Method for producing soft pellet, method for producing dried coffee residue, and soft pellet

Abstract

To provide a method for producing a soft pellet which is contributive to expand recycling application of a coffee residue.SOLUTION: A method for producing a soft pellet using a coffee residue includes: a preparation step (S10) of preparing a coffee residue; and a granulation step (S20) of extrusion granulating the coffee residue by an extrusion granulating device and obtaining at least one soft pellet.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing soft pellets, a method for producing dried coffee grounds, and soft pellets. [Background technology]

[0002] The Sustainable Development Goals (SDGs) adopted by the United Nations include waste management and reduction as a goal under Goal 12, "Responsible Consumption and Production." Summary of the Invention [Problem to be solved by the invention]

[0003] Coffee is enjoyed by so many people that it is considered one of the world's three most popular beverages, and effectively reusing coffee grounds after brewing coffee has great social significance, including contributing to the SDGs mentioned above.

[0004] An object of the present disclosure is to provide a method for producing soft pellets, a method for producing dried coffee grounds, and soft pellets that contribute to expanding the reuse applications of coffee grounds. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems, a method for producing soft pellets according to one embodiment of the present disclosure includes a preparation step of preparing coffee grounds, and a granulation step of extruding and granulating the coffee grounds using an extrusion granulation device to obtain at least one soft pellet.

[0006] In order to solve the above-described problems, a method for producing dried coffee grounds using coffee grounds according to one embodiment of the present disclosure includes a preparation step of preparing coffee grounds, a granulation step of extruding and granulating the coffee grounds using an extrusion granulator to obtain at least one soft pellet, and a drying step of drying the soft pellets obtained by the granulation step to a predetermined moisture content to obtain dried coffee grounds.

[0007] In order to solve the above-mentioned problems, soft pellets according to one embodiment of the present disclosure are obtained by extrusion granulating coffee grounds using an extrusion granulating device. [Effects of the Invention]

[0008] According to one aspect of the present disclosure, it is possible to provide a method for manufacturing soft pellets, dried coffee grounds, and soft pellets that contribute to expanding the reuse applications of coffee grounds. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating a series of processes for making coffee grounds suitable for reuse. [Figure 2] FIG. 1 is a schematic cross-sectional view of a granulator according to the present disclosure. [Figure 3] FIG. 1 is a schematic cross-sectional view of a fluidized bed dryer according to the present disclosure. [Figure 4] 1 is a table showing an example of particle size distribution when dried coffee grounds are ground after a drying process. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to FIG.

[0011] [Coffee grounds] Coffee grounds are the wet coffee grounds and caffeine-containing residues that remain after brewing coffee. Coffee grounds are a by-product of the coffee extraction process. Because coffee grounds are typically discarded, effectively reusing them can contribute to waste management and reduction. Coffee grounds have traditionally been partially reused. However, they have typically been used as compost or in deodorizers, where the coffee grounds are used as is.

[0012] [Uses of coffee grounds] Against this background, the inventors of the present application discovered that by processing coffee grounds to make them easier to dry, they can be reused for a wider range of applications. If coffee grounds can be processed to make them easier to dry, coffee grounds can be reused for applications that were not previously envisioned.

[0013] Below, we will explain the method for producing soft pellets using coffee grounds according to the present disclosure, which enables coffee grounds to be reused for such a wide range of applications.

[0014] 〔overview〕 First, a series of processes according to the present disclosure will be outlined with reference to Fig. 1. Fig. 1 is a diagram for explaining a series of processes for coffee grounds suitable for reuse. The diagram indicated by reference numeral 100 in Fig. 1 shows an example of equipment for producing dried coffee grounds from coffee grounds via soft pellets. The diagram indicated by reference numeral 110 in Fig. 1 shows an example of a flowchart for producing dried coffee grounds from coffee grounds via soft pellets. Details of each process will be described later with reference to Fig. 2 etc.

[0015] First, in the preparation step (S10), coffee grounds are prepared. The coffee grounds are coffee grounds remaining in a coffee filter, and can be prepared in various states, such as in the shape of a coffee filter (cone shape) or in a state where the original cone shape has been broken. Typically, the moisture content of coffee grounds is 50% or more.

[0016] Next, in the granulation step (S20), the prepared coffee grounds are extruded and granulated in a granulator 20 to obtain at least one soft pellet. Here, the soft pellet refers to the coffee grounds after being processed in the granulator 20 and removed from the granulator 20. At this time, the soft pellet has a moisture content similar to that of the coffee grounds before being fed into the granulator 20.

[0017] Typically, granulators use a granulation promoter such as a binder to aggregate the raw materials and form them into the desired shape. In the process of the present disclosure, the granulator 20 does not use a binder, but instead pelletizes the coffee grounds using the binding force of the moisture contained in the coffee grounds. The soft pellets of the present disclosure are preferably hard enough that they can be easily broken by hand.

[0018] Next, steps S30 and S40 will be described. Steps S30 and S40 correspond to the method for producing dried coffee grounds.

[0019] In the drying step (S30), the soft pellets granulated in the granulation step are dried in a fluidized bed dryer 30 to a predetermined moisture content to obtain dried coffee grounds. The predetermined moisture content may be determined depending on the intended use of the coffee grounds, and as an example, but not limited to, 2 to 5% when the coffee grounds are to be used for furniture or boards. The fluidized bed dryer 30 may also be another dryer, such as a tray dryer.

[0020] Finally, in the grinding step (S40), the dried coffee grounds obtained in the drying step are ground to a predetermined standard by a grinder 40. The predetermined standard may be determined depending on the intended use of the coffee grounds. As an example, but not limited to, when the coffee grounds are used for furniture or boards, the particle size of the ground coffee grounds after grinding may be set to 5% or less of particles equal to or larger than 500 μm. The grinder 40 may be a grinder such as an impact mill.

[0021] The series of processes according to the present disclosure have been described above. Each step (S20 to S40) will now be described in detail.

[0022] [Granulation process] In the granulation step, the prepared coffee grounds are extruded and granulated using an extrusion granulator to obtain soft pellets. As an example of an extrusion granulator according to the present disclosure, a granulator 20 will be described with reference to Figure 2. Figure 2 is a schematic cross-sectional view of the granulator 20 according to the present disclosure.

[0023] The granulator 20 includes a screw 21 that sends coffee grounds introduced into the granulator 20 forward (toward a die 24, described below) via a hopper (not shown), and a screw case 22 that holds the raw material (coffee grounds). The screw 21 causes the raw material (coffee grounds) to reach an extrusion blade 23. The granulator 20 also includes a die 24 with multiple holes, and a die holder 25 that supports the die 24. The extrusion blade 23 pressurizes the coffee grounds in the direction of the die 24, causing the coffee grounds to pass through the multiple holes in the die 24 to the outside of the granulator 20. The coffee grounds that have been extruded and granulated and passed through the multiple holes in the die 24 are extracted as soft pellets.

[0024] Although a known granulator may be used as the granulator 20, extrusion granulation is preferred because it is easy to obtain soft pellets of the desired particle size and to control the particle size. The granulator 20 may be, for example, a front extrusion type, a dome extrusion type, a side extrusion type, or a vacuum extrusion type, but a front extrusion type or a dome extrusion type is preferred to reduce the effect of moisture contained in the coffee grounds. As an example, the granulator 20 may be an EXDF type granulator manufactured by Dalton Co., Ltd.

[0025] Granulation conditions can be set appropriately. For example, the die 24 may have an extrusion hole diameter of 3 mm to 10 mm. The screw 21 may rotate at a rotation speed of, for example, 60 rpm to 100 rpm.

[0026] The extrusion granulation device according to the present disclosure may be an extruder. Generally, an extruder has an internal screw, mixes raw materials, and extrudes the raw materials after subjecting them to processes such as heating and / or pressurization, thereby shaping the raw materials. The extruder may be either a single-screw or twin-screw type.

[0027] [Drying process] In the drying step, the soft pellets granulated in the granulation step are dried to a predetermined moisture content. For example, a known dryer may be used in the drying step. An example of such a dryer will be described with reference to FIG. 3. FIG. 3 is a schematic cross-sectional view of a fluidized bed dryer 30 according to the present disclosure.

[0028] The fluidized bed dryer 30 shown in Fig. 3 is a continuous fluidized bed dryer. A known technology (device) may be used for the dryer. As an example, the fluidized bed dryer 30 may be a DFA type fluidized bed dryer manufactured by Dalton Co., Ltd.

[0029] The fluidized bed dryer 30 is a device that fluidizes and dries soft pellets by blowing hot air or drying air into the dryer from the bottom, thereby obtaining dried coffee grounds. The fluidized bed dryer 30 has a main body 31, a blower 32, a heat exchanger 33, branch pipes 34, an exhaust fan 35, a cooling blower 36, a material inlet 37, a material outlet 38, and a fluidizing plate 39. The fluidizing plate 39 has many holes.

[0030] The main body 31 defines the outer shape of the fluidized bed dryer 30, and the interior where the drying air flows in is divided into multiple rooms. In the example of FIG. 3, the lower part of the main body 31 is divided into five rooms R1 to R5. A blower 32, a heat exchanger 33, and two branch pipes 34 are connected to R1 and R2. An exhaust fan 35 is provided above (on the exhaust side of) R1 and R2. The same configuration applies to R3 and R4.

[0031] The blower 32 is provided below (on the intake side of) R1 and R2 and sends air outside the main body 31 to R1 and R2. The air sent to R1 and R2 is sucked in by the exhaust fan 35 and exhausted from the exhaust fan 35 to the outside of the main body 31.

[0032] The heat exchanger 33 warms the air sent from the blower 32. The air heated by the heat exchanger 33 is then sent to two branch pipes 34 connected to R1 and R2, respectively. The temperature of the air sent to the branch pipes 34 is set to, for example, 60°C to 120°C.

[0033] The air sent to the branch pipe 34 is then supplied to the inside of R1 and R2, passes through the fluidization plate 39, passes between the soft pellets being transported in the direction from the material inlet 37 to the material outlet 38, and is exhausted from the exhaust fan 35.

[0034] The above explanation may be similarly applied to R3, R4, and the blower 32 disposed below R3 and R4, and therefore the explanation thereof will be omitted.

[0035] R5 is located between R4 and the material outlet 38. A cooling fan 36 is provided below R5. No heat exchanger 33 is provided between the cooling fan 36 and R5. Therefore, the air taken in from the cooling fan 36 is supplied to R5 without being heated, passes through the fluidization plate 39, passes between the soft pellets being transported to the material outlet 38, and is exhausted from the exhaust fan 35.

[0036] The soft pellets are supplied into the main body 31 from the material inlet 37 and are transported by overflow from the material inlet 37 toward the material outlet 38, during which time they dry and become dried coffee grounds. The dried coffee grounds are then discharged from the material outlet 38 to the outside of the main body 31. It takes, for example, 30 to 40 minutes for the soft pellets to become dried coffee grounds and be discharged from the material outlet 38 to the outside of the main body 31. In this way, while passing from the material inlet 37 to the material outlet 38, the soft pellets are exposed to drying air warmed by the heat exchanger 33, causing a decrease in moisture content and turning into dried coffee grounds.

[0037] As mentioned above, coffee grounds usually have a moisture content of 50% or more. These coffee grounds are transformed into dried coffee grounds with a desired moisture content depending on the intended use, depending on the time spent passing through the fluidized bed dryer 30, the temperature at which the external air is heated by the heat exchanger 33, etc. Therefore, dried coffee grounds are not limited to a specific moisture content value (or range).

[0038] The soft pellets become hot as they pass from material inlet 37 to material outlet 38, becoming dried coffee grounds, but as they pass through R5, they are exposed to the air that has entered the main body 31 from cooling blower 36 and the temperature drops. The cooled dried coffee grounds are then carried out to the outside of main body 31 through material outlet 38.

[0039] The fluidized bed dryer 30 is a device that utilizes the excellent mixing, gas contact, and heat transfer properties of a fluidized bed for drying. As a result, the fluidized bed dryer 30 quickly transfers heat between the drying air and the soft pellets. This allows the fluidized bed dryer 30 to reduce uneven drying of the soft pellets (and thus the dried coffee grounds) and enable stable mass processing.

[0040] [Crushing process] In the grinding process, the dried coffee grounds obtained in the drying process are ground to a predetermined standard. For example, a known grinder may be used for the grinding process. One example is the "IM-150(G)" manufactured by Dalton Co., Ltd.

[0041] The grinder finely grinds the material (dried coffee grounds) by impact and friction between fixed pins and high-speed rotating pins. More specifically, the dried coffee grounds are fed into the material inlet and are subjected to impact and friction between the rotating grinding pins rotating at high speed and the fixed grinding pins, causing them to be finely ground.

[0042] In the crusher, the crushed product is discharged without retention, so it is less susceptible to the effects of heat.

[0043] An example of particle size distribution will be explained using Figure 4. Figure 4 is a table showing an example of particle size distribution when dried coffee grounds after the drying process are ground using a grinder manufactured by Dalton Co., Ltd. ("IM-150(G)"). The upper part of the table shows the particle size distribution of the dried coffee grounds before the grinding process, and the lower part of the table shows the particle size distribution of the dried coffee grounds after the grinding process. The grinder's high-speed rotating pin is set to a rotation speed of 14,000 rpm. The dried coffee grounds are adjusted to have a moisture content of 3 to 4%.

[0044] As shown in Figure 4, before the grinding process, the particle size of the dried coffee grounds was 500 μm or larger, accounting for 32.1% (= 4.4 + 13.5 + 14.2) of the total. In contrast, after the grinding process, the particle size of the dried coffee grounds was significantly reduced to 5.0% of the total. By appropriately adjusting the rotation speed of the high-speed rotating pins of the grinder, the dried coffee grounds can be ground into finer or coarser particles.

[0045] The granulation process, drying process, and grinding process according to the present disclosure have been described above. In this series of processes, coffee grounds are first extruded and granulated using a granulator 20 (extrusion granulation device) to produce soft pellets. After undergoing this granulation process, the coffee grounds are processed into dried coffee grounds in the subsequent drying process. Next, the coffee grounds are subjected to a drying process in which the coffee grounds are dried. In this drying process, the residence time of the dried coffee grounds in the fluidized bed dryer 30 (dryer) can be appropriately adjusted to dry the dried coffee grounds to a predetermined moisture content. The dried coffee grounds are then subjected to a grinding process in a dried state obtained in the drying process. In this grinding process, the dried coffee grounds can be ground to a predetermined standard by appropriately adjusting the rotation speed of the high-speed rotating pins of the grinder.

[0046] According to the above configuration, coffee grounds containing a large amount of moisture can be processed into a state that is easy to dry, and the dried coffee grounds can be crushed to a desired standard in the crushing process. As a result, coffee grounds can be reused in applications that were previously unimaginable. Examples of such applications include the aforementioned applications such as furniture and board materials, and as a substitute for resin materials.

[0047] The dried coffee grounds obtained in this way can be treated as recycled material, which contributes to the promotion of waste management and reduction as part of Goal 12 of the United Nations Sustainable Development Goals (SDGs), which is "Responsible Consumption and Production."

[0048] [Combination of granulation process and drying process] Next, the significance of combining the granulation step and the drying step will be explained.

[0049] As mentioned above, coffee grounds contain more than 50% water. In order to reuse coffee grounds with such a high water content for various purposes, the coffee grounds must be crushed, and as a first step, the coffee grounds must be dried.

[0050] One possible method is to omit the granulation process according to the present disclosure and subject the coffee grounds to the drying process (fluidized bed dryer) from the beginning. This method increases the drying efficiency by applying high-temperature drying air to the coffee grounds from below.

[0051] However, with this method, there are cases where agglomerates of coffee grounds remain and the interior of the agglomerates does not dry. This is thought to be because agglomerates are formed by the rolling action of the drying air and liquid (water and oil) bridging, which prevents the interior of the agglomerates from drying.

[0052] Therefore, a method of pre-drying the coffee grounds before supplying them to the fluidized bed dryer can be considered. For example, a tray dryer is used to pre-dry the coffee grounds by static drying, and then the soft pellets are supplied to the fluidized bed dryer.

[0053] However, although this method does not produce agglomerates of coffee grounds, the drying efficiency is insufficient because it requires static drying, and the drying process takes a long time, making it difficult to process large amounts of coffee grounds. This means that there is still room for improvement in terms of contributing to the SDGs.

[0054] Therefore, after extensive research, the inventors of the present application discovered a method in which coffee grounds are first fed into an extrusion granulation device and then pressed against a die to granulate them. A person skilled in the art would not normally conceive of a method of making granules from coffee grounds without using a binder paste. Furthermore, because coffee grounds are a coarse material (see the data before the grinding process in Figure 4) and have a high moisture content, a person skilled in the art would not normally conceive of granulating coffee grounds without using a binder.

[0055] The inventors of this application discovered that by first obtaining soft pellets from coffee grounds using an extrusion granulator and then subjecting them to a drying process, the coffee grounds can be thoroughly dried during the drying process, and this method is also effective for processing large quantities of coffee grounds. This method allows the soft pellets to break up during drying, allowing for thorough drying, and can reduce the drying time of the soft pellets by more than 50% compared to the process that includes the aforementioned pre-drying. Furthermore, because the soft pellets break up during drying, there is no need for a crushing process using a crusher after the drying process.

[0056] Furthermore, a person skilled in the art would consider using a grinder to break up the coffee grounds in order to quickly dry a cone-shaped solidified material such as coffee grounds.

[0057] However, the inventors of the present application have confirmed that when coffee grounds are broken down using a crusher, the moisture and oil in the coffee grounds can cause deposits to adhere to the cutters and other parts of the crusher, which can interfere with the crushing operation. This also shows that replacing the coffee grounds granulation process with a crushing process using a crusher makes it difficult to process large amounts of coffee grounds, and that there is still room for improvement from the perspective of "contributing to the SDGs."

[0058] 〔others〕 When reusing coffee grounds, it may be necessary to remove oil from the coffee grounds. In such cases, for example, a degreasing process may be performed before the granulation process or after the grinding process. The degreasing process may employ a solvent washing method using a solvent, an alkaline degreasing method using an alkaline agent, or an acid washing method using an acidic agent.

[0059] (summary) The method for producing soft pellets according to the first aspect of the present disclosure includes a preparation step of preparing coffee grounds, and a granulation step of extruding and granulating the coffee grounds using an extrusion granulator to obtain at least one soft pellet.

[0060] Coffee grounds generally contain more than 50% water. Therefore, if coffee grounds are to be reused for a wide range of purposes, they must be processed to make them easier to dry. However, there is no method of processing coffee grounds to make them easier to dry that also takes into account business profitability.

[0061] The present inventors focused on these problems and, after extensive research, discovered that by extruding and granulating coffee grounds using an extrusion granulator, the resulting lumps of coffee grounds (soft pellets) are more easily dried in the drying process that follows the extrusion granulator. Furthermore, the present inventors also discovered that the resulting soft pellets are more easily pulverized to the desired pulverization conditions in the pulverization process that follows the drying process.

[0062] According to the above configuration, a method for producing soft pellets can be provided that expands the scope for reusing coffee grounds for various purposes.

[0063] A method for producing soft pellets according to a second aspect of the present disclosure is the method according to the first aspect, wherein the extrusion granulation device is a granulator or an extruder.

[0064] By using a granulator or extruder as the extrusion granulation device, soft pellets that are easy to dry to the inside can be produced.

[0065] A method for producing dried coffee grounds according to aspect 3 of the present disclosure includes a preparation step of preparing coffee grounds, a granulation step of extruding and granulating the coffee grounds using an extrusion granulator to obtain at least one soft pellet, and a drying step of drying the soft pellets obtained by the granulation step to a predetermined moisture content to obtain dried coffee grounds.

[0066] According to the above configuration, the obtained dried coffee grounds can be easily ground under desired grinding conditions in the grinding step after the drying step.

[0067] The method for producing dried coffee grounds according to aspect 4 of the present disclosure is the same as that of aspect 3, and further includes a grinding step of grinding the dried coffee grounds obtained in the drying step to a predetermined standard.

[0068] According to the above configuration, it is possible to expand the scope for reusing coffee grounds for various purposes.

[0069] The soft pellets according to the fifth aspect of the present disclosure are obtained by extrusion granulating coffee grounds using an extrusion granulator.

[0070] According to the above-mentioned structure, the obtained soft pellets can be treated as recycled materials, which contributes to the promotion of waste management and reduction as part of Goal 12 of the Sustainable Development Goals (SDGs) adopted by the United Nations, which is "Responsible Consumption and Production."

[0071] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the disclosed technical means are also included in the technical scope of the present disclosure. Furthermore, new technical features can be formed by combining the disclosed technical means. [Explanation of symbols]

[0072] 20 Granulator 21 Screw 22 Screw Case 23 Extrusion blade 24 dice 25 Die holder 30 Fluidized bed dryer 31 Main Unit 32 Blower 33 Heat exchanger 34 Branch pipe 35 Exhaust fan 36 Cooling blower 37 Material input port 38 Material outlet 39 Fluid Plate 40 Crusher S10 Preparation process S20 Granulation process S30 Drying process S40 Crushing Process

Claims

1. A method for producing soft pellets using coffee grounds, a preparation step of preparing coffee grounds; and a granulation step of extruding and granulating the coffee grounds using an extrusion granulator to obtain at least one soft pellet.

2. The method for producing soft pellets according to claim 1 , wherein the extrusion granulation device is a granulator or an extruder.

3. A method for producing dried coffee grounds using coffee grounds, a preparation step of preparing coffee grounds; a granulation step of extruding and granulating the coffee grounds using an extrusion granulator to obtain at least one soft pellet; a drying step of drying the soft pellets obtained in the granulation step to a predetermined moisture content to obtain dried coffee grounds.

4. 4. The method for producing dried coffee grounds according to claim 3, further comprising a grinding step of grinding the dried coffee grounds obtained in the drying step to a predetermined standard.

5. Soft pellets made by extruding and granulating coffee grounds using an extrusion granulator.

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