JP7521273B2 - Powder and granular material hopper - Google Patents

Description

The present invention relates to a powder hopper that continuously dispenses powder onto a belt conveyor.

In thermal power plants, belt conveyors are used to transport powdered materials such as coal and wood pellets for fuel. In recent years, clean biomass fuels obtained from plants and animals have come to be used more and more. In this case, in order to reduce the cost of the conveyor equipment and save installation space, different types of fuels are sometimes transported using the same conveyor equipment. When wood pellets are transported using the same conveyor equipment as coal powder fuel, differences in physical properties can cause problems in the transport operation. In particular, due to differences in moisture and particle size of each fuel, they can adhere to the belt and hopper, causing the pellet fuel to not flow in the hopper and becoming clogged, making it difficult to transport smoothly.
In addition, in the hopper at the transfer point of each conveyor, if there is a difference in the conveyance amount of the supply side and the discharge side, it may be temporarily piled up in the hopper. At this time, the layer thickness and weight of the conveyed material itself acts on the powder and granules in the lower layer and the inner wall of the hopper, in other words, the forces are balanced as if a brace was put in, and the bottom surface of the powder and granules becomes like a bridge, and the conveyor belt's conveying force is not transmitted to the powder and it spins freely (slips). Furthermore, if the inside of the powder and granules is compressed and cannot flow, it will slip between the powder and the discharge side conveyor and cannot be discharged. In particular, cylindrical wood pellets are prone to this inconvenience because the fluidity in the piled layer is not as good as coal powder.

Conventionally, various measures have been taken to prevent accumulation inside a hopper (also called a chute). The chute disclosed in Patent Document 1 is equipped with a load cell that detects the load on the chute body, and issues an alarm and stops the chute when transported objects accumulate inside the chute body and the body becomes loaded.
The clog detection device disclosed in Patent Document 2 has a coal inlet hole and a rotating body in the clog detection space inside the chute, and when the coal accumulated in the rotating body through the coal inlet hole reaches a predetermined weight, a switch is turned on to detect the clog.
However, although the techniques disclosed in Patent Documents 1 and 2 can detect clogging of the conveyed material inside the chute, they cannot clear the clogging. Therefore, after clogging is detected, the conveyor must be stopped for maintenance, which results in non-productive time and poor operating efficiency.
In addition, granular transport materials such as wood pellets have a low specific gravity and a small internal friction angle, so they do not accelerate on the belt surface and may block the discharge port. In particular, when the conveyor has a large inclination and the belt speed is fast, they are likely to become stuck in the skirt under the hopper, causing the conveyor belt surface and the transported materials to slip, resulting in poor transport. If the materials are not discharged from the hopper and the amount of material piled up in the hopper increases, the layer thickness increases, the internal fluidity of the materials further decreases, and it becomes impossible to discharge them from the hopper to the conveyor. Furthermore, if the amount of material piled up in the hopper increases, the residence time in the hopper increases, causing the materials to be rubbed against the conveyor belt surface, pulverizing the pellets and scattering them as dust, reducing the volume of fuel.

JP 2005-96939 A JP 2000-53219 A

In view of the problems of the conventional technology described above, the problem that the present invention aims to solve is to provide a powder hopper that can maintain an appropriate layer thickness of the transported material that falls inside the hopper body and accumulates on the belt conveyor, and can dispense it stably.

As a first means for solving the above problems, the present invention provides a hopper body that is arranged on a belt conveyor and that dispenses objects that have formed a predetermined layer thickness therein onto the belt conveyor;
an opening provided on a side surface of the hopper body on an upstream side in a conveying direction of the belt conveyor, for discharging the material that has exceeded the predetermined layer thickness;
The object of the present invention is to provide a powder hopper comprising a branch area for supplying the material overflowing from the opening to the belt conveyor.
According to the first means, the transported objects which fall inside the hopper body and pile up on the belt conveyor can be maintained at an appropriate layer thickness, thereby realizing stable dispensing.

As a second means for solving the above problem, the present invention provides a powdered or granular hopper as in the first means, which is characterized by being equipped with an opening position adjustment unit that can move the opening in an upward and downward direction along the side of the hopper body to change the opening height from the belt conveyor.
According to the second means, the appropriate layer thickness, which differs depending on the properties of the transported goods, can be adjusted for each transported goods.

As a third means for solving the above problems, the present invention provides a hopper according to the second means, further comprising a side pressure measuring unit for measuring the pressure applied to the side by the objects accumulated inside the hopper body,
The object of the present invention is to provide a powder or granular material hopper characterized in that the opening position adjustment section adjusts the opening position when the measurement value of the side pressure measurement section exceeds the measurement value of the predetermined layer thickness.
According to the third means, the opening position of the opening can be adjusted without manual intervention, and the material being transported inside the hopper body can be maintained at an appropriate layer thickness.

As a fourth means for solving the above problem, the present invention provides a powdered or granular material hopper characterized in that, in any one of the first to third means, the branching area supplies the transported material upstream of the hopper body in the transport direction.
According to the fourth means described above, when the transported goods overflowing from the opening are accelerated by the belt conveyor and pass through the hopper body, a frictional force between the conveyor belt and the goods inside the hopper body can be secured when there are few goods inside the hopper body, and an appropriate layer pressure can be secured to make it easier to dispense the goods.

As a fifth means for solving the above-mentioned problems, the present invention provides a powdered or granular material hopper according to any one of the first to fourth means, characterized in that the hopper body has a curved portion whose lower end between the hopper body and the branch area is curved from the branch area toward above the hopper body along the conveying direction.
According to the fifth means described above, the gravity of the transported goods inside the hopper body can be supported by the curved portion, ensuring fluidity at the boundary portion, and making it easier to introduce the transported goods on the belt conveyor supplied from the branching area onto the underside of the hopper body (the area of the hopper body).

According to the present invention, the transported materials that fall inside the hopper body and accumulate on the belt conveyor can be maintained at an appropriate layer thickness, allowing for stable dispensing.

FIG. 2 is a cross-sectional side view of the powder/granular material hopper of the present invention.

The following describes in detail an embodiment of the powder hopper of the present invention with reference to the drawings.

[Powder and granular material hopper 10]
1 is a cross-sectional side view of a powdered or granular material hopper according to the present invention. As shown in the figure, the powdered or granular material hopper 10 according to the present invention includes a hopper body 12 arranged on a belt conveyor 1 so that the material 2 fed therein can form a predetermined layer thickness, an opening 20 provided on the side surface of the hopper body 12 on the upstream side in the conveying direction to discharge the material 2 that exceeds the predetermined layer thickness to the outside of the hopper body 12, and a branch area 30 to feed the material 2 that overflows from the opening 20 to the belt conveyor 1.
The hopper body 12 is a box-shaped container having openings on the top and bottom. The belt conveyor 1 is attached with a predetermined gap between it and the lower opening of the hopper body 12 so that the conveying surface faces the lower opening of the hopper body 12, and conveys the conveyed object 2 that drops from the hopper body 12 to a predetermined location in the subsequent process. The conveyed object 2 of the present invention will be described below using powdered material such as coal and wood pellets used as fuel in thermal power plants as an example.

The opening 20 is an opening provided on the side surface of the hopper body 12 on the upstream side in the conveying direction. The height between the belt conveyor 1 and the opening 20 is the layer thickness of the conveyed object 2 accumulated in the hopper body 12. The appropriate layer thickness of the conveyed object 2 varies depending on the properties of the powder or granular material to be the conveyed object 2, in other words, the type, specific gravity, fluidity, moisture content, particle size, etc. For this reason, an opening position adjustment unit 22 is provided that can change the opening height from the belt conveyor 1 by moving the opening 20 vertically along the side surface of the hopper body 12. The opening position adjustment unit 22 has a slide plate 24 that moves vertically along the side surface of the hopper body 12 and has an opening, and a drive cylinder 26 with a piston connected to the upper end of the slide plate 24 and a rod installed on the side surface of the hopper body 12. The opening position adjustment unit 22 configured in this way can slide the slide plate 24 vertically along the side surface of the hopper body 12 by the forward and backward movement of the drive cylinder 26, and the height position of the opening provided in the slide plate 24 can be arbitrarily set and changed.
The branch area 30 has an upper end connected to the opening 20, and a lower end disposed on the belt conveyor 1 upstream in the conveying direction from the hopper body 12. The branch area 30 configured in this way can supply the conveyed goods 2 that are discharged from inside the hopper body 12 beyond the opening 20, in other words, that overflow, onto the belt conveyor 1.

The gate 40 is attached to the side surface of the hopper body 12 downstream in the conveying direction to adjust the amount of the transported object 2 to be dispensed. The main surface of the gate 40 is curved along (towards) the conveying direction of the belt conveyor 1, in other words, formed in an arc shape expanding outward from the hopper body 12 in a side view. This gate 40 is attached to the side surface of the hopper body 12 downstream in the conveying direction via a rotation support part 42. The rotation support part 42 is arranged with its axis in a direction perpendicular to the conveying direction of the belt conveyor 1, so that the arc-shaped gate 40 can rotate freely in a fan shape, in other words, in the direction approaching or moving away from the conveyor. The gate 40 also has a drive cylinder 44 to which a piston is connected and a rod is installed on the side surface of the hopper body 12. With such a configuration of the gate 40, when the friction coefficient μ between the transported object 2 on the belt conveyor 1 and the conveyor surface is small, for example, a powder with low compactibility is compacted by the gate 40 to increase the weight W of the transported object 2 formed with a layer thickness, thereby ensuring a belt conveying speed F sufficient for conveyance.
The hopper body 12 is provided with a lateral pressure measuring unit 50 for measuring the pressure (lateral pressure) generated when the transported object 2 comes into contact with the side surface when a layer thickness of the transported object 2 is formed. The lateral pressure measuring unit 50 is a sensor in which a plurality of strain gauges are arranged in the vertical direction on the inner wall surface of the hopper body 12. The lateral pressure measuring unit 50 is electrically connected to the opening position adjusting unit 22. This allows the opening position adjusting unit 22 to change the setting of the height position of the opening 20 based on the measurement value of the lateral pressure measuring unit 50 so that the transported object 2 has an appropriate layer thickness.
The hopper body 12 is provided with a curved portion 60 at the lower end between the hopper body 12 and the branching area 30. The curved portion 60 is formed by bending the lower end of the hopper body 12 toward the upper opening of the hopper body 12 along the conveying direction of the belt conveyor 1, in other words, in an arc shape that spreads from the branching area 30 to the inside of the hopper body 12 in a side view. With such a configuration of the curved portion 60, the pressure of the transported goods 2 inside the hopper body 12 can be supported by the curved portion, ensuring the fluidity of the boundary portion, and the transported goods 2 on the belt conveyor 1 supplied from the branching area 30 can be easily introduced to the lower surface of the hopper body 12 (the area of the hopper body 12).

[Action]
The operation of the powder/granular material hopper of the present invention having the above-mentioned configuration will be described below.
The material 2 is fed into the powder/granular material hopper 10 and a predetermined layer thickness is formed inside. The opening 20 is set and adjusted by the opening position adjustment unit 22 to a position (height) where the material 2 can form an appropriate layer thickness. A more specific setting of the layer thickness of the material 2 varies depending on the properties of the material 2 (type, specific gravity, fluidity, moisture content, particle size, etc.), so the material 2 is conveyed for a predetermined time from the start of conveyance, and the material 2 that has formed a predetermined layer thickness in the hopper can move together with the conveyor, in other words, the layer thickness is adjusted to an appropriate weight W of the material 2 that presses against the upper surface of the conveyor.
When the transported material 2 supplied into the hopper exceeds the appropriate layer thickness, the transported material 2 is discharged from an opening 20 provided on the upstream side of the hopper body 12 in the transport direction, in other words, to prevent the material 2 from overflowing and becoming an abnormal layer thickness, and is supplied to the belt conveyor 1 upstream of the hopper body 12 through a branching area 30.

While the article 2 is being transported, the lateral pressure of the hopper wall surface is continuously measured by the lateral pressure measuring unit 50. The opening position adjusting unit 22 can change the height position of the opening 20 based on the measurement value of the lateral pressure measuring unit 50 so that the layer thickness of the article 2 is appropriate.
By supplying the objects 2 from the branching area 30 onto the belt conveyor 1 upstream of the hopper body 12 in a range of 10% to 60% of the total amount of the objects 2, the objects 2 can be accelerated to the conveying speed of the belt conveyor 1 before they reach the hopper body 12. This makes it possible to apply pressure to push the objects 2 stuck in the hopper body 12 in the conveying direction, thereby eliminating sticking and clogging.
In this embodiment, an opening position adjustment section 22 is provided that can adjust the stacking height depending on the type and properties of the transported material 2. However, if the physical properties of the transported material are known in advance, a damper (not shown) that automatically opens due to the stacking pressure acting on the inner wall surface of the hopper body 12 may be provided.
According to the present invention, the materials that fall into the hopper body and accumulate on the belt conveyor can be maintained at an appropriate layer thickness, realizing stable discharge. In addition, the retention inside the hopper body can be minimized, pellet powdering can be prevented, and the amount of dust generated can be suppressed, so that the loss of value as fuel can be reduced and the dusty environment can be improved.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and various modifications can be made without departing from the spirit and scope of the present invention.
Furthermore, the present invention is not limited to the combinations shown in the embodiments, but can be implemented in various combinations.

Reference Signs List 1 Belt conveyor 2 Transported object 10 Powder hopper 12 Hopper body 20 Opening 22 Opening position adjustment section 24 Slide plate 26 Drive cylinder 30 Branch area 40 Gate 42 Rotation support section 50 Side pressure measurement section 60 Curved section

Claims (5)

a hopper body that is disposed on a belt conveyor and that discharges the transported object that has formed a predetermined layer thickness therein onto the belt conveyor;
an opening provided on a side surface of the hopper body on an upstream side in a conveying direction of the belt conveyor, for discharging the material that has exceeded the predetermined layer thickness to the outside of the hopper body;
A powdered or granular material hopper comprising a branch area for supplying the material overflowing from the opening to the belt conveyor. 2. A powder/granular material hopper according to claim 1,
A powdered material hopper comprising an opening position adjustment unit that can change the opening height from the belt conveyor by vertically moving the opening along a side surface of the hopper body. 3. The powder/granular material hopper according to claim 2 ,
A side pressure measuring unit is provided for measuring the pressure applied to the side by the objects accumulated inside the hopper body,
The powder/granular material hopper according to claim 1, wherein the opening position adjusting unit adjusts the opening position when the measured value of the side pressure measuring unit exceeds the measured value of the predetermined layer thickness. A powder/granular material hopper according to any one of claims 1 to 3,
A powdered or granular material hopper, wherein the branching area supplies the transported material upstream of the hopper body in a transport direction. A powder/granular material hopper according to any one of claims 1 to 4,
A powdered or granular material hopper, characterized in that the hopper body has a curved portion at its lower end between the branch area and the branch area, the curved portion being curved along the conveying direction from the branch area toward an upper opening of the hopper body.

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