Switching control method for silos and silo discharge

Abstract

To provide a silo and a silo delivery switching control method for enabling more stable silo control.SOLUTION: A silo 1 includes: multiple hoppers 10 each having a storage part 100 for limestone L, a slide gate 110 that has a delivering port 111 at the bottom of the storage part 100, and a height measuring part 120 almost directly above the delivering port 111; and a control device 30 that can control the slide gate 110. The height measuring part 120 measures the height of the limestone L with a transmitting part 121 which transmits a microwave MW to be reflected onto the limestone L and a receiving part 122 which receives it. When the difference between measured values of adjacent hoppers 10 among measured values obtained by the height measuring part 120 exceeds a predetermined threshold value, the control device 30 executes at least either the operation of opening the slide gate 110 of the hopper 10 in which a larger measured value is measured or the operation of closing the slide gate 110 of the hopper 10 in which a smaller measured value is measured.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a silo and a switching control method for silo discharging.

Background Art

[0002] Conventionally, a technique for measuring the height of granular material (powder) stored in a silo (powder supply device) and controlling the silo based on the height has been known. Patent Document 1 is cited as an example of this type of technique. In Patent Document 1, a powder supply device includes a main body portion having an accommodation space for accommodating powder and an opening for discharging the powder, and a plurality of powder supply portions for supplying powder from above into the accommodation space. The amount of powder supplied from the plurality of powder supply portions is adjusted so that the average storage height of the powder in the accommodation space is 60% or more of the height of the accommodation space and the variation in the storage height of the powder in the accommodation space is within ±20%.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, as a method for measuring the height of the deposit of granular material (powder) stored for controlling a silo (powder supply device), there is a method of transmitting a wave such as a microwave, reflecting it from the deposit, and receiving the reflected wave. In this method, the measurement accuracy may vary depending on the surface shape of the deposit, and there is a risk that the silo cannot be stably controlled.

[0005] An object of the present invention is to provide a silo and a switching control method for silo discharging that enable more stable control of the silo.

Means for Solving the Problems

[0006] (1) The silo according to the present invention comprises a plurality of hoppers, each having a storage section capable of storing powdered or granular material, a discharge section having a discharge opening that opens at the bottom of the storage section and capable of discharging the powdered or granular material stored in the storage section by opening and closing the discharge opening, and a height measuring section provided substantially directly above the discharge opening for measuring the height of the accumulated powdered or granular material stored in the storage section, and a control unit capable of controlling the opening and closing operation of the discharge sections of the plurality of hoppers, wherein the height measuring section has a transmitting section capable of transmitting waves and a receiving section capable of receiving waves, and the height of the accumulated material is measured by the wave transmitted by the transmitting section being reflected by the accumulated material and received by the receiving section, and the control unit performs at least one of the following when the difference between the measured values ​​of two adjacent hoppers among a plurality of measured values ​​measured by the plurality of height measuring sections exceeds a predetermined threshold: opening the discharge section of the hopper with the larger measured value among the two adjacent hoppers, and closing the discharge section of the hopper with the smaller measured value.

[0007] Silo (1) allows for more stable silo control.

[0008] (2) In the silo according to the present invention, it is preferable that the control unit, when the difference between two adjacent hopper measurements among a plurality of height measurement units exceeds a predetermined threshold, performs the operation of opening the outlet of the hopper with the larger measurement value and closing the outlet of the hopper with the smaller measurement value.

[0009] In the silo described in (2), the shape of the granular material deposits can change more quickly to a shape that is less likely to cause a decrease in the level gauge reception intensity, thus enabling more stable control of the silo.

[0010] (3) In the silo according to the present invention, the wave is preferably a microwave, and the height measuring unit is preferably a microwave level meter that emits microwaves toward the sediment and measures the height of the sediment by receiving the microwaves reflected by the sediment.

[0011] (3) The silo is easy to install and maintain, which allows for more cost-effective and stable silo control.

[0012] (4) In the silo according to the present invention, the granular material is preferably limestone.

[0013] The silo described in (4) can also be applied to large-scale silos such as those used for storing limestone, and stable silo control can suppress significant losses due to silo shutdowns.

[0014] (5) The method for switching the outlet of a silo according to the present invention comprises a plurality of hoppers, each having a storage section capable of storing powdered material, an outlet opening at the bottom of the storage section, and capable of opening and closing the outlet to discharge the powdered material stored in the storage section, and a height measuring section provided approximately directly above the outlet to measure the height of the accumulated powdered material stored in the storage section, and a control unit capable of controlling the opening and closing operation of the outlets of the plurality of hoppers, wherein the height measuring section has a transmitting section capable of transmitting waves and a receiving section capable of receiving waves, and the waves transmitted by the transmitting section are reflected by the accumulated material and received by the receiving section A method for controlling the switching of silo discharge to be performed by a silo that measures the height of the deposit, comprising: a measurement value acquisition step of acquiring measurement values ​​measured by the height measuring units in a plurality of hoppers; and a discharge outlet switching step of performing at least one of the following when the difference between the measurement values ​​of two adjacent hoppers among a plurality of measurement values ​​measured by the plurality of height measuring units exceeds a predetermined threshold: opening the discharge outlet of the hopper where the larger measurement value was measured, and closing the discharge outlet of the hopper where the smaller measurement value was measured.

[0015] The silo discharge switching control method in (5) allows for more stable and accurate measurement of the height of the stored powder and granular material. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic diagram showing an example of a limestone receiving and transporting system S according to one embodiment of the present invention. [Figure 2] This is a schematic diagram showing an example of a silo related to one embodiment of the present invention. [Figure 3] A block diagram showing the hardware configuration of a silo related to one embodiment of the present invention. [Figure 4] This is a schematic diagram of a silo according to one embodiment of the present invention, in which adjacent hoppers dispense equally. [Figure 5] This is a schematic diagram of a silo according to one embodiment of the present invention, in which only one of the adjacent hoppers is dispensing. [Figure 6] This is a flowchart illustrating an example of outlet switching control performed by a silo according to one embodiment of the present invention. [Modes for carrying out the invention]

[0017] Hereinafter, an example of a limestone receiving and conveying system S equipped with a silo 1 according to one embodiment of the present invention will be described with reference to Figure 1. The limestone receiving and conveying system S according to one embodiment of the present invention is a system that receives limestone as a powder and conveys it to a slurry tank provided downstream. The arrows in Figure 1 indicate the direction in which the limestone is conveyed. In this embodiment, the powder will be described below as limestone, but it is not limited to this, and the powder may be a powder other than limestone.

[0018] The limestone receiving and transporting system S comprises a receiving and transporting section F, a silo 1 according to one embodiment of the present invention, an auxiliary silo 2, and a dispensing and transporting section C.

[0019] The receiving and conveying unit F is configured to receive the limestone transported by sea and convey it to the silo 1. The receiving and conveying unit F is constituted by, for example, a conveyor.

[0020] The silo 1 is configured to store the limestone carried in from the receiving and conveying unit F and discharge a required amount of the stored limestone. The silo 1 has four hoppers 10a, 10b, 10c, and 10d. In FIG. 1, the four hoppers 10a, 10b, 10c, and 10d of the silo 1 are shown arranged side by side for convenience, but actually, the hoppers 10c and 10d are arranged on the back side of the hoppers 10a and 10b when viewed from the front side of the paper of FIG. 1. Also, regarding the discharge conveyors C1 and C2 described later, they are shown arranged side by side for convenience, but actually, the discharge conveyor C2 is arranged on the back side of the discharge conveyor C1 when viewed from the front side of the paper of FIG. 1. Details of the silo 1 will be described later.

[0021] The auxiliary silo 2 is configured to store the limestone that is input from the vertical conveyor C4 described later and input into a slurry tank (not shown) on the downstream side. The slurry tank (not shown) is configured to make the limestone discharged from the auxiliary silo 2 into a slurry state and input it into a desulfurization device (not shown) on the downstream side.

[0022] The discharge conveying unit C is configured to convey the limestone discharged from the silo 1 to the auxiliary silo 2. The discharge conveying unit C includes a discharge conveyor C1, a discharge conveyor C2, a collecting conveyor C3, and a vertical conveyor C4.

[0023] Discharge conveyor C1 transports limestone discharged from the two hoppers 10a and 10b on the front side of silo 1 and feeds it into the collection conveyor C3, which will be described later. Discharge conveyor C2 transports limestone discharged from the two hoppers 10c and 10d on the back side of silo 1 and feeds it into the collection conveyor C3, which will be described later. Collection conveyor C3 transports the limestone fed in from discharge conveyors C1 and C2 and feeds it into the vertical transport conveyor C4, which will be described later. Vertical transport conveyor C4 transports the limestone fed in from collection conveyor C3 and feeds it into auxiliary silo 2.

[0024] <Silo> Next, a silo 1 according to one embodiment of the present invention will be described with reference to Figures 2 and 3. The silo 1 has the four hoppers 10a to 10d described above, an inlet 20, and a control device 30. Each of the four hoppers 10a to 10d has a storage section 100a to 100d, a slide gate 110a to 110d as a discharge section, and a height measuring section 120a to 120d. In this embodiment, unless otherwise distinguished, the hoppers 10a to 10d, storage sections 100a to 100d, slide gates 110a to 110d, and height measuring sections 120a to 120d will be described as hopper 10, storage section 100, slide gate 110, and height measuring section 120, respectively.

[0025] The storage section 100 is a container capable of storing limestone in powder form. The slide gate 110 has a discharge port 111 that opens at the bottom of the hopper 10, and a slide gate valve 112, shown in Figure 3, which can open and close the discharge port 111 to discharge the limestone stored in the storage section 100. The slide gate valve 112 is a valve that can move between an open position that opens the discharge port 111 and a closed position that closes the discharge port 111.

[0026] The height measuring unit 120 is located approximately directly above the discharge outlet 111. The height measuring unit 120 is configured to measure the height of the limestone deposited and stored in the storage unit 100. The height measuring unit 120 has a transmitter 121 capable of emitting waves and a receiver 122 capable of receiving waves. The height measuring unit 120 measures the height of the deposit by receiving waves emitted by the transmitter 121, which are reflected by the limestone deposit and received by the receiver 122.

[0027] The wave emitted by the transmitter 121 according to this embodiment is preferably, for example, a microwave MW. In this case, the transmitter 121 of the height measuring unit 120 emits a microwave MW towards the sediment, and the receiver 122 of the height measuring unit 120 receives the microwave MW reflected from the sediment to measure the height of the sediment. In this case, the height measuring unit 120 is, for example, a microwave level meter.

[0028] The input port 20 is an opening for loading limestone transported from the receiving and transporting section F into the silo 1, and is located approximately in the center of the multiple hoppers 10 in a plan view on the upper part of the silo 1.

[0029] The control device 30 is configured to control various operations of the silo 1. The control device 30 has a processor (not shown), and the control of various operations is realized by the processor performing calculation processing. Alternatively, the control of various operations of the silo 1 may be realized by a control circuit.

[0030] As shown in Figure 3, the control device 30 is communicatively connected to the slide gate valve 112 of the slide gate 110, and to the transmitter 121 and receiver 122 of the height measuring unit 120. The control device 30 can control the operation of the slide gate valve 112 based on the measurement results of the height measuring unit 120.

[0031] <Silo dispensing operation> Next, the discharge operation in silo 1 according to this embodiment will be explained using Figures 4 and 5. In silo 1 according to this embodiment, the height measuring unit 120 constantly measures the height of the limestone L deposit in the storage unit 100, and the discharge outlet is switched based on the measurement result. As shown in Figure 4, the transmitter 121 of the height measuring unit 120 irradiates microwaves MW toward the center of the storage unit 100 in a plan view.

[0032] As shown in Figure 4, the four storage sections 100a to 100d are positioned such that their respective central parts are approximately directly above the corresponding outlets 111a to 111d. As the limestone L deposit is discharged, the amount of limestone L decreases from the position approximately directly above the outlet 111 in a plan view. As a result, the surface LS of the limestone L deposit becomes concave from the part corresponding to the outlet 111 in a plan view, taking on a mortar shape. In other words, the surface LS of the limestone L deposit takes on a mortar shape centered on the central part of the storage section 100.

[0033] As described above, the height measuring unit 120 measures the height when microwaves MW emitted by the transmitting unit 121 are reflected by the object to be measured, and the reflected microwaves MW are received by the receiving unit 122. Consequently, as the material is dispensed, the part directly above the dispensing outlet 111 in a plan view becomes concave, and as shown in Figure 5, the angle of the mortar-shaped slope with respect to the horizontal plane increases. When the angle exceeds a predetermined angle, the proportion of microwaves MW reflected towards the height measuring unit 120 decreases, and the reception strength decreases. The predetermined angle is, for example, 40 degrees as shown in Figure 5.

[0034] On the other hand, the central part of the mortar shape has a small slope even when it is concave due to dispensing. Therefore, when microwave MW is irradiated onto the central part of the mortar shape, the proportion of microwave MW reflected toward the height measuring unit 120 becomes large. Accordingly, in this embodiment, the height measuring unit 120 is configured so that the transmitter 121 and receiver 122 of the height measuring unit 120 are positioned in the central part of the mortar shape, that is, approximately directly above the dispensing outlet 111.

[0035] By the way, in the silo 1 according to this embodiment, if the amount of limestone L required in the subsequent process is small, discharge may be performed from only some of the multiple hoppers 10. For example, as shown in Figure 5, if discharge is performed only to hopper 10b, the limestone L is discharged from the discharge port 111b of hopper 10b, and the surface LSb of the limestone L deposit in hopper 10b becomes concave. Then, the bowl shape caused by the discharge from hopper 10b extends to the surface Lsa of the limestone L deposit in the adjacent hopper 10a.

[0036] In other words, the microwave MW emitted from the height measuring unit 120a of hopper 10a adjacent to hopper 10b, where the discharge is taking place, is directed towards the bowl-shaped slope created by the discharge from hopper 10b. In the example shown in Figure 5, the inclination angle of the limestone L deposits in hopper 10b becomes a predetermined angle of 40 degrees.

[0037] As described above, when the slope of the surface LS of the sediment irradiated with microwaves MW is small, a large proportion of microwaves MW are reflected toward the height measuring unit 120. However, in Figure 5, since the slope angle of the surface LSa is greater than a predetermined angle, the proportion of microwaves MW reflected from the surface LS of the sediment toward the receiving unit 122a of the height measuring unit 120a is small.

[0038] Therefore, the way in which microwaves MW emitted from the transmitter 121 of the height measuring unit 120 are reflected changes, which may prevent accurate height measurement. In other words, the reception strength of the receiver 122a of the height measuring unit 120a in the hopper 10a in the state shown in Figure 5 may decrease, making measurement impossible.

[0039] Therefore, in the silo 1 according to one embodiment of the present invention, the control is such that when the difference in the measurement values ​​of two adjacent hoppers 10 measured by the height measuring unit 120 exceeds a predetermined threshold, the discharge outlet is switched. For example, in the silo 1 according to this embodiment, as shown in Figure 5, in the two adjacent hoppers 10a and 10b, the difference between the measurement value measured by the height measuring unit 120a and the measurement value measured by the height measuring unit 120b is 1.1m, which exceeds the predetermined threshold of 1.0m. In this case, the control is such that the slide gate 110a of the hopper 10a with the larger measurement value and higher deposit height is opened, and the slide gate 110b of the hopper 10b with the smaller measurement value and lower deposit height is closed.

[0040] Furthermore, the control of switching the discharge outlet is not limited to this; it is also possible to simply open the slide gate 110 of the hopper 10 with the higher sediment height among the adjacent hoppers 10, or to simply close the slide gate 110 of the hopper 10 with the lower sediment height.

[0041] Furthermore, the predetermined threshold is set to a height such that the mortar-shaped structure formed on the surface LS of the sediment in the adjacent hopper 10 extends to the destination of the microwave MW emitted by the height measuring unit 120, as shown in Figure 5. The predetermined threshold is, for example, 1.0 m. However, the setting of the predetermined threshold is not limited to this, and may be a value that includes a margin of safety.

[0042] <Dispensing outlet switching control> Next, the switching control performed by silo 1 according to this embodiment will be explained with reference to Figure 6. This control is executed when the control device 30 is operated to start the switching control.

[0043] The control device 30 first causes the discharge outlet 111 to open at the slide gate 110 of a predetermined hopper 10 among the multiple hoppers 10, thereby initiating the discharge operation (step S10). Next, as a measurement value acquisition step, the control device 30 acquires height information of the limestone L deposits in all hoppers 10 (step S11). Next, it calculates the difference in height of the limestone L deposits for all combinations of adjacent hoppers (step S12).

[0044] Next, it is determined whether any of the multiple measurements taken by the multiple height measuring units 120 have a difference that exceeds a predetermined threshold (step S13). If none of the multiple measurements taken by the multiple height measuring units 120 have a difference that exceeds a predetermined threshold (step S13: NO), the process moves to step S11, and the acquisition and determination of height information of the limestone L deposits in all hoppers 10 is continued.

[0045] On the other hand, if there is a case where the difference between adjacent hoppers 10 among the multiple height measurement units 120 exceeds a predetermined threshold (step S13: YES), the control device 30, for each combination of hoppers 10 that exceeds the predetermined threshold, opens the slide gate 110 of the hopper 10 with the larger measurement value and closes the slide gate 110 of the hopper 10 with the smaller measurement value, thereby performing a discharge outlet switching step (step S14).

[0046] Next, the control device 30 checks whether the operation to stop the switching control has been performed (step S15). If the operation to stop the switching control has not been performed (step S15: NO), the control device 30 proceeds to step S11 and again acquires and determines the height information of the limestone L deposits in all hoppers 10, switches the slide gates 110, etc. On the other hand, if the operation to stop the switching control has been performed (step S15: YES), the control device 30 terminates the switching control.

[0047] The silo described above for this implementation provides the following benefits: The limestone receiving and storage facility may be configured to discharge from multiple hoppers as a measure against blockage in the dead space within the sea transport receiving silo. In addition, depending on the specifications of the desulfurization equipment, the limestone receiving and storage facility may have only one inlet for loading into the limestone slurry tank. Furthermore, the limestone receiving and storage facility may include an auxiliary silo for temporary storage between the sea transport receiving silo and the limestone slurry tank to prevent blockage in the lower hopper of the sea transport silo.

[0048] In these cases, the limestone receiving and storage facility is configured to supply limestone in the following order: for example, a sea receiving silo with four hoppers, two discharge conveyors, one consolidation conveyor, one vertical conveyor, one auxiliary silo, one discharge conveyor, one limestone slurry tank, and a desulfurization facility.

[0049] Such limestone receiving and storage facilities incur significant investment and maintenance costs, and because the conveyors lack backup systems, there remains a risk of disruptions to the limestone supply due to malfunctions.

[0050] In this case, a possible limestone receiving and storage facility would be configured to supply limestone in the following order: a sea receiving silo with two hoppers, two discharge conveyors, a limestone slurry tank, and a desulfurization facility. This would eliminate the need for auxiliary silos, reducing capital investment costs. Furthermore, the number of pieces of equipment would be reduced, minimizing maintenance costs. In addition, since there is a backup system for the conveyors, operation can continue even if a supply disruption occurs in one system.

[0051] However, in the limestone receiving and storage facility with the above configuration, if discharge is continued on one of the two hopper receiving silos, the tilt angle of the powder inside the silo increases, which may reduce the received signal strength in microwave level measurements and lead to detection failures. Therefore, in silo 1 according to one embodiment of the present invention, alternating discharge conveyor operation is performed taking into account the powder angle, enabling more stable control of silo operation without reducing the received signal strength of the level meter.

[0052] In other words, the silo 1 according to this embodiment comprises a plurality of hoppers 10 having a storage section 100 capable of storing limestone L, a discharge outlet 111 opening at the bottom of the storage section 100, a slide gate 110 that can open and close the discharge outlet 111 to discharge the limestone L stored in the storage section 100, and a height measuring section 120 provided approximately directly above the discharge outlet 111 to measure the height of the deposit of limestone L stored in the storage section 100, and a control device 30 capable of controlling the opening and closing operation of the slide gates 110 of the plurality of hoppers 10, the height measuring section 120 having a transmitter 121 capable of emitting microwave MW and a receiver for microwave MW The device has a reliable receiving unit 122, and measures the height of the limestone deposits L by receiving microwaves MW transmitted by the transmitting unit 121 which are reflected by the limestone deposits L and received by the receiving unit 122. The control device 30 performs at least one of the following actions when the difference between the measurements of two adjacent hoppers 10 among the multiple height measurement units 120 exceeds a predetermined threshold: opening the slide gate 110 of the hopper 10 with the larger measurement value, and closing the slide gate 110 of the hopper 10 with the smaller measurement value.

[0053] This makes it possible to provide a silo and silo discharge switching control method that enables more stable silo control.

[0054] [Differentiation] In this embodiment, the silo 1 was configured to determine whether or not to switch based on whether or not the height difference exceeded a predetermined threshold, but this is not limited to this configuration. For example, the time required for the height difference to exceed the predetermined threshold may be measured in advance, and the decision to switch or not to switch may be made based on that time. This modified configuration will be described below. Note that configurations that are common or similar to those already described may be given the same name and their detailed descriptions may be omitted.

[0055] The switching time for limestone receiving silo discharge was examined under the following conditions. (1) Maximum payout: 11 t / h (2) Limestone specific gravity 1.0t / m 3 (3) Silo inner diameter 15.7m (4) Others The change in the limestone level (height) inside the silo due to discharge is calculated only for the discharge system side (half of the entire silo).

[0056] The level difference of limestone inside the silo caused by continuous discharge from only one system was calculated and evaluated over time. (1) The rate of decrease in the limestone level inside the silo per hour was calculated. First, the area inside the silo in this embodiment was calculated as shown in equation (1).

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[0057] Table 1 shows that, during maximum discharge, the level drop exceeds 1.0m when the operating time exceeds 9 hours, so the discharge outlet should be switched when the operating time exceeds 8 hours. Similarly, during normal discharge, the level drop exceeds 1.0m when the operating time exceeds 22 hours, so the discharge outlet should be switched when the operating time exceeds 21 hours. Thus, since the discharge switching control can be performed based on a pre-calculated switching time, the control can be made simpler. Note that the switching time is not limited to the above-described modifications, and may be a time according to the specifications of the silo, such as the maximum discharge amount of the silo, the normal discharge amount, the specific gravity of the limestone stored, and the inner diameter of the silo. The switching time may also include a margin of safety.

[0058] [Differentiation] Furthermore, the present invention is not limited to the embodiments described above, and any modifications, improvements, etc., that can achieve the objectives of the present invention are included within the scope of the present invention. [Explanation of Symbols]

[0059] L Powder MW Microwave (Wave) S11 Measurement acquisition step S14 Discharge Outlet Switching Step 10 Hoppers 30 Control device (control unit) 100 Storage section 110 Slide gate (dispensing section) 111 Discharge Outlet 120 Height measuring section 121 Transmission Unit 122 Receiving Unit

Claims

1. A plurality of hoppers, each having a storage section capable of storing powdered or granular material, a discharge section having a discharge outlet opening at the bottom of the storage section and capable of discharging the powdered or granular material stored in the storage section by opening and closing the discharge outlet, and a height measuring section provided directly above the discharge outlet for measuring the height of the accumulated powdered or granular material stored in the storage section. The system comprises a control unit capable of controlling the opening and closing operation of the dispensing sections of multiple hoppers, The height measuring unit comprises a transmitting unit capable of emitting waves and a receiving unit capable of receiving waves, and measures the height of the sediment by having the waves emitted by the transmitting unit reflected by the sediment and received by the receiving unit. The control unit performs at least one of the following actions when the difference between two adjacent hoppers measured by a plurality of height measuring units exceeds a predetermined threshold: opening the dispensing section of the hopper with the larger measurement value, and closing the dispensing section of the hopper with the smaller measurement value.

2. The silo according to claim 1, wherein the control unit, when the difference between two adjacent hopper measurements among a plurality of height measuring units exceeds a predetermined threshold, performs the operation of opening the outlet of the hopper with the larger measurement value and closing the outlet of the hopper with the smaller measurement value.

3. The aforementioned wave is a microwave, The silo according to claim 1 or 2, wherein the height measuring unit is a microwave level meter that measures the height of the sediment by transmitting microwaves toward the sediment and receiving microwaves reflected by the sediment.

4. The silo according to claim 1 or 2, wherein the granular material is limestone.

5. A plurality of hoppers, each having a storage section capable of storing powdered or granular material, a discharge section having a discharge outlet opening at the bottom of the storage section and capable of discharging the powdered or granular material stored in the storage section by opening and closing the discharge outlet, and a height measuring section provided directly above the discharge outlet for measuring the height of the accumulated powdered or granular material stored in the storage section. The system comprises a control unit capable of controlling the opening and closing operation of the discharge outlets of multiple hoppers, The height measuring unit comprises a transmitting unit capable of transmitting waves and a receiving unit capable of receiving waves, and the height of the sediment is measured by the wave transmitted by the transmitting unit being reflected by the sediment and received by the receiving unit, and the method for controlling the switching of silo discharge to be performed by the silo, A measurement value acquisition step in which the height measuring unit in a plurality of hoppers acquires the measurement value measured by the height measuring unit, A silo discharge switching control method, comprising: a discharge port switching step, which, when the difference between two adjacent hoppers among a plurality of height measurements taken by a plurality of height measuring units exceeds a predetermined threshold, performs at least one of the following: opening the discharge port of the hopper with the larger measurement value, and closing the discharge port of the hopper with the smaller measurement value.

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