Roasting apparatus

Abstract

[Problem] To provide a roasting apparatus in which a hot air system is employed and with which it is possible to roast several kilograms of coffee beans at a time. [Solution] A roasting device comprising: a cylindrical body that is made of a carbon material and constitutes a roasting chamber for roasting coffee beans; a blower that supplies an airflow for raising the coffee beans from the bottom surface of the roasting chamber; 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 being erected and fixed, and the cross-sectional area (S1) of the upper part of the roasting chamber being greater than the area (S2) of the bottom surface. In the roasting chamber, the inner wall surface of the roasting chamber may be inclined so that the cross-sectional area increases along the height direction from the bottom surface, or the roasting chamber may be configured from a combination of a tapered part of which the inside diameter increases upward in the height direction from the bottom surface and a cylindrical part that is fixed at the maximum inside diameter of the tapered part.

Description

Roasting equipment

[0001] This invention relates to a hot air roasting apparatus for coffee beans.

[0002] For small-scale coffee bean roasting in homes or cafes, a compact roasting system is commonly used in which the coffee beans are agitated in hot air. Such a system incorporates a hot air fluidized bed chamber, into which heated air is supplied with sufficient force to lift the coffee beans within the chamber. As the beans tumble and circulate within this fluidized bed, heat is transferred to them, resulting in roasting.

[0003] As an example of such a roasting apparatus, Japanese Patent No. 4847622 (Patent Document 1) proposes a roasting apparatus that uses a combination of a blower and an electric heater as a means of generating hot air, and injects the generated hot air into the 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 the hot air flow. By constructing the roasting chamber from heat-resistant glass, the state of the beans inside the roasting chamber can be observed.

[0004] Furthermore, Patent No. 6679302 (Patent Document 2) proposes placing an infrared sensor on the outside of a glass roasting container to detect the temperature of the object being roasted by receiving infrared rays from the object, and controlling the temperature of the heating means (heater).

[0005] Furthermore, Japanese Patent Publication No. 2022-537527 (Patent Document 3) proposes a roasting apparatus comprising a chamber, an airflow driver, and an electric heater positioned below the bottom opening of the chamber, wherein the apparatus includes a conduit for propelling a hot airflow from the heater to the bottom opening of the roasting chamber, the conduit having a localized transverse constriction that reduces the cross-section of the conduit to a minimum cross-section, and at least one temperature probe positioned in 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 rise while heating and stirring the beans. The heater is operable to heat the airflow generated by the airflow driver. In a specific embodiment, the heater is positioned between the fan and the bottom opening of the chamber and is heated before the airflow enters the chamber to lift the beans. (0044) The constriction forces various heterogeneous flows to mix, and as a result, the airflow has the same temperature in all other cross-sections of the constriction. As a result, the constricted section homogenizes the airflow, and the airflow and temperature measured by the probe in the constricted section accurately reflect the temperature of the hot air flow supplied to the bottom of the chamber, and can be reliably used in the heating control feedback loop (

[0051] ).

[0006] Japanese Patent Publication No. 4847622, ​​Japanese Patent Publication No. 6679302, Japanese Patent Publication No. 2022-537527, Japanese Patent Publication No. 2025-036818

[0007] The hot air heating method proposed in Patent Documents 1 to 3 controls 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 furthermore, the beans are stirred by a heated airflow. Therefore, in terms of energy costs to generate enough hot air for heating and stirring for roasting, this method is limited to roasting equipment that roasts enough beans for a few cups, such as in homes or cafes.

[0008] This invention was made in view of the above circumstances, and its purpose is to provide a technology that can be applied to roasting equipment that employs a hot air method and is capable of roasting several kilograms of coffee beans at once.

[0009] The inventors of the present invention conducted various studies on a roasting apparatus that can heat and agitate coffee beans using hot air. In conventional hot air roasting apparatuses, which blow hot air from the bottom of the roasting chamber, scaling up results in insufficient agitation of the beans by airflow, leading to a decrease in the homogeneity of the roasted beans. The inventors of the present invention discovered that a tornado flow can be generated by hot air from the bottom and air blown from the side to agitate the coffee beans, and filed a patent application (Patent Document 4). However, the amount of energy required to generate a tornado flow sufficient for agitation is large, posing a challenge in terms of energy cost.

[0010] The inventors, after further investigation, arrived at the present invention. That is, the roasting apparatus of the present invention has the following characteristics: [1] A cylindrical body made of carbon material constituting a roasting chamber for roasting coffee beans; a blower supplying an airflow to raise the coffee beans from the bottom surface of the roasting chamber; a first heater for heating the air from the blower; and a second heater for heating the peripheral wall of the cylindrical body, wherein the cylindrical body is fixed upright, and the cross-sectional area (S) of the upper part of the roasting chamber １ ) is the area of ​​the bottom surface (S ２ A roasting device larger than ).

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

[0012] [4] The roasting apparatus according to embodiment 1 or 2, wherein the second heater is attached to the peripheral wall of the cylindrical body. [5] The roasting apparatus according to embodiment 4, wherein the second heater is a stick-type heater 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 embodiments 1 to 5, wherein the upper end of the roasting chamber is provided with a powder separation means for separating the coffee bean dust generated by roasting. [7] The roasting apparatus according to embodiment 1, wherein the second heater is a band heater installed so as to cover the outer surface of the cylindrical body. [8] The roasting apparatus according to embodiment 1, wherein the normal airflow of the blower can be controlled to decrease from the initial stage of roasting to the later stage of roasting.

[0013] According to the roasting apparatus of the present invention, when the cross-sectional area above the roasting chamber through which the hot air passes increases, the pressure of the hot air that raises the coffee beans decreases, causing a lateral flow, and thus the coffee beans circulate. Moreover, since the perimeter wall of the roasting chamber is made of a carbon material with excellent thermal conductivity, the beans can be exposed to far-infrared rays by coming into contact with the perimeter wall as they move from top to bottom. By using far-infrared exposure and hot air in combination, roasting is performed efficiently, and since far-infrared rays can directly heat the inside of the multilayer structure of the coffee beans, even when roasting large quantities of coffee beans exceeding 1 kg, the variation in roasting degree between batches is kept small.

[0014] This is a schematic diagram showing the configuration of one embodiment (Embodiment 1) of the roasting chamber used in the roasting apparatus of the present invention, where (A) is a top view and (B) is a cross-sectional view. This is a schematic diagram showing the configuration of another embodiment of the roasting chamber used in the roasting apparatus of the present invention, where (A) is a top view and (B) is a cross-sectional view. This is a schematic diagram showing the configuration of another embodiment of the roasting chamber used in the roasting apparatus of the present invention, where (A) is a top view and (B) is a cross-sectional view. This is a schematic diagram showing the configuration of one embodiment of a cartridge-type heater. This is a block diagram showing the configuration of one embodiment of a roasting apparatus equipped with the roasting section of the embodiment shown in Figure 1. This is a schematic diagram showing the configurations of roasting chambers No. 1 to No. 4 evaluated in the embodiment. This is a schematic top view (A) and a schematic cross-sectional view (B) showing the configuration of roasting chamber No. 5 used in the embodiment. This is a schematic longitudinal cross-sectional view showing the configuration of Embodiment 2. This is a graph showing the time-dependent changes in the heating temperatures of the first and second heaters and the temperatures of the cylindrical body and coffee beans in Embodiment 1. This graph shows the time-dependent changes in the heating temperatures of the first and second heaters, and the temperatures of the cylindrical body and coffee beans in Embodiment 2.

[0015] The roasting apparatus of the present invention comprises: a cylindrical body made of carbon material constituting a roasting chamber for roasting coffee beans; a blower supplying an upward airflow to raise the coffee beans from the bottom of the roasting chamber; a first heater for heating the air from the blower; and a second heater for heating the peripheral wall of the cylindrical body, wherein the cylindrical body is fixed upright, and the cross-sectional area (S) of the upper part of the roasting chamber １ ) is the cross-sectional area of ​​the bottom (S ２ It is a larger roasting machine than ).

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

[0017] The roasting chamber used in the roasting apparatus of the present invention is composed of a cylindrical body made of carbon material, and is erected and fixed in the height direction of the cylindrical body, with the inside of the cylindrical body serving as the roasting chamber. Airflow sent out from a blower is blown in from the bottom surface of the cylindrical body, creating an upward airflow that circulates the coffee beans inside the roasting chamber.

[0018] The type of carbon material used to construct the cylindrical body is not particularly limited, but its bulk density should be between 1.2 and 2.2 g / cm³.３ and preferably 1.3 to 2.0 g / cm ３ , more preferably 1.5 to 1.9 g / cm ３ and is preferably composed of a carbon material. Further, the thermal conductivity at 25°C is 60 W / m·K or more, preferably 80 W / m·K or more, more preferably 100 W / m·K or more, and the upper limit is preferably usually 200 W / m·K or less.

[0019] Examples of such carbon materials include graphite (graphite), carbon fiber reinforced carbon composite material (CC composite), glassy carbon (non-graphitized carbon obtained by carbonizing a thermosetting resin such as a phenolic resin), porous carbon (porous carbon graphite), etc. Among these, graphite and CC composite are preferable, and more preferably graphite. As graphite, in addition to natural graphite and artificial graphite, charcoal, carbides of pitch and synthetic resins, etc. can be used. In addition, a coating such as a ceramic coating, a glass coating, a glassy carbon coating, a polysiloxane-based heat-resistant coating, or a pyrolytic carbon graphite coating may be applied to the inner wall surface and the outer wall surface of the cylindrical body as needed.

[0020] The shape of the cylindrical body is such that it has a cross-sectional area (S ２ ) larger than the area of the bottom surface portion of the roasting chamber (S １ ). The cross-sectional area S １ may be any cross-sectional area from the middle part to the upper part in the height direction of the cylindrical body. The air blown through the bottom surface of the small area (S ２ ) passes through the cross-sectional area of the large area (S １ ), so that the air flow spreads in the direction of the wall surface of the cylindrical body, which is the roasting chamber, and the rising air pressure decreases. As a result, the coffee beans pushed up by the rising air flow are transferred to the wall surface of the cylindrical body and descend along the wall surface. That is, the recirculation of the coffee beans in the roasting chamber is achieved. The shape of the cylindrical body is preferably such that the cross-sectional area 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-sectional area S ｍ ≧S ｎ holds).

[0021] The shape of the cylindrical body and the roasting chamber inside the cylindrical body may be any as long as it satisfies the above requirements. Representative forms of the cylindrical body and the roasting chamber are shown in FIGS. 1 to 3. The cylindrical body and the roasting chamber can be manufactured by cutting a block of artificial graphite that has been integrally formed into a desired shape to a specified dimension. When composed of a CC composite, necessary processing may be performed after the thermosetting molding of the composite material, or necessary processing may be performed in a semi-cured state and then fully cured to give a desired shape.

[0022] In the embodiment of FIG. 1, the bottom surface (area S ２ , inner diameter D ２ ) of the roasting chamber formed by the structure inside the cylindrical body 1 gradually expands upward to an inner diameter D １ of the cross-sectional area S １ , and is composed of a combination of a tapered portion 1a with an expanding diameter and a cylindrical portion 1b with a constant inner diameter of D １ . The cylindrical portion 1b and the tapered portion 1a may be formed by cutting inside the cylindrical body, or the tapered portion 1a and the cylindrical portion 1b may be formed separately and integrally joined. A cylindrical portion may be further provided below the tapered portion 1a, a tapered portion may be further provided above the cylindrical portion 1b, or it may be provided with a plurality of tapered portions with different angles without a cylindrical portion, and the longitudinal sectional contour line of the tapered portion (including the taper described later) may be curved.

[0023] Note that the tapered portion 1b is preferably at least 1 / 3 of the cylindrical body. That is, it is preferable that the ratio of the height t of the tapered portion 1b to the height T of the cylindrical body 1 is at least 1 / 3 of T. If the ratio of the tapered portion 1b is too small, the recirculation of coffee beans described later will be small and the far-infrared effect will be insufficient. The upper limit of the tapered portion 1b does not particularly need to be set, and it may be 2 / 3 or less of the cylindrical body, 40 to 60% of the cylindrical body, etc.

[0024] Also, in the embodiment shown in FIG. 2, the inside of the cylindrical body 2 made of a carbon material has a taper with an inner diameter that expands from the bottom surface to the top surface. The bottom surface of the inside of the cylindrical body 2 (roasting chamber 2A) has an inner diameter D ２ and an area S ２ , and the upper end surface of the roasting chamber has an inner diameter D ２ larger than the inner diameter D１ and has an area S ２ greater than the area S １ .

[0025] The area S １ , S ２ is not particularly limited, but preferably, the area ratio of S １ to S ２ (S ２ / S １ ) is 1.3 or more and 10 or less, preferably about 1.5 or more and 3 or less. Thereby, as shown by the arrows in FIGS. 1 to 3, the upward airflow blown through the bottom surface of the roasting chamber (area S ２ ) passes through the large area (S １ ), the air pressure drops, and the upward force of the beans decreases, so that a return flow in which the lifted beans descend can be formed.

[0026] The angle of the tapered portion or the taper (vertical cross-sectional contour line) with respect to the horizontal direction (the upper surface of the holding plate 20) is appropriately set through hot air pressure simulation, tests, etc., and can be, for example, 95 to 120°, 97 to 110°, 99 to 103°, etc. Note that the smaller the angle with respect to the horizontal direction, the lower the average thickness of the cylindrical body can be reduced, and thereby the weight reduction and heat efficiency improvement of the cylindrical body can be achieved. However, considering that the stirring effect becomes small, it can be set as appropriate.

[0027] A holding plate 20 with a large number of holes sized such that the airflow blown from the bottom surface can pass through and the coffee beans cannot pass through is attached to the bottom surface of the cylindrical body that forms the bottom of the roasting chamber. 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 in which 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 may be made of metal for ease of processing such as attachment and removal of the cylindrical body 1 and the access port 31.

[0028] An inlet 30 serving as an air inlet for blowing the airflow from the blower into the roasting chamber 1A is connected to the bottom surface of the carbon material cylindrical body 1 that constitutes the roasting chamber 1A.

[0029] The inlet 30 has an outlet 31 for removing roasted beans, and the outlet 31 for removing the roasted beans that have been transported from the roasting room is fitted with an openable and closable door.

[0030] The inlet 30 may be made of carbon material, similar to the cylindrical body, but it is preferable that it be made of a metal such as iron or stainless steel, from the viewpoint of ease of processing of the cylindrical body 1 and the outlet 31, as well as strength.

[0031] The shape of the tubular carbon material body constituting the roasting chamber was cylindrical in the configurations shown in Figures 1 and 2, but the shape of the roasting chamber used in this invention is not limited to this. For example, in the configuration shown in Figure 3, the cross-section is approximately semicircular. The area S of the bottom surface of the roasting chamber 3A, which is inside the tubular body 3 with a semicircular cross-section. ２ Area S of the upper end surface １ So, S ２ <S １ To satisfy this relationship, the taper increases from the radius L2 of the approximately semicircular lower end to the radius L1 of the approximately semicircular upper end. In Figure 3, the same reference numerals as in Figures 1 and 2 indicate the same members, and the reference numerals with dashes indicate the same functional members that differ only in shape.

[0032] Furthermore, the cylindrical body may be a rectangular prism, and the shape of the roasting chamber inside may be a triangle or trapezoid with a cross-section in the height direction. It is preferable that the cross-sectional shape of the roasting chamber be circular, as this ensures a constant distance from the inner surface of the cylindrical body, allowing the coffee beans to receive the effects of far-infrared rays more stably.

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

[0034] The peripheral walls of the cylindrical bodies 1, 2, and 3 shown in Figures 1, 2, and 3 have through-holes 10 and 11 running through them along the height direction of the cylindrical bodies 1, 2, and 3. These through-holes 10 and 11 serve as housings for the second heater, which is a stick-type heater. There are six through-holes 10 and 11 that serve as housings for the stick-type heater, spaced equally apart in the circumferential direction.

[0035] The thickness of the walls of the cylindrical bodies 1, 2, and 3 (the walls of the cylindrical parts) is not particularly limited, but in this embodiment, it is usually 20 to 50 mm, preferably 20 to 30 mm. If it is too thin, it will be difficult to drill through holes 10 and 11 that will serve as the housings for the stick-type heaters. On the other hand, if it is too thick, the amount of heat required for heating will increase, so from an energy-saving standpoint, it is sufficient to have a thickness that is necessary and sufficient to provide the heater housings.

[0036] In the configurations shown in Figures 1, 2, and 3, six through-holes for housing the stick-type heaters were provided on the peripheral wall surface. However, the roasting chamber used in this invention is not limited to this configuration. Any number of heaters is sufficient to heat the entire carbon material cylindrical body almost uniformly and to emit far-infrared rays from the entire carbon material cylindrical body. The number of heaters can be appropriately selected depending on the size and type of stick-type heaters used.

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

[0038] The cartridge heater 12 shown in Figure 4 consists of a cylindrical heating element 12a, which generates heat when an electric current is applied (for example, a nichrome wire), inserted into a cylindrical outer tube 12b, with lead wires 12c extending outwards to supply power to the heating element. The lead wires 12c are brought out from the upper surface of the cylindrical body 1.

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

[0040] The roasting apparatus shown in Figure 5 comprises: a cylindrical body 1 made of carbon material equipped with a roasting chamber 1A having the configuration shown in Figure 1; a blower 32 that generates an airflow to be blown into the roasting chamber 1A; a first heater 33 that heats the airflow; a stick-type second heater 12 embedded in the peripheral wall of the cylindrical body made of carbon material for heating the cylindrical body; an inlet 30 connected to the bottom of the roasting chamber 1A that serves as an inlet for blowing hot air to roast and circulate the coffee beans; and a separation means 40 connected to the upper end of the roasting chamber for collecting residue (mainly chaff) generated during roasting.

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

[0042] Furthermore, the roasting chamber may be equipped with a collection unit 36 ​​for collecting the roasted beans discharged from the roasted bean outlet 31 of the inlet, and may also be equipped with a suction device 35 for cooling the roasted beans collected in the collection unit 36. The blower 32 for supplying air to the roasting chamber 1A may also be used as a suction device for cooling the roasted beans. In this case, for example, a three-way switching valve that selectively switches to cool the roasted products may be placed between the blower 32 and the first heater 33, so that air is supplied to the hot air generating heater 33 side during roasting, and after roasting is finished, heat from the collection unit 36 ​​side is sucked in and discharged.

[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 has an exhaust duct and an exhaust port 21a for discharging dust and roasting residue generated during roasting.

[0044] The separation means 40 is connected to an exhaust port 21a opened in the center of a lid 21 that closes the top surface of the roasting chamber, and includes a cyclone 42 for separating powder (chaff) mixed in the exhaust flow discharged from the exhaust port 21a, and a cock 44 for adjusting the exhaust flow rate and whether or not to exhaust. An intake fan that sends the exhaust flow to the cyclone 42 may be installed between the cyclone 42 and the cock 44.

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

[0046] The lid 21 closes the top of the roasting chamber 1A, but a portion corresponding to the heater housing 10 is left open, allowing lead wires 12c for heating the second heater (stick-type heater) housed in the heater housing 10 to be pulled out.

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

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

[0049] Hot air from the blower 32 passes through the inlet 30 and is blown into the roasting chamber 1A as an updraft from the bottom. Inside the roasting chamber 1A, the coffee beans are blown upwards by the incoming hot air (updraft). Meanwhile, the hot air flows through the cross-sectional area S of the inlet. ２ Area S that is larger than １As the air passes through, the upward pressure of the updraft decreases and it spreads radially. The coffee beans are carried by the radially spread airflow to the peripheral wall surface of the 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 the carbon material cylindrical body 1, and the beans receive far-infrared radiation from the heated carbon material.

[0050] Far-infrared radiation, absorbed by coffee beans which are bulky, multi-layered materials, causes molecular vibrations (thermal effects) that allow heating to penetrate to the core without excessively heating the surface. Therefore, by using both hot air and far-infrared heating, heating can be done efficiently, and the difference in heat energy received can be minimized, whether the amount of coffee beans is small or exceeding 1 kg. This helps to suppress variations in the degree of roasting of coffee beans roasted within the same batch.

[0051] Roasting conditions such as heating time (roasting time) and airflow (normal airflow) are set appropriately according to the configuration of the roasting apparatus and the type of product being roasted, including the type of coffee beans, the type of carbon material of the cylindrical body 1 that makes up the roasting chamber 1A, and the size of the cylindrical body 1.

[0052] By operating the cyclone 42 during roasting, air from inside the roasting chamber 1A is drawn in, and the cyclone 42 collects the green bean residue. This separates and removes chaff and other residues generated during roasting, thus reducing the effort required to clean the cylindrical body 1 after roasting and shortening the roasting interval. The degree to which the valve 44 is opened and closed allows for adjustment of the airflow rate and force during roasting.

[0053] When roasting is complete, the door of the inlet 30's outlet 31 is opened, and the holding plate 20 is tilted to allow the roasted beans in the roasting chamber to fall into the collection unit 36. The suction device 35 is then activated to cool the roasted beans by sucking out the heat from the collection unit 36.

[0054] In the roasting apparatus of the present invention having the above configuration, the roasting chamber 1A is configured so that the rising airflow is emitted upwards, allowing the coffee beans to circulate within the roasting chamber 1A. Furthermore, as the coffee beans descend, they are also heated by far-infrared rays from the cylindrical body 1 made of carbon material that constitutes the roasting chamber 1A, thus enabling efficient heating.

[0055] Therefore, conventionally, achieving sufficient roasting using only hot air required a large amount of energy for generating the hot air, which tended to hinder energy conservation. In this invention, the cylindrical body constituting the roasting chamber is also directly heated by the second heater, which prevents the air inside the roasting chamber from cooling down and also allows for efficient heating of the coffee beans to the inside using far-infrared rays. As a result, it becomes possible to roast coffee beans in quantities ranging from several hundred grams to several kilograms, which are the roasting units used by roasting bean manufacturers, at a practical level, not only for home or cafe use.

[0056] [Example] The energy required to generate the updraft and circulating airflow necessary for bean stirring was compared based 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 cylindrical body with the structure shown in Figure 7 in order to generate a tornado flow. Roasting chamber No. 5 shown in Figure 7 has four main passages 52 that penetrate the circumferential wall of the cylindrical body in the height direction of the cylinder, and communication holes 53 that are drilled radially in communication with each main passage. By blowing the airflow from the main passages 52 out through the communication holes 53, a tornado flow can be formed inside the roasting chamber. For No. 5, a large blower capable of supplying a larger volume of air than the blowers used in No. 1 to No. 4 was used to generate a tornado flow.

[0057] The airflow 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) needed to heat the first heater, assuming room temperature (20°C) and roasting temperature (250°C), into power (watts). A viewing window was also created in the peripheral wall of a cylindrical body made of carbon material to observe the state of the beans during roasting (stirring). These results are shown in Table 1.

[0058]

[0059] No. 3 changes the position of the retaining plate 20" to change the area S of the bottom surface of the roasting chamber. ２ and the cross-sectional area S of the upper part １ These two factors are equal. As a result, the rising airflow from the blower alone was not sufficient to agitate the beans during roasting. Increasing the airflow pressure also resulted in the beans accumulating at the bottom of the roasting chamber, making it difficult to circulate the beans within the chamber.

[0060] No. 4 is achieved by setting the retaining plate 20" at an angle, thereby increasing the area S of the air inlet. ２ The cross-sectional area S of the upper part of the roasting chamber. １ This was a larger version, and it was not possible to adequately agitate the beans through circulation.

[0061] Roasting chamber No. 5 was able to circulate the beans within the chamber by generating a tornado flow, but generating the tornado flow required a larger blower than those used in chambers No. 1 to No. 4, requiring more than three times the energy needed for updrafts alone. Applicability to roasting equipment for commercial quantities (at least 1 kg or more) was unsuitable from an economic and energy standpoint.

[0062] In this regard, the cross-sectional area S above the roasting chamber. １ However, the area S of the base ２ In the roasting apparatus of the present invention, which is equipped with roasting chambers No. 1 and No. 2 that are larger than those of the cylindrical roasting chambers (No. 3, 4), it was possible to circulate the beans with the same amount of energy as in the cylindrical roasting chambers (No. 3, 4). In particular, No. 1 (S ２ = 0.5 × S １ At t = 0.5 × T, the amount of energy required could be reduced to about half compared to a cylindrical roasting chamber.

[0063] (Embodiment 2) This embodiment differs from Embodiment 1 in that, as shown in Figure 8, the second heater is a band heater 62 installed to cover (enclose) the outer surface of the cylindrical body 6. This embodiment also includes a cylindrical body temperature sensor 65 and a coffee bean temperature sensor 66. The cylindrical body temperature sensor 65 can detect the temperature of the inner wall surface of the cylindrical body, and the coffee bean temperature sensor 66 can detect the temperature of coffee beans in contact with the sensor. Other configurations common to Embodiment 1 are omitted from this description.

[0064] The airflow (normal airflow) of the blower can be controlled to decrease (become weaker) from the initial to the later stages of roasting. Coffee beans in the initial stages of roasting contain a lot of moisture and therefore have a high density, while coffee beans in the later stages of roasting lose moisture and expand due to cracking, resulting in a lower density. For this reason, if the airflow is always the same, the coffee beans in the initial stages of roasting may not be sufficiently agitated, or in the later stages of roasting, they may be blown above the top surface of the cylindrical container (slammed against the lid on top). By controlling the airflow as described above, the beans can be raised and agitated to the same height level, ensuring a uniform far-infrared effect. Airflow control can be performed using a program, for example, and can be adjusted according to the type of coffee beans, the amount added, and the desired roast level. Furthermore, a sensor may be provided to monitor the internal conditions of the cylindrical container, and the airflow may be changed based on the sensor signal. The sensor can detect temperature, humidity, coffee bean speed, odor, etc. In this embodiment, two temperature sensors 65 and 66 are provided.

[0065] In the above embodiment 1, the wall thickness of the cylindrical body (cylindrical portion) was 20 to 50 mm. However, in this embodiment, by using a band heater 62 that tightly covers the outer surface of the cylindrical body as the second heater, it becomes unnecessary to drill through holes 10 and 11 that serve as housings for the stick-type heater, and the thickness can be reduced accordingly. The wall thickness of the cylindrical body (cylindrical portion) (D4-D3 / 2 in Figure 8) only needs to be sufficient to maintain adequate strength, and can be 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 surface of the cylindrical body, and other heaters may be used. The band heater 62 can be one that includes a heating element such as a nichrome wire, an insulator such as ceramic or mica, and an outer casing such as stainless steel.

[0066] Figures 9 and 10 show graphs illustrating the time-dependent changes in the heating temperatures of the first and second heaters, as well as the temperatures of the cylindrical body and coffee beans. Both cylindrical bodies were made by carving out black soot, and the dimensions (mm) and angles (°) of each part are as shown in Table 2 below. The angle is the angle between the tapered contour line in the longitudinal section and the upper surface of the retaining plate. The cylindrical body heights T1-10 are due to subtracting the thickness of the retaining plate. Other dimensions include the height T2 of the band heater 62, which is 290 mm, and the outer diameter D5 of the band heater, which is 310 mm. Table 3 shows the relationship between the temperature range of the hot air during roasting and the normal airflow rate.

[0067]

[0068]

[0069] As can be seen from Figure 9 of Embodiment 1 and Figure 10 of 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 180-190°C higher to make the surface temperature of the cylindrical body the same as in Embodiment 2, which uses a band heater. As a result, the total output was 5400W in Embodiment 1 and 4000W in Embodiment 2. In addition, the weight of the product was significantly reduced to about 21kg in Embodiment 1 and about 7kg in Embodiment 2. Furthermore, when the finished beans after roasting were visually inspected, almost no color unevenness was observed in either embodiment, but Embodiment 2 had slightly less color unevenness.

[0070] Furthermore, when the cylindrical inner surface was heated by the second heater, the temperature distribution was measured using thermography. In Embodiment 1, the temperature was high near the stick heater and slightly lower in the intermediate region, showing an uneven distribution. However, in Embodiment 2, there was no unevenness in the temperature distribution.

[0071] Furthermore, by using programmatic control of the hot air volume (normal air volume) as shown in Table 3, it was possible to maintain a nearly constant coffee bean lift height from the initial to the final stages of roasting.

[0072] It should be noted that all disclosed embodiments are illustrative and can be modified as appropriate. For example, heaters other than stick-type heaters and band heaters may be used, and additional or alternative sensors may be provided. The size can also be modified as appropriate depending on the application (household, retail, manufacturing, etc.).

[0073] The roasting apparatus of the present invention comprises 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 a cylindrical body made of carbon material that constitutes the roasting chamber. Therefore, it is possible to roast several hundred grams to several kilograms of coffee beans, which are the roasting units used by roasting manufacturers, at once at a practically acceptable energy cost.

[0074] By using hot air to agitate the beans and heating them by far-infrared rays as they come into contact with the cylindrical body wall made of carbon material during the bean circulation process, the roasting apparatus of the present invention can heat hundreds of grams to several kilograms, or even more, of coffee beans in a single batch to a nearly uniform degree of uniformity. Therefore, the roasting apparatus of the present invention is useful not only for home and cafe use, but also for commercial use by various roasting manufacturers of all sizes, from small to large.

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

Claims

1. A roasting apparatus comprising: a cylindrical body made of carbon material constituting a roasting chamber for roasting coffee beans; a blower supplying an airflow to raise the coffee beans from the bottom of the roasting chamber; a first heater for heating the air from the blower; and a second heater for heating the peripheral wall of the cylindrical body, wherein the cylindrical body is fixed upright, and the cross-sectional area (S) of the upper part of the roasting chamber １ ) is the area of ​​the bottom surface (S ２ A roasting device larger than ).

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

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

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

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

6. The roasting apparatus according to claim 1, wherein the upper end of the roasting chamber is provided with a powder separation means for separating the coffee bean dust generated by roasting.

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

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

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