Method for circularly baking coffee beans

Abstract

The invention provides a coffee bean circulating baking method, coffee beans are baked by using a hot air type baking device, the hot air type baking device comprises a combustor, an air supply pipeline, a baking device and an air return pipeline, the combustor comprises a combustion cylinder and a heating device, and the baking device comprises a baking chamber; return air from the baking chamber is directly introduced from the upper portion of the combustion cylinder, the air return pipeline connector is located on the upper portion of the combustion cylinder and below the air supply pipeline connector, and a first spiral structure is used at the position, corresponding to the air return pipeline connector, in the combustion cylinder to lengthen an air return path, so that the return air passes through the first spiral structure. A part of impurities and smoke in the return air are burnt out in the high-temperature burning cylinder, and the impurities which are not burnt out fall down under the action of gravity, so that the impurities in the return air are separated from hot air. When the baking method disclosed by the invention is used for baking, the temperature can be regulated and controlled, the temperature rise is fast, the beans are uniformly heated, the hot air circulation times are more, and the baked cooked coffee beans have higher quality and good taste.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coffee bean roasting equipment, and more particularly to a coffee bean circulation roasting method. BACKGROUND

[0002] Coffee roasting equipment is a core tool for converting green beans into rich-flavored roasted beans through heating. Common coffee roasting equipment in the prior art includes hot air roasting machines and drum roasting machines. The hot air roasting machine introduces high-temperature and high-speed hot air into a bean compartment to roast coffee beans. The drum roasting machine stirs coffee beans in a rotating and heated metal drum, and the heat source comes from a gas or electric heater below the drum. The hot air roasting machine can make the heating of coffee beans more uniform and has higher thermal efficiency than the drum roasting machine.

[0003] The patent for a system for roasting coffee particles with publication number CN113693249B discloses a hot air roasting equipment, which includes a combustion cylinder provided with a unit (2) for generating heat capable of heating air, and further includes a unit (25) for assisting the introduction of air into the combustion cylinder to obtain a step of post-combustion of flue gas to be directed to the exhaust flue when needed, i.e., the unit (25) is used for post-combustion of tail gas. The unit (2) of this scheme is used for heating air, and a cyclone separator is arranged between the combustion cylinder and the rotating drum. The cyclone separator receives a hot air stream mixed with air and / or solid impurities from the rotating drum and formed during roasting. The combustion cylinder delivers the hot air stream with impurities to the combustion cylinder through a suction unit.

[0004] The patent application for a coffee bean roasting machine with publication number CN106617198A also discloses a hot air roasting equipment. A combustion chamber provides hot air, coffee beans are located in a roasting drum, and a cyclone dust collector is connected between the combustion chamber and the roasting drum. Air mixed with coffee bean skins can be preliminarily purified after entering the cyclone dust collector. The cyclone dust collector filters out most of the coffee bean skins with larger volumes in the air. At this time, only a small amount of coffee bean skins with smaller volumes and other impurities remain in the air. The air filtered by the cyclone dust collector enters the combustion chamber from the pipeline C. The air mixed with a small amount of coffee bean skins and other organic matters with smaller volumes enters the combustion chamber and is heated to 700-850 degrees Celsius by the burner, thereby burning off the coffee bean skins and other organic matters in the air. This part of the air can be recycled. This part of the air still has a high temperature. It only needs less heat to heat this part of the air to 700-850 degrees Celsius, thereby saving energy of the burner.

[0005] Both patents describe hot air roasting equipment where the hot airflow circulates within the system. Cyclone dust collectors are installed between the burner providing the hot airflow and the roasting chamber for roasting the beans. These collectors initially filter impurities from the hot airflow exiting the roasting chamber, and the initial impurity separation and waste heat recovery are completed in two separate steps. However, both patents only explain the principle of hot air generation within the system and do not address how to improve the burner's calorific value or the hot air circulation rate. Calorific value refers to the heat released by the complete combustion of a unit mass (or volume) of fuel. The calorific value of the fuel combustion and the hot air circulation rate in the burner determine the rate at which the bean temperature rises, directly affecting the internal chemical changes of the coffee beans (such as the Maillard reaction and caramelization), flavor development, and final cupping performance. During roasting, insufficient calorific value in the dehydration stage leads to prolonged dehydration time and low efficiency, resulting in slowly dried coffee beans that may have a grassy taste, affecting bean quality and flavor. Higher calorific value allows for more frequent hot air circulation, better penetration into the beans, and better flavor and higher quality roasted coffee beans. With more frequent hot air circulation, smoke and impurities are better removed and re-burned in the burner, resulting in better and cleaner coffee bean flavor. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a coffee bean circulating roasting method that can improve the calorific value of the burner and the hot air circulation rate to improve the roasting quality of coffee beans.

[0007] A circulating roasting method for coffee beans uses a hot air roasting device to roast coffee beans. The hot air roasting device includes a burner, an air supply duct, a roasting device, and a return air duct. The burner includes a combustion cylinder and a heating device. The roasting device includes a roasting chamber. The heating device is located at the bottom of the combustion cylinder, and the air supply duct is located at the top of the combustion cylinder. Return air from the roasting chamber is directly introduced into the combustion cylinder from the top. The return air duct interface is located at the top of the combustion cylinder and below the air supply duct interface. A spiral structure is used in the combustion cylinder at the corresponding position of the return air duct interface to lengthen the return air path. As the return air passes through the spiral structure, some impurities and smoke in the return air are burned off in the high-temperature combustion cylinder. The unburned impurities fall downwards under the action of gravity, thus achieving the separation of impurities and hot air in the return air.

[0008] In this invention, the air supply duct is used to deliver hot air from the combustion chamber into the baking chamber. One end of the air supply duct is connected to the combustion chamber, and the other end is connected to the baking chamber. The return air duct is connected to the baking chamber at one end and to the combustion chamber at the other end, and is used to return the return air (including hot air, silver residue, and flue gas) from the baking chamber to the combustion chamber. A centrifugal fan is installed on the return air duct to create negative pressure in the baking chamber, causing the hot air to circulate. By controlling the motor speed of the centrifugal fan, the circulating air volume and the negative pressure in the baking chamber can be controlled.

[0009] The unique feature of this invention is that it eliminates the need for a cyclone integrator. The return air from the roasting chamber is directly introduced into the combustion chamber. Specifically, a spiral structure is installed in the combustion chamber at the corresponding point of the return air duct interface. During return air flow, the return air rotates through the spiral structure, which lengthens the return air path. Heavier impurities fall downwards, while lighter impurities and smoke are burned off in the high-temperature combustion chamber. Furthermore, the hot air in the return air is reheated by the combustion chamber and re-enters the air supply duct to roast the materials in the roasting chamber. This invention separates hot air and impurities through the spiral structure in the combustion chamber, achieving integrated cyclone separation and combustion. This shortens the circulation path, reduces fuel consumption, and increases the burner's calorific value and hot air circulation rate. The hot air in the return air still carries a high temperature, requiring only a small amount of heat to heat it to the specified roasting temperature, thus saving energy. The spiral structure separates the hot air and impurities in the return air, ensuring that the hot air re-entering the air supply duct is clean and free of impurities, preventing impurities and smoke from re-entering the roasting chamber and adhering to the surface of the coffee beans, thus affecting the quality of the coffee beans.

[0010] Existing technology separates hot air and impurities in the return air by first using a cyclone integrator for preliminary purification and filtration, removing most of the larger coffee bean skins from the air. The remaining small amounts of smaller coffee bean skins and other impurities in the return air then enter the burner for complete combustion. In other words, the separation of hot air and impurities in the return air is carried out in two steps and through two containers. This invention incorporates a spiral structure in the burner, requiring only one step and one container to complete the separation of hot air and impurities. This shortens the circulation path, reduces fuel consumption, and improves the burner's calorific value and hot air circulation rate.

[0011] Secondly, in existing technologies, the return air enters from the bottom of the burner; in this invention, there is no need for a cyclone integrator, and the return air from the baking chamber directly enters the burner, and the return air enters from the top of the burner.

[0012] Furthermore, the end of the combustion cylinder equipped with the heating device is an inverted cone shape with a diameter that gradually increases from bottom to top. The heating device heats the air in the combustion cylinder, and the inverted cone structure allows the hot air to enter the thicker upper part of the combustion cylinder from the narrower lower part, thus accelerating the entry of the hot air into the air supply duct.

[0013] Furthermore, the outer edge of the spiral structure is tangent to the inner wall of the combustion chamber; a central pipe is provided at the center of the spiral structure to connect with the air supply pipe interface, so that the reheated return air returns to the air supply pipe through the central pipe under the action of negative pressure.

[0014] Furthermore, a spiral structure is installed in the central duct to accelerate the entry of air into the air supply duct.

[0015] Furthermore, the combustion chamber is divided into three parts, from bottom to top: a connecting cylinder, a return air duct, and an air supply duct. The heating device is located at the bottom of the connecting cylinder. The first spiral structure and the second spiral structure are located in the return air duct, and the return air duct interface is opened on the return air duct. The air supply duct interface is opened on the air supply duct. A partition is set between the return air duct and the air supply duct to isolate the air supply duct from the return air duct and the connecting cylinder, so that the hot air in the connecting cylinder enters the air supply duct through the central pipe and the air supply duct under negative pressure.

[0016] Furthermore, the first spiral structure is left-handed, causing the return air to flow downwards; the second spiral structure is right-handed, causing the hot air to flow upwards.

[0017] Furthermore, a waste bin is provided at the bottom of the combustion cylinder, which is connected to the bottom of the combustion cylinder to collect falling impurities.

[0018] Furthermore, a cooling spray device is installed to cool the impurities in the waste bin.

[0019] Furthermore, the roasting apparatus includes a furnace and a stirring device. The furnace is fixed, and the stirring device is movably connected to both ends of the furnace via a shaft. During roasting, the furnace does not rotate, while the stirring device rotates to stir the coffee beans.

[0020] Existing roasting chambers typically feature a rotating drum with blades mounted on its inner wall. The drum rotates to roast the coffee beans. In this invention, the furnace chamber (equivalent to the rotating drum in the prior art) remains stationary, while the blades are mounted on a rotating shaft. The rotation of the blades roasts the coffee beans within the furnace chamber. This invention only involves shaft rotation; compared to a rotating furnace chamber, the furnace chamber of this invention has better sealing at both ends, reducing heat loss within the roasting chamber.

[0021] During the roasting process, hot air enters the roasting apparatus from the burner's combustion chamber through the air duct, roasting the coffee beans. The control system automatically adjusts the gas pressure and airflow of the heating element in the burner to regulate the temperature of the hot air in the combustion chamber, thereby controlling the roasting temperature within the apparatus. This allows for precise control from light to dark roasts. A centrifugal fan is installed on the return air duct, and its motor speed is controlled by a frequency converter, thus controlling the circulating air volume and the negative pressure within the roasting chamber. The stirring action of the agitator ensures uniform temperature within the roasting chamber, keeping the temperature difference within ±1℃, ensuring even heating of the coffee beans.

[0022] Furthermore, the gas is natural gas.

[0023] Furthermore, a damper is installed on the air supply duct. During baking, the damper is closed; after shutdown, the damper is opened to allow cold outside air to enter the circulation system to cool the system.

[0024] In this invention, the gas pressure regulating device and air conditioning device of the burner regulate the temperature of the hot air in the combustion chamber (i.e., regulate the temperature in the baking chamber). The air supply device is used for cooling the equipment after baking is stopped. During baking, the damper is closed; it is only opened after shutdown to allow cold air to enter the circulation system.

[0025] The present invention has the following beneficial effects:

[0026] Compared with existing technologies, this invention has a higher calorific value and hot air circulation rate, which is achieved through the following methods: 1. The return air is directly introduced into the combustion chamber, which shortens the circulation path, reduces gas consumption, and increases the calorific value of the burner and the hot air circulation rate.

[0027] 2. The combustion cylinder is an inverted cone shape with a thicker upper part and a gradually decreasing diameter at the lower part. This structure allows hot air to enter a larger space from a smaller space, accelerating the flow of hot air.

[0028] 3. A central pipe is installed at the center of spiral structure one, which is connected to the air supply pipe interface. Spiral structure two is installed in the central pipe to accelerate the air entering the air supply pipe.

[0029] 4. Reuse of Return Air: Hot air circulates through the burner, supply duct, baking device, return duct, and burner. The return air from the baking device returns to the burner. Heavier impurities in the return air fall downwards, while lighter impurities and smoke are burned off in the high-temperature combustion chamber. The hot air in the return air is reheated by the combustion chamber and then re-enters the supply duct to bake the materials in the baking chamber. The return air still carries a high temperature, allowing for rapid heating to the set baking temperature with only a small amount of heat. The combustion of impurities and smoke also provides heat.

[0030] 5. Fix the blades of the stirring device to the rotating shaft to improve the sealing of both ends of the furnace and reduce heat loss in the baking chamber.

[0031] 6. The heating device includes a gas pressure regulating device and an air conditioning device. The gas pressure regulating device regulates the pressure of the gas, and the air conditioning device controls the air flow. The regulated gas and air are mixed in the gas mixer. By regulating the gas pressure and the air flow, the gas can be burned more completely, thereby increasing the calorific value of the burner.

[0032] The above six points enable rapid heating of the air in the combustion chamber and accelerate the flow of hot air, thereby increasing the calorific value, speeding up the roasting process, and preventing the roasted beans from having a grassy taste. Higher calorific value results in more frequent hot air circulation, better penetration into the beans, and better flavor and higher quality coffee beans. Testing shows that the roasting equipment described in this invention has a thermal efficiency of over 85%: compared to traditional roasters (typically 50%-60%), it significantly reduces gas consumption, saving 20%-30% in energy costs over long-term use.

[0033] The hot air in the return air can be re-burned in the combustion chamber, and the combustion exhaust gas can be recycled, reducing carbon emissions and meeting environmental protection regulations. Attached Figure Description

[0034] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the burner used in hot air circulating coffee roasting in Example 1; Figure 2 This is a schematic diagram (partially cut open) of the burner used in hot air circulating coffee roasting in Example 1. Figure 3 These are schematic diagrams of the baking equipment used in Examples 2 and 3; Figure 4 A schematic diagram of the burner and air supply duct structure; Figure 5 A schematic diagram of the return air duct and centrifugal fan; Figure 6 A schematic diagram of the vacuum feeding device and material cart structure; Figure 7 This is a schematic diagram of the feeding hopper structure of a vacuum feeding device; Figure 8 This is a schematic diagram of the material cooling device. Figure 9 A schematic diagram of the cooling and stirring device and the discharge device; Figure 10 This is a schematic diagram of the air supply duct structure; Figure 11 This is a cross-sectional view of the baking apparatus; Figure 12 This is a schematic diagram of the stirring device. Figure 13 This is a schematic diagram of the baking equipment, including the air supply duct, return air duct, feeding hopper, and discharging device. Figure 14 This is a schematic diagram of a baking apparatus (with the outer casing hidden). Figure 15 A partial view of the baking apparatus; Figure 16 This is a schematic diagram of the discharge device. Figure 17 This is a schematic diagram of a vacuum filtration device. Figure 18 This is a schematic diagram of the exhaust system.

[0035] The serial numbers are as follows: 1-burner, 1a-combustion cylinder, 1a1-connecting cylinder, 1a2-return air duct, 1a3-air supply duct, 1b-spiral structure one, 1c-air supply duct interface, 1d-return air duct interface, 1e-waste bin, 1g-air conditioning device, 1h-gas mixer, 1i-combustion nozzle, 1j-exhaust pipe, 1k-cooling spray device, 1m-intermediate pipe, 1n-spiral structure two; 2-air supply duct; 3-baking device, 3a - Baking chamber, 3a1- Shell, 3a2- Furnace chamber, 3a3- Connection between furnace chamber and hollow structure, 3a4- Outlet of fixed section, 3b- Stirring device, 3b1- Rotating shaft, 3b2- Blades, 3b3- Fixed bracket, 3c- Mounting base, 3c1- Hollow structure, 3c2- Connection between feeding hopper and mounting base; 4- Return air duct, 4a- Centrifugal fan one, 4b- Fixed section, 4c- Connecting cylinder, 4d- Connection between fixed section and hollow structure; 5- Material cart; 6-Vacuum feeding device, 6a-Feeding hopper, 6a1-Vacuum port, 6a2-Feeding inlet, 6a3-Feeding cylinder, 6a4-Unloading mechanism, 6a5-Cylinder cover, 6a6-Observation window one, 6b-Vacuum filtration device, 6b1-Vacuum pump, 6b2-Filter one, 6b3-Connecting pipe, 6b4-Waste box, 6b5-Connection to vacuum port; 7-Material cooling device, 7a-Cooling and stirring device, 7a1-Stirring cylinder, 7a2-Drive device three, 7a3-Agitator rake, 7b-Exhaust device, 7b1-Centrifugal fan, 7b2-Filter two, 7b3-Exhaust duct, 7b4-Support; 8-Frame assembly; 9-Electrical control system; 10-Make-up air device, 10a-Drive device two, 10b-Opening and closing mechanism, 10c-Air damper; 11-Discharge device, 11a-Fixed baffle, 11b-Modible baffle, 11c-Drive mechanism four, 11d-Observation window two. Detailed Implementation

[0036] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0037] Example 1 A circulating roasting method for coffee beans uses a hot air roasting device to roast coffee beans. The hot air roasting device includes a burner, an air supply duct, a roasting apparatus, and a return air duct. The burner includes a combustion cylinder and a heating device. The roasting apparatus includes a roasting chamber. The heating device is located at the bottom of the combustion cylinder, and the air supply duct is located at the top of the combustion cylinder. The method specifically includes the following steps: S1: The heating device is placed at the bottom of the combustion cylinder, and the air supply pipe and return air pipe are connected to the upper part of the combustion cylinder, wherein the interface of the air supply pipe on the combustion cylinder is located above the interface of the return air pipe; the heating device mixes the gas and air and then heats the air in the combustion cylinder through the nozzle combustion. The hot air enters the roasting chamber containing coffee beans through the air supply pipe under negative pressure to roast the coffee beans. S2: The return air from the baking chamber flows back into the combustion chamber from the top of the combustion chamber through the return air duct; S3: A spiral structure is provided at the corresponding location of the return air duct interface. The return air enters the spiral structure tangentially. The spiral structure increases the return air path. The heavier impurities in the return air fall downward under the action of gravity, while the lighter impurities and smoke are burned in the high-temperature combustion chamber. The spiral structure is left-handed, which makes the return air flow downward. S4: The hot air in the return air is reheated to the set baking temperature in the combustion chamber by the heating device, and then enters the baking chamber again through the air supply duct; S5: Repeat steps S2 to S4 until the coffee beans are roasted.

[0038] In step S1, the end of the combustion cylinder equipped with the heating device is an inverted cone shape with a diameter that gradually increases from bottom to top. The heating device heats the air in the combustion cylinder. The inverted cone structure allows the hot air to enter the thicker upper part of the combustion cylinder from the narrower lower part, thus accelerating the entry of the hot air into the air supply duct.

[0039] In step S3, the outer edge of the first spiral structure is set to be tangent to the inner wall of the combustion chamber; a central pipe is set at the center of the first spiral structure, connecting to the air supply pipe interface, so that the reheated return air returns to the air supply pipe under negative pressure through the central pipe. A second spiral structure is set in the central pipe to accelerate the air entering the air supply pipe. The second spiral structure is right-handed, causing the hot air to flow upwards.

[0040] The combustion chamber is divided into three parts, from bottom to top: a connecting cylinder, a return air duct, and an air supply duct. The heating device is located at the bottom of the connecting cylinder. The first spiral structure and the second spiral structure are located in the return air duct, and the return air duct interface is located on the return air duct. The air supply duct interface is located on the air supply duct. A partition is installed between the return air duct and the air supply duct to isolate the air supply duct from the return air duct and the connecting cylinder, so that the hot air in the connecting cylinder enters the air supply duct through the central duct and the air supply duct under negative pressure.

[0041] A waste bin is also provided at the bottom of the combustion cylinder. The waste bin is connected to the bottom of the combustion cylinder to collect the falling impurities, and a cooling spray device is provided to cool the impurities in the waste bin.

[0042] The roasting apparatus includes a furnace and a stirring device. The furnace is fixed, and the stirring device is movably connected to both ends of the furnace via a shaft. During roasting, the furnace does not rotate, while the stirring device rotates to stir the coffee beans.

[0043] The air supply duct is equipped with a damper. During baking, the damper is closed; after shutdown, the damper is opened to allow cold outside air to enter the circulation system to cool it.

[0044] Example 2 A burner for use in the method described in Embodiment 1 is provided. The burner includes a combustion chamber 1a and a heating device, the heating device heating the gas inside the combustion chamber 1a; as shown Figure 1 and Figure 2 As shown, the heating device is located at the bottom of the combustion cylinder 1a. The combustion cylinder 1a includes a connecting cylinder 1a1, a return air cylinder 1a2, and an air supply cylinder 1a3 connected sequentially from bottom to top. The heating device is connected to the connecting cylinder 1a1. A spiral structure 1b is provided in the return air cylinder 1a2. A return air duct interface 1d is opened on the return air cylinder 1a2, and an air supply duct interface 1c is opened on the air supply cylinder 1a3. The spiral structure 1b is composed of multiple layers of blades connected end to end. The spiral structure 1b rotates in a left-hand direction. The return air duct interface 1d is located between the two uppermost layers of blades, and the air supply duct interface 1c is located above the spiral structure 1b.

[0045] The spiral structure 1b rotates around the combustion chamber axis. A central pipe 1m is located at the center of the spiral structure 1b. A spiral structure 1n is located in the central pipe 1m. The spiral structure 1n consists of multiple layers of blades connected end to end. The spiral structure 1n rotates in a right-hand direction. A partition is provided between the return air duct 1a2 and the air supply duct 1a3. The partition has holes that allow the central pipe 1m to connect with the air supply duct 1a3.

[0046] like Figure 2 As shown, the outer edge of spiral structure one is tangent to the interior of the combustion cylinder, and the outer edge of spiral structure two is tangent to the middle pipe.

[0047] like Figure 1 As shown, the connecting cylinder 1a1 of the combustion cylinder 1a has an inverted cone shape, which is thicker at the top and gradually decreases in diameter at the bottom. Figure 2 As shown, the combustion chamber 1a and the connecting cylinder 1a1 are inverted conical, while the return air duct 1a2 and the supply air duct 1a3 are cylindrical with equal outer diameters.

[0048] The heating device includes a gas pressure regulating device, an air conditioning device 1g, a gas mixer 1h, and a combustion nozzle 1i; the gas pressure regulating device and the air conditioning device 1g are respectively connected to the gas mixer 1h through pipes, the combustion nozzle 1i is connected to the gas mixer 1h, and the combustion nozzle 1i is located in the combustion cylinder 1a.

[0049] like Figure 2 As shown, an exhaust pipe 1j is also provided at the top of the combustion cylinder 1a. One end of the exhaust pipe 1j is connected to the outside, and the other end extends into the combustion cylinder 1a. The exhaust pipe 1j is coaxial with the combustion cylinder 1a. The exhaust pipe 1j extends into the spiral structure 1n.

[0050] A cooling spray device 1k is also provided on one side of the waste bin 1e. The cooling spray device 1k is used to cool the waste in the waste bin 1e. Figure 2 As shown, the cooling spray device 1k, the gas pressure regulating device, and the air conditioning device 1g are integrated into one box. The cooling spray device 1k is connected to the waste bin 1e through a pipeline, and the gas and air pipelines are respectively connected to the gas mixer 1h. The combustion nozzle 1i is located at the bottom center of the combustion cylinder 1a.

[0051] The gas pressure regulator adjusts the gas pressure entering the combustion chamber 1a. In this embodiment, natural gas is used as the gas. The air conditioning device 1g adjusts the air flow rate entering the combustion chamber 1a. After adjustment, the gas and air enter the gas mixer 1h for mixing, and then pass through the combustion nozzle 1i for combustion. By adjusting the gas pressure and air flow rate, a higher calorific value of the fuel combustion can be ensured, while simultaneously regulating the temperature in the combustion chamber 1a. The combustion nozzle 1i heats the air in the combustion chamber 1a. The hot air enters the roasting chamber 3a containing coffee beans through the air supply duct 2. After passing through the roasting chamber 3a, the hot air returns to the combustion chamber 1a through the return air duct 4. The return air carries smoke and silver residue. The return air passes through the spiral structure 1b, which increases the return air path. The heavier silver residue falls downward into the waste bin 1e, while the lighter silver residue and smoke are burned in the combustion chamber 1a. The higher-temperature return air is further heated and sent back to the roasting chamber 3a. The combustion of the lighter silver residue and smoke also generates heat. Excess exhaust gas is discharged from the exhaust pipe 1j at the top of the combustion chamber 1a. The hot air enters the air supply duct through the intermediate duct 1m, the spiral structure 1n, and the air supply duct interface 1c. In this embodiment, according to the temperature set by the program, the gas pressure regulating device and the air conditioning device 1g are controlled by the control system to automatically adjust the temperature in the combustion chamber 1a, that is, to automatically adjust the temperature in the roasting chamber 3a. The airflow exiting the baking chamber 3a returns to the combustion cylinder 1a, and the return air, smoke, and silver residue in the airflow can be reused, saving energy and reducing production costs. The ignition of the regulated mixture of gas and air increases the calorific value of the burner 1. The spiral structure 1b allows for the separation of hot air and impurities in a single step using only one container, resulting in a simple and efficient structure. The combustion cylinder 1a is an inverted cone shape, wider at the top and gradually decreasing in diameter at the bottom. The heating device heats the air in the combustion cylinder 1a, causing the hot air to rise. The inverted cone shape, narrower at the bottom and wider at the top, allows the hot air to quickly enter the wider upper part of the combustion cylinder 1a from the narrower lower part, accelerating the flow of hot air. The combustion cylinder 1a is also wrapped with an insulation layer.

[0052] Example 3 Provides a baking apparatus used in the method described in Embodiment 1, such as... Figure 3 As shown, the system includes a burner 1, an air supply duct 2, a baking device 3, a return air duct 4, a material cart 5, a vacuum feeding device 6, a material cooling device 7, a frame assembly 8, and an electrical control system 9. The burner is the same as described in Example 2. The burner 1, air supply duct 2, baking device 3, and return air duct 4 are connected sequentially, and the outlet of the return air device is also connected to the burner 1 to form a circulation system. Figure 5As shown, a centrifugal fan 4a is installed on the return air duct 4 to provide power for the flow of air in the circulation system; the burner 1 is the burner for hot air circulating coffee roasting described in Example 1.

[0053] like Figure 11 As shown, the roasting apparatus 3 includes a roasting chamber 3a and a stirring device 3b. Coffee beans are placed in the roasting chamber 3a, and the stirring device 3b stirs the coffee beans in the roasting chamber 3a to ensure that the coffee beans are heated evenly. The burner 1 provides hot air, which passes through the air supply duct 2, the roasting chamber 3a, and the return air duct 4, and then returns to the combustion chamber 1a of the burner 1.

[0054] Material cart 5: Material cart 5 is used to store raw coffee beans and has a weighing function.

[0055] Vacuum feeding device 6: The vacuum feeding device 6 is used to transport coffee beans from the material cart 5 to the feeding hopper 6a via vacuum suction, and finally into the roasting chamber 3a. Figure 6 As shown, the vacuum feeding device 6 includes a feeding hopper 6a and a vacuum filtering device 6b, as... Figure 13 As shown, the feeding hopper 6a is installed on the roasting device 3 and connected to the furnace 3a2. The feeding hopper 6a is connected to the material cart 5 through a pipe. The vacuum filtration device 6b creates a vacuum in the feeding hopper 6a, generating the power to suck up the coffee beans from the material cart 5 and drawing impurities from the coffee beans into the filter 6b2 during the feeding process, thus purifying the coffee beans. The feeding hopper 6a is used to temporarily store coffee beans and control the timing of coffee beans entering the roasting chamber 3a. At the same time, it seals the inlet of the roasting chamber 3a to prevent hot air from leaking out of the feeding hopper 6a.

[0056] like Figure 7 As shown, the feeding hopper 6a includes a vacuum port 6a1 for connection to the vacuum filter device 6b, a feeding port 6a2 for connection to the material cart 5, a feeding cylinder 6a3 for storing coffee beans, a discharge mechanism 6a4 located at the bottom of the feeding cylinder 6a3, and a cylinder cover 6a5 for sealing the feeding cylinder 6a3. An observation window 6a6 is also provided at the bottom of the feeding cylinder 6a3 to facilitate observation of the coffee bean content in the feeding cylinder 6a3. In this embodiment, the vacuum port 6a1 is located at the cylinder cover 6a5, and a filter box is provided at the connection between the vacuum port 6a1 and the cylinder cover 6a5. The discharge mechanism 6a4 is controlled by a control system to open at the appropriate time, thereby controlling the timing of coffee beans entering the roasting chamber 3a, while simultaneously sealing the inlet of the roasting chamber 3a to prevent hot air from leaking from the feeding hopper 6a. Figure 17As shown, the vacuum filtration device 6b includes a vacuum pump 6b1 for generating a vacuum, a filter 6b2 for absorbing impurities from coffee beans in the feed hopper 6a, a connecting pipe 6b3 connected to the filter 6b2, and a waste container 6b4 located at the bottom of the filter 6b2. The connecting pipe 6b3 is used to connect to the vacuum port 6a1 of the feed hopper 6a.

[0057] Material cooling device 7: such as Figure 3 As shown, the material cooling device 7 is located at the outlet of the roasting chamber 3a. Its function is to rapidly cool the roasted coffee beans to maintain their flavor. The cooling rate directly affects the quality of the coffee beans; therefore, a high-power centrifugal fan 7b1 is needed to generate cold air and continuously stir the beans to ensure uniform cooling. Figure 8 As shown, the material cooling system includes a cooling and stirring device 7a and an exhaust device 7b. Figure 9 As shown, the cooling and stirring device 7a includes a stirring cylinder 7a1 for receiving roasted coffee beans, a drive unit 7a2, and a stirring rake 7a3 fixed to the output end of the drive unit 7a2. The stirring rake 7a3 is disposed in the stirring cylinder 7a1, and the drive unit 7a2 drives the stirring rake 7a3 to rotate and stir the coffee beans in the stirring cylinder 7a1 to promote heat dissipation. Figure 18 As shown, the exhaust device 7b includes a centrifugal fan 7b1, a filter 7b2, an exhaust duct 7b3, and a support 7b4. The centrifugal fan 7b1 and the filter 7b2 are installed on the exhaust duct 7b3, which is fixed to and connected to the mixing cylinder 7a1 via the support 7b4. The exhaust device 7b quickly removes the heat from the coffee beans during the mixing process and filters out heavier impurities. The filtered hot air is then reintroduced into the combustion chamber 1a, reducing heat loss and lowering equipment energy consumption.

[0058] Rack assembly 8: Baking device 3 is mounted on rack assembly 8.

[0059] Electrical control system 9: Used to collect equipment operating parameters, set baking processes and parameters, control the correct operation of equipment, and store production recipes.

[0060] like Figure 4 As shown, the air supply duct 2 is equipped with a makeup air device 10, such as... Figure 10 As shown, the air supply device 10 includes a drive device 10a, an opening and closing mechanism 10b, and a damper 10c connected in sequence; the damper 10c is located on the air supply duct 2, specifically on the connecting cylinder 4c of the air supply duct 2, as shown. Figure 13 As shown. Drive device 2 10a drives the opening and closing mechanism 10b to rotate. The rotation of the opening and closing mechanism 10b drives the damper 10c to open, allowing cold air from the outside to enter the air supply duct 2, thereby cooling the system.

[0061] like Figure 11 As shown, the baking device 3 includes a baking chamber 3a and a stirring device 3b. The baking chamber 3a includes a shell 3a1 and an oven chamber 3a2 fixed in the shell 3a1. The stirring device 3b includes a rotating shaft 3b1, blades 3b2 and a driving device. The blades 3b2 are mounted on the rotating shaft 3b1, which passes through the oven chamber 3a2. The driving device drives the rotating shaft 3b1 to rotate, and the rotating shaft 3b1 drives the blades 3b2 to rotate in the oven chamber 3a2.

[0062] like Figure 12 As shown, the blade 3b2 includes multiple stirring blades and multiple return blades. The stirring blades are distributed and rotate around the rotating shaft 3b1 as the axis, and the return blades are located in the space enclosed by the stirring blades. A fixed bracket 3b3 is provided on the rotating shaft 3b1, and the stirring blades and the return blades are fixed to the fixed bracket 3b3 respectively.

[0063] like Figure 13 and Figure 14 As shown, the return air duct 4 includes a fixed section 4b and a connecting cylinder 4c that are interconnected. The fixed section 4b passes through the housing 3a1 and is a through hole on the housing 3a1, as shown. Figure 11 and Figure 14 As shown, the fixed section 4b is arranged parallel to the rotating shaft 3b1; a mounting base 3c is also provided on the housing 3a1. The mounting base 3c is a hollow structure 3c1 and communicates with the baking chamber 3a. Figure 15 As shown, the furnace chamber connects to the hollow structure at point 3a3. The hollow structure 3c1 of the mounting base 3c also communicates with the fixed section 4b, so that return air can enter the fixed section 4b from the baking chamber 3a, as shown. Figure 15 As shown, the fixed section connects to the hollow structure at point 4d. (As indicated...) Figure 13 As shown, the feeding hopper 6a is also fixed on the mounting base 3c, and a feeding hopper communication point 3c2 is opened on the mounting base. Figure 15 As shown, one end of the fixed section 4b is connected to the hollow part of the mounting base 3c, and the other end of the fixed section 4b is the outlet located on the housing 3a1. The centrifugal fan 4a of the return air duct 4 is installed at the outlet 3a4 of the fixed section, and the centrifugal fan 4a is fixed to the housing 3a1. In this embodiment, the baking device 3 has the mounting base 3c sealed by the unloading mechanism 6a4 of the feeding hopper 6a. A discharge port is opened at one end of the furnace 3a2, and the material cooling device 7 is placed at the discharge port of the furnace 3a2. During baking, the discharge port is sealed by the discharge device 11. Figure 16As shown, the discharge device 11 includes two fixed baffles 11a, a movable baffle 11b between the two fixed baffles 11a, and a drive mechanism 11c connected to the movable baffle 11b. The drive mechanism 11c drives the movable baffle 11b to open or seal the discharge port. An observation window 11d is also provided on the movable baffle 11b. The drive mechanism 11c includes a cylinder and a rotating mechanism. The rotating mechanism includes a connecting rod and a movable shaft. The movable shaft passes through the two fixed baffles 11a in sequence. The movable baffle 11b and the movable shaft are fixedly located between the two fixed baffles 11a. The cylinder drives the connecting rod to rotate the movable shaft.

[0064] The roasting process is as follows: The vacuum filter 6b provides negative pressure, causing the feeding hopper 6a to draw coffee beans from the material cart 5. The unloading mechanism 6a4 opens, and the coffee beans enter the roasting chamber 3a. The combustion nozzle 1i of the heating device is located in the combustion cylinder 1a. The combustion nozzle 1i ignites and heats the air in the combustion cylinder 1a. The hot air enters the air supply duct 2 through the combustion cylinder 1a. The power for the circulation of the hot air is generated by the centrifugal fan 4a on the return air duct 4, creating negative pressure in the roasting chamber 3a. The hot air enters the roasting chamber 3a to roast the coffee beans. The stirring device 3b rotates to stir the coffee beans, ensuring even heating. The roasting temperature in the roasting chamber 3a is regulated by the gas pressure regulator and air conditioning device 1g in the heating device, and the temperature can be raised rapidly. Under the negative pressure of centrifugal fan 4a, the return air from baking chamber 3a re-enters combustion chamber 1a via return air duct 4. The return air enters from the top of combustion chamber 1a, carrying silver scale-like impurities and smoke. The spiral structure 1b extends the path of the return air within combustion chamber 1a. Heavier impurities fall into waste bin 1e below combustion chamber 1a, while lighter impurities and smoke are burned out in combustion chamber 1a. The return air, now at a certain temperature, is reheated to the system's specified temperature within combustion chamber 1a and then re-enters baking chamber 3a via air supply duct 2. The residual temperature of the return air, the combustion of impurities and flue gas are utilized by the system, saving energy and increasing the calorific value of burner 1. Waste bin 1e is connected to cooling spray device 1k, which cools the impurities in waste bin 1e. The combustion chamber 1a, roasting chamber 3a, air supply duct 2, and return air duct 4 are all wrapped with an insulation layer. The stirring device 3b uses a shaft rotation to drive the blades 3b2 for stirring. The roasting chamber 3a has good sealing performance at both ends. The air supply duct 2 and return air duct 4 are tightly connected to the roasting chamber 3a. During the roasting process, the connection between the feeding hopper 6a and the roasting chamber 3a, and the connection between the discharging device 11 and the roasting chamber 3a, have good sealing, resulting in minimal hot air loss from the system. After roasting, the discharging device 11 is opened, and the coffee beans enter the material cooling device 7 for cooling. The heat generated during the cooling process is reintroduced into the combustion chamber 1a through the exhaust device 7b. The thermal efficiency of the burner 1 of this invention is as high as 85% or more. When it is necessary to stop the machine, the damper 10c of the air supply device 10 is opened, allowing outside air to enter the system and cool it down.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the present invention.

Claims

1. A circulating roasting method for coffee beans, using a hot air roasting device to roast coffee beans, the hot air roasting device comprising a burner, an air supply duct, a roasting device, and a return air duct, wherein the burner comprises a combustion cylinder and a heating device, and the roasting device comprises a roasting chamber; the heating device is disposed at the bottom of the combustion cylinder, and the air supply duct is located at the upper part of the combustion cylinder; characterized in that, The return air from the baking chamber enters directly from the top of the combustion chamber. The return air duct interface is located at the top of the combustion chamber and below the air supply duct interface. A spiral structure is used at the corresponding position of the return air duct interface in the combustion chamber to lengthen the return air path. As the return air passes through the spiral structure, some impurities and smoke in the return air are burned off in the high-temperature combustion chamber. The unburned impurities fall downwards under the action of gravity, thus achieving the separation of impurities and hot air in the return air.

2. The coffee bean circulating roasting method according to claim 1, characterized in that, The end of the combustion cylinder equipped with the heating device is an inverted cone shape with a diameter that gradually increases from bottom to top. The heating device heats the air in the combustion cylinder. The inverted cone structure allows the hot air to enter the thicker upper part of the combustion cylinder from the narrower lower part, thus accelerating the entry of the hot air into the air supply duct.

3. The coffee bean circulating roasting method according to claim 1, characterized in that, The outer edge of the spiral structure is tangent to the inner wall of the combustion chamber; a central pipe is set at the center of the spiral structure to connect with the air supply pipe interface, so that the reheated return air returns to the air supply pipe through the central pipe under the action of negative pressure.

4. The coffee bean circulating roasting method according to claim 3, characterized in that, A spiral structure is installed in the central duct to accelerate the entry of air into the air supply duct.

5. The coffee bean circulating roasting method according to claim 4, characterized in that, The combustion chamber is divided into three parts, from bottom to top: a connecting cylinder, a return air duct, and an air supply duct. The heating device is located at the bottom of the connecting cylinder. The first spiral structure and the second spiral structure are located in the return air duct, and the return air duct interface is located on the return air duct. The air supply duct interface is located on the air supply duct. A partition is installed between the return air duct and the air supply duct to isolate the air supply duct from the return air duct and the connecting cylinder, so that the hot air in the connecting cylinder enters the air supply duct through the central duct and the air supply duct under negative pressure.

6. The coffee bean circulating roasting method according to claim 5, characterized in that, The first spiral structure is left-handed, causing the return air to flow downwards; the second spiral structure is right-handed, causing the hot air to flow upwards.

7. The coffee bean circulating roasting method according to claim 1, characterized in that, A waste bin is also provided at the bottom of the combustion cylinder, and the waste bin is connected to the bottom of the combustion cylinder to collect the falling impurities.

8. The coffee bean cyclic roasting method according to claim 7, characterized in that, A cooling spray device is installed to cool the impurities in the waste bin.

9. The coffee bean circulating roasting method according to claim 1, characterized in that, The roasting apparatus includes a furnace and a stirring device. The furnace is fixed, and the stirring device is movably connected to both ends of the furnace via a shaft. During roasting, the furnace does not rotate, while the stirring device rotates to stir the coffee beans.

10. A method for cyclically roasting coffee beans according to claim 9, characterized in that, An air damper is installed on the air supply duct. During baking, the damper is closed; after shutdown, the damper is opened to allow cold outside air to enter the circulation system to cool it.

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