K or less.

[0019] Examples of such carbon materials include graphite, carbon fiber reinforced carbon composite materials (CC composites), glassy carbon (non-graphitized carbon obtained by carbonizing thermosetting resins such as phenolic resins), and porous carbon (porous carbon graphite). Of these, graphite and CC composites are preferred, and graphite is more preferred. As graphite, natural graphite, artificial graphite, charcoal, pitch, carbonized synthetic resins, and the like can be used. If necessary, the inner and outer wall surfaces of the cylindrical body may be coated with a ceramic coating such as alumina, silica, or zirconia, a glass coating, a glassy carbon coating, a polysiloxane-based heat-resistant coating, or a pyrolytic carbon graphite coating.

[0020] The cylindrical body may have any shape as long as it has a cross section with an area (S1) larger than the area (S2) of the bottom surface of the roasting chamber. The cross section with area S1 may be any cross section from the middle to the top in the height direction of the cylindrical body. When air is blown in through the bottom surface with the small area (S2), it passes through the cross section with the large area (S1), causing the airflow to spread toward the wall surface of the cylindrical body, which is the roasting chamber, and the ascending air pressure decreases. As a result, coffee beans pushed up by the ascending air current are transported to the wall surface of the cylindrical body and descend along the wall surface. In other words, a circulation of coffee beans within the roasting chamber is achieved. The cylindrical body may have a shape such that the cross section of the roasting chamber increases uniformly from the bottom surface upward (when any two points are m and n (m is above n), the cross section of the cross section S m ≧S n It is preferable that the following holds true.

[0021] The shape of the cylindrical body and the roasting chamber inside the cylindrical body may be any shape that satisfies the above requirements. Representative shapes of the cylindrical body and the roasting chamber are shown in Figures 1 to 3. The cylinder and roasting chamber can be manufactured by cutting a block of artificial graphite that has been molded into the desired shape to the specified dimensions. When made of CC composite, the necessary processing can be carried out after the composite material has been thermoset, or the necessary processing can be carried out in a semi-cured state, followed by full curing to give the desired shape.

[0022] In the embodiment shown in Figure 1, the roasting chamber is made up of an inner structure of a cylindrical body 1. The inner diameter of the cylindrical body 1 is a combination of a tapered section 1a that expands upward from the bottom (area S2, inner diameter D2) of the roasting chamber to an inner diameter D1 of a cross section with an area of ​​S1, and a cylindrical section 1b with a constant inner diameter D1. The cylindrical section 1b and tapered section 1a may be formed by cutting the inside of the cylinder, or the tapered section 1a and the cylindrical section 1b may be formed separately and joined together. An additional cylindrical section may be provided below the tapered section 1a, or above the cylindrical section 1b. Alternatively, there may be no cylindrical section and multiple tapered sections with different angles may be provided, and the longitudinal cross-sectional contour of the tapered section (including the taper described below) may be curved.

[0023] It is preferable that the tapered portion 1b is 1 / 3 or more of the cylinder. In other words, it is preferable that the ratio of the height t of the tapered portion 1b to the height T of the cylinder 1 is 1 / 3 or more of T. If the ratio of the tapered portion 1b is too small, the circulation of the coffee beans, which will be described later, will be reduced, and the far-infrared effect will be insufficient. There is no need to set an upper limit for the tapered portion 1b, and it may be 2 / 3 or less of the cylinder, or 40 to 60% of the cylinder, for example.

[0024] 2, the inside of the carbon cylinder 2 is tapered, with the inner diameter increasing from the bottom to the top. The bottom of the inside of the cylinder 2 (roasting chamber 2A) has an inner diameter D2 and an area S2, while the upper end of the roasting chamber has an inner diameter D1 larger than the inner diameter D2 and an area S1 larger than the area S2.

[0025] There are no particular restrictions on the areas S1 and S2, but the area ratio of S2 to S1 (S2 / S1) is preferably between 1.3 and 10, and more preferably between 1.5 and 3. As a result, as shown by the arrows in Figures 1 to 3, the ascending air current blown in through the bottom surface of the roasting chamber (area S2) passes through the large area (S1) portion, reducing the air pressure and the upward force on the beans, creating a circular current in which the lifted beans descend.

[0026] The angle of the tapered portion or taper (longitudinal cross-sectional contour) relative to the horizontal direction (upper surface of holding plate 20) is set appropriately through hot air pressure simulations, tests, etc., and can be, for example, 95 to 120°, 97 to 110°, 99 to 103°, etc. Note that the smaller the angle relative to the horizontal direction, the more the average thickness of the cylindrical body can be reduced, which allows for a lighter cylindrical body and improved thermal efficiency, but the stirring effect will be reduced, so the angle should be set taking this into consideration.

[0027] On the bottom surface of the cylindrical body that forms the bottom of the roasting chamber, a holding plate 20 with numerous holes sized such that an air flow blown in from the bottom surface can pass through but coffee beans cannot is attached. The holding plate 20 is pivotally supported on the wall surfaces of the cylindrical bodies 1 and 2 so that it can be in a horizontal state (see FIG. 1) during roasting and can be moved to a tilted state where the roasted product can fall after roasting. The constituent material of such a holding plate 20 is not particularly limited. It may be made of the same material (carbon material) as the cylindrical body 1 (or 2) that constitutes the roasting chamber 1A (or 2A), or it may be made of metal for ease of processing such as the attachment and removal of the cylindrical body 1 and the opening 31 for taking out.

[0028] On the bottom surface of the carbon material cylindrical body 1 that constitutes the roasting chamber 1A, an inlet 30 that serves as an air inlet for blowing the air flow from the blower into the roasting chamber 1A is connected.

[0029] An outlet 31 for taking out roasted beans is provided in the inlet 30, and a door that can be opened and closed is attached to the outlet 31 for taking out the roasted product transferred from the roasting chamber.

[0030] The inlet 30 may be made of carbon material like the cylindrical body, or preferably made of metal such as iron or SUS from the viewpoints of ease of processing of attaching the cylindrical body 1, the outlet 31, etc., and strength.

[0031] The shape of the carbon material cylindrical body that constitutes the roasting chamber was a cylindrical body in the forms shown in FIGS. 1 and 2, but the shape of the roasting chamber used in the present invention is not limited to this. For example, in the form shown in FIG. 3, the cross-section is substantially semi-circular. It has a taper that expands from the radius L2 of the substantially semi-circular lower end to the radius L1 of the substantially semi-circular upper end so that the relationship S2 < S1 is satisfied between the area S2 of the bottom surface and the area S1 of the upper end surface of the roasting chamber 3A inside the cylindrical body 3 with a semi-circular cross-section. In FIG. 3, the same reference numerals as in FIGS. 1 and 2 denote the same members, and the reference numerals with dashes denote the same functional members with only different shapes.

[0032] Furthermore, the cylindrical body may be shaped like a prism, and the shape of the internal roasting chamber may be a polygonal shape such as a triangle or trapezoid in cross section relative to the height direction. It is preferable that the cross section of the roasting chamber be circular, as this ensures a constant distance from the inner peripheral surface of the cylindrical body and makes it easier for the coffee beans to receive the effects of far infrared rays in a stable manner.

[0033] The carbonaceous cylindrical body that constitutes the roasting chamber is equipped with a second heater for heating the air in the roasting chamber. The second heater may be attached to the wall of the cylindrical body that constitutes the roasting chamber, or electrodes may be attached to the carbonaceous cylindrical body so that the entire body generates heat. In this embodiment, a rod-shaped heater is embedded in the peripheral wall that constitutes the cylindrical body.

[0034] 1, 2 and 3, through holes 10 and 11 are formed in the peripheral walls of the cylindrical bodies 1, 2 and 3 along the height direction of the cylindrical bodies 1, 2 and 3, and these through holes 10 and 11 serve as accommodation sections for stick-type heaters, which are second heaters. Six through holes 10 and 11, which serve as accommodation sections for stick-type heaters, are formed at equal intervals in the circumferential direction.

[0035] The thickness of the wall surface (wall surface of the cylindrical portion) of the cylindrical bodies 1, 2, and 3 is not particularly limited, but in this embodiment it is usually 20 to 50 mm, and preferably 20 to 30 mm. If it is too thin, it becomes difficult to provide the through holes 10 and 11 that serve as the housing for the stick-type heater. On the other hand, if it is too thick, the amount of heat required for heating increases, so from the perspective of energy conservation, it is sufficient that the thickness is sufficient to provide the heater housing.

[0036] In the embodiments shown in Figures 1, 2, and 3, six through-holes for accommodating stick-type heaters are provided on the peripheral wall surface, but the roasting chamber used in the present invention is not limited to this. The number of through-holes can be selected appropriately depending on the size and type of stick-type heaters used, as long as the entire carbonaceous cylindrical body is heated almost evenly and far-infrared rays are emitted from the entire carbonaceous cylindrical body.

[0037] The stick-type heater is not particularly limited, but for example, a cartridge-type heater 12 as shown in FIG. 4 can be used.

[0038] 4, a cylindrical heater 12a, such as a nichrome wire, which generates heat when an electric current is applied, is inserted into a cylindrical outer tube 12b, and a lead wire 12c for supplying power to the heater is drawn out from the outer tube 12b. The lead wire 12c is drawn out to the top surface of the cylindrical body 1.

[0039] Next, the roasting apparatus of the present invention will be described with reference to Fig. 5. Fig. 5 shows the configuration of one embodiment of a roasting apparatus equipped with the roasting chamber shown in Fig. 1.

[0040] The roasting apparatus shown in Figure 5 comprises a carbon cylinder 1 equipped with a roasting chamber 1A having the configuration shown in Figure 1; a blower 32 that generates an air current to be blown into the roasting chamber 1A; a first heater 33 that heats the air current; a stick-type second heater 12 that is embedded in the peripheral wall of the carbon cylinder and heats the cylinder; an inlet 30 that is connected to the bottom of the roasting chamber 1A and serves as an inlet for blowing hot air for roasting and circulating the coffee beans; and a separation means 40 that is connected to the top of the roasting chamber and collects residue (mainly chaff) generated during roasting.

[0041] The air passage from the blower 32 to the port 30a of the inlet 30 is provided with a first heater (hot air generation heater) 33 for heating the airflow from the blower 32 and an air volume control valve 34 for adjusting the volume of air blown in. The hot air generation heater 33 is preferably equipped with a temperature control means (temperature control controller: not shown). The temperature control means is preferably electrically or electronically connected to a temperature sensor (not shown) attached to the cylindrical body 1.

[0042] The roasting chamber 1A may also be provided with a collection section 36 that collects roasted beans discharged from the inlet roasted bean outlet 31, and may further be provided with a suction device 35 for cooling the roasted beans collected in the collection section 36. The blower 32 for blowing air into the roasting chamber 1A may also serve as a suction device for cooling the roasted beans. In this case, for example, a three-way valve that can be selectively switched to cool the roasted product may be placed between the blower 32 and the first heater 33, so that air is blown toward the hot air generating heater 33 during roasting, and heat is sucked in and discharged from the collection section 36 after roasting is completed.

[0043] The top surface of the cylindrical body 1 is closed by a lid 21. The lid 21 that closes the top surface of the cylindrical body 1 is provided with an exhaust duct and an exhaust port 21a for discharging dust and roasted residues generated during roasting.

[0044] The separating means 40 is connected to the exhaust port 21a located in the center of the lid 21 that closes the top surface of the roasting chamber, and is equipped with a cyclone 42 that separates powder (chaff) mixed in the exhaust airflow discharged from the exhaust port 21a, and a cock 44 that adjusts the exhaust airflow rate and whether or not to exhaust air. An intake fan that sends the exhaust airflow into the cyclone 42 may be installed between the cyclone 42 and the cock 44.

[0045] Hopper 41 for supplying coffee beans to the roasting chamber may be attached to lid 21, or may be configured to be attached only when necessary. The cock 44 may also be a lever that selectively switches between a supply passage communicating with the hopper 41 and a suction passage connected to the cyclone 42 .

[0046] The top side of the roasting chamber 1A is closed off by the lid 21, but the portion corresponding to the heater housing section 10 is open, allowing the lead wire 12c for heating the second heater (stick-type heater) housed in the heater housing section 10 to be drawn out.

[0047] [How to use the roasting device] Next, a method for roasting coffee beans using a roasting apparatus (FIG. 5) equipped with the roasting chamber shown in FIG. 1 will be described. First, as shown in Figure 5, with holding plate 20 set horizontally, cylindrical body 1 is heated by energizing cartridge-type heater 12. Once cylindrical body 1 has been heated to a predetermined temperature, green coffee beans are supplied from hopper 41 to roasting chamber 1A.

[0048] A predetermined amount of green coffee beans is added, and then blower 32 and first heater 33 are operated to blow hot air into roasting chamber 1A. Taking into account the expansion of the coffee beans due to roasting, the amount of green beans can be set to 2 / 3 or less, or 60% or less, of the volume of roasting chamber 1A.

[0049] Hot air from blower 32 passes through inlet 30 and is blown in as an ascending air current from the bottom surface of roasting chamber 1A. Inside roasting chamber 1A, the coffee beans are blown upward by the blown-in hot air (upward air current). Meanwhile, when the hot air passes through area S1, which is larger than cross-sectional area S2 of the air inlet, the upward pressure of the ascending air current decreases and it spreads radially. The coffee beans are carried by the air current that spreads radially and are transported to the peripheral wall surface of cylindrical body 1. Then, by colliding with the peripheral wall surface, they descend along the peripheral wall surface of the cylindrical body. As they descend, they come into contact with cylindrical body 1 made of carbon material, and are therefore exposed to far infrared rays from the heated carbon material.

[0050] Far infrared rays are absorbed by coffee beans, which are bulky lumps with a multi-layered structure, causing molecular vibrations (thermal action), and can heat the beans to the center without overheating the surface. Therefore, by using both hot air and far-infrared heating, not only can heating be performed efficiently, but also the difference in the heat energy received can be reduced, even for small amounts of coffee beans, even if the amount exceeds 1 kg. This reduces the variation in roast level among coffee beans roasted in the same batch.

[0051] Roasting conditions such as heating time (roasting time) and air volume (normal air volume) are set appropriately depending on the configuration of the roasting apparatus, such as the type of coffee beans, the type of carbon material of the cylindrical body 1 that constitutes the roasting chamber 1A, and the size of the cylindrical body 1, and the type of roasted object.

[0052] By operating the cyclone 42 during roasting, air is sucked into the roasting chamber 1A and the raw bean residue is collected by the cyclone 42. This allows chaff and other substances generated during roasting to be separated and removed, eliminating the need to clean the cylindrical body 1 after roasting and shortening the roasting interval. The blowing flow rate and blowing force during roasting can be adjusted by opening and closing the cock 44.

[0053] When roasting is finished, the door of the outlet 31 of the inlet 30 is opened, and the holding plate 20 is tilted to drop the roasted beans in the roasting chamber into the collection section 36. The suction machine 35 is operated to suck the heat from the collection section 36, thereby cooling the roasted beans.

[0054] In the roasting device of the present invention having the above-described configuration, roasting chamber 1A is configured so that the ascending air current is dissipated upward, allowing the coffee beans to circulate within roasting chamber 1A. Moreover, as the coffee beans descend, they are also heated by far infrared rays from cylindrical body 1 made of a carbon material that constitutes roasting chamber 1A, allowing for efficient heating.

[0055] Therefore, in the past, in order to achieve sufficient roasting using only hot air, a large amount of energy was required to generate the hot air, which tended to hinder energy conservation. In the present invention, the cylindrical body that constitutes the roasting chamber is also directly heated by the second heater, which not only prevents the air in the roasting chamber from cooling, but also allows for efficient heating of the coffee beans to their interiors using far infrared rays. Therefore, it is possible to roast coffee beans at a practical level, not only for homes or cafes, but also in the roasting unit of several hundred grams to several kilograms, which is the roasting unit used by roaster manufacturers.

[0056] [Example] We compared the energy required to generate the ascending air currents and circulating air currents necessary for bean agitation, depending on the shape of the roasting chamber. The structures of roasting chambers No. 1 to No. 4 used are shown in Figure 6. No. 5 is a cylinder with the structure shown in Figure 7, which is designed to generate a tornado flow. Roasting chamber No. 5 shown in Figure 7 has four main flow passages 52 penetrating the cylindrical wall that makes up the roasting chamber in the height direction of the cylinder, and communication holes 53 drilled in the radial direction to communicate with each main flow passage. By blowing the airflow from main flow passages 52 out through communication holes 53, a tornado flow can be created within the roasting chamber. For No. 5, a large fan capable of blowing a larger volume of air than the fans used for Nos. 1 to 4 was used to generate a tornado flow.

[0057] The air volume and pressure inside the inlet duct were measured when roasting 5 kg of beans. The energy required for roasting was calculated by converting the amount of heat (joules) required to heat the air volume exhausted from the blower using the first heater, assuming room temperature (20°C) and roasting temperature (250°C), into power (watts). In addition, a viewing window was opened in the peripheral wall of the carbonaceous cylindrical body, and the state of the beans (stirring state) during roasting was observed. The results are shown in Table 1.

[0058] [Table 1]

[0059] In No. 3, by changing the position of the holding plate 20", the area S2 of the bottom of the roasting chamber and the cross-sectional area S1 of the upper part are made equal. As a result, the beans could not be roasted while being stirred using only the upward airflow from the blower. Even when the airflow pressure was increased, the beans remained at the bottom of the roasting chamber, making it difficult to circulate the beans within the roasting chamber.

[0060] In No. 4, the holding plate 20" was set at an angle, making the area S2 of the air inlet larger than the cross-sectional area S1 of the upper part of the roasting chamber, and this meant that the beans could not be sufficiently stirred by the circulation.

[0061] Roasting chamber No. 5 was able to circulate the beans within the chamber by generating a tornado airflow, but to generate the tornado airflow, a larger fan was required than those used in chambers No. 1 to No. 4, and more than three times the amount of energy required for the updraft alone. This made it economically and energy inappropriate for use in roasting equipment that roasts commercial quantities of beans (at least 1 kg).

[0062] In this regard, the roasting device of the present invention, which is equipped with roasting chambers No. 1 and No. 2, where the upper cross-sectional area S1 of the roasting chamber is larger than the bottom area S2, was able to circulate the beans with the same amount of energy as the cylindrical roasting chambers (No. 3 and No. 4). In particular, No. 1 (S2=0.5×S1 and t=0.5×T) was able to reduce the required energy to about half of that of the cylindrical roasting chambers.

[0063] (Embodiment 2) As shown in Fig. 8, this embodiment differs from embodiment 1 in that the second heater is a band heater 62 that is installed so as to cover (surround) the outer peripheral surface of the cylindrical body 6. Furthermore, this embodiment is equipped with a cylindrical body temperature sensor 65 and a coffee bean temperature sensor 66. The cylindrical body temperature sensor 65 is capable of detecting the temperature of the inner wall surface of the cylindrical body, and the coffee bean temperature sensor 66 is capable of detecting the temperature of coffee beans that come into contact with the sensor. Other configurations that are common to embodiment 1 above will not be described here.

[0064] The fan's air volume (normal air volume) can be controlled to decrease (reduced air force) from the early to late stages of roasting. Coffee beans in the early stages of roasting contain a lot of moisture and therefore have a high density, while coffee beans in the later stages of roasting have a low density due to moisture loss and expansion caused by cracks and other factors. Therefore, if the air volume is always the same, the coffee beans may not be sufficiently stirred in the early stages of roasting, or may be blown above the top of the cylindrical body (slamming against the top lid) in the later stages of roasting. By controlling the air volume as described above, the beans can be raised and stirred to a uniform height, thereby achieving a uniform far-infrared effect. Air volume control can be performed using a program, for example, and can be adjusted depending on the type of coffee beans, the amount of coffee added, the desired roast condition, and other factors. A sensor for monitoring the conditions inside the cylindrical body may also be provided, allowing the air volume to be adjusted based on the sensor signal. Sensors capable of detecting temperature, humidity, coffee bean speed, odor, and other factors can be used. In this embodiment, two temperature sensors 65 and 66 are provided.

[0065] In the first embodiment, the wall thickness of the cylindrical body (cylindrical portion) was 20 to 50 mm. However, in the present embodiment, the second heater is a band heater 62 that tightly covers the outer peripheral surface of the cylindrical body. This eliminates the need for through-holes 10 and 11 that serve as housings for the stick-type heaters, allowing for a correspondingly smaller wall thickness. The wall thickness of the cylindrical body ((D4-D3) / 2 in FIG. 8) may be any thickness that maintains sufficient strength, specifically, 5 to 20 mm, 8 to 15 mm, etc. This reduces the amount of heat required to heat the cylindrical body and the weight of the cylindrical body. The band heater 62 is an example of a heater that tightly covers the outer peripheral surface of the cylindrical body. Other heaters may also be used. The band heater 62 may include a heating element such as nichrome wire, an insulator such as ceramic or mica, and an exterior made of stainless steel or the like.

[0066] Figures 9 and 10 show graphs illustrating the changes over time in the heating temperatures of the first and second heaters and the temperatures of the cylindrical body and coffee beans. Each cylindrical body was made by carving out black smoke. The dimensions (mm) and angles (°) of each part are as shown in Table 2 below, where the angle is the angle between the outline of the tapered portion in the vertical cross section and the upper surface of the holding plate. The height of the cylindrical body is T1-10, which is the result of subtracting the thickness of the holding plate. Other dimensions include a height T2 of 290 mm for the band heater 62 and an outer diameter D5 of 310 mm for the band heater. Table 3 shows the relationship between the temperature range of the hot air during roasting and the normal air volume.

[0067] [Table 2]

[0068] [Table 3]

[0069] As can be seen from Figure 9 for Embodiment 1 and Figure 10 for Embodiment 2, in Embodiment 1, which uses a stick-type heater as the second heater, the heating temperature of the second heater needed to be about 180 to 190°C higher to maintain the same surface temperature of the cylindrical body compared to Embodiment 2, which uses a band heater. As a result, the total output was 5400 W for Embodiment 1 and 4000 W for Embodiment 2. Furthermore, the product weight was approximately 21 kg for Embodiment 1 and approximately 7 kg for Embodiment 2, achieving a significant weight reduction. Furthermore, visual inspection of the finished beans after roasting revealed almost no color unevenness in either case, although the color unevenness was slightly less in Embodiment 2.

[0070] Furthermore, when the temperature distribution on the inner surface of the cylindrical body was measured using thermography while it was heated with the second heater, it was found that in embodiment 1, there was unevenness in the temperature, with the temperature being high near the stick heater and slightly lower in the middle area, whereas in embodiment 2, there was no unevenness in the temperature distribution.

[0071] In addition, by using program control of the hot air volume (normal air volume) as shown in Table 3, it was possible to maintain a nearly constant coffee bean blow-up height from the beginning to the end of the roasting period.

[0072] The disclosures of the embodiments are all examples and can be modified as appropriate. For example, heaters other than stick-type heaters and band heaters can be used, and additional or alternative sensors can be provided. The size can also be modified as appropriate depending on the application (home use, store use, manufacturer use, etc.). [Industrial Applicability]

[0073] The roasting device of the present invention is equipped with a first heater that generates hot air and a second heater that directly heats the roasting chamber, and further utilizes the far-infrared effect from the carbon-material cylindrical body that constitutes the roasting chamber. This makes it possible to roast a few hundred grams to several kilograms of coffee beans, the roasting unit used by roasting manufacturers, all at once at a practically acceptable energy cost.

[0074] The beans are agitated using hot air, and as the beans circulate, they come into contact with the wall of the carbon cylinder, where they are heated by far infrared rays.This means that even when roasting hundreds of grams to several kg, or even larger amounts of coffee beans in a single batch, they can be heated almost uniformly.Therefore, the roasting device of the present invention is useful not only for homes and cafes, but also as a roasting device for commercial use by various types of roasting manufacturers, including small, medium, and large scale manufacturers. [Explanation of symbols]

[0075] 1, 2, 3, 6 Carbon material cylindrical body 1A, 2A, 3A roasting room 10, 11, 11' Heater housing (through hole) 12 Stick-type heater (second heater) 20, 20' retaining plate 21 Lid 30, 30' inlet 31 Roasted goods outlet 32 Blower 33 Heating means (first heater) 34 Air volume control means (air volume control valve) 35 Suction machine 36 Collection Department 40 Separation means 41 Hopper 42 Cyclone 50 Carbon material cylindrical body 51 Heater housing 52 Main passage (through passage) 53 Sub-channel (communication hole) 62 Band heater 65 Cylindrical temperature sensor 66 Coffee bean temperature sensor

Claims

1. A roasting apparatus comprising: a cylindrical body made of a carbon material that forms a roasting chamber in which coffee beans are roasted; a blower that supplies air from the bottom of the roasting chamber to cause the coffee beans to rise; a first heater that heats the air from the blower; and a second heater that heats a peripheral wall of the cylindrical body, The cylindrical body is fixed upright, and the cross-sectional area (S １ ) is the area of ​​the bottom surface (S ２ ) A roasting device larger than the standard.

2. 2. The roasting apparatus according to claim 1, wherein the inner wall surface of the roasting chamber is inclined so that the cross-sectional area of ​​the roasting chamber increases in the height direction from the bottom surface.

3. 2. The roasting apparatus according to claim 1, wherein the roasting chamber is configured by a combination of a tapered section whose inner diameter increases from the bottom surface upward in the height direction and a cylindrical section fixed at the maximum inner diameter of the tapered section.

4. The roasting device according to claim 1 , wherein the second heater is attached to the peripheral wall of the cylindrical body.

5. 5. The roasting apparatus according to claim 4, wherein the second heater is a stick-type heater and is housed in the peripheral wall of the roasting chamber along the height direction of the roasting chamber.

6. 2. The roasting apparatus according to claim 1, further comprising a powder separating means at an upper end of the roasting chamber for separating dust from the coffee beans produced by roasting.

7. 2. The roasting apparatus according to claim 1, wherein the second heater is a band heater installed so as to cover the outer peripheral surface of the cylindrical body.

8. 2. The roasting apparatus according to claim 1, wherein the normal airflow rate of the blower can be controlled to decrease gradually from the early stage of roasting to the later stage of roasting.

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