Pellet manufacturing device and pellet manufacturing method

Abstract

To provide a pellet manufacturing device which manufactures a pellet usable as fuel using a raw material containing coffee extraction residue.SOLUTION: A pellet manufacturing device includes: a plurality of rollers 2 which has prescribed widths and is arranged in a circular shape around a driving main shaft, the rollers rotating while revolving with the driving main shaft 1 as an axis; a pellet manufacturing die 3 which has a raw material push-in surface 3a abutting on the rollers; and a motor for driving the rollers. The pellet manufacturing die has a plurality of through holes each of which has a prescribed cross sectional area S and a prescribed depth L and which penetrates in a direction orthogonal to the raw material push-in surface. The rollers roll on the raw material push-in surface, push the raw materials accumulated on the raw material push-in surface into the through holes, and mold a pellet. The pellet manufacturing device further includes a guide plate 5 which horizontally rotates with the driving main shaft as an axis and moves the raw materials on the raw material push-in surface to the driving main shaft side. The guide plate extends from the driving main shat side toward an outer peripheral side, extends across a region having the plurality of through holes in a radial direction, and has the lower end close to the raw material push-in surface.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention mainly relates to a pellet manufacturing apparatus and a method for manufacturing pellets, which use coffee extraction residues (coffee grounds) with a high water content after extraction as raw materials.

Background Art

[0002] In recent years, the consumption of coffee beverages has increased significantly as a favorite beverage, and accordingly, the consumption of coffee beans has also been increasing. Therefore, a large amount of coffee extraction residues (coffee extraction sludge obtained by extracting roasted and ground coffee beans with hot water for drinking coffee) is generated.

[0003] However, only a small part of it is effectively utilized, and most of it is currently discarded as general waste or industrial waste and incinerated.

[0004] Therefore, paying attention to such coffee extraction residues, a method for manufacturing fuel pellets using coffee extraction residues has been proposed (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Even the inventor of the present application considered manufacturing fuel pellets using coffee extraction residues and conducted intensive research in consideration of environmental concerns. Initially, an attempt was made to pelletize coffee extraction residues using a conventional pellet manufacturing apparatus, but unlike conventional biomass materials such as wood materials, pellets with sufficient durability values were not completed.

[0007] Therefore, after years of research, when attempting to manufacture pellets using coffee extraction residues, it was found that the cross-sectional area and depth of the die holes in the pellet manufacturing apparatus greatly affect the durability value. Furthermore, it was found that the durability of the pellets can be improved by controlling the rotational speed of the roller pressing the die and the temperature of the die, and thus the present invention was made.

[0008] On the other hand, from another perspective, when grinding coffee beans, the difference in the size of the ground powder has a great influence on the taste and aroma of the coffee. Therefore, not all the powder will be exactly the same size, and there will be a mixture of small-sized powder, medium-sized powder, large-sized powder, and powders of various sizes.

[0009] When there are various sizes mixed, such as the grinding particle size of coffee, by using the Rosin-Rammler distribution for analysis, the grinding condition of the coffee can be known in more detail and accurately. The Rosin-Rammler distribution is suitable for representing the size distribution (how much of each size is included) when various sizes are mixed.

[0010]

Number

[0011] In the Rosin-Rammler distribution, the particle size characteristic number De refers to the size of the particles among the ground coffee particles where 36.8% of them are larger than that size. It corresponds to the position one standard deviation minus the mean in a normal distribution and is an index commonly used statistically when representing the data distribution. The particle size characteristic number De indicates that 36.8% of the particles in the ground coffee are larger than that specific size. Thus, it is possible to know how many particles are larger than that size and to evaluate the grinding condition based on that size. Note that with a general sieve shaker and sieve, the particle size characteristic number De and the uniformity number n can be calculated.

[0012] In order to use pellets as fuel, the finer the particle size of the coffee extraction residue, the higher the durability. However, if it is too fine, it is likely to bridge during transportation and the dust is likely to fly, which is not desirable. Since the particle size of the coffee extraction residue greatly affects the durability of the pellets, research has been repeated on the particle size characteristic number De that serves as a particle size standard in the Rosin-Rammler distribution described above, and the present invention has been completed.

[0013] The present invention provides a pellet manufacturing apparatus and a manufacturing method that can obtain the required durability and can be used as fuel.

Means for Solving the Problems

[0014] A pellet manufacturing apparatus according to one aspect of the present invention is a pellet manufacturing apparatus that manufactures pellets using a raw material containing coffee extraction residue, and while revolving around a driving main shaft, it rotates around a roller shaft, and is arranged in a circular shape around the driving main shaft. It includes a plurality of rollers with a predetermined width, a die for pellet manufacturing having a raw material pressing surface that abuts against the rollers, and a motor that drives the rollers. The die for pellet manufacturing has a plurality of through holes with a predetermined cross-sectional area S and a predetermined depth L that penetrate in a direction orthogonal to the raw material pressing surface. The rollers roll on the raw material pressing surface of the die for pellet manufacturing at a predetermined rotational speed, and while pressing the rollers against the raw material pressing surface, push the raw material accumulated on the raw material pressing surface into the through holes to form pellets. It further includes a guide plate that horizontally rotates around the driving main shaft and moves the raw material on the raw material pressing surface of the die for pellet manufacturing toward the driving main shaft side. The guide plate extends from the driving main shaft side toward the outer peripheral side, spans the region with the plurality of through holes in the radial direction, and its lower end is close to the raw material pressing surface. ru It is characterized by this.

[0015] By using the manufacturing apparatus with this configuration, when the raw material on the die is carried outward by the rotation of the roller or the like, the raw material can be guided toward the center side by a guide plate that extends to a region with through-holes and guided to the through-holes for forming pellets, and it is possible to manufacture pellets having sufficient durability even in the case of pellets using coffee extraction residues. Further, since the guide plate extends from the driving main shaft side toward the outer peripheral side and spans the region with a plurality of through-holes in the radial direction, the outer coffee residues can be smoothly guided to the through-holes along the guide plate.

[0016] Further, in this manufacturing apparatus, the predetermined cross-sectional area in the through-hole is 7 mm 2 or more and 50 mm 2 or less, and the predetermined depth is 30 mm or more and 100 mm or less. According to this configuration, it is possible to manufacture pellets having sufficient durability using coffee extraction residues.

[0017] Further, this manufacturing apparatus is characterized in that the area S0 through which the roller rotates and passes on the raw material pressing surface, the cross-sectional area S of the through-hole, and the number k satisfy the following formula. (Formula) 0.15 < kS / S0 < 0.5

[0018] According to this configuration, by setting the cross-sectional area and the number of through-holes within this range, that is, by setting the total area of the openings of the through-holes, that is, the opening ratio, with respect to the roller passing area on the die within this range, it is possible to manufacture even more durable pellets. If the opening ratio is too large, the range in which the roller presses the raw material expands, so the force is dispersed and the durability of the formed pellets decreases. Note that if the opening ratio is too small, the pressing force increases, but the production quantity decreases.

[0019] Further, this manufacturing apparatus is characterized in that the cross-section of the through-hole is a circular cross-section, and the diameter of the circular cross-section is 3 mm or more and 8 mm or less. According to this configuration, cylindrical pellets with sufficient durability can be manufactured. Also, unlike angular pellets, since there are no corners, load concentration is less likely to occur, and the durability against external forces is also improved.

[0020] Further, it is desirable that this manufacturing apparatus has a countersink formed on the side of the raw material pressing surface that serves as the inlet portion of the raw material in the through-hole. According to this configuration, the countersink makes it easier for the raw material to be introduced into the through-hole, improving productivity. Also, since the opening area increases due to the countersink, the efficiency of pressing by the roller also increases.

[0021] Further, it is desirable that this manufacturing apparatus has a countersink formed on the surface side opposite to the raw material pressing surface that serves as the outlet portion of the raw material in the through-hole. According to this configuration, when the pellets formed below the die are pushed out, the separation from the die is improved, and productivity is enhanced.

[0022] Further, this manufacturing apparatus is characterized in that the rotational speed of the roller is 70 rpm or more and 120 rpm or less. According to this configuration, by pressing the die with the roller at a rotational speed within this range, it becomes possible to manufacture pellets with even higher durability. The higher the rotational speed of the roller, the more times the raw material is pressed and pushed into the through-hole per unit time, so the durability of the pellets improves. However, if the speed is too high, the raw material cannot be pressed firmly, or the load on the motor increases.

[0023] Further, this manufacturing apparatus is characterized in that the guide plate is in the shape of a long plate that extends from the drive main shaft side toward the outer peripheral side with a predetermined width in the height direction. According to this configuration, since the guide plate has a width in the height direction and is in the shape of a long plate that extends from the drive main shaft side toward the outer peripheral side, it is easy to guide the coffee residue accumulated on the surface to the area with the central through-hole.

[0024] Further, this manufacturing apparatus is characterized in that the guide plate is inclined toward the advancing direction rather than in a direction orthogonal to the advancing direction of rotation.

[0025] According to this configuration, by making the guide plate have the above-described inclined shape, the raw material can be further guided toward the center side, and productivity can be improved.

[0026] Further, this manufacturing apparatus is characterized in that at least the outer peripheral side in the longitudinal direction of the guide plate is curved toward the advancing direction rather than in a direction orthogonal to the advancing direction of rotation.

[0027] According to this configuration, by making the guide plate have the above-described curved shape, the coffee residue carried to the outside can be reliably guided toward the center side, and productivity can be further improved.

[0028] Further, in this manufacturing apparatus, the region of the guide plate having the plurality of through holes is linearly configured from the drive main shaft side, and beyond the region having the plurality of through holes, it is curved toward the advancing direction rather than in a direction orthogonal to the advancing direction of rotation. According to this configuration, it is easy to guide the outer coffee residue to the region of the raw material pressing surface having the through holes.

[0029] Further, this manufacturing apparatus is characterized in that the lower end portion of the guide plate is close to the raw material pressing surface and has a notch in a portion passing through the region of the raw material pressing surface having the through holes. According to this configuration, due to the notch of the guide plate, the guide plate can guide the raw material to the region where the through holes are arranged.

[0030] Further, this manufacturing apparatus further includes a cooling means using a liquid for cooling the die for pellet manufacturing. According to this configuration, by manufacturing the pellets while cooling the die for pellet manufacturing by the cooling means, the die for pellet manufacturing whose temperature rises due to friction or the like can be cooled and maintained at a predetermined temperature. Thereby, pellets with high durability can be manufactured.

[0031] Here, the cooling means using a liquid includes, for example, water cooling and oil cooling, etc. From the viewpoints of safety and cost, etc., it is desirable that the cooling means is water cooling. In addition to the above, there is also air cooling, etc. for the cooling means. However, since the temperature rise of the die is large during pellet production, it is desirable to cool the die by the cooling means using a liquid.

[0032] Moreover, as the water cooling means, for example, a water cooling jacket provided so as to cover the outer periphery, inner periphery, and lower surface of the die for pellet production and through which a liquid can pass, a configuration in which a pipe through which a liquid can pass is attached by crawling on the pellet production die, a method of providing a passage through which a liquid can pass inside the pellet production die, etc. can be considered.

[0033] Further, this manufacturing apparatus includes a peripheral wall surrounding the periphery of the pellet production die and the roller. According to this configuration, it is possible to prevent the raw material from scattering to the outside. Note that the peripheral wall surrounding the periphery of the pellet production die and the roller includes a peripheral wall surrounding a part of the pellet production die and a part of the roller. Also, in order to prevent the raw material from scattering to the outside, it is sufficient that at least the upper and lower portions near the die surface of the pellet production die are surrounded.

[0034] A method for manufacturing a pellet according to one aspect of the present invention is a method for manufacturing a pellet by using the above-described pellet manufacturing apparatus to manufacture a pellet using a raw material containing coffee extraction residue. The roller is rolled on the raw material pressing surface of the pellet production die, and while the raw material accumulated on the raw material pressing surface is pressed against the raw material pressing surface by the roller, it is pushed into a plurality of through holes of the pellet production die to form a pellet. The raw material is characterized in that the particle size characteristic number De in the Rosin-Rammler distribution is 0.4 or more and less than 1.51.

[0035] By setting the particle size characteristic number De of the raw material in the Rosin-Rammler distribution to a particle size of 0.4 or more and less than 1.51, pellets with sufficient durability and usable as fuel can be produced. The reason for setting the above range is that the finer the particles, the higher the durability, but on the other hand, if it is too fine, there is a high possibility that the through-holes of the die will be clogged and the pellets cannot be extruded.

[0036] Moreover, in this method for manufacturing pellets, it is more preferable that the raw material has a particle size characteristic number De in the Rosin-Rammler distribution of 0.4 or more and 1.2 or less, and it is even more desirable that the particle size characteristic number De in the Rosin-Rammler distribution is 0.4 or more and less than 0.7. In this way, the durability of the pellets can be further improved.

[0037] In addition, this method for manufacturing pellets is characterized in that the moisture content of the raw material is 5% or more and less than 20%. Here, the moisture content is the target value after adjusting the raw material. Thereby, sufficient durability of the manufactured pellets is ensured. The reason for setting the moisture content in the above range is that if it is less than 5%, there is a risk that the extruded raw material may not solidify or may clog the through-holes of the die, and if it is 20% or more, there is a risk that the extruded raw material may not solidify. Moreover, it is more desirable that the moisture content of the raw material is 5% or more and 14% or less. By setting the moisture content in the above range, pellets with high durability can be manufactured.

[0038] In addition, this method for manufacturing pellets is characterized in that the moisture content of the pellets is 4% or more and 12% or less. Thereby, sufficient durability of the manufactured pellets can be ensured, and since the risk of mold generation increases when the moisture content of the pellets exceeds 12%, this range is suitable. Moreover, it is more desirable that the moisture content of the pellets is 10% or less.

[0039]

[0040] ​Further, the method for manufacturing the pellet is characterized by comprising a step of fermenting the coffee extraction residue. According to this configuration, by passing through the step of fermenting the coffee extraction residue, it is possible to increase the strength of the formed pellet. The method of fermentation is that the extracted coffee extraction residue is left for one day or several days to ferment. And after being fermented to a certain extent, the coffee extraction residue is dried to be used as a raw material. Note that it may be fermented by adding water to the dried coffee extraction residue.

[0041] Further, the method for manufacturing the pellet is characterized in that the raw material is the coffee extraction residue or a mixture of the coffee extraction residue and a woody material. From this configuration, the coffee extraction residue can be effectively utilized without being discarded, and pellets with sufficient durability can be manufactured.

[0042] Further, the method for manufacturing the pellet is characterized in that the die for pellet manufacturing has a cooling means for cooling the die, and the pellet is manufactured while the die for pellet manufacturing is maintained at a temperature of 80°C or lower by the cooling means.

[0043] As a result of the inventors' experimental research on pellet manufacturing, it was found that when the temperature of the die is higher than 80°C, there is no problem in the case of wood pellets, but when the coffee extraction residue is used as a raw material, the oil content contained in the coffee becomes an inhibitory factor for binding and sufficient binding cannot be obtained, and there is also a risk that the raw material will clog the through holes of the die. By manufacturing while maintaining the die at a temperature of 80°C or lower as in the above configuration, such risks can be suppressed.

[0044] Further, the method for manufacturing the pellet is characterized in that the die for pellet manufacturing has a cooling means for cooling the die, and the pellet is manufactured while the die for pellet manufacturing is maintained at a temperature of 60°C or lower by the cooling means.

[0045] Furthermore, by suppressing the temperature rise of the die by the cooling means and setting the temperature of the die to 60°C or lower, it is possible to manufacture pellets with even higher durability while suppressing the above risks. That is, by setting the temperature to 60°C or lower, the floating and clogging of the oil component of coffee are suppressed, and the manufactured pellets have high durability.

Advantages of the Invention

[0046] The pellet manufacturing apparatus and manufacturing method of the present invention can manufacture pellets with sufficient durability.

Brief Description of the Drawings

[0047]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0048] <1. Structure of pellet manufacturing apparatus> Hereinafter, a pellet manufacturing apparatus according to an embodiment of the present invention will be described. FIG. 1 is a perspective view showing a pellet manufacturing apparatus according to an embodiment of the present invention (excluding the raw material hopper). FIG. 2 is a schematic view showing the configuration of the pellet manufacturing apparatus of the present embodiment. FIG. 3 is a view showing a die for pellet manufacturing of the pellet manufacturing apparatus, (a) is a plan view, and (b) is a side view. FIG. 4 is a partially enlarged view of the pellet manufacturing apparatus, (a) is a partially enlarged view of the die for pellet manufacturing, and (b) is a partially enlarged view of the roller and the die for pellet manufacturing. FIG. 5 is a view showing the relationship between a guide provided in the die for pellet manufacturing of the pellet manufacturing apparatus and the pellet forming holes. FIG. 6 is a cross-sectional view showing a water cooling means of the pellet manufacturing apparatus.

[0049] As shown in FIGS. 1 and 2, the pellet manufacturing apparatus 10 mainly includes a driving main shaft 1 that is rotationally driven, two rollers 2 that revolve with this as a vertical axis while rotating about a roller shaft 2a, and a die 3 for pellet manufacturing disposed below it.

[0050] The driving main shaft 1 is rotationally driven by a motor (not shown), and while the rollers 2 connected to both sides of the roller shaft 2a connected to the driving main shaft 1 rotate, they roll on the raw material pushing surface 3a of the die 3 for pellet manufacturing. Then, the raw material of the pellet is introduced onto the raw material pushing surface 3a from a raw material hopper 8 that introduces the raw material disposed above the driving main shaft. Due to the rotation of the rollers 2, the raw material accumulated on the raw material pushing surface 3a is pushed into a plurality of pellet forming holes 3aa that penetrate in the thickness direction of the die 3 for pellet manufacturing while being pressed against the raw material pushing surface 3a.

[0051] The raw material that has passed through the pellet forming holes 3aa is extruded from the bottom surface of the pellet manufacturing die 3 as elongated cylindrical pellets, and then cut to a predetermined length by a rotary cutter 7 attached to the bottom surface of the pellet manufacturing die 3, and is sequentially stored in the pellet storage section 9B via the shooter 9A. Note that it is also possible to configure the extruded pellets to break and fall under their own weight without providing a cutter, but it is preferable to provide a cutter because it allows pellets of a predetermined length to be formed.

[0052] The pellet manufacturing apparatus 10 is also provided with a cover 4 having a peripheral wall of a predetermined height so as to surround the roller 2 and the pellet manufacturing die 3. This cover 4 prevents the raw material from scattering.

[0053] As shown in FIG. 3 and FIG. 4, the width of the roller 2 is 1 mm. The width of the annular region S is larger than that of the driving main shaft 1. The roller is wider than the previous roller so that the raw material is smoothly pressed onto the pellet forming hole 3aa.

[0054] The roller 2 is shaped like a gear with a series of recessed and protruding parts, and is configured to scrape out the raw material with the recessed parts while pressing the raw material with the protruding parts. The continuous recessed and protruding parts allow the roller 2 to rotate smoothly on the raw material pressing surface 3a of the pellet manufacturing die 3 without slipping.

[0055] The rotation speed of the roller 2 is set to 100 rpm in this embodiment, although the higher the rotation speed, the more times the raw material is pushed in per unit time, and therefore the durability of the formed pellets increases. At this time, the motor is set to 70 Hz. Note that the higher the rotation speed of the roller 2, the better the durability of the formed pellets, but increasing the rotation speed increases the load on the motor, so the rotation speed is preferably 70 rpm or more and 115 rpm or less. Within this range, pellets with sufficient durability can be produced, and the load on the motor can also be reduced.

[0056] As shown in FIGS. 3 and 4, the die 3 for pellet production is configured in a substantially cylindrical shape with a circular plane. And at the position where the roller 2 passes, a plurality of pellet forming holes 3aa are arranged in an annular shape. These pellet forming holes 3aa are through holes with a circular cross-section, penetrate the die 3 for pellet production in the thickness direction, and have countersinks formed on the upper raw material pressing surface 3a side and the lower raw material pressing surface 3b side. Thereby, the raw material is smoothly introduced into the pellet forming holes 3aa, and the separation from the raw material pressing surface 3b is made smooth.

[0057] Further, the pellet forming holes 3aa of the present embodiment have a circular cross-section with a diameter of 5 mm, and the cross-sectional area is about 19.6 mm 2 , and the depth including the countersink is 80 mm. Also, The number of the pellet forming holes 3aa of the present embodiment is 384 arranged in an annular region on the raw material pressing surface 3a of the die 3 for pellet production through which the roller 2 passes.

[0058] Note that the dimensions of the pellet forming holes 3aa are an example, and the diameter of the cross-section may be a diameter such as 4 mm, 6 mm, 7 mm, etc., the depth may be 40 mm, 60 mm, 100 mm, etc., and the shape of the cross-section may also be a shape other than a circle such as a rectangle or an ellipse.

[0059] Also, as shown in FIG. 5, on the raw material pressing surface 3a, a plate-shaped guide 5 is provided to guide the raw material located on the outer side toward the center side, that is, toward the side where the annular region (pellet forming holes 3aa) is located. The guide plate 5 is a curved and elongated long plate shape, is attached to the driving main shaft 1, extends toward the outer periphery of the die 3 for pellet production, and is curved so as to separate in the direction of the rotation progress with respect to the radial direction.

[0060] Further, the curved shape of the guide plate 5 curves and extends from the end on the driving main shaft side toward the outer periphery of the die 3 for pellet production, and is configured to extend in the advancing direction of rotation by a predetermined dimension along the outer periphery of the die 3 for pellet production (the tip side of the guide plate 5). The guide plate 5 is erected such that the lower end of the long plate shape is close to the raw material pressing surface 3a, and a notch 5a is formed in a portion passing through the region where the pellet forming holes 3aa are formed in the raw material pressing surface 3a.

[0061] When this guide plate 5 rotates together with the rotation of the roller 2, the raw material is guided so as to be brought closer to the region where the pellet forming holes 3aa are formed. Without this guide plate 5, the raw material is carried outward by centrifugal force. However, due to the shape of this guide plate 5, the raw material can be surely carried to the region of the pellet forming holes 3aa, thereby improving the productivity of the pellets.

[0062] That is, (i) when the roller 2 passes over the region of the pellet forming holes 3aa, the raw material above the pellet forming holes 3aa becomes uneven, and (ii) the pushing force downward is different between the center side (inner side) and the outer peripheral side (outer side) of the roller 2. It is difficult to use all the pellet forming holes 3aa completely evenly, but all the pellet forming holes 3aa can be used as evenly as possible to improve productivity.

[0063] Note that even with the guide 5, there is still some difference in the production amount between the center side and the outer peripheral side. However, with the guide 5, all the pellet forming holes 3aa including the outer side can be used, so it is possible to significantly improve the production amount.

[0064] Also, since the outer peripheral side portion of the roller 2 moves a long distance during one rotation, the force for pushing the raw material on the outer peripheral side portion is uniformly dispersed over a wide range. On the other hand, since the center side portion of the roller 2 moves only a short distance during one rotation, the force for pushing the raw material on the center side portion is likely to concentrate in a narrow range, and the force is more concentrated here. Therefore, a difference in the pushing force downward occurs between the outer peripheral side portion of the roller 2 and the center side portion of the roller 2, but the influence can also be reduced.

[0065] Further, as shown in FIGS. 1, 2, and 6, a water-cooling jacket 6 for suppressing the temperature rise of the die is provided around the die 3 for pellet production. This water-cooling jacket 6 is composed of a jacket body 6A having a hollow annular shape with a space through which a liquid passes inside, and a water supply pipe 6B for supplying water to the jacket body 6A extends downward, and a drain pipe 6C (not shown) for discharging water extends upward and is connected. Further, the water supply pipe 6B and the drain pipe 6C are connected to a radiator and a circulation pump (not shown), and the water supplied to the jacket body 6A is circulated.

[0066] This water-cooling jacket 6 adjusts the flow of cooling water so that the temperature of the die and the raw material does not rise during pellet molding and does not exceed a certain temperature. In this embodiment, the die temperature is adjusted to be maintained at 60° C. or lower.

[0067] The reason for maintaining the die temperature at 60° C. or lower is that when the roller 2 rotates, the die temperature rises due to friction or the like when the die 3 for pellet production is rotated. If pellets are molded with the die temperature remaining high, the raw material becomes hot, and the durability value of the molded pellets decreases. Therefore, by maintaining the die temperature at 60° C. or lower by the water-cooling jacket 6, the durability value of the molded pellets can be increased.

[0068] <2. Method for manufacturing pellets> When the drive main shaft 1 of the pellet manufacturing apparatus 10 configured in this way rotates, the roller 2 fixed to the drive main shaft 1 revolves around the drive main shaft 1 while rotating around its own roller shaft, and rolls on the raw material pressing surface 3a of the die 3 for pellet production. Then, when the raw material is supplied through the raw material hopper 8, the raw material is put onto the raw material pressing surface 3a of the die 3 for pellet production from the raw material hopper 8.

[0069] At that time, the guide plate 5 attached to the drive main shaft 1 rotates together with the roller 2, so that the raw material is guided to converge in the region where the pellet forming holes 3aa are located, and the raw material is guided to the region of the pellet forming holes 3aa.

[0070] Then, the rotating roller 2 scrapes the accumulated raw material with the groove 2b formed on the outer peripheral surface, and while pressing it against the raw material pressing surface 3a, it is pushed into the pellet forming hole 3aa. The raw material pushed into the pellet forming hole 3aa is formed into an elongated cylindrical rib shape in the pellet forming hole 3aa and is pushed out from the raw material pressing surface 3b side.

[0071] Then, the pellet material connected in a rib shape is cut to an appropriate length by the rotary cutter 7 attached to the raw material pressing surface 3b side, passes through the shooter 9A, and is accommodated in the pellet accommodating portion 9B.

[0072] Regarding the raw material, the recovered coffee extraction residue is fermented over one day to several days, then dried and used as the raw material for pellet production. Note that it may be fermented after adding water to the dried coffee extraction residue. Also, the raw material may be only the coffee extraction residue, or it is also possible to use a raw material in which the coffee extraction residue is used as the main raw material and mixed with a binder such as wood chips or corn starch. The reason for fermenting the coffee extraction residue is that the strength of the formed pellets is improved compared to the raw material dried without going through the fermentation process.

[0073] <3. Conditions of the Pellet Manufacturing Apparatus> In the pellet manufacturing apparatus 10 configured as described above, the durability of the pellets formed using the coffee extraction residue as the raw material is important. This is because if the durability is low and brittle, there is a risk that the pellets will break into pieces during transportation or handling of the pellets and become unusable. Also, the durability of the pellets was measured by the method described later.

[0074] Then, in order to manufacture pellets with sufficient durability using the coffee extraction residue, conditions such as the pellet forming hole 3aa of the manufacturing apparatus are important. Particularly important are the cross-sectional area and depth of the pellet forming hole 3aa.

[0075] As described above, the pellet forming hole 3aa of the present embodiment has a circular cross-section with a diameter of 5 mm, and the cross-sectional area is about 19.6 mm 2 , and the depth including the countersink is 80 mm .

[0076] When the diameter of the cross-section is less than 3 mm, in addition to the fact that the coffee extraction residue as the raw material is difficult to enter, the compression due to the hole diameter is too strong, making it difficult for the pellets to come out of the clogged holes. Also, when the diameter of the cross-section is 8 mm or more, the compression is weak and the pellets become brittle. Further, when the depth of the hole is less than 30 mm, the formed pellets become brittle because the distance that the coffee extraction residue as the raw material passes through the hole is short. When it exceeds 100 mm, the compression of the hole is strong and the formed pellets are difficult to come out of the clogged holes. Therefore, the diameter of the cross-section is preferably 3 mm or more and 8 mm or less, and more preferably 4 mm or more and 7 mm or less.

[0077] Also, the number of pellet forming holes 3aa in the present embodiment is 384, which are arranged in the annular region through which the roller 2 passes. When the cross-sectional area S of the pellet forming hole 3aa, the number k, and the area S0 of the raw material pressing surface 3a through which the roller 2 rotates and passes are considered, the pellet forming holes 3aa are arranged so that 0.15 < kS / S0 < 0.5.

[0078] When this value is 0.5 or more, the force pressed by the roller 2 is dispersed, and the durability of the pellets decreases. Also, when it is 0.15 or less, the number of formed pellets is small and the productivity decreases. In the present embodiment, kS / S0 ≒ 19.7. In this case, the durability value of the pellets is 92.8%. This numerical value is the numerical value of the mechanical durability of the pellets measured by the test described later.

[0079] Also, as shown in the following table, when the hole diameter of the pellet forming hole 3aa is changed to 7 mm, kS / S0 ≒ 38.6, and the durability of the pellets at that time is 74.8. Although 74.8 is a durability that can be used somehow, as described above, it is preferably 80% or more, and more preferably 90% or more.

[0080]

Table 1

[0081] Also, regarding the depth of the pellet forming hole 3aa, that is, the die 3 for pellet production, the durability of the formed pellet increases with greater thickness, but it is not the case that the thicker the better. If it is too thick, more force is required to push downward, and the compression also becomes stronger, so there is a risk that the raw material will not clog the hole.

[0082] Note that for the durability value of the formed pellet, in the durability test described later, at least 70% or more is required, preferably 80% or more, and more preferably 90% or more. In addition to the conditions of the manufacturing apparatus described above, the durability of the pellet is also improved by factors such as the rotation speed of the roller, the particle size and moisture content of the raw material, and the temperature. Hereinafter, the durability test and other preferable conditions will be described.

[0083] <4. Regarding the Durability Test> Subsequently, the relationship between the particle size (particle size characteristic number De) and the mechanical durability of the pellet was investigated. Here, the mechanical durability of the pellet indicates the resistance to breakage of the pellet and is defined by the mass ratio DU (%) of the portion that did not break after applying a certain amount of mechanical impact.

[0084] (Test Method for Mechanical Durability) This test method is a method for determining the anti - pulverization performance of wood pellets against mechanical impact force and is standardized in accordance with the European standard EN15210 - 1 for wood pellets. As a sieve, a metal sieve with a circular aperture diameter (nominal mesh size) of 3.15 mm specified in JIS Z8801 - 2 was used, and as a scale, one that can measure up to 1 kg at most and can measure up to the 0.1 g digit was used.

[0085] (Measuring Instruments) The structure and specifications of the durability tester are as shown in Figure 7. As shown in Fig. 7(a), the rotating box 11 is made of steel, aluminum or acrylic resin with a smooth surface. The protrusions such as rivets and nails are finished with rounded corners as small as possible, or have a structure without gaps so that fine powder does not leak. The dimensions are 300 (length) × 300 (width) × 125 (thickness) mm. Inside, buffer wings 11a (230 × 50 mm) are firmly attached in the diagonal direction, and a sample input door 11b is provided at one location on the side surface.

[0086] In order to rotate the rotating box 11 at a speed of 50 rpm, as shown in Fig. 7(b), the measuring instrument 12 is clamped, and a rotating shaft 13 is attached perpendicular to the wall at the center position of the wall (side surface) of 300 (length) × 300 (width) mm. The durability tester is of a twin type with two rotating boxes 11, enabling two measurements at a time.

[0087] [Table 2]

[0088] From Table 2, it was found that the finer the particle size, the higher the mechanical durability. Note that although the mechanical durability increases as the particle size becomes finer, if it is too fine, it is likely to bridge during transportation and the dust is likely to fly. Also, to make the particle size finer, the production capacity of the crusher decreases and the price increases. From these facts, the particle size characteristic number De, which is a measure of the particle size in the Rosin-Rammler distribution, is preferably 0.60 - 0.65 (mm). Note that a coffee bean grinder was used as the crusher. Next, the relationship between the moisture content and the mechanical durability was investigated.

[0089] [Table 3]

[0090] In Table 3, the test results for the cases of the moisture content target value (moisture content target value) of 11% and 15% of the bio-based raw material showed that the durability was higher when the target value was 15% with a higher value.

[0091] In addition, the results of tests conducted at target values of 15%, 17%, and 19% showed that when comparing the case of 15% with the other cases, the durability was higher for the cases of 17% and 19% with higher target values, but there was no difference between 17% and 19%.

[0092] Therefore, a target value of around 17% is considered good in terms of durability. However, when the compressing force increases, it may also affect the appropriate moisture content.

[0093] Also, considering only durability, the above results are obtained. On the other hand, when there is a lot of moisture, the risk of mold growth increases. Considering the risk of mold, conversely, a lower moisture content is better. As a conclusion, considering these conditions, it was found that it is necessary to manufacture under the condition of a moisture content of 13% or less. Therefore, the moisture content of the bio - raw material is desirably in the range of 9 - 13%.

[0094] On the other hand, it is desirable for the pellet to have a moisture content of 10% or less. This is because if it is too low, it tends to become brittle. Also, if it exceeds 12%, the risk of mold occurrence increases, so it is desirable to set it at 10% or less to ensure a safety factor. To make it 10% or less, it is desirable to make the moisture content of the raw material before molding 13% or less.

[0095] Subsequently, the results of tests on the relationships between the addition of additives (binders), the filling amount (input amount) of bio - raw materials, the rotational speed of rollers, the presence or absence of cooling water, and mechanical durability are shown in Tables 4 to 7.

[0096]

Table 4

[0097] Even when the proportion of the additive was increased, there was little effect on durability. Although adding the additive itself is thought to have an impact, increasing the proportion did not have a significant effect. Coffee is different from the case of forming conventional wood pellets in that the particle shape varies due to being in powder form, there are no binding components such as lignin, and heat is not applied during forming. It is thought that some of these differences are the factors.

[0098] As for the types of additives, starch-based corn starch had somewhat of an effect, and cellulose-based CMC and methocel had a greater effect than corn starch.

[0099] The greater the mechanical durability, the smaller the difference in the presence or absence of the additive tends to be. When the durability exceeds 80%, data was obtained that the durability increases by about 3% at most, and about 1 - 2% near 90% by adding the additive. However, there are demerits such as an increase in cost and a greater risk of mold generation.

[0100] Therefore, although there is a merit that the durability increases when there is an additive, considering the demerits it is considered that the additive may not be necessary.

[0101] And considering the cost, the risk of mold, and that it can be used for combustion even without it, there is no problem without the additive. However, depending on the application, if it is necessary to increase the durability, it is desirable to have an additive.

[0102]

Table 5

[0103] The durability increases when the input amount (filling amount kg / h) is small. This is thought to be because the raw material is held in the die for a long time. As a result, the durability increases as the production volume decreases, but it reaches a saturation state at some point, and it is necessary to consider productivity. Therefore, it is desirable to ensure a minimum filling amount of about 100 kg / h of the bio - raw material.

[0104]

Table 6

[0105] Also, the higher the roller rotation speed (number of rotations), the higher the durability. This is because even if the amount of biofuel pushed in per unit time is the same, the number of pushes increases. 60 Hz is the normal rotation speed, and considering the load on the motor, if it exceeds 80 Hz, the load is considered too large. Therefore, operation at around 70 Hz is practical, and the rotation speed at this time is 100 rpm.

[0106] (Presence or absence of cooling water) Also, the effect of cooling by the water-cooled jacket 6 provided in the pellet manufacturing apparatus 10 was also verified. This test measured the mechanical durability when the temperature of the pellet and the die was high and when it was not (pellet temperature 90°C or lower, die temperature 60°C or higher). Note that the method of raising these temperatures was to overfeed the bran and forcibly raise it by the temperature due to friction, and the temperature of the pellet was measured using a thermometer that could measure the surface temperature. The results are as shown in Table 7. The results are as shown in Table 7.

[0107]

Table 7

[0108] From these results, it was found that, unlike wood pellets, the durability of pellets made from coffee extraction residues decreases as the temperature increases. In the case of wood pellets, lignin, which has the properties of a thermoplastic resin, is included. When heated, it becomes soft, and when cooled, it becomes hard. In short, in the case of wood pellets, they harden when formed at a high temperature, but since coffee does not contain lignin, it is considered that the binding relies on the forces of hydrogen bonds and intermolecular bonds. Since the oil content in coffee floats on the surface of the biomass raw material as the temperature rises, the oil content contained in coffee becomes an inhibitory factor for binding, and it is considered that the durability decreases when the temperature is increased.

[0109] Therefore, it was found that in order to form pellets using coffee extraction residues, it is important to form the die at a low temperature (60°C or lower). Therefore, it is desirable to use the water-cooled jacket 6 provided in the pellet manufacturing apparatus 10 to set the die temperature to a temperature of 60°C or lower.

[0110] <5. Other Embodiments> As described above, the embodiments of the present invention have been described with reference to the drawings, but various additions, changes, or deletions are possible without departing from the spirit of the present invention.

[0111] ·In the above embodiment, coffee extraction residues are used as the raw material, but it is also possible to use a mixture in which such coffee extraction residues are mixed with other biomass materials.

[0112] ·The groove shape of the roller can be, in addition to straight grooves parallel to the axis, inclined grooves inclined with respect to the axis, V-shaped grooves, or dimple-shaped grooves.

[0113] ·In addition to the above-described curved shape, the shape of the guide plate can also be configured to be inclined toward the traveling direction rather than the direction orthogonal to the traveling direction of rotation (see Fig. 8). Although the effect may be lower than that of the curved shape, a certain effect can be expected for the drawing-in of the raw material.

[0114] · Also, in the above embodiment, the water-cooling jacket 6 is configured to cover the outer peripheral side of the die 3 for pellet production. However, the present invention is not limited thereto. For example, a configuration in which a water-cooling jacket is attached to the inner peripheral side, a configuration in which water-cooling jackets are attached to both the outer and inner peripheries, a configuration in which a water-cooling jacket is attached to the lower surface of the die for pellet production, etc. can also be adopted. By doing so, for example, when the diameter of the die for pellet production is large, it is difficult to cool the central side only with the water-cooling jacket on the outer peripheral side, or there is a possibility of temperature unevenness, and this can be eliminated.

Explanation of Signs

[0115] 1 Driving main shaft 2 Roller 2a Roller shaft 2b Groove 3 Die for pellet production 3a Raw material pressing surface 3aa Pellet forming hole 3b Raw material extrusion surface 4 Cover 5 Guide plate 5a Notch 6 Water-cooling jacket 6A Jacket body 6B Water supply pipe 6C Drain pipe 7 Rotary cutter 8 Raw material hopper 9A Shooter 9B Pellet storage section

Claims

1. A pellet manufacturing apparatus for manufacturing pellets using a raw material containing coffee extraction residue, a plurality of rollers having a predetermined width arranged in a circular shape around the drive main shaft, which revolve around the drive main shaft while rotating around the roller shaft, a die for pellet manufacturing having a raw material pressing surface that contacts the rollers, and a motor for driving the rollers, the die for pellet manufacturing has a plurality of through holes with a predetermined cross-sectional area S and a predetermined depth L that penetrate in a direction perpendicular to the raw material pressing surface, the rollers roll on the raw material pressing surface of the die for pellet manufacturing at a predetermined rotational speed, and push the raw material accumulated on the raw material pressing surface into the through holes while pressing the rollers against the raw material pressing surface to form pellets, further comprising a guide plate that horizontally rotates around the drive main shaft and moves the raw material on the raw material pressing surface of the die for pellet manufacturing toward the drive main shaft side, the guide plate extends from the drive main shaft side toward the outer peripheral side, spans the region with the plurality of through holes in the radial direction, and its lower end is close to the raw material pressing surface, characterized in that it is a pellet manufacturing apparatus.

2. The through holes, The predetermined cross-sectional area is 7 mm 2 or more and 50 mm 2 or less, and are characterized in that the predetermined depth is 30 mm or more and 100 mm or less, The pellet manufacturing apparatus according to claim 1.

3. The area S through which the roller rotates and passes on the raw material pressing surface 0 and the cross-sectional area of the through-hole S and the number k satisfy the following formula, The pellet manufacturing apparatus according to claim 2. (Formula 1) 0.15 < kS / S 0 < 0.5

4. The cross-section of the through hole is a circular cross-section, the diameter R of the circular cross-section is 3 mm or more and 8 mm or less, The pellet manufacturing apparatus according to claim 2.

5. The rotational speed of the rollers is 70 rpm or more and 120 rpm or less, The pellet manufacturing apparatus according to claim 2.

6. The guide plate, is characterized in that it is a long plate shape that extends from the drive main shaft side toward the outer peripheral side with a predetermined width in the height direction, The pellet manufacturing apparatus according to claim 1.

7. The guide plate, is inclined toward the traveling direction rather than in a direction perpendicular to the traveling direction of rotation, The pellet manufacturing apparatus according to claim 1.

8. The guide plate, at least the outer peripheral side in the longitudinal direction is curved toward the traveling direction rather than in a direction perpendicular to the traveling direction of rotation, The pellet manufacturing apparatus according to claim 1.

9. The guide plate, The area with the plurality of through-holes is linearly configured from the driving main shaft side, and beyond the area with the plurality of through-holes, it curves in the advancing direction rather than in the direction orthogonal to the advancing direction of rotation. The pellet manufacturing apparatus according to claim 8.

10. The guide plate is characterized in that it has a notch in a portion passing through the area with the through-holes on the raw material pressing surface. The pellet manufacturing apparatus according to claim 1.

11. The pellet manufacturing apparatus further includes a cooling means using a liquid for cooling the pellet manufacturing die. The pellet manufacturing apparatus according to claim 1.

12. A method for manufacturing pellets, which uses a raw material containing coffee extraction residue to manufacture pellets by the pellet manufacturing apparatus according to any one of claims 1 to 11. The roller is rolled on the raw material pressing surface of the pellet manufacturing die, and by the roller, while pressing the raw material accumulated on the raw material pressing surface against the raw material pressing surface, it is pushed into a plurality of through-holes of the pellet manufacturing die to form pellets. The method for manufacturing pellets is characterized in that the raw material has a particle size characteristic number De in the Rosin-Rammler distribution of 0.4 or more and less than 1.

51.

13. The method for manufacturing pellets according to claim 12, wherein the raw material has a particle size characteristic number De in the Rosin-Rammler distribution of 0.4 or more and 1.2 or less.

14. The method for manufacturing pellets according to claim 12, wherein the raw material has a particle size characteristic number De in the Rosin-Rammler distribution of 0.4 or more and less than 0.

7.

15. The raw material has a moisture content of 5% or more and less than 20%. The method for manufacturing pellets according to claim 12.

16. The raw material has a moisture content of 5% or more and 14% or less. The method for manufacturing pellets according to claim 12.

17. The pellets have a moisture content of 4% or more and 12% or less. The method for manufacturing pellets according to claim 12.

18. The pellets have a moisture content of 4% or more and 10% or less. The method for manufacturing pellets according to claim 12.

19. The method for manufacturing pellets according to claim 12 is characterized by including a step of fermenting the coffee extraction residue. The method for manufacturing pellets according to claim 12.

20. The raw material is coffee extraction residue or a mixture of coffee extraction residue and a woody material. The method for manufacturing pellets according to claim 12.

21. The pellet manufacturing die has a cooling means for cooling the die. While maintaining the die for pellet production at a temperature of 80°C or lower by the cooling means, pellets are produced. The method for producing pellets according to claim 12.

22. The die for pellet production has a cooling means for cooling the die. While maintaining the die for pellet production at a temperature of 60°C or lower by the cooling means, pellets are produced. The method for producing pellets according to claim 12.

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