JP2022108401A - Powder and granular material hopper, operation method for powder and granular material hopper - Google Patents

Abstract

To provide powder and granular material hopper that can maintain an appropriate layer thickness and stably discharge a conveyance material that falls in a hopper body and deposits on a belt conveyor, and an operation method for the powder and granular material hopper.SOLUTION: A powder and a granular material hopper 10 of the present invention includes: a layer thickness measurement part 20 which measures lateral pressure applied to a plurality of locations in a height direction of an inner wall surface due to a conveyance article 14 deposited inside of a hopper body 16 that is arranged above a belt conveyor 12 and discharge the conveyance article 14 having a predetermined layer thickness formed inside above the belt conveyor 12; and a control part 30 which calculates a deposition speed of the conveyance article 14 based on a measurement value of the layer thickness measurement part 20 and controls to avoid an abnormal layer thickness.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a granular material hopper that continuously discharges granular material onto a belt conveyor, and a method of operating the granular material hopper.

2. Description of the Related Art In thermal power plants, belt conveyors are used to convey powders such as coal for fuel and wood pellets. In recent years, biomass fuel obtained from plants has come to be used. At this time, in order to reduce the cost of the conveyor equipment, different types of fuel are conveyed using the same conveyor equipment. When wood pellets are transported on the same conveyor as coal fuel, differences in physical properties may cause problems in transportation. In particular, due to the difference in water content and particle size of each fuel, the fuel pellets adhere to the belt and the hopper, and the fuel pellets do not flow into the hopper and clog the hopper, hindering smooth transportation.

In addition, in the hoppers of the transfer section of each conveyor, if there is a variation in the conveying amount of the conveyer on the supply side and the discharge side, it may temporarily accumulate in the hopper. At this time, the layer thickness weight of the conveyed material acts on the lower layer of powder and granules and the inner wall of the hopper. The conveying force of the belt is not transmitted to the powder and the belt slips. Furthermore, if the inside of the granular material is also compressed and cannot flow, it slips between the granular material and the conveyer on the delivery side and cannot be discharged. In particular, cylindrical wood pellets tend to cause this problem because they do not have good fluidity in sedimentary layers.

Conventionally, various measures are taken to prevent deposits in the hopper (also called chute). The chute disclosed in Patent Document 1 is equipped with a load cell for detecting the load of the chute body, and warns and stops when the body is weighted due to accumulation of conveyed objects inside the chute body.
The clogging detection device disclosed in Patent Document 2 includes a coal inflow hole and a rotating body in a clogging detection space inside a chute, and when coal accumulated in the rotating body reaches a predetermined weight through the coal inflow hole. It can switch on and detect jams.
However, although the technologies disclosed in Patent Literatures 1 and 2 are capable of detecting clogging of the transported material inside the chute, they cannot eliminate the clogging at the time the clogging occurs. Therefore, after clogging is detected, the conveyor must be stopped for maintenance, resulting in non-productive time and poor operating efficiency.

Conveyed materials such as wood pellets have a small specific gravity and a small internal coefficient. In particular, when the conveyor has a large inclination and the belt speed is high, the material tends to stay in the skirt under the hopper, causing slippage between the conveyor belt surface and the material to be transported, resulting in poor transport. As the amount of material deposited in the hopper increases without being discharged from the hopper, the layer thickness increases and due to friction and adhesion, when it reaches a certain layer, a supporting force that balances the pressure above it is generated and closed. As a result, it becomes impossible to discharge from the hopper to the conveyor.

JP-A-2005-96939 JP-A-2000-53219

The problem to be solved by the present invention, in view of the above-mentioned problems of the prior art, is to maintain an appropriate layer thickness of the material to be conveyed that falls in the hopper body and accumulates on the belt conveyor, and can stably dispense the material. To provide a method for operating a hopper and a granular material hopper.

As a first means for solving the above problems, the present invention is arranged above a belt conveyor and inside a hopper body that discharges a conveyed product having a predetermined layer thickness inside the belt conveyor. a layer thickness measuring unit that measures the lateral pressure applied to multiple points in the height direction of the inner wall surface by the conveyed object;
a control unit that calculates the deposition rate of the conveyed object based on the measured value of the layer thickness measurement unit and performs control to avoid an abnormal layer thickness;
To provide a granular material hopper characterized by comprising
According to the first means, it is possible to perform operation control capable of avoiding an operation failure (abnormal accumulation) caused by excessive accumulation during accumulation of the conveyed material in the hopper main body.

According to the present invention, as a second means for solving the above problems, in the first means, the control unit measures the thickness of the inner wall surface of the hopper body in the height direction based on the measured value of the layer thickness measurement unit. A granular material hopper characterized in that one or more of the balance of discharge or charging of the hopper main body is obtained from the layer thickness at a plurality of locations, the deposition time is predicted from the layer thickness change per unit time, and the layer thickness variation is obtained. to provide.
According to the second means, the deposition speed and deposition time are predicted from the measured values (layer thickness) at multiple points in the height direction of the inner wall surface, and the judgment to avoid abnormal deposition such as the balance of discharging or loading of the hopper main body is performed. A reference is obtained.

As a third means for solving the above-mentioned problems, the present invention provides, in the first or second means, the control unit adjusts the input amount of the hopper body and the opening by a gate provided at the bottom of the hopper body. The object of the present invention is to provide a granular material hopper characterized by avoiding the abnormal layer thickness by controlling any one or more of expansion of the area, formation of a steep slope by the gate, and application of vibration to the hopper.
According to the third means, it is possible to avoid abnormal deposition and reduce the loss of operating time.

According to the present invention, as a fourth means for solving the above problems, in the powdery or granular material hopper according to any one of the first to third aspects, the layer thickness measuring section measures the opening of the side surface of the hopper body. A flexible plate for covering, a plurality of strain gauges attached along the height direction of the flexible plate, and a protective cover for covering the strain gauges, which are attached from the outside of the hopper body. A powder hopper is used.
According to the fourth means, the hopper body can be attached and detached from the outside with a simple structure, and inspection and replacement work can be easily performed.

As a fifth means for solving the above-mentioned problems, the present invention provides a hopper body that discharges a conveyed product arranged above a belt conveyor and formed with a predetermined layer thickness inside the belt conveyor. A step of measuring lateral pressure applied to a plurality of locations in the height direction of the inner wall surface by the conveyed object with a layer thickness measuring unit;
a step of calculating the deposition rate of the conveyed object based on the measured value of the layer thickness measuring unit and performing control to avoid an abnormal layer thickness;
It is to provide a method for operating a granular material hopper characterized by having
According to the fifth means, it is possible to perform operational control that can avoid operational failures (abnormal accumulation) caused by excessive accumulation during accumulation of conveyed materials in the hopper main body.

According to the present invention, it is possible to perform operation control capable of avoiding operational failure (abnormal accumulation) caused by excessive accumulation during accumulation of the conveyed material in the hopper main body.

It is a structural schematic diagram of the granular material hopper of the present invention. It is explanatory drawing of a layer thickness measurement part. It is a graph which shows the relationship between layer thickness and time.

Embodiments of the granular material hopper and the method for operating the granular material hopper of the present invention will be described in detail below with reference to the drawings.

[Particle hopper 10]
FIG. 1 is a schematic diagram of the configuration of the granular material hopper of the present invention. As shown in the figure, the granular material hopper 10 of the present invention is arranged above the belt conveyor 12 and deposited inside the hopper body 16 that discharges the conveyed material 14 formed with a predetermined layer thickness on the belt conveyor 12. A layer thickness measuring unit 20 for measuring the side pressure applied to a plurality of locations in the height direction of the inner wall surface by the conveyed object 14, and calculating the deposition rate of the conveyed object 14 based on the measured values of the layer thickness measuring unit 20. A control unit 30 is provided to perform control to avoid an abnormal layer thickness.

The hopper body 16 is a box-shaped container having an opening on its top surface. The belt conveyor 12 has a conveying surface facing the lower opening of the hopper main body 16 with a predetermined gap therebetween, and conveys the articles 14 dropped from the hopper main body 16 to a predetermined location in the subsequent process. The conveyed object 14 of the present invention will be described below using, as an example, powdery material such as coal for fuel of a thermal power plant or wood pellets.

The gate 18 is attached to the side surface of the hopper main body 16 on the downstream side in the conveying direction, and adjusts the discharge amount of the conveyed article 14 . The main surface of the gate 18 is formed along (toward) the conveying direction of the belt conveyor 12 .
The gate 18 is attached to the side surface of the hopper body 16 on the downstream side in the conveying direction via a rotation support portion 18a. The rotation support portion 18a is arranged with its axis perpendicular to the conveying direction of the belt conveyor 12, and the gate 18 is fan-shaped, in other words, it is arranged so as to be rotatable toward or away from the conveyor. The gate 18 also has a drive cylinder 18b to which a piston connects and to which a rod is mounted around the hopper body 16. As shown in FIG.
With such a configuration of the gate 18, the opening area of the gate 18 is enlarged and the gate 18 forms a steep slope, so that when the friction coefficient between the conveyed object 14 on the belt conveyor 12 and the conveyor surface is small, for example, compaction can be achieved. A belt conveying speed sufficient for conveying can be ensured by consolidating a small conveyed article by the gate 18 and increasing the weight of the conveyed article 14 in which a layer thickness is formed.

(Layer thickness measurement unit 20)
FIG. 2 is an explanatory diagram of the layer thickness measuring section. The hopper main body 16 is provided with a layer thickness measuring section 20 for measuring the lateral pressure when the layer thickness of the conveyed material 14 is formed.
The layer thickness measuring unit 20 includes a flexible plate 22 covering an opening provided in the inner wall surface of the hopper body 16, a plurality of strain gauges 24 attached along the height direction of the flexible plate 22, and the strain gauges 24 A protective cover 26 is provided to cover the
The flexible plate 22 is a flexible and wear-resistant metal plate that covers the opening provided on the side surface of the hopper body 16 .
The strain gauges 24 are sensors arranged along the height direction of the outer surface of the flexible plate 22 .
The protective cover 26 is a cover that covers the strain gauge and has dustproof and waterproof functions.
In the layer thickness measuring unit 20 having such a configuration, as the material is accumulated on the hopper body 16, the lower flexible plate is bent by the pressure of the material 14 in order. This deflection is detected by the strain gauge 24 . The measured value is configured to be able to be transmitted to the control section 30, which will be described later. In addition, the layer thickness measuring unit 20 is made into a unit that has a flexible plate 22, a strain gauge 24, and a protective cover 26 as an integral structure, and can be attached and detached using a fastening bolt or the like to the side opening of the hopper body 16, and can be inspected and replaced. It has a structure that facilitates work.

(control unit 30)
The control unit 30 is electrically connected to the layer thickness measuring unit 20, calculates the deposition rate of the conveyed object 14 based on the measured value of the layer thickness measuring unit 20, and performs control to avoid an abnormal layer thickness.
FIG. 3 is a graph showing the relationship between layer thickness and time. In the figure, the vertical axis indicates the layer thickness and the horizontal axis indicates time. The strain gauges 24a to 24e of the layer thickness measuring unit 20 are plotted, and the measurement values of each gauge when the conveyed object 14 is put in at a constant amount and at a constant speed are plotted. It is what I did.
By measuring the strain gauges 24a-e, individual layer thicknesses (loads) can be detected with the strain gauges above the hopper body 16 depending on the build-up of the material being conveyed.
The deposition rate is obtained from the measurement time of the layer thickness of each of the strain gauges 24a-e, in other words, the load generation time.
The layer thickness and the deposition rate can be estimated from the slopes (load gradients ΔH/Δt) of the strain gauges 24a to 24e, and the deposition time can be predicted from the change in layer thickness per unit time.
In a state where the measured values of the strain gauges 24a to 24e are at a constant load balance value, the balance between discharging and loading of the hopper main body 16 can be determined from the layer thickness variation. The pressure can be estimated from the values of H2 between 24a-c, H3 between strain gauges 24a-d, and H4 between strain gauges 24a-e.
The control unit 30 obtains the deposition rate and pressure from the measured values during the deposition, and if there is a possibility that an abnormal layer thickness will occur, the following avoidance method is executed.
A specific method for avoiding the abnormal layer thickness by the control unit 30 is that the hopper main body 16 is electrically connected to the input conveyor 11 for inputting the conveyed articles 14 , and control can be performed to reduce the supply amount of the conveyed articles 14 . The control unit 30 is electrically connected to the drive cylinder 18b, and can control the opening area of the lower opening of the hopper body 16 (for example, to enlarge it). Further, the control unit 30 can perform control to form a steep slope in the gate 18 by forward and backward movement of the drive cylinder 18b, thereby promoting discharge of the excessively deposited material 14 to be conveyed. Furthermore, the control unit 30 can perform control to accelerate the discharge of the accumulated conveyed materials 14 by applying vibration to the hopper body 16 (eg, vibrating the hopper body by hammering means (not shown)).

[Method of operating powder hopper]
According to the method of operating the granular material hopper of the present invention, the conveyed material 14 disposed above the belt conveyor 12 and having a predetermined layer thickness formed therein is discharged above the belt conveyor 12. The layer thickness measuring unit 20 measures the lateral pressure applied to a plurality of points in the height direction of the inner wall surface.
Based on the measured value of the layer thickness measuring unit 20, the control unit 30 calculates the deposition rate of the conveyed object 14 and performs control to avoid an abnormal layer thickness.
From the measured values of the layer thickness measuring unit 20, the control unit 30 obtains the layer thickness (load) of each of the strain gauges 24a to 24e, the deposition rate, the estimation of the deposition time, and the balance between the discharging and loading of the hopper body 16. Based on one or more pieces of information such as this layer thickness, if there is a possibility that abnormal deposition will occur, the input amount of the material 14 to be fed by the input conveyor 11 is adjusted (decreased, etc.), and the steep inclination of the gate 18 is adjusted by the drive cylinder 18b. Abnormal deposition is avoided by controlling one or more of formation and application of vibration to the hopper body.
The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments, and various modifications are possible without departing from the gist of the present invention.
Moreover, the present invention is not limited to the combinations shown in the embodiments, and can be implemented in various combinations.

10 Granular material hopper 11 Input conveyor 12 Belt conveyor 14 Conveyed object 16 Hopper main body 18 Gate 18a Rotation support part 18b Drive cylinder 20 Layer thickness measurement part 22 Flexible plate 24 Strain gauge 26 Protective cover 30 Control part

Claims (5)

The lateral pressure applied to multiple points in the height direction of the inner wall surface by the accumulated material inside the hopper body, which is placed above the belt conveyor and has a predetermined layer thickness formed inside, is discharged to the upper side of the belt conveyor is measured. a layer thickness measuring unit to
a control unit that calculates the deposition rate of the conveyed object based on the measured value of the layer thickness measurement unit and performs control to avoid an abnormal layer thickness;
A powder or granular material hopper comprising: In the granular material hopper according to claim 1,
Based on the measured value of the layer thickness measuring unit, the control unit predicts the layer thickness at a plurality of locations in the height direction of the inner wall surface of the hopper body, the deposition time from the layer thickness change per unit time, and the layer thickness variation A granular material hopper, characterized in that one or more of the balance of discharging or charging the hopper main body is obtained. In the granular material hopper according to claim 1 or 2,
The control unit controls one or more of the following: adjustment of the input amount of the hopper body, enlargement of an opening area by a gate provided at the bottom of the hopper body, formation of a steep slope by the gate, and application of vibration to the hopper body. A granular material hopper characterized by avoiding the abnormal layer thickness by control. In the granular material hopper according to any one of claims 1 to 3,
The layer thickness measuring unit includes a flexible plate covering the side opening of the hopper body, a plurality of strain gauges attached along the height direction of the flexible plate, and a protective cover covering the strain gauges. and attached from the outside of the hopper main body. Side pressure applied to a plurality of points in the height direction of the inner wall surface by the accumulated material inside the hopper body that discharges the material that has been placed above the belt conveyor and has a predetermined layer thickness formed therein is layered. a step of measuring with a thickness measuring part;
a step of calculating the deposition rate of the conveyed object based on the measured value of the layer thickness measuring unit and performing control to avoid an abnormal layer thickness;
A method for operating a granular material hopper, comprising:

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