Powder and granular material drying device and powder and granular material drying method

Abstract

To provide a device of drying granules and a method of drying granules, capable of efficiently drying a raw material of a low allowable upper limit temperature.SOLUTION: A drying device 1 is a continuous drying device of an airflow type to be used for drying a granulated material prepared from a low melting point substance as a raw material, such as a medicine, and comprises a granulated material feeder 11, a dryer 12 and a product discharger 13. The dryer 12 comprises a drying treatment pipe 25 including a plurality of straight pipes 31 and bent pipes 32 each connecting the straight pipes 31. The bent pipes 32 are each equipped with an additional-air feeding pipe 34 for additionally feeding air into the drying treatment pipe 25. Each of the additional-air feeding pipes 34 is disposed on a position away from a deviation section X where a granulated material 36 in the pipe is present while deviating and opens at a position where the presence of the granulated material 36 is sparse. Additional air at a temperature of a melting point or higher of the granulated material 36 is fed into the drying treatment pipe 25 from the additional-air feed pipe 34.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an airflow type drying apparatus and method for continuously drying powder or granular material, and in particular to a drying apparatus and method capable of efficiently drying powder or granular material made from substances with a low upper limit allowable processing temperature, such as pharmaceuticals. [Background technology]

[0002] Conventionally, known devices for drying granular powders used in pharmaceuticals and the like include fluidized bed dryers that dry powders in a batch process, and devices that perform continuous drying using a rotary feeder or the like, as in Patent Document 1. In addition, spray dryers (spray drying devices) as in Patent Document 2 are used to produce granules, and loop-type airflow dryers as in Patent Document 3 are used to dry waste materials such as sludge and toner particles.

[0003] Furthermore, in recent years, demands for lower prices and higher quality products have led to demands for improved productivity and quality in production lines for dried granules of pharmaceuticals, etc., and there is a demand for further space-saving and shorter processing times in production systems. Therefore, the present applicant has created and proposed an airflow type powder and granule dryer, as disclosed in Patent Document 4, which supplies additional air during the drying process, as an airflow type powder and granule dryer with high drying capacity, excellent quality stability, and high efficiency for producing high-quality dried granules. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 58-72868 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-33269 [Patent Document 3] Japanese Patent Application Laid-Open No. 2000-292975 [Patent Document 4] Japanese Patent Publication No. 2021-139527 Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, flash drying generally dries materials in a short time using hot air at high temperatures of 200-300°C, and while this is an effective method for materials that can withstand high temperatures, it is difficult to apply to materials that have low melting points and low allowable upper limit temperatures (generally 120°C or less). For this reason, powders and granular materials with low allowable upper limit temperatures must be dried using hot air below the upper limit temperature, and in this case, the material cannot be sufficiently dried unless the processing volume is reduced, resulting in a corresponding decrease in production efficiency.

[0006] In this regard, the device of Patent Document 4 aims to improve drying efficiency by raising the temperature of the drying air during the process by supplying additional air to the drying path. However, even in this case, it is unavoidable that the temperature of the drying air gradually decreases along the path (see FIG. 3(a)), and the improvement in production efficiency for powders and granules with a low allowable upper limit temperature is limited compared to powders and granules made from raw materials that can be supplied with high-temperature additional air.

[0007] An object of the present invention is to provide a drying apparatus and a drying method for powder and granular material that can efficiently dry even powder and granular material made from raw materials with a low allowable upper limit temperature. [Means for solving the problem]

[0008] The powder or granular material drying apparatus of the present invention is an airflow type drying apparatus that dries powder or granular material containing moisture by air, and includes a powder or granular material input section having a powder or granular material inlet into which the powder or granular material is input and an air inlet through which the air is supplied, a drying treatment section that is provided downstream of the powder or granular material input section and communicates with the powder or granular material input section, through which the powder or granular material flows together with the air, and a product discharge section that is provided downstream of the drying treatment section and communicates with the drying treatment section, through which the powder or granular material that has passed through the drying treatment section is discharged together with the air, and the drying treatment section includes a drying treatment pipe formed by a tubular member, and a product discharge section that is connected to the drying treatment pipe and opens into the drying treatment pipe. Additional air having a temperature higher than the allowable upper limit of the temperature of the powder or granule is introduced into the drying treatment pipe.and an additional air supply pipe for supplying additional air, the additional air supply pipe being spaced apart from a biased portion where the powder or granular material flowing through the drying treatment pipe is biased. and arranged at a position where the additional air supplied from the additional air supply pipe becomes lower than the allowable upper limit temperature in the bias portion. It is characterized by:

[0009] In the powder or granular material drying apparatus, A plurality of the additional air supply pipes may be provided so that the additional air supplied from the additional air supply pipes has a greater amount of heat as it is supplied to the downstream side. The upper limit allowable temperature of the powder or granular material may be a melting point, and the powder or granular material may be a low-melting-point raw material having a melting point of 120° C. or less. Furthermore, a plurality of additional air supply pipes may be provided, and the additional air supplied from the additional air supply pipes may have a higher temperature and a larger air volume toward the later stage.

[0010] The drying process tube may be provided with a plurality of straight pipe sections and bent sections disposed between the straight pipe sections to connect the front and rear straight pipe sections, and the additional air supply pipe may be attached to the bent sections. In this case, the additional air supply pipe may be attached to the upper inner periphery of the bent section. Alternatively, the additional air supply pipe may be attached to a position between directly above and directly to the side of the bent section. Furthermore, the additional air supply pipe may be attached to a position diametrically opposite the biased section formed in the bent section at a diagonally downward position on the outer periphery of the drying process tube.

[0011] Additionally, the drying process tube may be provided with a straight pipe section extending linearly, and the additional air supply pipe may be attached to the straight pipe section. In this case, the additional air supply pipe may be attached directly above the straight pipe section or at a position 45° downward in the circumferential direction from directly above the straight pipe section. Furthermore, the additional air supply pipe may be attached to the straight pipe section at a position diametrically opposed to the biased portion formed at the bottom of the drying process tube.

[0012] On the other hand, the powder or granular material drying method of the present invention is an airflow type drying method in which moist powder or granular material is dried by air, and is characterized in that the powder or granular material is introduced into a drying treatment pipe formed by a tubular member together with main drying air having a temperature below the allowable upper limit temperature of the powder or granular material, and then auxiliary drying air having a temperature equal to or higher than the allowable upper limit temperature of the powder or granular material is additionally supplied to a position away from the biased portion where the powder or granular material flowing through the drying treatment pipe is unevenly distributed, thereby drying the powder or granular material.

[0013] In the powder or granular material drying method, the auxiliary drying air may be supplied from a portion of the drying treatment pipe that is separated from the biased portion and where the powder or granular material is sparsely present. The upper allowable temperature of the powder or granular material may be a melting point, and the powder or granular material may be a low-melting-point material having a melting point of 120°C or less. The auxiliary drying air may be supplied multiple times, with the temperature and volume of air being higher toward the later stages. [Effects of the Invention]

[0014] According to the powder / granular material drying apparatus of the present invention, an airflow type drying apparatus for drying moist powder / granular material with air includes a drying pipe and an additional air supply pipe for supplying additional air to the drying pipe in a drying processing section through which the powder / granular material flows together with the air. The additional air supply pipe is located away from the biased portion of the powder / granular material flowing through the drying pipe, and additional air at a temperature above the upper limit of the powder / granular material's allowable temperature can be supplied to the drying pipe from the additional air supply pipe. This allows auxiliary drying air supplied at a temperature above the upper limit to be cooled to below the upper limit before being supplied to the powder / granular material. This enables efficient drying of powder / granular material at higher temperatures than conventional methods while maintaining a high temperature within the drying path. As a result, efficient continuous drying can be achieved without affecting the raw material, for example, when drying powder / granular material using low-melting-point raw materials.

[0015] Furthermore, according to the powder / granular material drying method of the present invention, a powder / granular material drying method using air currents dries moist powder / granular material by introducing the powder / granular material into a drying pipe together with main drying air at a temperature below the upper limit of the allowable temperature range. Then, auxiliary drying air at a temperature equal to or higher than the upper limit of the allowable temperature range for the powder / granular material is supplied to a location away from the biased portion of the powder / granular material flowing through the drying pipe. This allows the auxiliary drying air supplied at a temperature above the upper limit to be cooled to a temperature below the upper limit before being supplied to the powder / granular material. This allows the powder / granular material to be efficiently dried at a higher temperature than conventionally possible while maintaining a high temperature within the drying path. As a result, for example, efficient continuous drying of powder / granular material using low-melting-point raw materials can be achieved without affecting the raw materials. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is an explanatory diagram showing the overall configuration of a continuous granule manufacturing system in which a drying device according to one embodiment of the present invention is used. [Figure 2] FIG. 1 is an explanatory diagram showing the state of the wet granulated material in the drying processing pipe and the positional relationship of the additional air supply pipe. [Figure 3] 1A and 1B are explanatory diagrams showing changes in the temperature of dried air due to additional air supply, where FIG. 1A shows the temperature change in a conventional device, and FIG. 1B shows the temperature change in a drying device according to the present invention. [Figure 4] 1 is a table showing the formulation of raw materials used in the inventors' experiments. [Figure 5] 1 is a table showing the results of experiments conducted by the inventors on drying processes using a conventional device and a device according to the present invention. [Figure 6] 10A and 10B are explanatory diagrams showing modified examples of the arrangement of the additional air supply pipe. DETAILED DESCRIPTION OF THE INVENTION

[0017] An embodiment of the present invention will be described below. FIG. 1 is an explanatory diagram showing the overall configuration of a continuous granulation production system that uses a powder and granular material drying apparatus 1 (hereinafter abbreviated as drying apparatus 1) according to one embodiment of the present invention. As shown in FIG. 1, the continuous granulation production system that uses the drying apparatus 1 according to the present invention comprises a wet granulation process and a drying process, and is primarily used for processing powder and granules made from low-melting-point raw materials with a melting point of 120°C or less, such as pharmaceuticals. The granules produced by this system undergo a sieving and sizing process, and are then manufactured into granules or tablets. In the case of tablets, after the sieving and sizing process, a lubricant is mixed in, and the tablets are tableted in a tablet press, and then appropriately coated in a coating machine to produce the product.

[0018] The wet granulation process can use various known wet granulators, such as a high-speed agitator granulator 2 and an extrusion granulator 3. The granules produced in the wet granulation process are supplied in a fixed quantity to the dryer 1 by a continuous wet granulation supply device 4 (hereinafter abbreviated as granulation supply device 4). The high-speed agitator granulator 2 serves as both a powder mixer and a powder kneader. Raw materials are placed in a container, and the agitator and chopper are rotated at high speed to agitate and knead the raw materials. The extrusion granulator 3 is a wet granulation device such as an extruder equipped with a screw shaft (e.g., a twin-shaft parallel configuration). The screw compresses and kneads the raw materials, and by adding water as needed, the raw materials are converted into columnar wet granules.

[0019] The configurations of the high-speed agitation granulator 2 and extrusion granulator 3 described above are merely examples, and these devices can be widely applied to other devices as long as they have the functions of agitation, granulation, and sizing, regardless of their configuration or operating mode. Furthermore, it is possible to add a sizing machine (not shown) or omit the granulation supply device 4 depending on the state of the granulated material and the product specifications. In other words, the devices combined with the drying device 1, such as sizing machines, tablet presses, and coating machines in the sieving and sizing process, including the wet granulation process, can be selected and changed as appropriate depending on the processing mode of the powder and granules, and the continuous granulation production system according to the present invention is not limited to the combination of devices described above.

[0020] The drying apparatus 1 in this continuous granule manufacturing system is broadly composed of a granulated material input section (powdered material input section) 11, a drying treatment section 12, and a product discharge section 13, and the drying method of the present invention is also carried out in the drying apparatus 1. The drying apparatus 1 is an airflow type continuous drying apparatus, in which the wet granulated material (powdered material) supplied at the granulated material input section 11 is dried with hot air in the drying treatment section 12, which has a bent piping arrangement, and is then discharged and sent to the next process from the product discharge section 13. Here, the drying treatment section 12 has a multi-stage straight bend type configuration in which a straight piping is bent twice at right angles.

[0021] 1, the piping is depicted as extending in the vertical direction to make it easier to understand the overall configuration of the drying apparatus 1, but the drying processing section 12 of the drying apparatus 1 has piping that is bent on the same plane from the granulated material input section 11 to the product discharge section 13. In other words, FIG. 1 shows the piping of the drying processing section 12 as viewed from above.

[0022] Hot air (dry air) for drying treatment at a temperature (for example, about 70 to 120°C) below the upper limit temperature tolerance of the material to be treated (here, the melting point) is supplied as treatment gas from hot air supply device 14 to granulated material input section 11 at a wind speed of about 8 to 12 m / s, preferably about 10 m / s. In this case, in a general air current type dryer used to dry fertilizer, cement, etc., the wind speed of the treatment gas is 20 to 30 m / s, whereas in dryer 1, the wind speed of the dry air is set lower than usual.

[0023] The granulated material charging section 11 is equipped with an inlet pipe 21 having a circular cross section, an outer diameter of approximately 50 mm, and a wall thickness of approximately 2 to 3 mm. The inlet pipe 21 is made of a metal circular pipe (e.g., a stainless steel pipe), and is generally T-shaped. The inlet pipe 21 is provided with a granulated material inlet (powder / granular material inlet) 22 through which the wet granulated material, which is the material to be treated in the drying device 1, is charged, and a hot air inlet (air inlet) 23 through which heated air for drying treatment is supplied. A hopper 24 is attached to the granulated material inlet 22, and the wet granulated material is supplied from the granulated material supply device 4. The hot air inlet 23 is disposed upstream of the granulated material inlet 22 and is connected to the hot air supply device 14. The inlet pipe 21 may be made of not only a metal circular pipe, but also other materials such as synthetic resin or glass.

[0024] The drying treatment unit 12 is disposed downstream of the granulated material input unit 11 and includes a drying treatment pipe 25 formed of a metallic circular pipe member (for example, a stainless steel pipe). The drying treatment pipe 25 includes a plurality of straight pipe sections (pipes) 31 extending linearly and bent sections 32 connecting the respective straight pipe sections 31. In the system of this embodiment, the drying treatment unit 12 has a two-bend, three-stage configuration, and three straight pipe sections 31 are disposed between the granulated material input unit 11 and the product discharge unit 13 (first to third straight pipe sections 31a to 31c, hereinafter abbreviated as straight pipe sections 31a to 31c).

[0025] The three straight pipe sections 31 are arranged so as to bend at right angles at the connection between straight pipe sections 31a and 31b and at the connection between straight pipe sections 31b and 31c. Each connection section has a bent section 32 (first and second bent sections 32a and 32b, hereinafter abbreviated as bent sections 32a and 32b), to which a bent pipe (elbow) made of the same circular pipe material as the straight pipe sections 31 is attached. Each bent section 32 has the same diameter as the straight pipe sections 31 before and after it.

[0026] A product discharge section 13 equipped with a cyclone collector (powder and granular material collecting device) 26 is disposed downstream of the drying treatment section 12. The cyclone collector 26 is connected to the end (straight pipe section 31c) of the drying treatment pipe 25 via a connecting pipe 27. The granulated material dried in the drying treatment section 12 is collected in the product collecting pipe of the cyclone collector 26. A sieving device (not shown) that performs a sieving and sieving process is connected downstream of the cyclone collector 26.

[0027] In the drying apparatus 1, the granulated material is dried as follows. First, the wet granulated material is supplied from the granulated material supply device 4 to the granulated material inlet 22. At this time, a negative pressure is created inside the introduction pipe 21 of the granulated material supply section 11 by the suction force of the cyclone collector 26, and the granulated material fed from the granulated material supply device 4 into the hopper 24 is introduced into the granulated material inlet 22 without being blown upward. Meanwhile, high-pressure hot air (dry air) is supplied from the hot air supply device 14 to the hot air inlet 23, and the granulated material fed into the introduction pipe 21 is transported by this dry air toward the drying treatment section 12. The granulated material dried in the drying treatment section 12 is then carried by the dry air and discharged from the drying treatment pipe 25, and is collected by the cyclone collector 26 via the connecting pipe 27.

[0028] In the drying device 1, additional dry air is supplied at the bent portions 32a and 32b, thereby suppressing a decrease in the temperature inside the pipes. As shown in FIG. 1, additional air supply pipes 34 (first and second additional air supply pipes 34a and 34b, hereinafter abbreviated as additional air supply pipes 34a and 34b) are attached to the corners 33 of the bent portions 32a and 32b, respectively. Auxiliary dry air is supplied to the additional air supply pipes 34 from an additional air supply device 35, in addition to the main dry air from the hot air supply device 14. As a result, in the drying processing unit 12, auxiliary dry air is added midway along the drying path, thereby suppressing a decrease in the drying capacity of the drying processing unit 12.

[0029] 2 is an explanatory diagram showing the state of the wet granulated material 36 at the bend 32 and the positional relationship of the additional air supply pipe 34, with (a) showing the configuration of bend 32a and (b) showing bend 32b. As shown in FIG. 2, the additional air supply pipe 34 is attached to the upper part of bend 32 and disposed diagonally downward from directly above. In this case, if directly above is 12 o'clock on a clock, then the additional air supply pipe 34 is disposed in the 10 to 11 o'clock direction at bend 32a, and in the same manner, the additional air supply pipe 34 is disposed in the 1 to 2 o'clock direction at bend 32b (hereinafter, "xx o'clock" will be described based on the clock face).

[0030] As can be seen from FIG. 2 , in the bent portion 32, gravity and centrifugal force cause the granulated material 36 (powder and granular material) to flow diagonally downward (slightly above directly below) on the outer periphery of the pipe (outside the bend). As described above, in the drying process 1, the wind speed of the drying air is slower than usual, and the airflow is slow, so the granulated material 36 tends to accumulate at the bottom due to the influence of gravity. Then, due to the influence of gravity and centrifugal force in the bent portion 32, biased portions X are formed in the bent portion 32a toward the lower right and in the bent portion 32b toward the lower left, where the granulated material 36 is biased. That is, biased portions X exist in the 4 o'clock to 5 o'clock direction in the bent portion 32a, and in the 7 o'clock to 8 o'clock direction in the bent portion 32b. Note that because the wet granulated material contains almost no fine powder, gravity and centrifugal force cause the granulated material 36 to be biased toward the biased portion X.

[0031] Therefore, in the drying process 1, the additional air supply pipe 34 is disposed at a location away from the biased portion X, that is, at an upper portion on the inner circumferential side (inside the bend) of the bent portion 32, which is a position facing the biased portion X (for example, a position 180° opposite along the circumferential direction). Therefore, the opening 37 of the additional air supply pipe 34 is formed in the bent portion 32 of the drying process pipe 25 at a location that is the farthest from the biased portion X in the diameter direction and where the presence of the granulated material 36 is sparse, and auxiliary dry air is additionally supplied into the drying process pipe 25 from there.

[0032] However, the biased portion X is formed by the flow of the powder and granular material, and its position has a spread of about ±45° (range 90°). Therefore, the position of the additional air supply pipe 34 (position of opening 37) is not pinpointed at the minute hand position of 10:30 or 2:30 (position 45° downward from directly above), but has an allowable range of about ±45° above and below. In other words, the additional air supply pipe 34 is positioned between directly above and directly to the side (within 90° downward from the vertical along the outer periphery of the pipe) depending on the granulated material, processing conditions, etc., specifically, between 9 o'clock and 12 o'clock at bend portion 32a, and between 12 o'clock and 3 o'clock at bend portion 32b (installation range Y).

[0033] Heated, low-humidity auxiliary drying air is supplied from the additional air supply pipe 34. In the drying device 1, hot air having a temperature higher than that of the main drying air (approximately 80 to 120°C) is supplied as the auxiliary drying air. At this time, hot air at a temperature equal to or higher than the melting point (upper limit temperature allowable) of the granulated material 36 is supplied as the auxiliary drying air. In this case, in conventional drying processes, air at a temperature high enough to melt or sublimate the material to be treated is not supplied. That is, not only as the main drying air, but also in devices such as those described in Patent Document 4, additional air at a temperature equal to or higher than the melting point is generally not supplied.

[0034] In contrast, in the drying apparatus 1 according to the present invention, air above the melting point is intentionally supplied as auxiliary drying air. Therefore, there is a concern that the addition of auxiliary drying air may affect the material to be treated. However, as mentioned above, the auxiliary air supply pipe 34 is located at the farthest point from the biased portion X, where the granulated material 36 is thin, and its opening is positioned so that the heat of the auxiliary drying air is diffused before it reaches the granulated material 36, causing the temperature to drop (see FIG. 2). Therefore, in the drying apparatus 1, the auxiliary drying air is supplied at a temperature that is as low as possible so that it is below the melting point at the position of the granulated material 36. This allows the temperature of the drying air to be raised to near the upper limit of the material to be treated at the position where the auxiliary drying air is added, enabling continuous drying at a higher temperature. The main drying air is below the melting point to prevent the material from adhering to the inside of the pipe.

[0035] FIG. 3 is an explanatory diagram showing changes in the temperature of dried air due to additional air supply, where (a) shows the temperature change in a conventional device (Patent Document 4) and (b) shows the temperature change in the drying device 1 according to the present invention. As shown in FIG. 3(a), the conventional device supplies additional air twice at the upper limit temperature allowable for the workpiece (78°C in this case). In contrast, as shown in FIG. 3(b), the drying device 1 supplies additional air at 90°C and 120°C. In this case, the temperature and air volume of the third air supply are higher than those of the second air supply. This is because the air volume in the piping is increased by the second air supply, and therefore, in order to achieve the same temperature increase effect in the subsequent stages as in the previous stages, it is necessary to supply a larger amount of heat by the increased air volume.

[0036] As shown in Figure 3(a), in conventional devices, the temperature of the dry air in the piping rises each time additional air is supplied, but it does not rise to near the allowable upper limit temperature, and the temperature generally tends to decrease. In other words, if the temperature of the additional supply air is set to the allowable upper limit temperature, the temperature in the drying path will only decrease. In contrast, in the drying device 1 according to the present invention, as can be seen from Figure 3(b), additional air supply causes the dry air temperature to rise to near the allowable upper limit temperature without exceeding it. In other words, even if air is supplied at a temperature higher than the allowable upper limit temperature, the temperature in the drying path will not exceed the allowable upper limit temperature, and the temperature is maintained above a certain level overall.

[0037] Therefore, the drying device 1 makes it possible to perform drying at a higher temperature (below the melting point) than conventionally. In drying, a higher temperature is more advantageous for drying even when the amount of heat (temperature x air volume) is the same. By using the drying device 1, it is possible to perform highly efficient drying of powders and granules made from low-melting-point raw materials with a melting point of 120°C or less, especially those with a melting point of 80°C or less that could previously only be dried with warm air below that temperature. As a result, a higher degree of dryness can be achieved at the same processing speed as conventionally, and if the same degree of dryness as conventionally is sufficient, continuous drying can be performed at a faster processing speed.

[0038] Figures 4 and 5 are tables showing the results of comparative experiments conducted by the inventors regarding the apparatus and method of the present invention. Figure 4 shows the formulation of the raw material used in the experiment, and Figure 5 shows the results of drying treatment using a conventional apparatus and an apparatus according to the present invention. As shown in Figure 4, the raw material used was a mixture of 20% by weight of ibuprofen as the active ingredient, 62% by weight of mannitol, 15% by weight of microcrystalline cellulose, and 3% by weight of hydroxypropyl cellulose as additives, uniformly mixed in a tumbler mixer. The moisture content of the mixed powder was approximately 1% (measured by an infrared moisture meter at 80°C for 10 min), and the drying target was to keep the moisture content below this level. The details of Experimental Examples 1 to 3 are explained below (see Figure 5).

[0039] (Experimental example 1: Conventional method without additional air supply, processing speed 5 kg / h) First, in Experimental Example 1, a drying process was carried out using a conventional device without additional air supply. Here, the mixed powder was fed from a feeder at a rate of 83 g / min (= 5 kg / h), and 25% by weight of water was added to the powder to obtain wet granules by a twin-screw kneading granulation method. Next, a 11.5 m 3 The above wet granules were sequentially fed into a flash dryer (conventional equipment) to which dry air at 76°C was supplied at 1000 / min, yielding dried granules. The resulting dried granules had a D50 of 250 μm and a moisture content of 0.9 wt%, which were acceptable physical properties, but there was little margin for moisture tolerance. Therefore, increasing the processing speed would likely result in insufficient drying, making it difficult to further increase the processing speed in order to improve production efficiency.

[0040] (Experimental Example 2: Method of the present invention, processing speed 5 kg / h) Next, in Experimental Example 2, a drying treatment was carried out using the apparatus according to the present invention. In Experimental Example 2, as in Experimental Example 1, the mixed powder was fed from the feeder at a rate of 83 g / min (= 5 kg / h), and 25% by weight of water was added to the powder to obtain wet granules by the twin-screw kneading granulation method. Next, in Experimental Example 2, a 6.5 m 3 The wet granules were sequentially fed into a flash dryer (the present invention) to which dry air of 76°C was supplied at 1 / min. 3 / min 90°C additional air supply (2nd air), 3m 3Additional air (third air) at 120°C was supplied sequentially to obtain dried granules (total volume of dry air was 11.5 m 3 (The results are the same as in Experimental Example 1.) The obtained dried granules had a D50 of 250 μm and a moisture content of 0.6% by weight, demonstrating that the drying was more advanced than in Experimental Example 1, which had the same processing speed. These results demonstrate that the method and apparatus of the present invention have ample drying capacity, and confirm the possibility of being able to handle even higher processing speeds.

[0041] (Experimental Example 3: Method of the present invention, processing speed 20 kg / h) Since the possibility of processing at a higher speed was confirmed in Experimental Example 2, an experiment was conducted using the device of the present invention, with the processing speed increased to 333 g / min (= 20 kg / h). That is, mixed powder was fed from a feeder at a rate of 333 g / min, and water was added in an amount of 25% by weight to the powder, and wet granulated material was obtained by the twin-screw kneading granulation method. Next, a 6.5 m 3 The wet granules were sequentially fed into a flash dryer (the present invention) to which dry air of 76°C was supplied at 1 / min. 3 / min 90°C additional air supply (2nd air), 3m 3 / min and additional 120°C air (third air) are sequentially supplied to obtain dried granules. The resulting dried granules had a D50 of 250 μm and a moisture content of 0.8 wt %. Experimental Example 3 demonstrated that the same drying process could be achieved even at a processing speed four times faster than Experimental Example 1. These results confirmed that the method and apparatus of the present invention can achieve a drying process equivalent to conventional methods at high processing speeds. Furthermore, with airflow drying, there is almost no opportunity for the objects to come into contact with each other, and processing speeds can be flexibly changed. If processing speeds can be increased using the same equipment, processing efficiency can be effectively improved.

[0042] As described above, in the drying method and apparatus according to the present invention, the granulated material transported to the drying section 12 is dried while circulating in the drying process pipe 25 on the warm air. In the drying apparatus 1, additional dry air is supplied from the additional air supply pipes 34a and 34b at the bent portions 32a and 32b. At this time, air at or above the melting point of the raw material is supplied from the additional air supply pipes 34a and 34b as auxiliary drying air. The auxiliary drying air is supplied from the portion of the pipe farthest from the granulated material 36 and is set so that its temperature is below the melting point at the position of the granulated material 36. Therefore, the additional supply of air above the melting point does not affect the physical properties of the granulated material 36. As a result, in the drying section 12, the gas temperature in the process pipe does not decrease even downstream, and the drying process is carried out with the dry air temperature maintained at or above a constant level.

[0043] Furthermore, in the drying apparatus 1, fresh dry air is supplied during the drying process, so the humidity inside the pipe does not become saturated and the drying efficiency does not decrease. Therefore, the drying apparatus 1 according to the present invention can suppress the saturation of humidity inside the pipe while suppressing the decrease in drying capacity in the drying processing section 12. As a result, even for granulated materials using low-melting-point raw materials with a low allowable upper limit temperature, it is possible to perform the drying process with a processing gas at a higher temperature than conventional (however, below the upper limit temperature at the position of the processed material), making it possible to continuously and efficiently dry granulated materials with a low allowable upper limit temperature. Furthermore, the improved drying efficiency allows the length of the drying processing pipe to be shorter than conventional machines, thereby shortening the drying time and increasing the processing volume per hour.

[0044] In addition, according to the present invention, it is possible to increase the upper limit of drying capacity of existing equipment, which has a set upper limit for air volume, simply by carrying out additional construction work. Increasing the drying capacity of an existing drying device typically requires modifying the entire device, such as changing the capacity of the intake and exhaust blowers, changing the capacity of the air conditioner, changing the capacity of the heater, and creating a new drying path. In contrast, with the configuration of the present invention, the total air volume remains the same as with the existing device, so the air conditioner, drying path, and exhaust blower can be used as is, and modifications can be made by simply adding an intake blower and a heater, allowing for specification changes at a lower cost than modifying the entire device.

[0045] Furthermore, the dryer 1 allows for flexible combinations of the temperature, air volume, and speed of the initial main drying air and the additional auxiliary drying air. This allows for appropriate adjustments of drying conditions depending on the type and amount of material to be treated, particle size, moisture content, etc., making it possible to flexibly accommodate a variety of materials. Furthermore, because the dryer 1 has a short processing time, it also allows for feedback control of critical quality attributes (CQAs) such as particle size, moisture, and bulk density, which affect the purity, content, drug release, and stability of the formulation.

[0046] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit and scope of the present invention. For example, in the above-described embodiment, additional air supply pipes 34a, 34b are arranged at each of bent portions 32a, 32b, but they may also be arranged at straight pipe portions 31a, 31b to additionally supply auxiliary drying air, as shown in Fig. 6(a). In this case, in straight pipe portions 31a, 31b, as shown in Fig. 6(b), granulated material 36 flows at the bottom of the pipe due to gravity, and biased portion X is present at the bottom of the pipe. Therefore, additional air supply pipes 34a, 34b are installed directly above the pipe (at 12 o'clock) or at a position 45° circumferentially downward from directly above (at 10:30 or 2:30) (installation range Y).

[0047] Furthermore, in the drying apparatus 1, the drying process pipe 25 has a three-stage structure consisting of the first to third straight pipe sections 31a-31c, but the number of drying process stages is not limited to three. For example, a two-stage or four-stage structure is also possible. In principle, installing more additional air supply pipes at closer intervals can reduce the decrease in drying capacity. However, the introduction cost of additional air, such as the installation of additional air supply pipes and additional air supply devices, increases. Considering factors such as cleanability, a three-stage structure (two additional air supplies) is preferable, balancing cost with the benefits of improved processing speed. In practice, one air supply is insufficient, and five air supplies would make the device too large. According to experiments conducted by the inventors, with a piping length of approximately 20 m and two additional air supplies, the temperature drop from preheating was less than 5°C, and a nearly uniform temperature could be maintained with two additional air supplies, demonstrating a good balance.

[0048] It is also possible to arrange the drying processing pipe 25 in a straight line without providing any bends, and to arrange the additional air supply pipe therein as shown in Fig. 6. The additional air supply pipe 34 may be installed at an angle (about 10 to 45°) to the extending direction of the bends 32 and straight pipe portion 31 (direction of dry air flow), so that additional air is supplied obliquely along the wind direction.

[0049] Furthermore, in the above embodiment, an example was shown in which dry air was additionally supplied to the additional air supply pipes 34a, 34b from an additional air supply device 35 separate from the hot air supply device 14, but although temperature control would be required, dry air may be supplied from the hot air supply device 14, or an additional air supply device may be provided separately for each additional air supply pipe. In addition, although the additional air is generally supplied at a constant air flow and speed during treatment, for example, when drying materials that are highly moist and difficult to move, air may be supplied intermittently or the air volume may be changed in a pulsed manner to prevent stagnation.

[0050] Furthermore, the various dimensions and specifications shown in the above-described embodiment, such as the outer diameter and number of stages (number of bends) of the drying process pipe 25, and the installation position and number of the additional air supply pipe 34, can be changed as appropriate, and the present invention is not limited to the above-described dimensions and specifications. Furthermore, it is of course possible to use high-temperature dry air exceeding 200°C in the drying apparatus of the present invention, or to adopt the present invention in new and existing apparatuses that are currently designed to handle high temperatures but may use low-melting-point raw materials in the future.

[0051] In the above-described embodiment, an example was shown in which the melting point was used as the allowable upper limit temperature for the powder or granular material, but the upper limit temperature is not limited to the melting point, and the allowable upper limit temperature can be appropriately selected to suit the raw material of the powder or granular material, based on the temperature at which the powder or granular material may be altered. [Industrial Applicability]

[0052] The present invention can be applied not only to the drying of wet granulated materials used in pharmaceuticals, but also to the drying of powdered and granular materials such as foods and fertilizers that use raw materials with low allowable upper limit temperatures. It can also be used with raw materials that can withstand high temperatures, not just those with low allowable upper limit temperatures. However, for raw materials that can withstand high temperatures, it is often more efficient to increase the temperature of the main drying air rather than supplying additional air. [Explanation of symbols]

[0053] 1 Powder drying equipment 2. High-speed mixing granulator 3. Extrusion Granulator 4. Continuous wet granulation supply device 11 Granule input section (powder input section) 12 Drying processing section 13 Product discharge section 14 Hot air supply device 21 Inlet piping 22 Granule inlet (powder inlet) 23 Warm air inlet 24 Hopper 25 Drying treatment tube 26 Cyclone collector 27 Connecting pipe 31 Straight pipe section 31a 1st straight pipe section 31b 2nd straight pipe section 31c 3rd straight pipe section 32 Bend 32a 1st bending part 32b 2nd bend, 33 Corner 34 Additional air supply pipe 34a First additional air supply pipe 34b Second additional air supply pipe 35 Additional air supply device 36 Granulated material (material to be processed) 37 Opening X eccentric part Y Additional air supply pipe installation range

Claims

1. An airflow type drying device that dries powder or granular material containing moisture using air, a powder / granular material input unit including a powder / granular material input port into which the powder / granular material is input and an air blowing port through which the air is supplied; a drying processing section provided downstream of the powder / granular material inlet section and in communication with the powder / granular material inlet section, through which the powder / granular material flows together with the air; a product discharge section provided downstream of the drying processing section in communication with the drying processing section, for discharging the powder or granular material that has passed through the drying processing section together with the air, the drying processing section includes a drying processing pipe formed by a tubular member, and an additional air supply pipe connected to the drying processing pipe, opening into the drying processing pipe, and supplying additional air having a temperature equal to or higher than an allowable upper limit temperature of the powder or granular material into the drying processing pipe; A powder or granular material drying apparatus characterized in that the additional air supply pipe is separated from a biased portion where the powder or granular material flowing through the drying processing pipe is unevenly distributed, and is positioned at a position where the additional air supplied from the additional air supply pipe has a temperature below the allowable upper limit in the biased portion.

2. 2. The powder / granular material drying apparatus according to claim 1, A plurality of the additional air supply pipes are provided, A powder or granular material drying apparatus, wherein the additional air supplied from the additional air supply pipe has a greater heat content toward the later stage.

3. 2. The powder / granular material drying apparatus according to claim 1, A powder / granular material drying apparatus characterized in that the upper limit of the allowable temperature of the powder / granular material is the melting point, and the powder / granular material is made of a low-melting-point raw material having a melting point of 120°C or less.

4. 2. The powder / granular material drying apparatus according to claim 1, A plurality of the additional air supply pipes are provided, The powder or granular material drying apparatus is characterized in that the additional air supplied from the additional air supply pipe has a higher temperature and a larger air volume toward the downstream stage.

5. The powder or granular material drying apparatus according to any one of claims 1 to 4, the drying treatment pipe includes a plurality of straight pipe sections and bent sections disposed between the straight pipe sections and connecting the front and rear straight pipe sections, The powder or granular material drying apparatus is characterized in that the additional air supply pipe is attached to the bent portion.

6. 6. The powder or granular material drying apparatus according to claim 5, The powder or granular material drying apparatus is characterized in that the additional air supply pipe is attached to an upper part of the inner periphery of the bent portion.

7. 7. The powder or granular material drying apparatus according to claim 6, The powder or granular material drying apparatus is characterized in that the additional air supply pipe is attached at a position between directly above and directly to the side of the bent portion.

8. 7. The powder or granular material drying apparatus according to claim 6, the biased portion of the bent portion is formed at a position obliquely downward on an outer circumferential side of the drying processing tube, The powder or granular material drying apparatus is characterized in that the additional air supply pipe is attached at a position diametrically opposed to the biasing portion.

9. The powder or granular material drying apparatus according to any one of claims 1 to 4, the drying treatment tube has a straight tube portion extending linearly, The powder or granular material drying apparatus is characterized in that the additional air supply pipe is attached to the straight pipe portion.

10. 10. The powder or granular material drying apparatus according to claim 9, The powder or granular material drying apparatus is characterized in that the additional air supply pipe is installed between directly above the straight pipe portion or at a position 45° downward from directly above in the circumferential direction.

11. 10. The powder or granular material drying apparatus according to claim 9, the biased portion in the straight pipe portion is formed in a pipe bottom portion of the drying treatment pipe, The powder or granular material drying apparatus is characterized in that the additional air supply pipe is attached at a position diametrically opposed to the biasing portion.

12. An airflow drying method for drying powder or granular material containing moisture by air, comprising the steps of: The powder or granule is introduced into a drying treatment pipe formed by a tubular member together with main drying air having a temperature lower than the allowable upper limit temperature of the powder or granule, and then A powder or granular material drying method characterized by additionally supplying auxiliary drying air having a temperature equal to or higher than the allowable upper limit temperature of the powder or granular material to a position away from the biased portion where the powder or granular material circulating within the drying processing pipe is unevenly distributed, thereby drying the powder or granular material.

13. The powder or granular material drying method according to claim 12, The method for drying powder or granular material, wherein the auxiliary drying air is supplied from a portion of the drying processing pipe that is separated from the biased portion and where the powder or granular material is sparsely present.

14. The powder or granular material drying method according to claim 12, A method for drying powder or grain, characterized in that the upper limit of the allowable temperature of the powder or grain is the melting point, and the powder or grain is made from a low-melting-point raw material having a melting point of 120°C or less.

15. The powder or granular material drying method according to claim 12, The powder or granular material drying method is characterized in that the auxiliary drying air is supplied multiple times, and the air in the later stages has a higher temperature and a larger air volume.

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