HIGH-DENSITY PNEUMATIC TRANSPORT METHOD FOR USE IN POWDER OR GRANULAR MATERIAL AND SYSTEM FOR PRACTISING THE METHOD

Abstract: An improved method and a related system for pneumatically transporting a powder or granular material placed in an airtight storage container (3) through a transport pipe (5) in high density. The material is formed into a long column (P) in a horizontal upper pipe (5c) of the transport pipe (5) and is transported at very slow speed and in high density by performing such an operation that the material is first increased and then reduced in speed and again accelerated while being moved up through a vertical riser pipe (5b) connected to the horizontal pipe (5a) and is once more reduced in speed when the material enters the horizontal upper pipe (5c).

Description: BACKGROUND OF THE INVENTION I. Field of the Invention The present invention relates to an improved method and a related system for pneumatically transporting a powder or granular material in high density, and more particularly to a method of pneumatically transporting a powder or granular material contained in an airtight storage container efficiently to a collector at a very low speed while forming the material into a long column inside a transport pipe and to a system for practising the method. II. Prior Art Fig. 4 shows a powder or granular pneumatic transport system of a general type conventionally used. The system is of the construction in which the powder or granular material placed in an airtight storage container 100 is transferred from the container to a lower pipe 102a of a transport pipe 102 by the gas supplied from a gas feed pipe 101, and the material is formed into a plug-shaped material by supplying pressurized gas from a pressure nozzle 103 disposed intermediately of the lower pipe 102a, the plug-shaped material is pneumatically transported through an inclined pipe 102b of the transport pipe 102 through an upper pipe 102c and is finally received by a collector 104. However, when the powder or granular material is pneumatically transported in the form of a plug by the system described above, clearance 106 is often formed above the plug-shaped material while it passes through the transport pipe 102 (see Fig. 5), with the result that the material A on the surface of the plug-shaped material 105 is first transferred and the plug shape is broken. Thus that eventually results in unsatisfactory transfer. Moreover, since any of those conventional systems as described above transfers the plug-shaped material at an extremely high speed like several meters per second for example, the material is obliged to incur strong shock when being received by the collector 104, thus easily incurring severe damage or disintegration. Furthermore, that causes another problem of mutual collision between the powder or granular materials inside the transport pipe 102. Accordingly, when the method above mentioned is applied to transporting of medicine tablets which are comparatively liable to break, a production rate of defectives tends to increase. SUMMARY OF THE INVENTION Accordingly, a primary object of the invention is to provide an improved method capable of pneumatically transporting a powder or granular material in high density without imparting impulse to the material or causing segregation of the material. Another object of the invention is to provide an improved system capable of pneumatically transporting a powder or granular material in high density efficiently without imparting impulse to the material or causing segregation thereof. The above objects are achieved by the invention, and the invention is characterized in that it includes the following active steps. Namely, in the first step, the powder or granular material in an airtight storage container is fed under pressure to a lower pipe, and in the second step, immediately thereafter, the material thus fed into the lower pipe is accelerated. In the third step, the material is moved upward inside a vertical riser pipe connected to the lower pipe, while being once reduced in speed and being again increased in speed midway through its vertically upward transport. In the fourth step, the material thus moved up is again reduced in speed as soon as it enters a horizontal upper pipe connected to the vertical riser pipe, whereby the material is successively formed into a long column ins ide the horizontal upper pipe and is pneumatically transported to the collector at very low speed. And in the final step, the material which has been transported in the form of a long column is received in the collector in the state of substantially gravitational fall. According to the invention, the material is successively formed into a long column and is pneumatically transported at very low speed and is finally received into the collector disposed at the terminal end of the transport pipe in the state of substantially gravitational fall. At the same time, the system proposed by the invention comprises, in combination, an airtight storage container containing a powder or granular material therein, a transport pipe which the powder or granular material passes through, and a collector, characterised in that the transport pipe comprises a lower transport pipe with an accelerating reducer, the pipe being connected to the airtight storage container, a horizontal upper pipe with a decelerating reducer at the upstream end thereof, the pipe being connected to the collector, and a vertical riser pipe with, in the direction of transport, an a decelerating and an accelerating reducer arranged in a pair, the pipe connecting the lower pipe to the horizontal pipe, in that the system further comprises a speed reduction means at the terminal end of the pipe for reducing the speed of the material which has been transported in the form of a long column so that the material is received in the collector in the state of substantially gravitational fall. In a preferred embodiment, the lower pipe has a convergent conical tube as an accelerating reducer, the horiziontal pipe has a divergent conical tube as a decelerating reducer disposed at the upstream end thereof, and the vertical riser pipe has a divergent conical tube as a decelerating reducer and a convergent conicle tube as an accelerating reducer arranged in a pair. BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the invention will be apparent from the following description, the appending claims and the accompanying drawings, wherein: Fig. 1 is a schematic diagram of a preferred embodiment of the system of the invention; Fig. 2 is a sectional view of a reducer; Fig. 3 is a fragmentary section of the transport pipe, explaining how the powder or granular material in the horizontal pipe is pneumatically transported; Fig. 4 is a schematic diagram of a conventional system; and Fig. 5 is a fragmentary section of the transport pipe, explaining how the material in the conventional system is transported. DETAILED DESCRIPTION OF THE INVENTION The invention will be described in detail with reference to a preferred embodiment thereof. Fig. 1 is a schematic diagram showing one embodiment of the system of the invention. In the system, pressurized air is used as transport gas, and medicine tablets are used as a powder or granular material to be transported respectively. In Fig. 1, the numeral 1 designates a feeder having a hopper 11. The hopper 11 is designed to store tablets fed from a compression molding machine 2 therein. The tablets stored in the hopper 11 are supplied to a hopper 31 for an airtight storage container 3 through a trough 13 by driving a magnetic vibrator 12 disposed below the hopper 11. The airtight storage container 3 has a valve 32 between the container 3 and the hopper 31. When the valve 32 is opened, the tablets stored in the hopper 31 are fed into the container 3. The opening and closing of the valve 32 is controlled in interlocking relation with the magnetic vibrator 12 of the feeder 1 in such a manner that the valve 32 is closed when the tablets in the container 3 are taken out into a lower pipe 5a of transport pipe 5 and is opened when the tablets are supplied from the feeder 1. A gas feed pipe 4 is connected to the container 3 and the tablets in the conta iner 3 are taken out under pressure into the lower pipe 5a of the transport pipe 5 by supplying pressurized air from the pipe 4. The transport pipe 5 includes a horizontal lower pipe 5a connected to the delivery outlet at the lower end of the container 3, a horizontal upper pipe 5c connected to the upper end inlet of a collector 6, and a vertical riser pipe 5b connecting the pipe 5a to the pipe 5c. A convergent conical tube constituting an accelerating reducer 71 is disposed intermediately of the lower pipe 5a, a divergent conical tube constituting a decelerating reducer 72 and a convergent conical tube constituting an accelerating reducer 73 thereabove are disposed intermediately of the vertical riser pipe 5b, and a divergent conical tube constituting a decelerating reducer 74 is disposed at the upstream end of the horizontal pipe 5c, and a decelerating elbow pipe 8 with an enlarged caliber larger than that of the horizontal pipe 5c, is provided at the terminal end of the pipe 5c. As shown in Fig. 2, the suitable size of the accelerating or decelerating reducer 71,(72,73) may be set such that the large caliber R is about 1.5 times larger than the small caliber r and the length l of the reducer is about 4 to 20 times longer than the small caliber r. Reducers of 37.5 mm in larger caliber R , 25 mm in smaller caliber r , and 250 to 500 mm in length l may be used in a preferred embodiment. The numeral 9 designates a sight glass for watching how the powder or granular material is transferred in the transport pipe. The glass 9 is disposed between the reducers 72 and 73 at the midway point of the vertical riser pipe 5b. The method of the invention is performed by the system of the construction described above in the following manner. The tablets in the container 3 are taken out under pressure from the container 3 to the lower pipe 5a by supplying pressurized air from the gas feed pipe 4, and immediately thereafter, the material is accelerated by means of the accelerating reducer 71 and then the material is moved upward in the vertical riser pipe 5b in the state of the material filling the pipe in high density to a degree just before blocking of the pipe. On the way of its upward transport, the material is once decelerated by the decelerating reducer 72 and is accelerated again by the accelerating reducer 73 with the material held in high density. As a result that the material gets sufficient pushing force to continue to move up toward the upper pipe 5c. However, in this case, without reducers 72, 73, the tablets in transit would be broken by receipt of impulse in the middle of the riser pipe 5b and would move partly upward and partly downward. That makes it difficult for the material to reach the horizontal upper pipe 5c without chips or cracks. In this way, the tablets are moved up toward the horizontal upper pipe 5c and are decelerated again by the decelerating reducer 74 at the upstream end of the horizontal upper pipe 5c just after the change of their course when the tablets enter the horizontal upper pipe 5c, as the result that the tablets are gathered in the form of a long column P as shown in Fig. 3, and are pneumatically transferred to the collector 6 at a very low speed through the horizontal upper pipe 5c without any clearance in the pipe 5c. Accordingly, the tablets forming the surface layer of the column P are not transferred first to brake the column nor do mutual collisions among the tablets occur in the horizontal upper pipe 5c to be thereby broken. And according to the invention, since the tablets thus transported in the form of a long column and at a very low speed through the horizontal upper pipe 5c are further decelerated by a elbow 8 with an enlarged caliber at the terminal end of the pipe 5c, the tablets are finally dropped su bstantially gravitationally into a collector 6. As a result it becomes possible to pneumatically transport the tablets without any chips or cracks. It should be noted that the length of the column P tends to become longer in proportion to the length of the horizontal upper pipe 5c. Experiments having been conducted by the present inventors showing that when the pipe 5c was 5 meters long, the column length L became more than one meter, and when the pipe 5c was 20 meters long, the column length L became more than about three meters. And the experiments also showed that the transport speed of the material was slowed down to about 0.1 m/s. In the embodiment described above, a description has been given of the case wherein the tablets are used as an example of a powder or granular material. Besides the description, the invention may be applicable to the pneumatic transport of candies, electric or electronic parts and compression moldings, powder, granules, and other solid materials. And it should be understood that, besides the pressurized air used in the above embodiment, inert nonpoisonous gas such as nitrogen, carbon dioxide may be also used. As is apparent from the description so far given, the invention makes it possible to pneumatically transport the powder or granular material at a very low speed without any chips or cracks. And inexpensive reducers may be employed in place of expensive transport pressure nozzles which are indispensable for a conventional system. Consequently, the invention may remarkably reduce expenses for the whole system. The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description.

Claims: A high density pneumatic transport method of pneumatically transporting a powder or granular material placed in an airtight storage container to a collector through a transport pipe by the use of pressurized gas, characterized by the following steps: supplying the pressurized gas to the airtight storage container (3) so as to take the material out of the container (3) under pressure and feed the material into a lower pipe (5a) of the transport pipe (5); increasing the speed of the material after having taken out the material from the container (3) to the lower pipe (5a); moving up the material in high density in a vertical riser pipe (5b) connected to the lower pipe (5a), while once reducing the speed of the accelerated material and again increasing the speed of the material midway through its vertically upward transfer inside the vertical pipe (5b); shifting the direction of the moved up material in high density to a horizontal direction by means of a horizontal upper pipe (5c) connected to the vertical pipe (5b), and immediately thereafter reducing the speed of the material whereby the material is successively formed into a long column (P) inside the horizontal pipe (5c) and pneumatically transported to the collector (6) at a very low speed; and finally receiving the material, which has been transported in the form of a long column (P), in the collector (6) in the state of substantially gravitational fall. A high density pneumatic transport system for pneumatically transporting a powder or granular material placed in an airtight storage container (3) to a collector (6) through a transport pipe (5) by the use of pressurized gas, characterized in that said transport pipe (5) comprises a lower pipe (5a), connected to the airtight storag e container (3), with an accelerating reducer (71), a horizontal upper pipe (5c), connected to the collector (6), with a decelerating reducer at the upstream end thereof, and a vertical riser pipe (5b), connecting the lower pipe (5a) to the horizontal pipe (5c), with, in the direction of transport, a decelerating and an accelerating reducer (73, 72) arranged in a pair, and in that said system further comprises a speed reduction means (8) at the terminal end of the pipe for reducing the speed of the material which has been transported in the form of a long column so that said material is substantially received by gravitation in the collector (6). The high density pneumatic transport system according to claim 2, characterized in that said accelerating reducers (71, 73) are convergent conical tubes and decelerating reducers (72, 74) are divergent conical tubes. The high density pneumatic transport system according to claim 2 or 3, characterized in that said speed reduction means (8) is an elbow pipe with an enlarged caliber larger than that of said horizontal pipe (5c). The high density pneumatic transport system according to any of claims 2 to 4, characterized in that the large caliber (R) of the reducer tubes is 1,5 times larger than the small caliber (r) while the length (l) is about 4 to 20 times longer than the small caliber (r).

Inventors: IWAMOTO, AKIKAZU KYOWA-APARTMENT 202, MORIMOTO, KIYOSHI, MORIYAMA, MASUO, SONODA,ATSUROH C/O OSAKA WORKS OF K.K.MAT.SEIS.
Applicants: KABUSHIKI KAISHA MATSUI SEISAKUSHO, KYOWA HAKKO KOGYO CO., LTD.
Application year: 1987
Main classification: B65G53
IPC codes: B65G53