Pellet manufacturing apparatus and pellet manufacturing method

Abstract

To provide an apparatus for producing pellets which have necessary mechanical durability and can be used as fuel. [Solution] This is a pellet manufacturing device using raw material containing coffee extraction residue, and is equipped with a plurality of rollers of a predetermined width arranged in a circle around the drive main shaft, which revolve around the drive main shaft as an axis while rotating around a roller shaft as an axis, a pellet manufacturing die having a raw material pushing surface that abuts against the rollers, and a motor that drives the rollers. The pellet manufacturing die has a plurality of through holes of a predetermined cross-sectional area S and a predetermined depth L that penetrate in a direction perpendicular to the raw material pushing surface, and the rollers roll on the raw material pushing surface of the pellet manufacturing die at a predetermined rotational speed, and the raw material accumulated on the raw material pushing surface is pushed into the through holes while pressing the rollers against the raw material pushing surface to form pellets. The through holes have a predetermined cross-sectional area of ​​7 mm 2 More than 50mm 2 The predetermined depth is 30 mm or more and 100 mm or less.

Description

[Technical field]

[0001] The present invention relates to a pellet manufacturing apparatus and a pellet manufacturing method that mainly uses coffee extraction residue (coffee grounds) having a high moisture content after extraction as a raw material. [Background technology]

[0002] In recent years, the consumption of coffee drinks as a beverage of choice has increased significantly, and the consumption of coffee beans has also increased accordingly. This has resulted in the generation of a large amount of coffee extraction residue (coffee extract residue obtained by extracting roasted and ground coffee beans with hot water for drinking coffee).

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

[0004] In response to this, attention has been focused on such coffee extraction residue, and a method for producing fuel pellets using coffee extraction residue has been proposed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4672286 Summary of the Invention [Problem to be solved by the invention]

[0006] The inventors of the present application also considered the possibility of using coffee extract residue to produce fuel pellets, taking into consideration the environment, and conducted extensive research. Initially, they attempted to pelletize coffee extract residue using a conventional pellet manufacturing device, but unlike conventional biomass materials such as wood materials, they were unable to produce pellets with sufficient durability.

[0007] Therefore, after many years of research, the inventors discovered that when trying to produce pellets using coffee extraction residue, the cross-sectional area and depth of the holes in the die of the pellet production equipment have a significant effect on durability, and further discovered that the durability of the pellets can be improved by controlling the rotation speed of the rollers that press the die and the temperature of the die, thereby completing the present invention.

[0008] On the other hand, from another perspective, when grinding coffee beans, the size of the ground powder has a significant impact on the taste and aroma of the coffee, so not all the powder is exactly the same size; there is a mixture of small, medium, and large powders of various sizes.

[0009] When there is a mixture of different sizes, such as coffee grind size, the Rosin-Rammler distribution can be used to analyze the coffee grind in more detail and more accurately. The Rosin-Rammler distribution is suitable for showing the distribution of sizes (how many of each size are included) when there is a mixture of different sizes.

[0010]

number

[0011] In the Rosin-Rammler distribution, the characteristic particle size number De refers to the particle size of the ground coffee particles that is equal to or larger than 36.8%. It corresponds to minus one standard deviation from the mean in a normal distribution, and is a commonly used statistical indicator to express the distribution of data. The characteristic particle size number De indicates that 36.8% of the particles in the ground coffee are equal to or larger than a certain size. This allows us to determine how many particles are larger than a certain size, and to evaluate the grinding quality based on that size. Note that the characteristic particle size number De and the uniformity number n can be calculated with a general sieve shaker and sieve.

[0012] To use pellets as fuel, the finer the grain size of the coffee extract residue, the higher its durability, but if it is too fine, it is prone to bridging during transportation and dust is likely to fly around, which is undesirable. Since the grain size of the coffee extract residue has a large effect on the durability of the pellets, we have conducted extensive research into the grain size characteristic number De, which is an indicator of grain size in the rosin-Rammler distribution mentioned above, and have developed this invention.

[0013] The present invention provides an apparatus and method for producing pellets that have the required durability and can be used as fuel. [Means for solving the problem]

[0014] A pellet manufacturing apparatus according to one aspect of the present invention is an apparatus for manufacturing pellets using a raw material containing coffee extraction residue, the apparatus comprising: a plurality of rollers of a predetermined width arranged in a circle around a drive main shaft, the rollers rotating about a roller shaft while revolving around a drive main shaft; a pellet manufacturing die having a raw material pushing surface that comes into contact with the rollers; and a motor for driving the rollers; The pellet manufacturing die has a plurality of through holes, each having a predetermined cross-sectional area S and a predetermined depth L, penetrating in a direction perpendicular to the raw material intrusion surface, and the roller rolls on the raw material intrusion surface of the pellet manufacturing die at a predetermined rotational speed, and the raw material accumulated on the raw material intrusion surface is pressed into the through holes while pressing the roller against the raw material intrusion surface, thereby forming pellets. The through hole has a predetermined cross-sectional area of ​​7 mm 2 More than 50mm 2 The predetermined depth is not less than 30 mm and not more than 100 mm.

[0015] By using a manufacturing apparatus having this configuration, it is possible to manufacture pellets using coffee extraction residue that have a sufficient durability.

[0016] In addition, this manufacturing apparatus is characterized in that the area S0 of the raw material pushing surface through which the roller rotates and passes, the cross-sectional area S of the through holes, and the number k of the through holes satisfy the following formula. (formula) 0.15 <kS / S0<0.5

[0017] According to this configuration, by setting the cross-sectional area and number of the through holes within this range, i.e., by setting the total area of ​​the openings of the through holes relative to the roller passing area on the die, i.e., the aperture ratio, within this range, it is possible to produce pellets with even higher durability. If the aperture ratio is too large, the area over which the roller presses the raw material becomes wider, dispersing the force and reducing the durability of the molded pellets. If the aperture ratio is too small, the pressing force increases, but the production volume decreases.

[0018] In addition, this manufacturing apparatus is characterized in that the cross section of the through hole is circular, and the diameter of the circular cross section is 3 mm or more and 8 mm or less. With this configuration, cylindrical pellets with sufficient durability can be manufactured, and unlike angular pellets, since there are no corners, concentration of load is less likely to occur and durability against external forces is improved.

[0019] In addition, in this manufacturing apparatus, it is preferable that the through hole has a countersunk portion formed on the side of the raw material pushing surface that serves as the inlet of the raw material. According to this configuration, the countersunk portion makes it easier for the raw material to be introduced into the through hole, improving productivity. In addition, the countersunk portion increases the opening area, which improves the efficiency of pressing by the roller.

[0020] In addition, in this manufacturing apparatus, it is preferable that the through hole is countersunk on the surface opposite to the raw material pushing surface which serves as the raw material outlet. With this configuration, when the molded pellets are pushed out from below the die, they are easily separated from the die, improving productivity.

[0021] This manufacturing device is also characterized in that the rotation speed of the roller is 70 rpm or more and 120 rpm or less. With this configuration, by pressing the die with the roller at a rotation speed in this range, it is possible to manufacture pellets with higher durability. The faster the rotation speed of the roller, the more times the raw material is pressed into the through holes per unit time, improving the durability of the pellets. However, if the rotation speed is too fast, the raw material cannot be pressed firmly and the load on the motor increases.

[0022] This manufacturing apparatus is also characterized by further comprising a cooling means using a liquid to cool the pellet manufacturing die. With this configuration, by manufacturing pellets while cooling the pellet manufacturing die with the cooling means, the pellet manufacturing die, whose temperature rises due to friction or the like, can be cooled and maintained at a predetermined temperature. This makes it possible to manufacture pellets with high durability.

[0023] Here, cooling means using a liquid include, for example, water cooling and oil cooling, and water cooling is preferable from the viewpoints of safety and cost, etc. In addition to the above, there is also air cooling, but since the die temperature rises significantly during pellet production, it is preferable to cool the die by a cooling means using a liquid.

[0024] Possible water cooling means include, for example, a water-cooled jacket that covers the outer periphery, inner periphery, and underside of the pellet production die and allows liquid to pass through it; a configuration in which a pipe through which liquid can pass is attached to the pellet production die; and a method in which a passage through which liquid can pass is provided inside the pellet production die.

[0025] The manufacturing apparatus further comprises a guide plate that rotates horizontally about a drive main shaft to move the raw material on the raw material intrusion surface of the pellet manufacturing die toward the drive main shaft.

[0026] With this configuration, the raw material on the die is carried outward by the rotation of the rollers, etc., but the guide plate guides the raw material toward the center and into the through holes from which pellets are formed, thereby improving productivity.

[0027] In addition, this manufacturing apparatus is characterized in that the guide plate is inclined toward the direction of rotation rather than in a direction perpendicular to the direction of rotation.

[0028] According to this configuration, by making the guide plate have the above-mentioned inclined shape, the raw material can be further guided toward the center, thereby improving productivity.

[0029] In addition, this manufacturing apparatus is characterized in that the guide plate is curved toward the direction of rotation rather than in a direction perpendicular to the direction of rotation.

[0030] According to this configuration, by forming the guide plate in the above-mentioned curved shape, the raw material can be reliably guided toward the center, and productivity can be further improved.

[0031] With this configuration, the raw material on the die is carried outward by the rotation of the rollers, etc., but the guide plate guides the raw material toward the center and into the through holes from which pellets are formed, thereby improving productivity.

[0032] In addition, this manufacturing apparatus is characterized in that the lower end of the guide plate is close to the raw material pushing surface and has a notch in a portion passing through the region of the raw material pushing surface where the through holes are located. With this configuration, the notch in the guide plate enables the guide plate to guide the raw material to the region where the through holes are located.

[0033] The manufacturing apparatus also includes a peripheral wall surrounding the pellet manufacturing die and the roller. This configuration can prevent the raw material from scattering to the outside. The peripheral wall surrounding the pellet manufacturing die and the roller includes a peripheral wall surrounding a part of the pellet manufacturing die and a part of the roller. In order to prevent the raw material from scattering to the outside, it is sufficient that at least the upper and lower sides near the die surface of the pellet manufacturing die are surrounded.

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

[0035] As a result, by making the particle size of the raw material such that the particle size characteristic number De in the Rosin-Rammler distribution is between 0.4 and 1.51, it is possible to manufacture pellets that have sufficient durability and can be used as fuel. The reason for setting the above range is that the finer the particle size, the higher the durability, but on the other hand, if it is too fine, there is a high possibility that the through holes in the die will get clogged and the pellets will not be able to be extruded.

[0036] In addition, in the pellet manufacturing method, 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 preferable that the particle size characteristic number De in the Rosin-Rammler distribution of 0.4 or more and less than 0.7. In this way, the durability of the pellets can be further improved.

[0037] This pellet manufacturing method is also characterized in that the moisture content of the raw material is 5% or more and less than 20%. Here, the moisture content is a target value after raw material adjustment. This ensures sufficient durability of the manufactured pellets. The moisture content is set in the above range because if it is less than 5%, the extruded raw material may not solidify or may clog the through holes of the die, and if it is 20% or more, the extruded raw material may not solidify.

[0038] In addition, in this pellet manufacturing method, it is more preferable that the moisture content of the raw material is 5% or more and 14% or less, because by keeping the moisture content within the above range, pellets with high durability can be manufactured.

[0039] The pellet manufacturing method is also characterized in that the moisture content of the pellets is 4% or more and 12% or less. This ensures sufficient durability of the manufactured pellets, and is preferable because a moisture content of the pellets exceeding 12% increases the risk of mold growth. It is more preferable that the moisture content of the pellets is 10% or less.

[0040] The pellet manufacturing method is also characterized by including a step of fermenting the coffee extraction residue. According to this configuration, the strength of the formed pellets can be increased by passing through the step of fermenting the coffee extraction residue. The fermentation method involves leaving the extracted coffee extraction residue for one or several days to ferment. After a certain amount of fermentation, the coffee extraction residue is dried to use as a raw material. Water may be added to the dried coffee extraction residue for fermentation.

[0041] The pellet manufacturing method is also characterized in that the raw material is coffee extraction residue or coffee extraction residue mixed with wood material. With this configuration, the coffee extraction residue can be effectively utilized without being discarded, and pellets with sufficient durability can be manufactured.

[0042] Furthermore, this pellet manufacturing method is characterized in that the pellet manufacturing die has a cooling means for cooling the die, and pellets are manufactured while maintaining the pellet manufacturing die at a temperature of 80°C or less by the cooling means.

[0043] The inventors conducted research and testing on pellet production and discovered that, although there is no problem with wood pellets when the die temperature exceeds 80°C, when using coffee extraction residue as the raw material, the oil contained in the coffee becomes an inhibitor of bonding, preventing sufficient bonding, and there is also a risk of the raw material clogging the through-holes of the die. By manufacturing while maintaining the die temperature at 80°C or lower as in the above configuration, it is possible to reduce such risks.

[0044] Furthermore, this pellet manufacturing method is characterized in that the pellet manufacturing die has a cooling means for cooling the die, and pellets are manufactured while maintaining the pellet manufacturing die at a temperature of 60°C or less by the cooling means.

[0045] Furthermore, by using a cooling means to suppress the temperature rise of the die and keep the die temperature at 60°C or less, pellets with even higher durability can be produced while suppressing the above risks. In other words, by keeping the temperature at 60°C or less, the floating and clogging of coffee oils are suppressed, and the produced pellets have high durability. Effect of the Invention

[0046] The pellet manufacturing apparatus and method of the present invention are capable of manufacturing pellets having sufficient durability. [Brief description of the drawings]

[0047] [Figure 1] FIG. 1 is a perspective view showing a pellet manufacturing apparatus according to an embodiment of the present invention (excluding a raw material hopper). [Diagram 2] 1 is a schematic diagram showing a configuration of a pellet manufacturing apparatus according to an embodiment of the present invention. [Diagram 3] 1A and 1B are diagrams showing a pellet manufacturing die of the pellet manufacturing apparatus, in which (a) is a plan view and (b) is a side view. [Figure 4] 1A is a partially enlarged view of the pellet manufacturing apparatus, and FIG. 1B is a partially enlarged view of the roller and the pellet manufacturing die. [Diagram 5] FIG. 2 is a diagram showing the relationship between a guide and a pellet forming hole provided in a pellet manufacturing die of the pellet manufacturing apparatus. [Figure 6] FIG. 4 is a cross-sectional view showing a water cooling means of the pellet manufacturing apparatus. [Figure 7] FIG. 1A is a perspective view showing the rotating box of the durability tester, and FIG. 1B is a perspective view showing the durability tester (twin rotating box). [Figure 8] FIG. 13 is a diagram showing a modified example of a guide provided on a pellet manufacturing die of a pellet manufacturing device, and shows the relationship between the guide and a pellet forming hole. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0049] As shown in Figures 1 and 2, the pellet manufacturing apparatus 10 mainly comprises a rotationally driven drive main shaft 1, two rollers 2 that revolve around the drive main shaft 1 as a vertical axis and rotate on roller shafts 2a, and a pellet manufacturing die 3 disposed below the drive main shaft 1.

[0050] The drive main shaft 1 is rotated by a motor (not shown), and the rollers 2 connected to both sides of a roller shaft 2a connected to the drive main shaft 1 rotate on their own axes while rolling on the raw material pushing surface 3a of the pellet manufacturing die 3. The raw material for the pellets is then fed onto the raw material pushing surface 3a from a raw material hopper 8 that feeds the raw material and is disposed above the drive main shaft, and as the rollers 2 rotate, the raw material accumulated on the raw material pushing surface 3a is pressed against the raw material pushing surface 3a and pushed into a plurality of pellet forming holes 3aa that penetrate the pellet manufacturing die 3 in the thickness direction.

[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 Figs. 3 and 4, the width of the roller 2 is made larger than the width of the annular region S centered on the drive shaft 1 in which the pellet-forming hole 3aa is formed. In particular, the outer portion is made wider than that of a conventional roller so that the raw material can be 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 Figures 3 and 4, the pellet manufacturing die 3 is configured to have a generally cylindrical shape with a circular plane. A plurality of pellet forming holes 3aa are arranged in an annular shape at the position where the roller 2 passes. The pellet forming holes 3aa are through holes with a circular cross section, which penetrate the pellet manufacturing die 3 in the thickness direction, and countersunk holes are formed on the upper raw material pushing surface 3a side and the lower raw material extrusion surface 3b side. This allows the raw material to be smoothly introduced into the pellet forming holes 3aa and to be smoothly separated from the raw material extrusion surface 3b.

[0057] In addition, the pellet forming hole 3aa in this embodiment has a circular cross section with a diameter of 5 mm and a cross-sectional area of ​​approximately 19.6 mm. 2 The depth including the countersink is 80 mm. In this embodiment, the number of pellet forming holes 3aa is 384, which are arranged in a circular region on the raw material pushing surface 3a of the pellet manufacturing die 3 through which the rollers 2 pass.

[0058] The dimensions of the pellet forming hole 3aa are just an example, and the cross-sectional diameter may be 4 mm, 6 mm, 7 mm, etc., and the depth may be 40 mm, 60 mm, 100 mm, etc., and the cross-sectional shape may be rectangular or elliptical other than circular.

[0059] 5, a plate-like guide 5 is provided on the raw material pushing surface 3a to guide the raw material located on the outside toward the center, i.e., toward the side where the annular area (pellet forming hole 3aa) is located. The guide plate 5 is a curved, elongated plate that is attached to the driving main shaft 1 and extends toward the outer periphery of the pellet manufacturing die 3 and is curved so as to move away from the radial direction in the direction of rotation.

[0060] The curved shape of the guide plate 5 extends from the end on the drive shaft side toward the outer periphery of the pellet manufacturing die 3, and is configured to extend a predetermined distance in the direction of rotation along the outer periphery of the pellet manufacturing die 3 (the tip side of the guide plate 5). The guide plate 5 is erected so that its long plate-like lower end is close to the raw material pushing surface 3a, and a notch 5a is formed in the portion that passes through the area of ​​the raw material pushing surface 3a where the pellet forming hole 3aa is located.

[0061] The guide plate 5 rotates together with the roller 2, and guides the raw material toward the area where the pellet forming holes 3aa are located. Without the guide plate 5, the raw material would be carried outward by centrifugal force, but the shape of the guide plate 5 ensures that the raw material is carried to the area of ​​the pellet forming holes 3aa, thereby improving pellet productivity.

[0062] That is, (i) when the roller 2 passes over the area of ​​the pellet forming holes 3aa, the raw material above the pellet forming holes 3aa becomes uneven, and (ii) the downward pushing force differs between the center side (inner side) and the outer periphery side (outer side) of the roller 2. For these reasons, it is difficult to use them completely evenly; however, it is possible to use all of the pellet forming holes 3aa as evenly as possible, thereby increasing productivity.

[0063] Although the guide 5 causes some difference in production volume between the center and the outer periphery, the guide 5 makes it possible to use all of the pellet forming holes 3aa, including the outer ones, and therefore makes it possible to significantly improve the production volume.

[0064] In addition, since the outer peripheral portion of the roller 2 moves a long distance during one rotation, the force pushing the material at the outer peripheral portion is uniformly distributed over a wide range. On the other hand, since the central portion of the roller 2 moves only a short distance during one rotation, the force pushing the material at the central portion tends to concentrate in a small range, and since the force is more concentrated here, there is a difference in the pushing force between the outer peripheral portion of the roller 2 and the central portion of the roller 2, but the effect of this difference can be reduced.

[0065] 1, 2, and 6, a water-cooled jacket 6 is provided around the pellet manufacturing die 3 to suppress a rise in temperature of the die. The water-cooled jacket 6 is connected to a jacket body 6A formed in a hollow annular shape having a space inside through which liquid passes, a water supply pipe 6B that supplies water to the jacket body 6A and extends downward, and a drain pipe 6C (not shown) that discharges water and extends upward. The water supply pipe 6B and the drain pipe 6C are connected to a radiator and a circulation pump (not shown), and circulate the water supplied to the jacket body 6A.

[0066] This water-cooling jacket 6 controls the temperature so that the die and raw material do not rise in temperature during pellet molding by flowing cooling water therethrough and does not exceed a certain temperature. In this embodiment, the die temperature is adjusted to be kept at 60° C. or less.

[0067] The die temperature is kept at 60°C or less because, when the rollers 2 rotate around the pellet manufacturing die 3, the die temperature rises due to friction, etc., and if pellets are molded while the die temperature remains high, the raw material becomes hot and the durability of the molded pellets decreases. Therefore, by using the water-cooling jacket 6 to keep the die temperature at 60°C or less, the durability of the molded pellets can be increased.

[0068] <2. Pellet manufacturing method> In the pellet manufacturing device 10 thus configured, when the driving main shaft 1 rotates, the rollers 2 fixed to the driving main shaft 1 revolve around the driving main shaft 1 as their axis and rotate around their roller axes, producing pellets. for manufacturing The pellets roll on the raw material pushing surface 3a of the die 3. When the raw material is supplied through the raw material hopper 8, the raw material is poured from the raw material hopper 8 onto the raw material pushing surface 3a of the die 3 for producing pellets.

[0069] At this time, the guide plate 5 attached to the driving shaft 1 rotates together with the rollers 2 to guide the raw material toward the area where the pellet forming holes 3aa are located, thereby guiding the raw material to the area of ​​the pellet forming holes 3aa.

[0070] The rotating roller 2 then takes in the accumulated raw material through the grooves 2b formed on the outer circumferential surface, and pushes it into the pellet forming hole 3aa while pressing it against the raw material pushing surface 3a. The raw material pushed into the pellet forming hole 3aa is molded into a long, thin cylindrical stripe in the pellet forming hole 3aa, and is extruded from the raw material extrusion surface b.

[0071] The streaked pellets are then cut to an appropriate length by a rotary cutter 7 attached to the raw material extrusion surface 3b side, passed through a shooter 9A, and stored in a pellet storage section 9B.

[0072] As for the raw material, the collected coffee extract residue is fermented for one to several days, then dried and used as the raw material for pellet production. Water may be added to the dried coffee extract residue before fermentation. The raw material may be only the coffee extract residue, or it may be a raw material in which the coffee extract residue is the main raw material and is mixed with wood chips or a binder such as cornstarch. The reason for fermenting the coffee extract residue is that the strength of the formed pellets is improved compared to raw material that is dried without going through a 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 from coffee extraction residues as raw materials is important. This is because if the durability is low and the pellets are brittle, there is a risk that the pellets will break into pieces during transportation or handling and become unusable. Also, the durability of the pellets was measured by the method described later.

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

[0075] As described above, 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 approximately 19.6 mm 2 , and the depth including the countersink is 80 mm.

[0076] And when the diameter of the cross-section is less than 3 mm, in addition to the fact that the coffee extraction residues as raw materials are difficult to enter, the compression due to the hole diameter is too strong and the pellets are difficult 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 are brittle. Also, when the depth of the hole is less than 30 mm, the distance that the coffee extraction residues as raw materials pass through the hole is short, so the formed pellets become brittle. 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 the pellet forming holes 3aa of the present embodiment is 384 arranged in the annular region through which the roller 2 passes. When the cross-sectional area S of the pellet forming holes 3aa, the number k, and the area S0 of the surface through which the roller 2 rotates and passes through the raw material pressing surface 3a are considered, the pellet forming holes 3aa are arranged so that 0.15 < kS / S0 < 0.5.

[0078] If this value is 0.5 or more, the pressing force of the roller 2 is dispersed, and the durability of the pellets decreases. If it is 0.15 or less, fewer pellets are molded, and productivity decreases. In this embodiment, kS / S0 is approximately 19.7. In this case, the durability of the pellets is 92.8%. This value is the mechanical durability of the pellets measured by the test described later.

[0079] Also, as shown in the table below, if the hole diameter of the pellet forming hole 3aa is changed to 7 mm, kS / S0 becomes 38.6, and the durability of the pellets becomes 74.8. Although 74.8 is still a usable durability, as mentioned above, it is desirable to have a durability of 80% or more, and more desirably 90% or more.

[0080] [Table 1]

[0081] In addition, the thicker the depth of the pellet forming hole 3aa, i.e., the pellet manufacturing die 3, the more durable the formed pellets will be, but it is not necessarily the case that the thicker the better. If the pellets are too thick, a greater downward pressure is required and the compression becomes stronger, which may prevent the raw material from being clogged in the hole and coming out.

[0082] The durability of the molded pellets must be at least 70% or more in the durability test described below, preferably 80% or more, and more preferably 90% or more. In addition to the above-mentioned conditions of the manufacturing device, the durability of the pellets can also be improved by the rotation speed of the rollers, the particle size and moisture content of the raw materials, the temperature, etc. The durability test and other preferable conditions are described below.

[0083] <4. Durability testing> Next, we investigated the relationship between the particle size (particle size characteristic number De) and the mechanical durability of the pellets. Here, the mechanical durability of the pellets indicates how difficult it is to break the pellets, and is defined as the mass percentage DU (%) of the part that does not break after a certain amount of mechanical impact is applied.

[0084] (Mechanical durability test method) This test method determines the resistance of wood pellets to mechanical shock and is standardized in accordance with the European standard for wood pellets, EN15210-1.The sieve used was a metal sieve with a circular hole diameter (nominal opening) of 3.15 mm as specified in JIS Z8801-2, and the balance used was one that could measure up to 1 kg and to the nearest 0.1 g.

[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 has a smooth surface made of steel, aluminum or acrylic resin, protruding parts such as rivets and screws are as small as possible, corners are rounded, and there are no gaps to prevent fine powder from leaking out. The dimensions are 300 (length) x 300 (width) x 125 (depth) mm, and buffer wings 11a (230 x 50 mm) are firmly attached diagonally inside, and a sample insertion door 11b is provided on one side.

[0086] In order to rotate the rotating box 11 at a speed of 50 rpm, a rotating shaft 13 is attached perpendicular to the wall at the center of a wall (side) measuring 300 (length) x 300 (width) mm, sandwiching the measuring instrument 12, as shown in Figure 7(b). The durability tester is of the twin type having two rotating boxes 11, enabling two measurements to be made at once.

[0087] [Table 2]

[0088] From Table 2, it was found that the finer the particle size, the higher the mechanical durability. Although the finer the particle size, the higher the mechanical durability, if the particle size is too fine, it is more likely to bridge during transportation and dust will fly. Furthermore, making the particle size finer reduces the production capacity of the grinder and increases the price. For these reasons, the particle size characteristic number De, which is a guideline for particle size in the Rosin-Rammler distribution, is preferably 0.60 to 0.65 (mm). A coffee bean grinder was used as the grinder. Next, the relationship between moisture content and mechanical durability was investigated.

[0089] [Table 3]

[0090] In Table 3, when the target moisture content of the bio-based raw material was 11% and 15%, the higher target value of 15% showed better durability.

[0091] In addition, when testing target values ​​of 15%, 17%, and 19%, the results showed that durability was improved when comparing the 15% target value with the other values, with the higher target values ​​of 17% and 19%, but there was no difference between 17% and 19%.

[0092] Therefore, a target value of about 17% is considered to be good from the standpoint of durability. However, if the compressive force becomes too large, it may affect the appropriate moisture content.

[0093] Also, if only durability is considered, the results are as above, but on the other hand, high moisture content increases the risk of mold growth. Conversely, when considering the risk of mold, a lower moisture content is better. In conclusion, taking these conditions into account, it was found that production must be carried out under conditions with a moisture content of 13% or less. Therefore, it is desirable for the moisture content of bio-based raw materials to be in the range of 9-13%.

[0094] On the other hand, it is desirable for the moisture content of pellets to be 10% or less. If it is too low, they tend to become brittle. Also, if it exceeds 12%, the risk of mold growth increases, so it is desirable to ensure a safety factor and set it at 10% or less. To achieve a moisture content of 10% or less, it is desirable to set the moisture content of the raw material before molding at 13% or less.

[0095] Next, Tables 4 to 7 show the results of tests conducted on the relationship between the addition of additives (binders), the filling amount (input amount) of biomaterials, the rotation speed of the rollers, and the presence or absence of cooling water and mechanical durability.

[0096] [Table 4]

[0097] Increasing the proportion of additives had almost no effect on durability. It is believed that adding them in themselves has an effect, but increasing the proportion did not have a significant effect. Unlike conventional wood pellet molding, coffee has a different grain shape because it is a powder, it does not contain binding components such as lignin, and heat is not applied during molding. It is believed that some of these differences may be the cause.

[0098] In terms of type of additive, starch-based cornstarch had some impact, while cellulose-based CMC and metolose had a greater impact than cornstarch.

[0099] The higher the mechanical durability, the smaller the difference between having and not having additives tends to be. Data has been obtained that adding additives increases durability by a maximum of about 3% when durability exceeds 80%, and by about 1-2% when it is around 90%, but there are disadvantages such as higher costs and a higher risk of mold growth.

[0100] Therefore, although the presence of additives has the advantage of increasing durability, considering the disadvantages, it is thought that it is not necessary to have additives.

[0101] Considering the cost, the risk of mold, and the fact that the material can be used for combustion without additives, it is not a problem to use them without additives, but if increased durability is required depending on the application, it is desirable to have additives.

[0102] [Table 5]

[0103] The smaller the input amount (loading amount kg / h), the higher the durability, but this is thought to be because the raw material is held in the die for a longer period of time. As a result, the lower the production amount, the higher the durability, but at some point it will reach saturation and productivity must be taken into consideration. Therefore, it is desirable to ensure a minimum loading amount of about 100 kg / h of bio-raw materials.

[0104] [Table 6]

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

[0106] (With or without cooling water) We also verified the effect of cooling by the water-cooled jacket 6 provided in the pellet manufacturing apparatus 10. This test measured the mechanical durability when the pellet and die temperatures were high and when they were not (pellet temperature 90°C or less, die temperature 60°C or more). The method for increasing the temperature was to add an excess of rice bran, forcibly increasing the temperature through friction, and measure the pellet temperature using a thermometer that can measure the surface temperature. The results are shown in Table 7.

[0107] [Table 7]

[0108] These results show that, unlike wood pellets, the durability of pellets made from coffee extract residue decreases as the temperature rises. This is because wood pellets contain lignin, which has the properties of a thermoplastic resin, and softens when heated and hardens when cooled. In short, wood pellets harden when molded at high temperatures, but coffee does not contain lignin, so it is thought that the bonds rely on the power of hydrogen bonds and intermolecular bonds, and the higher the temperature, the more the oil in coffee floats to the surface of the bio-raw material, so it is thought that the oil in the coffee acts as an inhibitor of bonds, and that raising the temperature reduces durability.

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

[0110] <5. Other embodiments> As described above, the embodiment of the present invention has been described with reference to the drawings, but various additions, modifications, and omissions can be made without departing from the spirit of the present invention.

[0111] In the above embodiment, the coffee extract residue is used as the raw material, but it is also possible to use a mixture of such coffee extract residue and other biomaterials.

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

[0113] In addition to the curved shape described above, the guide plate can also be configured to be inclined toward the direction of rotation rather than perpendicular to the direction of rotation (see Figure 8). This may be less effective than a curved shape, but it can be expected to have a certain effect on drawing in the raw material.

[0114] In the above embodiment, the water-cooled jacket 6 covers the outer periphery of the pellet manufacturing die 3, but the present invention is not limited to this, and may be, for example, a water-cooled jacket attached to the inner periphery, a water-cooled jacket attached to both the inner and outer periphery, or a water-cooled jacket attached to the underside of the pellet manufacturing die. In this way, it is possible to solve the problem that, for example, when the diameter of the pellet manufacturing die is large, it is difficult to cool the center side with just the water-cooled jacket on the outer periphery, or there is a risk of temperature unevenness occurring. [Explanation of symbols]

[0115] 1 Drive shaft 2 Rollers 2a Roller shaft 2b Groove 3 Pellet manufacturing dies 3a Raw material pushing 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 device for manufacturing pellets using a raw material containing coffee extract residue, A plurality of rollers having a predetermined width are arranged in a circular shape around the drive main shaft, the rollers revolving around the drive main shaft and rotating around the roller shaft; A pellet producing die having a raw material pushing surface that contacts the roller; A motor for driving the roller, The die for pellet production has a plurality of through holes each having a predetermined cross-sectional area S and a predetermined depth L, the through holes penetrating in a direction perpendicular to the raw material pushing surface, The roller rolls on the raw material pushing surface of the pellet manufacturing die at a predetermined rotation speed, and pushes the raw material accumulated on the raw material pushing surface into the through holes while pressing the roller against the raw material pushing surface, thereby forming pellets. The through hole is The predetermined cross-sectional area is 7 mm 2 More than 50 mm 2 is as follows: The predetermined depth is 30 mm or more and 100 mm or less, A guide plate is further provided which rotates horizontally about the drive main shaft and moves the raw material on the raw material intrusion surface of the pellet manufacturing die toward the drive main shaft, The guide plate has a lower end portion adjacent to the raw material pushing surface and has a notch at a portion passing through an area of ​​the raw material pushing surface where the through hole is located. Pellet manufacturing equipment.

2. The area S of the raw material pushing surface through which the roller rotates 0 and the cross-sectional area of ​​the through hole S and the number k satisfy the following formula:

2. The pellet manufacturing apparatus according to claim 1. (Formula 1) 0.15<kS / S 0 <0.5

3. The through hole has a circular cross section, The diameter R of the circular cross section is 3 mm or more and 8 mm or less.

2. The pellet manufacturing apparatus according to claim 1.

4. The rotation speed of the roller is 70 rpm or more and 120 rpm or less.

2. The pellet manufacturing apparatus according to claim 1.

5. Further comprising a cooling means using a liquid for cooling the pelletizing die; 2. The pellet manufacturing apparatus according to claim 1.

6. The guide plate is It is tilted toward the direction of rotation rather than perpendicular to the direction of rotation.

2. The pellet manufacturing apparatus according to claim 1.

7. The guide plate is It is curved more in the direction of rotation than perpendicular to the direction of rotation.

7. The pellet manufacturing apparatus according to claim 6.

8. A pellet manufacturing method for manufacturing pellets using a raw material containing coffee extraction residue by the pellet manufacturing apparatus according to any one of claims 1 to 7, The roller is rolled on the raw material pushing surface of the die for pellet production, and the raw material accumulated on the raw material pushing surface is pushed into the plurality of through holes of the die for pellet production while being pressed against the raw material pushing surface by the roller, thereby forming pellets; The method for producing pellets is characterized in that the raw material has a particle size characteristic number De in a rosin-Rammler distribution of 0.4 or more and less than 1.

51.

9. 9. The method for producing pellets according to claim 8, wherein the raw material has a particle size characteristic number De in a Rosin-Rammler distribution of 0.4 or more and 1.2 or less.

10. 9. The method for producing pellets according to claim 8, wherein the raw material has a particle size characteristic number De in a Rosin-Rammler distribution of 0.4 or more and less than 0.

7.

11. The raw material has a moisture content of 5% or more and less than 20%. A method for producing the pellets according to claim 8.

12. The raw material has a moisture content of 5% or more and 14% or less. A method for producing the pellets according to claim 8.

13. The pellets have a moisture content of 4% or more and 12% or less. A method for producing the pellets according to claim 8.

14. The pellets have a moisture content of 4% or more and 10% or less. A method for producing the pellets according to claim 8.

15. The method comprises the step of fermenting the coffee extract residue. A method for producing the pellets according to claim 8.

16. The raw material is coffee extract residue or coffee extract residue mixed with wood material. A method for producing the pellets according to claim 8.

17. The pelletizing die has a cooling means for cooling the die, The pellets are produced while the pellet production die is kept at a temperature of 80° C. or less by the cooling means. A method for producing the pellets according to claim 8.

18. The pelletizing die has a cooling means for cooling the die, The pellets are produced while the pellet production die is kept at a temperature of 60° C. or less by the cooling means. A method for producing the pellets according to claim 8.

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