JP2024011670A - Pneumatic unloader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce maintenance frequency by eliminating clearance adjustment work.

SOLUTION: A pneumatic unloader comprises: a receiver tank 2 storing a sucked load; a first slide gate G1 and a second slide gate G2 provided in series in the order from below at an outlet portion 31 of the receiver tank; a first level sensor S1 for detecting the presence or absence of a load at a position between the first slide gate and the second slide gate; a second level sensor S2 for detecting the presence or absence of a load at a position above the second slide gate; and a control device E controlling the first slide gate and the second slide gate on the basis of the detection result of the first level sensor and the second level sensor.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present disclosure relates to pneumatic unloaders.

In general, ports are equipped with pneumatic unloaders that suck up bulk loads such as grains transported by ships and unload them.

This pneumatic unloader is equipped with a rotary feeder to discharge (cut out) the sucked up load at a substantially constant flow rate. By adjusting the gap between the blade at the tip of the rotor and the side cover and casing, the rotary feeder minimizes air leakage and efficiently discharges the load from the vacuum side to the atmosphere side. .

The position of the blades and the gap can be adjusted by attaching bolts inserted into the long holes of the blades to the rotor. As the blades wear out over long periods of use, the gaps become larger, increasing the amount of air leakage and reducing efficiency. Therefore, in such a case, adjustments are made to reduce the gap by shifting the mounting position of the blade.

JP2022-49771A

However, rotary feeders pose problems in terms of adjustment and maintenance due to blade wear. As the blade wears, its position needs to be adjusted and eventually the blade needs to be replaced. Such maintenance work must be performed in a narrow space on the unloader machine. Further, the rotary feeder may be transported to a factory for maintenance, and in this case, the rotary feeder must be removed in a narrow space on the unloader machine.

Further, even if the gap is adjusted, since the gap inevitably exists due to the structure, air leakage is unavoidable and may have a negative effect on the efficiency of the unloader.

The present disclosure has been devised in view of the above circumstances, and one purpose thereof is to provide a pneumatic unloader that can reduce maintenance frequency by eliminating clearance adjustment work.

Another object of the present disclosure is to provide a pneumatic unloader that can reduce the amount of leakage air by reducing the gap and improve efficiency.

According to one aspect of the present disclosure,
a receiver tank that stores the sucked load;
a first slide gate and a second slide gate provided in series from below at the outlet portion of the receiver tank;
a first level sensor for detecting the presence or absence of a load at a position between the first slide gate and the second slide gate;
a second level sensor for detecting the presence or absence of a load at a position above the second slide gate;
a control device that controls the first slide gate and the second slide gate based on detection results of the first level sensor and the second level sensor;
A pneumatic unloader is provided.

Preferably, the control device controls the first slide gate and the second slide gate so that a space in the receiver tank between the first slide gate and the first level sensor is filled with a load.

Preferably, the pneumatic unloader includes a third level sensor for detecting the presence or absence of a load at a position above the second level sensor,
The control device controls the first slide gate and the second slide gate based also on the detection result of the third level sensor.

Preferably, the pneumatic unloader includes a third slide gate located below the first slide gate.

Preferably, when the first slide gate or the second slide gate does not open even if an opening command is sent to the fully closed first slide gate or the second slide gate, the control device controls the third slide gate. Fully close the slide gate.

According to the present disclosure, maintenance frequency can be reduced by eliminating clearance adjustment work. In addition, the gap can be reduced to reduce the amount of leaked air and improve efficiency.

FIG. 1 is a schematic diagram of a pneumatic unloader according to an embodiment of the present disclosure. FIG. 2 is a side cross-sectional view showing the delivery device of the present embodiment. It is a top view which shows a fixed gate member. It is a top view which shows a movable gate member. It is a top view which shows the 1st slide gate when it is fully open. FIG. 3 is a side cross-sectional view showing the first slide gate when fully opened. FIG. 3 is a side cross-sectional view showing the first slide gate when it is half open. FIG. 3 is a side cross-sectional view showing the first slide gate when fully closed. It is a flowchart which shows the content of normal control in a sending-out apparatus. 3 is a flowchart showing the contents of diagnostic recovery control.

Embodiments of the present disclosure will be described below with reference to the accompanying drawings. Note that the present disclosure is not limited to the following embodiments.

As shown in FIG. 1, a ship S is anchored at a port, with cargo B, which is bulk goods such as grain, loaded in a hold K. A pneumatic unloader (hereinafter simply referred to as an unloader) 100 is installed on the quay Q of the port for sucking up and discharging the cargo B stored in the hold K. For convenience, the front, back, left, right, top and bottom directions are defined as shown in the figure.

A pair of rails R extending along the quay Q are installed, and the unloader 100 is equipped with a traveling frame 1 capable of traveling on the rails R. The unloader 100 also includes a receiver tank 2 that is rotatable on the traveling frame 1. The receiver tank 2 is pivotable with respect to the traveling frame 1 around a pivot axis C1 extending in the vertical direction as shown by an arrow a.

One end of an air suction pipe 3 is connected to the top of the receiver tank 2, and the other end of the air suction pipe 3 is connected to a vacuum pump 4 made of, for example, a Roots blower. The vacuum pump 4 is installed in a machine room 5 connected to the receiver tank 2.

A base end of a horizontal pipe 6 extending in the horizontal direction is connected via a ball joint 19 to an input port 35 (see FIG. 2) which is an inlet for the load B of the receiver tank 2 . The horizontal pipe 6 can be expanded and contracted in its longitudinal direction as shown by arrow b, so that the position of a nozzle 7, which is a suction port for the load B, in the horizontal direction or in the longitudinal direction of the horizontal pipe can be adjusted.

A base end of a boom 8 shown by a phantom line is attached to the receiver tank 2 so as to be movable up and down as shown by an arrow c. The horizontal pipe 6 is attached along the boom 8 and can be raised and lowered together with the boom 8. In the illustrated example, the horizontal pipe 6 and the boom 8 extend toward the sea side or the ship S side (front side).

At the distal end of the horizontal tube 6, the base end of a bent tube 9 bent 90 degrees downward is integrally attached. A base end or an upper end of a vertical pipe 10 extending in the vertical direction is connected to the tip of the curved pipe 9 via a swing joint 11 so as to be rotatable as shown by an arrow d.

During cargo handling work, the vertical pipe 10 is inserted into the hold K of the ship S through the hatch H. The vertical pipe 10 can be expanded and contracted in its longitudinal direction as shown by the arrow e, so that the height position of the nozzle 7 can be adjusted according to the height position of the cargo B or the ship S.

A nozzle 7 is attached to the top or bottom end of the vertical tube 10. The nozzle 7 is brought close to or in contact with the cargo B in the cargo hold K, and sucks the cargo B in the cargo hold K.

In order to be able to finely adjust the position and orientation of the nozzle 7, the upper and lower ends of the vertical tube 10 are formed by flexible tubes 12.

A filter, ie, a bag filter 13, is provided at the upper end of the receiver tank 2 to prevent the load B from being sucked toward the vacuum pump 4.

Further, a chute 14 is provided below the receiver tank 2, so that the load B discharged from the outlet of the receiver tank 2 is dropped and supplied to one end of the in-machine conveyor 15.

A ground chute 16 is provided at the other end of the in-machine conveyor 15 and projects downward. The load B conveyed to the other end of the in-machine conveyor 15 is dropped and supplied to the ground conveyor 17 through the ground chute 16. In this embodiment, a plurality of (two) ground chutes 16 are provided corresponding to a plurality of (two) ground conveyors 17. A slide gate 18 is provided at the upper end of each ground chute 16, so that the ground chute 16 used for supplying the load B to the ground conveyor 17 can be selected.

Note that the chute 14 and the in-machine conveyor 15 are installed on the traveling frame 1 side and do not rotate together with the receiver tank 2. The number of ground chute 16 may be one, and the slide gate 18 may be omitted.

Conventionally, a rotary feeder as a vacuum cutting device or a feeding device is provided in the middle of the chute 14, and the discharge flow rate of the load B to the in-machine conveyor 15 (the amount of load B discharged per unit time) is controlled by this rotary feeder. It was controlled to be approximately constant, and the vacuum side and the atmosphere side were isolated. That is, the upper side of the rotary feeder is the vacuum side, and the lower side is the atmosphere side.

However, when a rotary feeder is used, the above-mentioned problems occur, that is, troublesome maintenance and a decrease in efficiency due to gaps.

Therefore, in this embodiment, another feeding device is installed in place of the rotary feeder, and the above problem is solved using this.

FIG. 2 shows the feeding device of this embodiment. The delivery device 30 includes the above-mentioned receiver tank 2 that stores the sucked load B, and a first slide gate G1 and a second slide gate G2 that are provided in series from the bottom at the outlet portion 31 of the receiver tank 2. Equipped with.

The feeding device 30 also includes a first level sensor S1 for detecting the presence or absence of the load B at a position between the first slide gate G1 and the second slide gate G2, and a first level sensor S1 for detecting the presence or absence of the load B at a position above the second slide gate G2. a second level sensor S2 for detecting the presence of Be prepared.

Further, the delivery device 30 of this embodiment includes a third level sensor S3 for detecting the presence or absence of the load B at a position above the second level sensor S2. The control device E controls the first slide gate G1 and the second slide gate G2 based also on the detection result of the third level sensor S3.

Further, the feeding device 30 of this embodiment includes a third slide gate G3 provided at a position below the first slide gate G1.

Each part will be explained in detail below. The receiver tank 2 is a vertically long cylindrical container having a central axis C2 coaxial with the rotation axis C1. Hereinafter, the axial direction, radial direction, and circumferential direction with respect to the central axis C2 will be simply referred to as the axial direction, radial direction, and circumferential direction.

The receiver tank 2 includes a main cylinder part 32 having a constant radius, a tapered cylinder part 33 connected to the lower end of the main cylinder part 32 and gradually decreasing in diameter as it goes downward, and a main cylinder part connected to the lower end of the tapered cylinder part 33. and an outlet tube 34 having a constant radius smaller than 32. At a predetermined height position of the main cylinder portion 32, an input port 35 for supplying or inputting the load B into the receiver tank 2 is connected diagonally downward. This input port 35 is connected to the ball joint 19 shown in FIG. 1, and receives the load B from the ball joint 19. The outlet cylinder portion 34 defines an outlet 36 for the load B in the receiver tank 2 . The outlet tube portion 34 is connected in series to the chute 14 described above.

The first slide gate G1 and the second slide gate G2 are provided at a height below the input port 35 in the main cylinder portion 32. The first slide gate G1 is located at a height near the lower end of the main cylinder portion 32, and the second slide gate G2 is located at a height that is a predetermined distance higher than the first slide gate G1. The third slide gate G3 is provided in the outlet tube portion 34. These slide gates G1 to G3 open and close the corresponding cylinder portions to allow or block the flow of cargo.

Since each slide gate has substantially the same configuration, the first slide gate G1 will be explained here as an example.

FIG. 2 is a side sectional view showing the first slide gate G1 when it is fully opened. FIG. 3 is a plan view showing the fixed gate member 37, which is a component of the first slide gate G1. FIG. 4 is a plan view showing the movable gate member 38, which is a component of the first slide gate G1.

As shown in FIGS. 2 to 4, the first slide gate G1 includes a fixed gate member 37 and a movable gate member . The fixed gate member 37 has a plurality of (five in the illustrated example) links 39 extending in a direction perpendicular to the axial direction, that is, in a horizontal direction. These links 39 are arranged parallel to each other and extend across the inside of the main cylinder portion 32. In this embodiment, a circular ring-shaped rim 40 is attached to the inner peripheral surface of the main cylinder portion 32, and both ends of each link 39 are fixed to this rim 40. However, the rim 40 may be omitted and both ends of each link 39 may be directly fixed to the main cylinder portion 32. A total of a plurality of fixed slits 41 (six in the illustrated example) are formed between each link 39 for allowing the load B to pass through.

The upper surface part of the link 39 is formed to be inclined so that the load B that falls there can smoothly slide down into the fixed slit 41, and specifically, it is formed in a mountain-shaped cross section. In this embodiment, the cross-sectional shape of the link 39 is a pentagonal shape similar to a home base, and the link 39 has a solid structure. However, the structure and shape of the link 39 are not limited to this, and for example, the link 39 may be formed of a plate material having an L-shaped cross section (for example, L-shaped steel) and arranged so that the upper surface portion is chevron-shaped.

The movable gate member 38 is formed of a flat plate having a rectangular shape in plan view, and is superimposed on the lower surface of the fixed gate member 37 so as to be slidable in the front-rear direction as indicated by the arrow f. Note that the main cylinder portion 32 is provided with support members (not shown) that slidably support the left and right side edges of the movable gate member 38. The movable gate member 38 has a plurality of (six in the illustrated example) movable slits 42 that fully open the fixed slit 41 when the first slide gate G1 is fully opened. A closing portion 43 is provided between the movable slits 42 to fully close the fixed slit 41 when the first slide gate G1 is fully closed.

The link 39, the fixed slit 41, the movable slit 42, and the closing part 43 extend in a direction perpendicular to the sliding direction f.

The width W1 of the movable slit 42 in the sliding direction f is made equal to the width W2 of the fixed slit 41. Further, the width W3 of the closing portion 43 is made equal to the width W4 of the lattice 39. In the case of this embodiment, W1=W2=W3=W4. However, these dimensions can be set arbitrarily.

The first slide gate G1 includes an actuator 44 such as a hydraulic cylinder that drives the movable gate member 38. This actuator 44 is electrically connected to the control device E. When the actuator 44 operates according to a command from the control device E, the movable gate member 38 slides in the sliding direction f, and is opened and closed.

5 and 6 are a plan view and a side sectional view showing the first slide gate G1 when it is fully opened. At this time, the fixed slit 41 and the movable slit 42 have the same width and are perfectly aligned in the vertical or vertical direction, and the fixed slit 41 is completely opened by the movable slit 42. Further, at this time, the link 39 and the closing part 43 also have the same width and are perfectly aligned in the vertical direction or the vertical direction.

FIG. 7 is a side sectional view showing the first slide gate G1 when it is half open or at an intermediate opening degree. At this time, the movable gate member 38 is slid further rearward (or forward) than when fully opened. A part of the fixed slit 41 in the width direction is opened by the movable slit 42, but the remaining part of the fixed slit 41 is closed by the closing part 43 or the movable gate member 38, and the fixed slit 41 is in a half-open state.

FIG. 8 is a side sectional view showing the first slide gate G1 when fully closed. At this time, the movable gate member 38 is slid further rearward than when it is half-open. The closing part 43 is perfectly aligned in the vertical direction with the same width as the fixed slit 41, and the fixed slit 41 is completely closed by the closing part 43 or the movable gate member 38. Moreover, at this time, the movable slit 42 is perfectly aligned in the vertical direction with the same width as the link 39.

When fully closed, the fixed slit 41 is completely closed, and the movable gate member 38 is brought into close contact with the fixed gate member 37 by suction force. Therefore, the gap between the fixed gate member 37 and the movable gate member 38 can be reduced, and leakage of air passing through the first slide gate G1 can be suppressed.

The first level sensor S1 is located at a height below and near the first slide gate G1. The second level sensor S2 is located at a height above and near the first slide gate G1. The third level sensor S3 is located at a height above the second level sensor S2 and below the input port 35. The first to third level sensors S1 to S3 are configured, for example, by well-known paddle-type level sensors, and are turned on when load B is detected (when load B is at the height of the level sensor), and the load B is detected. When not in use (when load B is not at the height of the level sensor), it is turned off. Note that the first to third level sensors S1 to S3 may be configured with sensors other than paddle type level sensors.

The control device E is constituted by a well-known control unit including a CPU, memory, etc., and is electrically connected to the first to third level sensors S1 to S3 and the first to third slide gates G1 to G3.

The feeding device 30 has a gate position sensor 45 for each slide gate to detect the actual position of the movable gate member 38. The gate position sensor 45 is composed of, for example, a well-known encoder. These gate position sensors 45 are also electrically connected to the control device E. The control device E controls the position of the movable gate member 38 and the opening degree of the slide gate based on the signal from the gate position sensor 45.

Next, the operation of the unloader 100 and the delivery device 30 will be explained.

As shown in FIG. 1, during cargo handling operation of the unloader 100, the vacuum pump 4 is operated and the cargo B in the hold K is sucked in through the nozzle 7. This sucked load B rises within the vertical pipe 10 and reaches the horizontal pipe 6 through the curved pipe 9. Then, it moves within the horizontal pipe 6 and is thrown into the receiver tank 2 through the injection port 35.

Thereafter, the load B passes through the delivery device 30, and at this time, the flow rate of the load B is controlled. The load B discharged from the delivery device 30 is finally sent to the ground conveyor 17 via a route including the chute 14, the in-flight conveyor 15, and the ground chute 16.

Inside the receiver tank 2, the load B input from the input port 35 falls as shown by the arrow g, and the air flow rises as shown by the arrow h, so that the load B and the air flow are separated. The rising air flow passes through the bag filter 13, and at this time, the dust contained in the air flow is filtered out by the bag filter 13. After this, the air flow reaches the vacuum pump 4 and is released to the atmosphere through the exhaust pipe.

During such cargo handling operation, the first to third slide gates G1 to G3 are controlled by the control device E as follows. An example of control will be described below.

FIG. 9 is a flowchart showing the contents of normal operation and control in the delivery device 30. The code Sn (n is an integer) represents the step number. Here, as an initial state (S0), the receiver tank 2 is empty (there is no load B), so the first to third level sensors S1 to S3 are off, and the first to third slides are Assume that gates G1 to G3 are fully closed.

When the cargo handling operation is started from this initial state and the cargo B is supplied into the receiver tank 2, the cargo B accumulates on the second slide gate G2 in the receiver tank 2. First, the second level sensor S2 is turned on (S1), and then the third level sensor S3 is turned on (S2).

Then, the second slide gate G2 is fully opened (S3). As a result, the load B accumulated on the second slide gate G2 passes through the second slide gate G2 and falls, and is accumulated on the first slide gate G1. Further, the level of the load B decreases, the third level sensor S3 is turned off (S4), and the second level sensor S2 is turned off (S5).

Thereafter, the level of the load B accumulated on the first slide gate G1 rises, the first level sensor S1 is turned on (S6), and the second level sensor S2 is turned on (S7).

Then, the first and second slide gates G1 and G2 are half-opened, and the third slide gate G3 is fully opened (S8). As a result, the load B accumulated on the first slide gate G1 falls little by little, passes through the third slide gate G3, and is sent to the chute 14 and the in-machine conveyor 1. As a result, the load B is discharged from the delivery device 30 with the flow rate controlled to be substantially constant. The opening degrees of the first and second slide gates G1 and G2 are set so that the supply flow rate of the load B to the delivery device 30 and the discharge flow rate of the load B from the delivery device 30 are approximately equal.

In this way, the level of the load B decreases, and the second level sensor S2 is turned off (S9).

After this, if the discharge flow rate is greater than the supply flow rate, the level of the load B decreases and the first level sensor S1 is turned off (S10). In response to this, the first slide gate G1 is fully closed (S11). As a result, the discharge of the load B is stopped, the level of the load B accumulated in the first slide gate G1 rises, and the first level sensor S1 is turned on (S12).

After that, when the second level sensor S2 is turned on (S7), step S8 is repeated. In this way, the level of the load B is maintained so as not to fall below the second slide gate G2 as much as possible.

On the other hand, if the supply flow rate is greater than the discharge flow rate after step S9, the second level sensor S2 is turned on (S13). In response to this, the first slide gate G1 is fully opened (S14). As a result, the discharge flow rate of the load B is increased, and the level of the load B accumulated in the first slide gate G1 is reduced.

After that, when the second level sensor S2 is turned off (S15), the process returns to step S8, and the first slide gate G1 is left half open as before.

In this manner, in this embodiment, the level of the load B is maintained between the first level sensor S1 and the second level sensor S2 while the load B is being discharged. That is, at least the space within the receiver tank 2 between the first slide gate G1 and the first level sensor S1 is filled with the load B. Therefore, the inside of the receiver tank 2 can be substantially closed by the filled cargo B, and air leakage from the atmosphere side (below the filled cargo B) to the vacuum side (above the filled cargo B). can be prevented. Therefore, compared to conventional unloaders using rotary feeders, the gap is reduced (virtually eliminated), the amount of leakage air is reduced (virtually eliminated), and the efficiency (e.g. energy efficiency of the unloader) is increased. It can be improved.

Further, there is no need to adjust the gap for each of the slide gates G1 to G3. Therefore, it is possible to eliminate the work of adjusting the gap and reduce the frequency of maintenance. Also, the burden of maintenance can be significantly reduced.

By the way, the first to third slide gates G1 to G3 of this embodiment have a structure that allows extremely little air leakage when fully closed. On the other hand, when the first slide gate G1 or the second slide gate G2 is fully closed, the movable gate member 38 may be attracted to the fixed gate member 37, increasing sliding resistance, and the movable gate member 38 may not be able to slide. There is. Therefore, in this embodiment, the control device E performs diagnostic recovery control to deal with such a situation.

FIG. 10 is a flowchart showing the details of diagnostic recovery control. Diagnostic recovery control is performed individually for the first slide gate G1 and the second slide gate G2. Here, an example will be shown for the first slide gate G1, but the same applies to the second slide gate G2. Here, it is assumed that the first slide gate G1 is fully closed and the third slide gate G3 is fully open as an initial state (S20).

The control device E sends an opening command to the first slide gate G1 (S21). The opening command is a command signal for opening the first slide gate G1. There is no limitation on the degree of opening after the opening operation, and it may be half open or fully open.

Thereafter, the control device E determines whether or not the first slide gate G1 has actually opened, based on the signal from the gate position sensor 45 corresponding to the first slide gate G1 (S22). That is, the control device E detects the actual position of the movable gate member 38 after the opening command is issued from the signal of the gate position sensor 45, and determines whether the opening degree corresponding to the position is equal to the commanded opening degree.

The control device E ends when the first slide gate G1 actually performs an opening operation. However, if the opening operation does not actually occur, it is expected that the movable gate member 38 will be attracted by the negative pressure.

Therefore, in this case, the control device E fully closes the third slide gate G3 (S23). In this way, the pressure below the third slide gate G3 can be made negative, and the pressure difference between the upper and lower sides of the third slide gate G3 can be reduced. Therefore, it becomes possible to release the adsorption of the movable gate member 38 and operate the movable gate member 38.

After that, the control device E sends an opening command to the first slide gate G1 again (S24). Then, the control device E determines again whether the first slide gate G1 has actually opened (S25).

When the control device E determines that the opening operation has actually been performed, the third slide gate G3 is fully opened (S26), and the process ends.

On the other hand, if the control device E determines that the opening operation has not actually occurred, some kind of failure is assumed, so it starts a warning device (warning light, alarm, etc.) (not shown) (S27) and ends the process. At this time, the vacuum pump 4 or the unloader 100 may also be stopped.

As described above, according to the diagnostic recovery control of the present embodiment, it is possible to diagnose whether or not a temporary abnormality due to adsorption has occurred in the first slide gate G1 and the second slide gate G2, and if such a temporary abnormality has occurred, can be immediately resolved and recovered. Therefore, stable operation of the unloader 100 can be ensured.

The diagnostic recovery control is preferably performed in conjunction with the main control shown in FIG. However, it may be performed independently apart from the main control.

Although the embodiments of the present disclosure have been described in detail above, various embodiments and modifications of the present disclosure are possible.
(1) For example, in the first to third slide gates G1 to G3, the fixed gate member 37 may have a lattice instead of the plurality of links 39. Further, in the above embodiment, the fixed slit 41 and the movable slit 42 have a rectangular shape or a substantially rectangular shape that is long in one direction when viewed from above, but they may have other shapes such as a circle.
(2) In the above embodiment, the level of the load B is maintained between the first level sensor S1 and the second level sensor S2, but instead of this, the level of the load B is maintained between the second level sensor S2 and the third level sensor S3. You can also keep it at
(3) A simplified embodiment in which at least one of the third slide gate G3 and the third level sensor S3 is omitted is also possible.

The embodiments of the present disclosure are not limited to the above-described embodiments, but include all modifications, applications, and equivalents that fall within the spirit of the present disclosure as defined by the claims. Therefore, the present disclosure should not be construed in a limited manner, and may be applied to any other technology that falls within the spirit of the present disclosure.

2 Receiver tank 31 Exit section 100 Pneumatic unloader B Load E Control device G1 First slide gate G2 Second slide gate G3 Third slide gate S1 First level sensor S2 Second level sensor S3 Third level sensor

Claims (5)

a receiver tank that stores the sucked load;
a first slide gate and a second slide gate provided in series from below at the outlet portion of the receiver tank;
a first level sensor for detecting the presence or absence of a load at a position between the first slide gate and the second slide gate;
a second level sensor for detecting the presence or absence of a load at a position above the second slide gate;
a control device that controls the first slide gate and the second slide gate based on detection results of the first level sensor and the second level sensor;
A pneumatic unloader comprising: The control device controls the first slide gate and the second slide gate so as to fill a space in the receiver tank between the first slide gate and the first level sensor with a load. pneumatic unloader. comprising a third level sensor for detecting the presence or absence of a load at a position above the second level sensor,
The pneumatic unloader according to claim 1, wherein the control device controls the first slide gate and the second slide gate based also on the detection result of the third level sensor. The pneumatic unloader according to claim 1, further comprising a third slide gate provided at a position below the first slide gate. When the first slide gate or the second slide gate does not open even if an opening command is sent to the fully closed first slide gate or the second slide gate, the control device controls the third slide gate to open. The pneumatic unloader according to claim 4, wherein the pneumatic unloader is fully closed.

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