Powder and granular material conveying device and powder and granular material conveying method

Abstract

To provide a powder and grain conveyance device capable of suppressing a backflow of air and powder and grain bodies, while securing a conveyance force of a conveyance airflow at a low cost.SOLUTION: A powder and grain body conveyance device 1 includes: a suction nozzle 2 for sucking powder and grain bodies P; a first relay tank 3 where the powder and grain bodies P sucked by the suction nozzle 2 are supplied; a first airflow generation unit 4 for generating a suction airflow in suction piping 21 between the suction nozzle 2 and the first relay tank 3; a first valve 6A connected to a lower part of the first relay tank 3; a second relay tank 5 which is placed further below in the vertical direction than the first relay tank 3, and where the powder and grain bodies P are supplied from the first relay tank 3 via the first valve 6A; a second valve 6B connected to a lower part of the second relay tank 5; a second airflow generation unit 7 for generating a force feed airflow into a flow passage between the second valve 6B and a storage tank 9; and a control unit 8 for controlling the first valve 6A or the second valve 6B so that the storage amount of the powder and grain bodies P in the second relay tank 5 maintains a predetermined lower limit level LL2 or greater.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a granular material conveying device and a granular material conveying method for conveying granular materials by an air flow.

Background Art

[0002] In recent years, with the development of offshore aquaculture, the large-scale cultivation of sea bream cages and the automation of feeding have been promoted. In such offshore aquaculture, a storage tank for storing feed for feeding is installed on an offshore platform, and the feed in this storage tank is appropriately supplied to the sea bream cages (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses a conveying method using a suction blower (vacuum pump) as a method for replenishing feed from a ship loaded with feed to a storage tank. In this method, using a suction blower, the feed on the ship is sucked into a suction nozzle, and the sucked feed is pneumatically conveyed to the storage tank.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When pneumatically conveying granular materials such as feed from a ship to a storage tank on a platform as described above, there is a large height difference in the flow path from the ship to the upper part of the storage tank. In addition, since the conveyance on the offshore is greatly affected by changes in sea conditions, it is desirable to complete the conveyance in a short time. Due to these circumstances, a large conveying force is required for the conveying air flow.

[0006] If only a suction blower is used as the source of the conveying air flow as in the method disclosed in Patent Document 1, a large-capacity suction blower is required to ensure sufficient conveying force. However, a large-capacity suction blower is expensive as a device, and it is necessary to prepare a water cooling system for the large-capacity suction blower on the platform. For this reason, the cost for conveying increases significantly.

[0007] Therefore, the present inventors have considered using not only a suction blower but also a pressure blower as the source of the conveying air flow. For example, when the suction blower generates an air flow from the suction nozzle toward the relay tank and the pressure blower generates an air flow from the relay tank toward the storage tank, the required capacity of each of the suction blower and the pressure blower can be suppressed. However, in such a configuration, there is a possibility of backflow of air or powder from the air flow path by the pressure blower to the air flow path by the suction blower.

[0008] An object of the present invention is to provide a powder conveying device and a powder conveying method that can suppress backflow of air or powder while ensuring the conveying force of the conveying air flow at low cost.

Means for Solving the Problems

[0009] A powder conveying device according to a first aspect of the present invention is a powder conveying device that conveys powder to a storage tank, including a suction nozzle that sucks the powder, a first relay tank to which the powder sucked by the suction nozzle is supplied, a first air flow generating unit that generates a suction air flow in a flow path between the suction nozzle and the first relay tank, a first valve connected to a lower portion of the first relay tank, a second relay tank disposed vertically below the first relay tank and supplied with the powder from the first relay tank via the first valve, a second valve connected to a lower portion of the second relay tank, a second air flow generating unit that generates a pressure air flow in a flow path between the second valve and the storage tank, and a control unit that controls at least one of the first valve or the second valve so that the storage amount of the powder in the second relay tank is maintained at a predetermined lower limit level or higher.

[0010] In such a configuration, the first air flow generating unit generates a suction air flow in the flow path from the suction nozzle to the first relay tank, and the second air flow generating unit generates a pressure feeding air flow in the flow path from the second relay tank to the storage tank. As a result, while suppressing the capacities of the first air flow generating unit and the second air flow generating unit, it is possible to secure the conveying force of the conveying air flow required for each flow path. Further, due to the positional relationship between the first relay tank and the second relay tank, the powder and granular material in the first relay tank can be conveyed to the second relay tank mainly by gravity. Thereby, the conveying force of the conveying air flow can be secured at low cost. Further, in the above configuration, the storage amount of the powder and granular material in the second relay tank is maintained at a predetermined lower limit level or higher. Here, the predetermined lower limit level is a preset level, and it is sufficient that at least the powder and granular material covers the opening communicating with the second valve in the second relay tank and the powder and granular material can function as a material seal for the opening. The powder and granular material in the second relay tank can seal between the flow path of the air flow (suction flow path) generated by the first air flow generating unit and the flow path of the air flow (pressure feeding flow path) generated by the second air flow generating unit as a material seal. Thereby, it is possible to suppress the backflow of air or powder and granular material from the pressure feeding flow path to the suction flow path (for example, the backflow of air or powder and granular material from the second relay tank to the first relay tank).

[0011] In the first aspect of the present invention, it is preferable that the first valve and the second valve are each a rotary valve. According to such a configuration, by rotationally driving each rotating body of the first valve and the second valve, the powder and granular material can be continuously fed out. Further, inside each of the first valve and the second valve, since the upstream side and the downstream side are sealed by the rotating body, it is possible to more preferably suppress the backflow of air or powder and granular material from the pressure feeding flow path to the suction flow path as described above.

[0012] In a first aspect of the present invention, the rotary valve includes a rotating body having a plurality of blade portions, and a case body that houses the rotating body and has openings at the top and bottom, and it is preferable that a tip portion of the blade portions facing the inner wall of the case body is formed of a soft material. According to such a configuration, when the granular material to be conveyed has a pellet shape, cracking and chipping of the granular material can be reduced.

[0013] The granular material conveying device according to the first aspect of the present invention preferably further includes a first level detection unit that detects the storage amount of the granular material in the first relay tank. In such a configuration, the control unit may control the first air flow generation unit or the first valve and the second valve based on the detection result by the first level detection unit. Thereby, the storage amount of the granular material in the first relay tank can be controlled.

[0014] The granular material conveying device according to the first aspect of the present invention preferably further includes a second level detection unit that detects the storage amount of the granular material in the second relay tank. In such a configuration, the control unit may control at least one of the first valve and the second valve based on the detection result by the second level detection unit. Thereby, the storage amount of the granular material in the second relay tank can be suitably controlled.

[0015] In a first aspect of the present invention, the first relay tank, the first air flow generation unit, the second relay tank, and the second air flow generation unit may be installed on an offshore platform together with the storage tank. According to such a configuration, when operating a replenishment ship for granular materials, it is not necessary to install a source of the conveying air flow on the replenishment ship, and the granular materials can be efficiently loaded onto the replenishment ship.

[0016] The granular material conveying device according to the first aspect of the present invention further includes a moving mechanism that moves the suction nozzle in the vertical direction, and it is preferable that the moving mechanism is operated wirelessly. According to such a configuration, the crew of the supply ship does not need to land on the platform, nor does the supply ship need to be brought alongside the platform. This can eliminate various procedures required for landing. Also, the possibility of the supply ship coming into contact with the platform and being damaged can be reduced.

[0017] The method for transporting powder and granular materials according to the second aspect of the present invention is a method for transporting powder and granular materials to a storage tank, which includes a suction step of sucking the powder and granular materials by a suction nozzle and supplying the powder and granular materials sucked by the suction nozzle to a first relay tank, a relay step of sending out the powder and granular materials in the first relay tank to a second relay tank arranged vertically below the first relay tank via a first valve connected to the lower part of the first relay tank, and a pressure feeding step of pressure feeding the powder and granular materials in the second relay tank to the storage tank via a second valve connected to the lower part of the second relay tank. While both the relay step and the pressure feeding step are being carried out, the storage amount of the powder and granular materials in the second relay tank is maintained at a predetermined lower limit level or higher. According to such a method, similar to the effect of the above-described powder and granular material conveying device, as the source of the conveying air flow, a suction source and a pressure feeding source can be used, so the capacity required for each source can be suppressed. Also, the powder and granular materials stored in the second relay tank can be utilized as a material seal. Therefore, while ensuring the conveying force of the conveying air flow at low cost, the backflow of air or powder and granular materials from the pressure feeding flow path to the suction flow path (for example, the backflow of air or powder and granular materials from the second relay tank to the first relay tank) can be suppressed.

[0018] In the second aspect of the present invention, the first valve and the second valve are each a rotary valve, and the second relay tank is provided with a level detection unit for detecting the storage amount of the powder and granular materials. While both the relay step and the pressure feeding step are being carried out, it is preferable to further carry out a control step of controlling the driving of at least one of the first valve and the second valve based on the detection result by the level detection unit. According to such a method, even when there are fluctuations in the storage amount of the granular material in the second relay tank, the storage amount of the granular material can be suitably maintained at a level not lower than the lower limit level.

[0019] In the second aspect of the present invention, during the period when both the relay step and the pressure feeding step are being carried out, and when the storage amount of the granular material in the second relay tank is not lower than the lower limit level, it is preferable that the amount of the granular material sent out per unit time by the second valve is equal to the amount of the granular material sent out per unit time by the first valve. By such a method, the storage amount of the granular material in the second relay tank can be suitably maintained at a level not lower than the lower limit level.

[0020] In the second aspect of the present invention, the relay step is carried out together with the suction step after the start of the suction step, and during the period when both the suction step and the relay step are being carried out, it is preferable that the amount of the granular material sent out per unit time by the first valve is equal to the amount of the granular material sucked per unit time by the suction nozzle. According to such a method, the storage amount of the granular material in the first relay tank can be maintained at a predetermined amount or more. Here, when the granular material in the first relay tank is in an amount that can function as a material seal for the lower opening of the first relay tank, the backflow of air or granular material from the pressure feeding flow path to the suction flow path as described above can be more suitably suppressed.

[0021] In the second aspect of the present invention, it is preferable that the granular material is fish feed for aquaculture. That is, the granular material conveying method according to the second aspect of the present invention can be suitably used for offshore aquaculture.

Advantages of the Invention

[0022] According to the present invention, it is possible to provide a granular material conveying device and a granular material conveying method that can suppress the backflow of air and granular material while ensuring the conveying force of the conveying air flow at low cost.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0024] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the powder and granular material conveying device 1 of the present embodiment is a device for conveying the powder and granular material P from the supply ship S to the storage tank 9 on the offshore platform PF. The platform PF is, for example, a steel structure, and may be a fixed type with the bottom fixed to the seabed or a floating type using a floating body. Further, the powder and granular material conveying device 1 of the present embodiment is installed on the platform PF, and the powder and granular material conveying device 1 and the storage tank 9 together constitute a powder and granular material storage system 100 on the platform PF. Hereinafter, the case where the powder and granular material storage system 100 is used for offshore aquaculture will be mainly described. In this case, the powder and granular material P is feed for aquaculture and has, for example, a pellet shape.

[0025] (Configuration of the powder and granular material conveying device 1) As shown in FIG. 2, the powder and granular material conveying device 1 includes a suction nozzle 2 for sucking the powder and granular material P, a moving mechanism 23 for moving the suction nozzle 2, a first relay tank 3 to which the powder and granular material P sucked by the suction nozzle 2 is supplied, a first air flow generating unit 4 for generating a suction air flow in the suction nozzle 2, a second relay tank 5 to which the powder and granular material P is supplied from the first relay tank 3, a second air flow generating unit 7 for generating a pressure feeding air flow for pressure-feeding the powder and granular material P supplied from the second relay tank 5 to the storage tank 9, and a control unit 8 for controlling the operation of each part of the powder and granular material conveying device 1.

[0026] The suction nozzle 2 is connected to the tip of the suction pipe 21 and is connected to the first relay tank 3 via this suction pipe 21. The suction nozzle 2 sucks the granular material P loaded on the supply ship S together with air, and sends the sucked granular material P and air to the first relay tank 3.

[0027] As shown in FIG. 1, the moving mechanism 23 arranges the suction nozzle 2 at an arbitrary position by moving each part of the suction pipe 21. Specifically, the suction pipe 21 has a configuration in which a tip pipe 211, a first flexible pipe 212, a curved pipe 213, a first main body pipe 214, a second flexible pipe 215, and a second main body pipe 216 are connected in sequence from the suction nozzle 2 toward the first relay tank 3. The moving mechanism 23 includes a traction mechanism 231 that pulls the first main body pipe 214, a rotation mechanism 232 that rotates the curved pipe 213 with respect to the first main body pipe 214, and a traction mechanism 233 that pulls the tip pipe 211. Each mechanism of the moving mechanism 23 is configured to be wirelessly operable from an operation terminal on the supply ship S. The traction mechanism 231 includes a wire connected to the first main body pipe 214 and a winch that winds up the wire, and can change the vertical position of the suction nozzle 2 by raising and lowering the first main body pipe 214. The rotation mechanism 232 includes a motor and a speed reducer, and can change the position of the suction nozzle 2 in the horizontal plane by rotating the curved pipe 213 with respect to the first main body pipe 214. When replenishing the granular material P, the suction nozzle 2 can be arranged at an arbitrary position on the supply ship S by operating the traction mechanism 231 and the rotation mechanism 232 respectively. The traction mechanism 233 includes a wire connected to the tip pipe 211 and a winch that winds up the wire. During the period when the replenishment of the granular material P is not performed, the traction mechanism 233 pulls the tip pipe 211 toward the platform PF side so that the suction nozzle 2 is arranged so as not to obstruct the passage of the ship. Also, at the start of the replenishment of the granular material P, the traction mechanism 233 moves the tip pipe 211 to the side away from the platform PF by releasing the wound-up wire, and arranges the suction nozzle 2 on the supply ship S.

[0028] In FIG. 2, the first relay tank 3 is a receiver tank that temporarily stores the powder P supplied from the suction nozzle 2. The upper opening 31 of the first relay tank 3 is connected to the suction nozzle 2 via the suction pipe 21, and the upper opening 32 of the first relay tank 3 is connected to the first airflow generating unit 4 via the suction pipe 41. The lower opening 33 of the first relay tank 3 is connected to the first valve 6A. The interior of the first relay tank 3 is maintained in a negative pressure state by the first airflow generating unit 4. In the first relay tank 3, among the powder P and air fed from the upper opening 31, the powder P descends due to gravity and accumulates at the bottom of the first relay tank 3. On the other hand, the air separates from the powder P in the first relay tank 3 and is inhaled into the first airflow generating unit 4 through the suction pipe 41 from the upper opening 32. The first valve 6A can continuously send out the powder P accumulated at the bottom of the first relay tank 3 from the lower opening 33 of the first relay tank 3.

[0029] Also, the first relay tank 3 is provided with a first level detection unit 34 for detecting the level (storage amount) of the powder P stored inside. In the present embodiment, the first level detection unit 34 is an upper limit sensor that detects that the storage amount of the powder P in the first relay tank 3 has reached the upper limit level LH1. Note that the detection method of the first level detection unit 34 is not particularly limited, and for example, it may be a contact type or an ultrasonic type. Also, the upper limit level LH1 of the powder P in the first relay tank 3 may be any level for preventing the inflow of the powder P into the upper opening 32.

[0030] The first airflow generating unit 4 is a vacuum generator such as a suction blower, for example, and is connected to the upper opening 32 of the first relay tank 3 via the suction pipe 41. The first airflow generating unit 4 generates a suction airflow from the suction nozzle 2 toward the first relay tank 3 by maintaining the interior of the first relay tank 3 in a negative pressure state. Note that a pressure gauge 42, a dust collector 43, a check valve 44, a flow meter 45, etc. may be provided between the first airflow generating unit 4 and the first relay tank 3.

[0031] The second relay tank 5 is a transport tank that temporarily stores the granular material P supplied from the first relay tank 3 via the first valve 6A. This second relay tank 5 is disposed vertically below the first relay tank 3 (see FIG. 1). Further, the upper opening 51 of the second relay tank 5 is connected to the first valve 6A, and the lower opening 52 of the second relay tank 5 is connected to the second valve 6B. The inside of the second relay tank 5 is at approximately atmospheric pressure. In the second relay tank 5, the granular material P fed from the upper opening 51 descends by gravity and accumulates at the bottom of the second relay tank 5. The second valve 6B can continuously send out the granular material P accumulated at the bottom of the second relay tank 5 from the lower opening 52 of the second relay tank 5.

[0032] Also, the second relay tank 5 is provided with a second level detector 53 for detecting the level (storage amount) of the granular material P stored therein. In the present embodiment, the second level detector 53 includes an upper limit sensor 53A for detecting that the storage amount of the granular material P in the second relay tank 5 has reached the upper limit level LH2, and a lower limit sensor 53B for detecting that the storage amount of the granular material P in the second relay tank 5 has reached the lower limit level LL2. Note that the detection method of the second level detector 53 is not particularly limited, and for example, it may be a contact type or an ultrasonic type.

[0033] Here, the upper limit level LH2 of the granular material P in the second relay tank 5 may be any level as long as the granular material P does not reach the upper opening 51. For example, it is 90% by volume with respect to the volume of the second relay tank 5. Further, the lower limit level LL2 of the granular material P in the second relay tank 5 is a preset level, and it is sufficient that at least the granular material P covers the lower opening 52 of the second relay tank 5 and the granular material P can seal the lower opening 52 as a material seal. For example, it is within the range of 30 to 40% by volume with respect to the volume of the second relay tank 5.

[0034] The first valve 6A and the second valve 6B are each rotary valves. Here, FIG. 3 is a diagram schematically showing the configuration of the first valve 6A (or the second valve 6B). As shown in FIG. 3, the first valve 6A and the second valve 6B each include a case body 61, a rotor 62 rotatably supported within the case body 61, and a motor 63 (see FIG. 2) that rotates the rotation axis 621 of the rotor 62. The case body 61 has an upper opening 611 that opens upward and a lower opening 612 that opens downward, and the space between the upper opening 611 and the lower opening 612 is sealed by the rotor 62. The rotor 62 includes a rotation axis 621 and a plurality of blade portions 622 that project radially at equal angles from around the rotation axis 621. The tip portions 623 of the blade portions 622 face the inner wall of the case body 61. Note that there is a slight gap between the tip portions 623 of the blade portions 622 and the inner wall of the case body 61 such that the rotor 62 can rotate without problems. While most of the case body 61 and the rotor 62 are made of metal, the tip portions 623 of the blade portions 622 are formed of a soft material such as rubber or resin.

[0035] Also, as shown in FIG. 2, each motor 63 of the first valve 6A and the second valve 6B is driven and controlled by the control unit 8. Thereby, the first valve 6A controls the amount of powder P delivered per unit time from the lower opening 33 of the first relay tank 3, and the second valve 6B controls the amount of powder P delivered per unit time from the lower opening 52 of the second relay tank 5.

[0036] The second airflow generation unit 7 is an air compressor such as a pressure blower, and sends a pressure airflow into the transport pipe 71. An ejector 72 is provided in the transport pipe 71, and the second valve 6B is connected to this ejector 72. The ejector 72 generates an airflow from the second valve 6B toward the ejector 72 by the pressure airflow sent from the second airflow generation unit 7. The powder P sent out from the second valve 6B flows into the transport pipe 71 via the ejector 72. Note that a pressure gauge 73, a check valve 74, etc. may be provided between the second airflow generation unit 7 and the ejector 72.

[0037] A switching valve 75 is provided between an ejector 72 and a plurality of storage tanks 9 in a transfer pipe 71. That is, the transfer pipe 71 has an upstream pipe 711 connecting between the second air flow generating unit 7 and the inlet of the switching valve 75, and a plurality of downstream pipes 712 connecting between each outlet of the switching valve 75 and the storage tank 9. The switching valve 75 is controlled by a control unit 8 to allow the upstream pipe 711 to communicate with the downstream pipe 712 corresponding to the storage tank 9 which is the transfer destination. The granular material P flowing through the transfer pipe 71 is transferred to the storage tank 9 which is the transfer destination. In FIG. 2, one switching valve 75 and two storage tanks 9 are illustrated, but three or more storage tanks 9 may be connected by combining a plurality of switching valves 75.

[0038] The control unit 8 is configured by combining a dedicated driver with an existing computer system, and controls the operations of each part of the granular material conveying apparatus 1 by executing a program stored in a storage area. For example, the control unit 8 controls at least one of the first valve 6A and the second valve 6B so that the storage amount of the granular material P in the second relay tank 5 is maintained at or above the lower limit level LL2. In FIG. 2, control lines related to the control of the first valve 6A and the second valve 6B are illustrated.

[0039] In this embodiment, the storage tank 9 is a tank for storing the granular material P, and is assumed to have a larger volume than the first relay tank 3 and the second relay tank 5. An upper limit sensor 91 and a lower limit sensor 92 are provided in the storage tank 9 as level detection units for detecting the level (storage amount) of the granular material P stored inside. Further, the outlet 93 of the storage tank 9 is connected to a rotary valve 101, and the rotary valve 101 is connected to a supply pipe 102 via an ejector 103. A plurality of supply pipes 102 corresponding to the plurality of storage tanks 9 are connected to one airflow generation unit 105, and a check valve 104 is provided between the airflow generation unit 105 and each ejector 103. The check valve 104 communicates a flow path from the airflow generation unit 105 toward the supply pipe 102 corresponding to the storage tank 9 to be conveyed. The granular material P sent out from the outlet 93 of the storage tank 9 is conveyed to the tip of the supply pipe 102 (not shown) by the conveying airflow generated in the supply pipe 102 by the airflow generation unit 105. The tip of the supply pipe 102 may constitute a supply port arranged in the bamboo mat, or may be connected to a supply tank installed near the bamboo mat.

[0040] (Conveying method) A conveying method using the granular material conveying device 1 of this embodiment will be described. First, as shown in FIG. 1, a supply ship S loaded with the granular material P anchors near the platform PF. At this time, the crew of the supply ship S does not need to land on the platform PF, and the supply ship S does not need to come alongside the platform PF.

[0041] The crew of the supply ship S wirelessly operates the moving mechanism 23 and arranges the suction nozzle 2 directly above the granular material P on the supply ship S. Then, a supply start instruction is wirelessly transmitted to the control unit 8. The control unit 8 switches the state of the switching valve 75 so that the outlet of the switching valve 75 communicates with the storage tank 9 as the conveyance destination.

[0042] Then, the control unit 8 starts driving the first airflow generation unit 4, opening the check valve 44 in the suction pipe 41, and generating a suction airflow in the suction nozzle 2. Thereby, the suction nozzle 2 sucks the powder and granule P (suction step). Here, at the initial stage of the suction step, by continuously sucking the suction nozzle 2 for a predetermined time with the first valve 6A in the closed state, the powder and granule P is stored in the first relay tank 3 at a level equal to or higher than a predetermined level. It is preferable that this predetermined level is a level at which the powder and granule P can function as a material seal against the lower opening 33 of the first relay tank 3.

[0043] After a predetermined time has elapsed since the start of sucking the powder and granule P (that is, after the completion of the initial stage of the suction step), the control unit 8 starts driving the first valve 6A. Then, the powder and granule P in the first relay tank 3 is continuously sent out from the first valve 6A (relay step). Here, the control unit 8 controls the driving of the first valve 6A based on the measurement value by the flow meter 45. Specifically, the control unit 8 controls the driving of the first valve 6A so that the delivery amount per unit time by the first valve 6A is equal to the suction amount per unit time of the powder and granule P by the suction nozzle 2. Also, at the initial stage of the relay step, with the second valve 6B in the closed state, the powder and granule P is sent out from the first relay tank 3 for a predetermined time, so that the powder and granule P is stored in the second relay tank 5 at a level equal to or higher than the lower limit level LL2.

[0044] After a predetermined time has elapsed since the lower limit sensor 53B detected that the storage amount of the powder and granule P in the second relay tank 5 has reached a level equal to or higher than the lower limit level LL2 (that is, after the completion of the initial stage of the relay step), the control unit 8 starts driving the second valve 6B. In addition, the control unit 8 starts driving the second airflow generation unit 7, opening the check valve 74 in the conveyance pipe 71, and generating a pressure feed airflow in the conveyance pipe 71. Thereby, the powder and granule P in the second relay tank 5 is continuously sent out from the lower opening 52 and pneumatically conveyed to the storage tank 9 through the conveyance pipe 71 (pressure feed step). Here, the control unit 8 controls the drive of the second valve 6B so that the delivery amount of the granular material P per unit time by the second valve 6B is equal to the delivery amount of the granular material P per unit time by the first valve 6A. Thereby, the storage amounts of the granular material P in the first relay tank 3 and the second relay tank 5 are maintained respectively.

[0045] Thereafter, until the upper limit sensor 91 in the storage tank 9 to be conveyed detects the granular material P, the above-described suction process, relay process, and pressure feeding process are each continued, and the granular material P is pneumatically conveyed from the supply ship S to the storage tank 9.

[0046] Here, while the suction process, relay process, and pressure feeding process are all being performed, the control unit 8 monitors the storage amount of the granular material P in the first relay tank 3 by the first level detection unit 34 and monitors the storage amount of the granular material P in the second relay tank 5 by the second level detection unit 53, and controls at least one of the first valve 6A or the second valve 6B (control process). For example, when the storage amount of the granular material P in the second relay tank 5 becomes less than the lower limit level LL2, the control unit 8 may temporarily stop the drive of the second valve 6B, or may temporarily decrease the delivery amount of the second valve 6B. On the other hand, when the storage amount of the granular material P in the second relay tank 5 becomes equal to or higher than the upper limit level LH2, the control unit 8 may temporarily stop the drive of the first valve 6A, or may temporarily decrease the delivery amount of the first valve 6A. Further, when the storage amount of the granular material P in the first relay tank 3 becomes equal to or higher than the upper limit level LH1, the control unit 8 may decrease the flow rate of the suction air flow generated by the first air flow generation unit 4, or may temporarily stop the first air flow generation unit 4. Alternatively, the control unit 8 may temporarily increase the respective delivery amounts by the first valve 6A and the second valve 6B. Thereby, the storage amounts of the first relay tank 3 and the second relay tank 5 are maintained within a predetermined range even if unintended fluctuations occur.

[0047] When the upper limit sensor 91 in the storage tank 9 to be conveyed detects the powder P, the feeding of the powder P by the first valve 6A and the second valve 6B is stopped, and the conveyance of the powder P to the storage tank 9 is completed. Thereafter, the switching valve 75 may be controlled to convey the powder P to another storage tank 9 as the conveyance target. Note that the powder P may be supplied to a supply destination such as a raw silk basket while the powder P is being conveyed to the storage tank 9.

[0048] (Effect of this Embodiment) As described above, the powder conveying apparatus 1 of this embodiment includes a suction nozzle 2 that sucks the powder P, a first relay tank 3 to which the powder P sucked by the suction nozzle 2 is supplied, a first airflow generating unit 4 that generates a suction airflow in a suction pipe 21 between the suction nozzle 2 and the first relay tank 3, a first valve 6A connected to the lower part of the first relay tank 3, a second relay tank 5 disposed vertically below the first relay tank 3 and supplied with the powder P from the first relay tank 3 via the first valve 6A, a second valve 6B connected to the lower part of the second relay tank 5, a second airflow generating unit 7 that generates a pressure-feeding airflow in a flow path between the second valve 6B and the storage tank 9, and a control unit 8 that controls at least one of the first valve 6A and the second valve 6B so that the storage amount of the powder P in the second relay tank 5 is maintained at a predetermined lower limit level LL2 or higher.

[0049] In such an embodiment, the first airflow generating unit 4 generates a suction airflow in the flow path from the suction nozzle 2 to the first relay tank 3, and the second airflow generating unit 7 generates a pressure-feeding airflow in the flow path from the second relay tank 5 to the storage tank 9. As a result, while suppressing the capacities of the first airflow generating unit 4 and the second airflow generating unit 7, it is possible to secure the conveying force of the conveying airflow required for each flow path. Further, due to the positional relationship between the first relay tank 3 and the second relay tank 5, the powder P in the first relay tank 3 can be conveyed to the second relay tank 5 mainly by gravity. Thereby, the conveying force of the conveying airflow can be secured at low cost. In addition, in the present embodiment, the storage amount of the granular material P in the second relay tank 5 is maintained at a predetermined lower limit level LL2 or higher. The granular material P in the second relay tank 5 functions as a material seal for the lower opening 52 of the second relay tank 5, and can seal between the flow path (suction flow path) of the air flow generated by the first air flow generating unit 4 and the flow path (pressure feeding flow path) of the air flow generated by the second air flow generating unit 7. Thereby, the backflow of air or granular material P from the pressure feeding flow path to the suction flow path (for example, the backflow of air or granular material P from the second relay tank 5 to the first relay tank 3) can be suppressed.

[0050] Such a granular material conveying device 1 can be suitably used for a granular material storage system 100 for offshore aquaculture. For example, even when there is a large elevation difference in the flow path from the supply ship S to the upper part of the storage tank 9, the conveyance can be performed without problems. In addition, the conveyance can be performed in a short time during a time when the sea state conditions are good, and the influence of the change in the sea state in the offshore can be avoided.

[0051] In the present embodiment, the first valve 6A and the second valve 6B are each a rotary valve. According to such a configuration, by rotationally driving each rotating body 62 of the first valve 6A and the second valve 6B, the granular material P can be continuously sent out. Further, inside each of the first valve 6A and the second valve 6B, since the space between the upper opening 611 and the lower opening 612 is sealed by the rotating body 62, the backflow of air or granular material P from the pressure feeding flow path to the suction flow path as described above can be more suitably suppressed.

[0052] In the present embodiment, each of the first valve 6A and the second valve 6B includes a rotating body 62 having a plurality of blade portions 622, and a case body 61 that houses the rotating body 62 and has an upper opening 611 and a lower opening 612. The tip portion 623 of the blade portion 622 that faces the inner wall of the case body 61 is made of a soft material. According to such a configuration, the sealing performance inside each of the first valve 6A and the second valve 6B can be improved. Further, when the granular material P to be conveyed has a pellet shape, cracking and chipping of the granular material P can be reduced.

[0053] The granular material conveying device 1 of this embodiment further includes a first level detector 34 for detecting the storage amount of the granular material P in the first relay tank 3. In such a configuration, the control unit 8 may control the first air flow generating unit 4 or the first valve 6A and the second valve 6B based on the detection result by the first level detector 34. Thereby, the storage amount of the granular material P in the first relay tank 3 can be controlled.

[0054] The granular material conveying device 1 of this embodiment further includes a second level detector 53 for detecting the storage amount of the granular material P in the second relay tank 5. In such a configuration, the control unit 8 may control at least one of the first valve 6A or the second valve 6B based on the detection result by the second level detector 53. Thereby, the storage amount of the granular material P in the second relay tank 5 can be controlled.

[0055] In this embodiment, the first relay tank 3, the first air flow generating unit 4, the second relay tank 5, and the second air flow generating unit 7 are installed on the offshore platform PF together with the storage tank 9. According to such a configuration, it is not necessary to install the source of the conveying air flow on the supply ship S, and the granular material P can be efficiently loaded onto the supply ship S.

[0056] The granular material conveying device 1 of this embodiment further includes a moving mechanism 23 for moving the suction nozzle 2 in the vertical direction, and the moving mechanism 23 is operated wirelessly. According to such a configuration, it is not necessary for the crew on the supply ship S to land on the platform PF, nor is it necessary to bring the supply ship S alongside the platform PF. Thereby, various procedures required for landing can be omitted. In addition, the possibility that the supply ship S contacts the platform PF and is damaged can be reduced.

[0057] As described above, the method for transporting powder and granular materials according to this embodiment includes a suction step of sucking the powder and granular materials P by the suction nozzle 2 and supplying the powder and granular materials P sucked by the suction nozzle 2 to the first relay tank 3, and a relay step of sending out the powder and granular materials P in the first relay tank 3 to the second relay tank 5 arranged vertically below the first relay tank 3 via the first valve 6A connected to the lower part of the first relay tank 3, and a pressure feeding step of pressure feeding the powder and granular materials P in the second relay tank 5 to the storage tank 9 via the second valve 6B connected to the lower part of the second relay tank 5. While both the relay step and the pressure feeding step are being carried out, the storage amount of the powder and granular materials P in the second relay tank 5 is maintained at a predetermined lower limit level LL2 or higher. According to such a method, similar to the effect of the above-described powder and granular material conveying device 1, the capacity required for the sources of the conveying air flow (the first air flow generating part 4 and the second air flow generating part 7) can be suppressed. Also, the powder and granular materials P deposited in the second relay tank 5 can be utilized as a material seal. Therefore, while ensuring the conveying force of the conveying air flow at low cost, backflow of air or powder and granular materials P from the pressure feeding flow path to the suction flow path (for example, backflow of air or powder and granular materials P from the second relay tank 5 to the first relay tank 3) can be suppressed. Moreover, the method for transporting powder and granular materials according to this embodiment can be suitably used for offshore aquaculture by using the feed for aquaculture as the powder and granular materials P.

[0058] In this embodiment, the second relay tank 5 is provided with a second level detection part 53 for detecting the storage amount of the powder and granular materials P. While both the relay step and the pressure feeding step are being carried out, a control step of controlling the driving of at least one of the first valve 6A and the second valve 6B is further carried out based on the detection result by the second level detection part 53. According to such a method, even when the storage amount of the powder and granular materials P in the second relay tank 5 fluctuates, the storage amount of the powder and granular materials P can be suitably maintained at the lower limit level LL2 or higher.

[0059] In the present embodiment, when the relay process and the pressure feeding process are both being carried out and the storage amount of the granular material P in the second relay tank 5 is equal to or higher than the lower limit level LL2, the amount of the granular material P discharged per unit time by the second valve 6B is equal to the amount of the granular material P discharged per unit time by the first valve 6A. According to such a method, the storage amount of the granular material P in the second relay tank 5 can be suitably maintained at a level equal to or higher than the lower limit level LL2.

[0060] In the present embodiment, the relay process is carried out together with the suction process after the start of the suction process. During the period when both the suction process and the relay process are being carried out, the amount of the granular material discharged per unit time in the relay process is equal to the amount of the granular material sucked per unit time in the suction process. According to such a method, the storage amount of the granular material P in the first relay tank can be maintained at a predetermined amount or more. Here, when the granular material P in the first relay tank 3 is in an amount that can function as a material seal for the lower opening 33 of the first relay tank 3, the backflow of air or the granular material P from the pressure feeding flow path to the suction flow path as described above can be more suitably suppressed. Furthermore, in the present embodiment, the suction process, the relay process, and the pressure feeding process are all continuously carried out together, not in batch units. Thereby, the time required for conveyance can be shortened.

[0061] (Modification example) The present invention is not limited to the above-described embodiment, and modifications and the like within the scope that can achieve the object of the present invention are included in the present invention. In the above embodiment, the first valve 6A and the second valve 6B are each rotary valves, and the tip 623 of the blade part 622 is formed of a soft material. However, the specific configurations of the first valve 6A and the second valve 6B are not particularly limited. For example, the first valve 6A and the second valve 6B may each be general rotary valves. Alternatively, as at least one of the first valve 6A and the second valve 6B, a valve other than a rotary valve (for example, a gate valve or a butterfly valve) may be used.

[0062] In the above embodiment, the first level detection unit 34 provided in the first relay tank 3 is an upper limit sensor, but it may include an upper limit sensor and a lower limit sensor. In this case, the control unit 8 may control at least one of the first air flow generation unit 4 or the first valve 6A so that the powder material P in the first relay tank 3 as well as the second relay tank 5 maintains a predetermined amount or more (for example, a level at which material sealing is possible).

[0063] In the above embodiment, the powder material conveying device 1 may not include the first level detection unit 34 and the second level detection unit 53. For example, the control unit 8 may control the first valve 6A and the second valve 6B based on each measured value such as the flow meter 45 and the pressure gauges 42, 73. Alternatively, the first valve 6A and the second valve 6B may be driven according to a preset delivery amount. That is, the control process for controlling the delivery amounts of the first valve 6A and the second valve 6B by the control unit 8 may not be performed.

[0064] In the above embodiment, the suction process, the relay process, and the pressure feeding process are all implemented, but the present invention is not limited thereto. For example, when the capacity of the first relay tank 3 is sufficient, the relay process and the pressure feeding process may be implemented during a temporary stop of the suction process. Also, in the above embodiment, after a predetermined amount of the powder material P is stored in the first relay tank 3 by the suction process, the relay process is started, but the present invention is not limited thereto. That is, the material seal by the powder material P may be realized at least in the second relay tank 5 and may not be realized in the first relay tank 3. Also, in the above embodiment, the suction amount per unit time of the powder material P by the suction nozzle 2, the delivery amount per unit time of the powder material P by the first valve 6A, and the delivery amount per unit time of the powder material P by the second valve 6B can be arbitrarily set and may be different from each other.

[0065] In the above-described embodiment, the case where the powder and granular material storage system 100 including the powder and granular material conveying device 1 is used for offshore aquaculture has been mainly described, but the present invention is not limited thereto. For example, the powder and granular material P may be a powder such as wheat or a granular material such as a wood pellet. The powder and granular material conveying device 1 and the storage tank 9 may be installed not on the offshore platform PF but at a port or the like.

Explanation of Reference Numerals

[0066] 1... Powder and granular material conveying device, 2... Suction nozzle, 21... Suction pipe, 211... Tip pipe, 23... Moving mechanism, 231... Towing mechanism, 3... First relay tank, 31... Upper opening, 32... Upper opening, 33... Lower opening, 232... Rotating mechanism, 34... First level detection unit, 4... First air flow generation unit, 41... Suction pipe, 42... Pressure gauge, 43... Dust collector, 44... Check valve, 45... Flow meter, 5... Second relay tank, 51... Upper opening, 52... Lower opening, 53... Second level detection unit, 53A... Upper limit sensor, 53B... Lower limit sensor, 6A... First valve, 6B... Second valve, 61... Case body, 611... Upper opening, 612... Lower opening, 62... Rotating body, 621... Rotating shaft, 622... Blade part, 623... Tip part, 63... Motor, 7... Second air flow generation unit, 71... Conveying pipe, 711... Upstream pipe, 712... Downstream pipe, 72... Ejector, 73... Pressure gauge, 74... Check valve, 75... Changeover valve, 8... Control unit, 9... Storage tank, 91... Upper limit sensor, 92... Lower limit sensor, 93... Outlet, 100... Powder and granular material storage system, 101... Rotary valve, 102... Supply pipe, 103... Ejector, 104... Check valve, 105... Air flow generation unit, P... Powder and granular material, PF... Platform, S... Supply ship.

Claims

1. A powder conveying device for conveying powder to a storage tank, comprising: a suction nozzle for sucking the powder; a first relay tank to which the powder sucked by the suction nozzle is supplied; a first air flow generating unit for generating a suction air flow in a flow path between the suction nozzle and the first relay tank; a first valve connected to a lower portion of the first relay tank; a second relay tank disposed vertically below the first relay tank and to which the powder is supplied from the first relay tank via the first valve; a second valve connected to a lower portion of the second relay tank; a second air flow generating unit for generating a pressure feeding air flow in a flow path between the second valve and the storage tank; a control unit for controlling at least one of the first valve or the second valve so as to maintain the storage amount of the powder in the second relay tank at a predetermined lower limit level or higher.

2. The powder conveying device according to claim 1, wherein the first valve and the second valve are each a rotary valve.

3. The rotary valve comprises: a rotating body having a plurality of blade portions; a case body that houses the rotating body and has openings at upper and lower portions thereof, wherein a tip portion of the blade portions facing an inner wall of the case body is formed of a soft material.

4. The powder conveying device according to claim 1, further comprising a first level detection unit for detecting a storage amount of the powder in the first relay tank.

5. The powder conveying device according to claim 1, further comprising a second level detection unit for detecting a storage amount of the powder in the second relay tank.

6. The powder conveying device according to claim 1, wherein the first relay tank, the first air flow generating unit, the second relay tank, and the second air flow generating unit are installed on an offshore platform together with the storage tank.

7. The powder conveying device according to claim 6, further comprising a moving mechanism for moving the suction nozzle in a vertical direction, wherein the moving mechanism is operated wirelessly.

8. A powder conveying method for conveying powder to a storage tank, comprising: a suction step of sucking the powder by a suction nozzle and supplying the powder sucked by the suction nozzle to a first relay tank; A relay step of sending the powder in the first relay tank through a first valve connected to the lower part of the first relay tank to a second relay tank disposed vertically below the first relay tank; A pressure feeding step of pressure-feeding the powder in the second relay tank to the storage tank through a second valve connected to the lower part of the second relay tank, are carried out. A method for transporting powder, wherein the storage amount of the powder in the second relay tank is maintained at a predetermined lower limit level or higher while both the relay step and the pressure feeding step are carried out.

9. The method for transporting powder according to claim 8, wherein the first valve and the second valve are each a rotary valve.

10. A level detection unit for detecting the storage amount of the powder is provided in the second relay tank. The method for transporting powder according to claim 8, further comprising a control step of controlling the driving of at least one of the first valve and the second valve based on a detection result by the level detection unit while both the relay step and the pressure feeding step are carried out.

11. When the storage amount of the powder in the second relay tank is equal to or higher than the lower limit level while both the relay step and the pressure feeding step are carried out, the amount of the powder sent out per unit time by the second valve is equal to the amount of the powder sent out per unit time by the first valve. The method for transporting powder according to claim 10.

12. The relay step is carried out together with the suction step after the start of the suction step. The method for transporting powder according to claim 10 or claim 11, wherein the amount of the powder sent out per unit time by the first valve is equal to the amount of the powder sucked per unit time by the suction nozzle while both the suction step and the relay step are carried out.

13. The method for transporting powder according to claim 8, wherein the powder is a feed for aquaculture.

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