JP2003207058A - Powder shut-off valve device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power shut-off valve device for reliably maintaining gas-sealing property. <P>SOLUTION: In linkage with the opening/closing of a passage 2, a gas supply/ collection means 20 supplies gas to the back side of an elastic body 7 to be stored in a storage area 15 on a valve seat 4 to apply preset pressure thereto and exhausts the gas from the back side to remove the applied pressure. In linkage with the sliding movement of a valve plate 5 with respect to the valve seat 4 in the approximately crossing direction, it exhausts the gas from the back side of the elastic body 7. While the front face of the elastic body 7 is put in such a normal condition that it is recessed as predetermined from seal surfaces 9a, 9b of the valve seat 4 to avoid damage to the elastic body 7, a seal face 5a of the valve plate 5 and seal surfaces 9a, 9b of the valve seat 4 have mutual slide contact for preventing the gripping of a powder in even quantity during the sliding movement of the valve plate 5 for closing the passage 2, in particular, to accomplish seating. On the other hand, the gas is supplied in linkage with the seating of the valve plate 5 to apply preset pressure thereto, whereby the elastic body 7 is elastically deformed and the front face thereof is put in close contact with the seal surface 5a of the valve plate 5 for sealing. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder cutoff valve device applied to a passage through which powder passes or occurs.

[0002]

2. Description of the Related Art For example, a powder cutoff valve device for opening and closing the outlet and the connecting portion is provided at the outlet and the connecting portion of a pipeline as a passage through which powder such as ash passes. In this powder cutoff valve device, when the inside of the pipeline is pressurized, it is required to ensure airtightness, especially when closed.

In such a powder shut-off valve device, the open end of the conduit is formed into an annular valve seat, and the valve plate slides in a direction transverse to the valve seat to separate from / seated. ,
A powder shutoff valve device called a plate valve that opens and closes a passage by this is known. In this device, each of the valve plate and the valve seat is made of metal having different hardness and has a flat seal surface as a seal portion.
When the valve plate slides to close the passage, the sealing surface of the valve plate slides on the sealing surface of the valve seat by a so-called metal touch, and the valve plate is seated on the valve seat by the surface contact to block the passage. Has been done.

[0004]

However, in this powder shut-off valve device, the sealing surface of the valve plate, which is the slide moving surface, is slid against the sealing surface of the valve seat, which is the fixed surface, and the surface contact is maintained as it is. Since the structure is seated at, the sealing surface pressure is weak and it is difficult to secure airtightness.

Therefore, in order to solve this problem, the valve plate is constructed so as to be movable by a predetermined amount in the direction facing the valve seat, and
On the back side of the valve plate, an inclined piece that is inclined downward in the sliding movement direction when the passage is closed is installed.Furthermore, a contact member that abuts the inclined surface of this inclined piece when the valve plate slides is fixed to the fixed side. Then, the slanted surface is brought into contact with the abutting member in accordance with the sliding movement of the valve plate when the passage is closed, so that the valve plate is gradually moved to the valve seat side, and the sealing surfaces are finally brought into close contact with each other with high surface pressure. There is known a device for causing the change.

However, in this device, it is difficult to slide the seal surfaces from the beginning while keeping them in close contact with each other and finally to bring them into close contact with each other with a high surface pressure (because the surfaces are bitten, the slide movement becomes impossible. (Or the seal surface is damaged), and there is a gap between the seal surfaces before the valve plate seats on the valve seat, powder enters this gap and the seal surfaces come into close contact in this state. The powder will be caught between the sealing surfaces. When powder entrapment occurs in this way, especially on metal surfaces, due to the pressure difference between the upstream side and the downstream side of the powder shutoff valve device, the entrained part of the powder is sharply scraped off in a groove by the gas flow. Therefore, it becomes difficult to ensure airtightness. In particular, when the pipe is arranged so as to extend in the vertical direction, and the powder passing from above to below is blocked by the valve plate that is located below the valve seat, the sliding movement of the valve plate At this time, the powder is accumulated on the sealing surface of the valve plate, so that the powder is further caught when the sealing surfaces are in close contact with each other, and it becomes impossible to secure the airtightness.

In addition to the plate valve, a spherical space is defined in the valve box connected to the pipe, and a ball having a through hole as a passage is rotatably arranged in the space. There is known a powder shutoff valve device called a ball valve that opens and closes a passage by opening and closing the passage of the ball by connecting the opening of the pipe and the passage of the ball by rotating the ball. This device has a drawback in that powder enters the sliding gap between the ball and the sliding surface on the valve box side that rotatably supports the ball and solidifies to cause malfunction.

In addition to the passage for ash and the like, if a dust combustion furnace such as a gasification furnace is installed under pressure even in the dust conveying passage, if the dust combustion furnace is installed under pressure, Airtightness is required by the powder shutoff valve device used in the dust transfer passage, but since dust particles such as dust are generated from the dust that is transported, airtightness is the same as for powder such as ash. It is difficult to secure sex.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a powder cutoff valve device which ensures airtightness.

[0010]

A powder shutoff valve device according to the present invention is applied to a passage through which powder passes or is generated, and a valve seat disposed on the opening side of a cylindrical body defining the passage. In the powder cutoff valve device in which the valve plate slides / seates in a substantially transverse direction to open / close the passage, the valve plate and the valve seat are separated when the valve plate slides / seated. Each of the valve seats has an annular sealing surface that is in sliding contact with the other, and the valve seat has an annular accommodation area that faces the sealing surface of the valve plate when the valve plate is seated, and its front surface is recessed in a predetermined manner with respect to the sealing surface of the valve seat. Gas is supplied to the annular elastic body that is housed in the housing area and that is elastically deformed when gas is supplied and pressurized and the back side of the elastic body in the housing area in conjunction with opening and closing of the passage. And pressurize it to the specified level, and the gas is discharged from the back side to remove the pressure. It is characterized by comprising a gas supply / recovery unit.

According to such a powder shutoff valve device, the gas is supplied to the back side of the elastic body accommodated in the accommodating region of the valve seat by the gas supply / recovery means in conjunction with the opening and closing of the passage. Since the gas is discharged to the predetermined position and the gas is discharged from the back surface side to remove the pressure, the gas on the back surface side of the elastic body is interlocked with the sliding movement of the valve plate in a direction substantially transverse to the valve seat. By discharging, the front surface of the elastic body is in a normal state in which the sealing surface of the valve seat is recessed in a predetermined state, and damage to the elastic body is avoided, and the sealing surfaces of the valve plate and the valve seat are in sliding contact with each other. In particular, when the valve plate slides when the passage is closed, it is so-called slid off and powder is prevented from being caught and seated.On the other hand, gas is supplied in conjunction with the seating of the valve plate to set the seat. By applying pressure, the elastic body elastically deforms and its front surface becomes the sealing surface of the valve plate. Seal is made is wearing.

Here, if the powder is ash, the function of the device of the present invention is sufficiently exerted.

Further, the function of the device of the present invention is sufficiently exerted even if the passage is used as a dust conveying passage for conveying dust and the powder is dust generated from the dust.

Further, when the valve plate is seated on the valve seat, the gas supply / recovery means supplies gas to pressurize the gas to a predetermined pressure, and discharges the gas immediately before the valve plate starts to separate from the valve seat.
The elastic body is reliably prevented from being damaged, and the close contact between the elastic body and the sealing surface of the valve plate is surely secured.

Further, when the elastic body is provided with a notch for promoting elastic deformation on its front surface, elastic deformation that tends to come into close contact with the sealing surface of the valve plate in accordance with the supply of gas is easily performed.

If at least one of the sealing surfaces is made of a wear resistant material, wear and abrasion are suppressed, and the life of the sealing surfaces is extended.

Further, when a pressing means for pressing the valve plate toward the valve seat side when the valve plate is seated is provided, the adhesion between the elastic body and the sealing surface of the valve plate when the valve plate is seated is improved. It is further enhanced.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the powder shutoff valve device according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a longitudinal sectional view showing a state where a valve plate of a powder shutoff valve device according to a first embodiment of the present invention is separated, and FIG. 2 is a valve plate of a powder shutoff valve device according to the first embodiment. It is a longitudinal cross-sectional view showing a state when seated. This powder cutoff valve device is provided, for example, in a discharge passage of a pyrolysis gas (combustible gas) generated by thermally decomposing and combusting combustible substances such as dust in a gasification furnace or the like pressurized to a predetermined pressure. It is provided at the outlet and connection, and the pipe as the discharge passage is opened and closed, and when it is closed, the flow of powder such as fly ash accompanying it with the pyrolysis gas is shut off and the pipe is closed at the same time. The airtightness is secured on the upstream side of the road.

As shown in FIG. 1, the powder cutoff valve device is arranged in the valve box 3 and is generally connected to the upstream side (gasification furnace side) of the pipeline 10 (cylindrical body). ) 2, a valve seat 4 installed at the peripheral edge of the downstream side opening of the conduit 2, and a valve plate 5 that is separated from / seated with respect to the valve seat 4 to open / close the conduit 2. .

The pipe line 2 forming the introduction pipe line of the valve box 3 is connected to the upstream pipe line 10 extending in the vertical direction to define a powder passage, and the powder is provided on the upstream side. Pipeline 10 and pipeline 2
Pass from above to below. Further, an outlet portion 3a for discharging the powder flowing through the pipe line 2 to a subsequent stage outside the valve casing 3 when the pipe line 2 is opened by the valve plate 5 is opened on the opposite side of the valve casing 3 from the pipe line 2. ing.

The valve plate 5 is a substantially disk body made of a wear-resistant material such as ceramic, and is a mover 11 (see FIG. 2) of an actuator (not shown) such as an air cylinder.
Is connected and fixed to the valve seat 4 via a connecting portion 12, and is slidable (forward and backward) in a direction transverse to the valve seat 4, and reciprocally moves between a seated position shown in FIG. 1 and a seated position shown in FIG. To do. As shown in FIG. 2, the valve plate 5 is provided with an annular convex portion 5b facing the valve seat 4 when it is located at the seating position, and the convex surface of the convex portion 5b is formed into a flat surface to form a sealing surface 5a. Is equipped with.

The valve seat 4 is arranged at the open end (lower end in the drawing) of the conduit 2 and the valve plate 5 is seated as shown in FIG.
It has a function as a seal portion that seals between the valve plate 5 and the pipe 2 when the pipeline 2 is closed, and as its constituent elements, a flange portion 6 serving as a base of the seal portion and a valve portion fixed to the flange portion 6 A seal ring 8 having seal surfaces 9a and 9b that are in sliding contact with the valve plate 5 when the plate 5 slides and a seal while the valve plate 5 is seated while being supported by the seal ring 8 is substantially provided. Elastic seal ring (elastic body)
7 is provided.

The flange portion 6 is an annular flange portion which is provided at the open end of the conduit 2 and faces outward, and is fixed by, for example, welding or the like.

The seal ring 8 is the inner seal ring 8
a and an outer peripheral side seal ring 8b which are divided into two parts and are circumferentially separated from each other, and are formed of a wear-resistant material such as ceramics, and the outer peripheral surface of the seal ring 8a and the inner peripheral part of the seal ring 8b. For example, a large number of screws are provided to the flange portion 6 so that an accommodation region (space) 15 having a T-shaped cross section and forming an annular shape is defined between the surface and the lower surface of the flange portion 6. It is fixed by etc. The lower surfaces of the seal rings 8a and 8b are flush with the sealing surfaces 9a and 9b which are flat surfaces. Further, an annular O-ring 30 is provided between the seal rings 8a and 8b and the flange portion 6 to prevent leakage through the accommodation area 15.
a and 30b are equipped respectively. The sealing surfaces 9a and 9b of the seal rings 8a and 8b are in sliding contact with the sealing surface 5a of the valve plate 5 when the valve plate 5 slides.
The positional relationship between the valve seat 4 and the valve plate 5 is set.

As shown in FIG. 1, the elastic seal ring 7 has a T-shaped cross section which is convex downward, and the inner and outer peripheral edges forming the hem of the convex portion are respectively formed on the seal rings 8a and 8b. It is an annular body that is placed and supported in the storage area 15 so as to be supported from below, and is formed of an elastic body. As the elastic body, rubber is preferable, but soft rubber or the like other than rubber may be used as long as the elastic body is elastically deformed when gas is supplied and pressurized.

The convex surface (lower surface in the figure) of the elastic seal ring 7 is the seal surface 9 of the seal rings 8a and 8b.
It is configured to be slightly recessed (having a step) with respect to a and 9b, and specifically, a step of about 1 mm is set.
Further, at the tip of the convex portion of the elastic body seal ring 7, when the N ₂ gas described later is supplied to the rear surface side (the upper surface side in the drawing) of the elastic seal ring 7 and a predetermined pressure is applied, the convex portion is elastically deformed downward. The V notch 7a for promoting is formed in an annular shape. Then, a predetermined gap that allows elastic deformation of the elastic seal ring 7 is set at an appropriate position between the outer surface of the elastic seal ring 7 and the surface defining the accommodation area 15.

Further, in the present embodiment, N ₂ gas (gas) is supplied to the rear surface side of the elastic seal ring 7 accommodated in the accommodating region 15 of the valve seat 4 to pressurize it to a predetermined level. A gas supply / recovery means 20 for removing N ₂ gas from the back side to remove pressure is additionally provided. Specifically, the gas supply / recovery means 20 has a through hole 20a vertically penetrating a position of the flange portion 6 facing the elastic body seal ring 7 and a through hole 20a connected to the through hole 20a. comprising a conduit 20b for discharging the N ₂ gas through the N ₂ gas supplies also through-holes 20a, and although more is not shown, the N ₂ gas from the N ₂ gas supply source and accommodating region 15 It is equipped with a branch pipe and a valve for collecting and releasing the air into the atmosphere. The predetermined pressure of N ₂ gas is set to about 5 × 10 ⁵ Pa in this embodiment. Further, the pressure of the elastic sealing ring 7 back side by the supply of N ₂ gas, with respect to the timing and duration of the discharge of the N ₂ gas will be described later.

According to the powder cutoff valve device thus constructed, the pipe line 2 is opened when the valve plate 5 is located at the separated position shown in FIG. The powder passes through. At this time, the elastic seal ring 7
The N ₂ gas on the back side is discharged and the pressure on the back side is removed. That is, the convex surface of the elastic seal ring 7 is slightly retracted from the seal surfaces 9a and 9b of the seal ring 8.

Here, when closing the conduit 2 as necessary, the actuator is driven to slide the valve plate 5 toward the valve seat 4, and the valve plate 5 closes the conduit 2. Go. When the valve plate 5 slides, the powder is falling, so that the powder is accumulated on the seal surface 5a.

Then, according to the sliding movement of the valve seat 5,
Seal face 5a of valve plate 5 and seal face 9 of seal ring 8
a and 9b are in sliding contact with each other. At this time, since the convex surface of the elastic body seal ring 7 is retracted with respect to the seal surfaces 9a and 9b of the seal ring 8, the elastic body seal ring 8 is not rubbed by the seal surface 5a of the valve plate 5 and the valve is closed. Seal surface 5a of plate 5
And the sealing surfaces 9a and 9b of the seal ring 8 are in sliding contact with each other.

As a result of this sliding contact, the powder on the seal surface 5a is transferred to the seal surface 5a and the seal surfaces 9a, 9 of the seal ring 8.
It is so-called slid between b and b, and is all removed from the seal surface 5a (between the seal surface 5a and the seal surfaces 9a and 9b), thereby preventing the powder from being caught.

Then, as shown in FIG. 2, when the valve plate 5 reaches the seating position and is seated, the conduit 2 is closed. Here, conventionally, it is difficult to secure airtightness by sealing between sealing surfaces because the surface pressure is weak.

Therefore, in the present embodiment, when the valve plate 5 is seated on the valve seat 4, the gas supply / recovery means 20 immediately supplies N ₂ gas to the back side of the elastic seal ring 7. It is pressurized to a predetermined pressure (about 5 × 10 ⁵ Pa described above). Then, the convex portion of the elastic seal ring 7 is elastically deformed downward due to the pressurization on the back surface side, and the convex portion comes into close contact with the sealing surface 5 a of the valve plate 5. Due to the close contact between the convex portion of the elastic seal ring 7 and the seal surface 5a of the valve plate 5, leakage is prevented, and airtightness on the upstream side of the pipe line 2 is secured. At this time, the lower surfaces of the inner peripheral edge and the outer peripheral edge which form the hem of the convex portion of the elastic body seal ring 7 are sealed by the seal rings 8a, 8
It is pressed against and closely adheres to the mounting portion of b, and a seal is also made here. Then, thereafter, the predetermined pressure is maintained.

Next, when the conduit 2 is opened as necessary, the valve plate 5 is moved to the valve seat 4 by the gas supply / recovery means 20.
Immediately before starting to separate from the seat, the N ₂ gas with which the back surface side of the elastic body seal ring 7 is discharged is released and the pressure on the back surface side is removed. As a result, the elastic seal ring 7
Returns to the normal state (original state) and the convex surface is the seal ring 8
Is slightly retracted with respect to the seal surfaces 9a and 9b, and the valve plate 5 slides in this state. Therefore, even when the valve plate 5 slides to open the conduit 2, the elastic seal ring 7 does not rub against the sealing surface 5a of the valve plate 5, and therefore the valve plate 5 that opens and closes the conduit 2 is closed. The elastic seal ring 7 is reliably prevented from being damaged during sliding movement.

As described above, in this embodiment, since the N ₂ gas on the back side of the elastic seal ring 7 is discharged to remove the pressurization, the elasticity of the valve plate 5 for opening and closing the conduit 2 when the slide is moved. While avoiding damage to the body seal ring 8, the sealing surface 9 is particularly during sliding movement of the valve plate 5 that closes the conduit 2.
The sliding contact between a and 9b and the seal surface 5a prevents the powder from being caught, and N ₂ gas is supplied to the rear surface side of the elastic seal ring 7 when the pipe line 2 is closed. As a result of being pressurized, the convex portion of the elastic seal ring 7 and the sealing surface 5a of the valve plate 5 are in close contact with each other, and reliable airtightness is ensured.

The seal rings 8a, 8b and the valve plate 5
Is formed of a wear-resistant material, so wear and abrasion of both are suppressed. Therefore, the life of the device is extended. Instead of forming the seal rings 8a and 8b and the valve plate 5 as a whole with a wear-resistant material such as ceramics, a metal lined with a wear-resistant material such as ceramics or a surface-hardened metal may be used. Alternatively, only the seal surfaces 9a, 9b and the seal surface 5a of the seal rings 8a, 8b may be made of a wear resistant material having a predetermined thickness. Further, although it is particularly effective that the seal ring 8 side and the valve plate 5 side are both made of a wear-resistant material, it is possible to prolong the life of the apparatus with either of them.

If a pressing means such as an air cylinder for pressing the valve plate 5 toward the valve seat 4 when the valve plate 5 is seated is provided, the elastic seal ring 7 for seating the valve plate 5 is provided. And the sealing surface 5a of the valve plate 5 are further improved in adhesion, and airtightness is further secured.

Incidentally, the convex surface of the elastic body seal ring 7 and the seal surface 9a of the seal ring 8 under normal conditions (when pressure is removed),
If the dimension of the step between 9b is too large,
Since the powder may be trapped when the valve plate 5 is slid during the sliding movement, it is necessary to set the size in consideration of this, and in this embodiment, it is set to about 1 mm.

FIG. 3 is a longitudinal sectional view showing a valve seat of a powder shutoff valve device according to a second embodiment of the present invention and its vicinity in an extracted manner.

The difference between the second embodiment and the first embodiment is that the arrangement of the valve seat 4 is changed so that the flange portion 6 is connected to the conduit 2
It is not the open end of the above, but the point which is connected to the open end on the other end side of the tubular body 16 which surrounds the pipe line 2 in the valve box 3 and has one end connected to the inner wall of the valve box 3.

It goes without saying that even with this structure, the same effects as those of the first and second embodiments can be expected.
The tubular body 16 may have one end connected to the pipe line 2 instead of the inner wall of the valve box 3, as shown by a phantom line in FIG. 3.

Although the present invention has been specifically described based on its embodiment, the present invention is not limited to the above embodiment. For example, in the above embodiment, the gas is supplied by the gas supply / recovery means. The gas used is N ₂ gas, but other gases may of course be used.

In the above embodiment, the application to the pipeline defining the powder passage in the vertical direction is described, but it is of course also applied to the pipeline defining the powder passage in a direction other than the vertical direction. It is possible.

Further, in the above embodiment, the application to the valve plate 5 which slides back and forth (goes straight) and substantially crosses the valve seat 4 is described, but the valve seat 4 is slid by rotation about one axis as a fulcrum. The present invention is also applicable to a valve plate that traverses substantially the same as that of FIG.

Further, in the above embodiment, the powder shutoff valve device is applied to the exhaust passage of the pyrolysis gas of the gasification furnace as being particularly effective, but for example, the bottom ash of the gasification furnace is used. It can also be applied to a passage for discharging.

Further, even in a dust conveying passage for conveying the dust to a dust combustion furnace such as a gasification furnace to be pressurized, dust such as dust is generated from the dust conveyed through the passage. The application of the powder shutoff valve device of the present invention is effective,
In short, it can be applied to a passage through which ash, dust, or other powder such as dust passes or is generated.

[0047]

In the powder shutoff valve device according to the present invention, gas is supplied to the back side of the elastic body accommodated in the accommodating region of the valve seat by the gas supply / recovery means in conjunction with the opening and closing of the passage. Since it is configured to pressurize to a predetermined level and discharge the gas from the rear surface side to remove the pressurization, the elastic body rear surface is interlocked with the sliding movement of the valve plate in a direction substantially transverse to the valve seat. By discharging the gas on the side, the front surface of the elastic body is set in a normal state in which the sealing surface of the valve seat is recessed in a predetermined state to avoid damage to the elastic body, and the sealing surfaces of the valve plate and the valve seat are separated from each other. When sliding the valve plates that are in sliding contact with each other to close the passage, so-called sliding is performed to prevent powder from being trapped and it is possible to form a seat. Is supplied to the elastic body to elastically deform the front surface of the elastic body. It is possible to seal by close contact with the sealing surface of the valve plate. Therefore, it becomes possible to reliably ensure the airtightness.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a state of a powder shutoff valve device according to a first embodiment of the present invention when a valve plate is separated.

FIG. 2 is a vertical cross-sectional view showing a state of the powder cutoff valve device according to the first embodiment of the present invention when the valve plate is seated.

FIG. 3 is a vertical cross-sectional view showing a valve seat of a powder shutoff valve device according to a second embodiment of the present invention and its vicinity in an extracted manner.

[Explanation of symbols]

2, 16 ... Pipe line (cylindrical body), 4 ... Valve seat, 5 ... Valve plate, 5a
... Sealing surface of valve plate, 6 ... Flange portion, 7 ... Elastic seal ring (elastic body), 7a ... Notch, 8, 8a, 8b ... Seal ring, 9a, 9b ... Sealing surface of valve seat, 15 ... Storage area , 20 ... Gas supply / recovery means, 20a ... Through hole, 20
b ... conduit.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hideaki Yoshida             4-21 Matsushima, Edogawa-ku, Tokyo             Within Barex Co., Ltd. F-term (reference) 3F047 AA01 CC23                 3F075 AA08 CC15 CD11                 3H053 AA02 AA31 BB13 BB17 BB20                       BB23 BB33 BB34 BB39 DA06

Claims (7)

[Claims] 1. A valve plate is applied to a passage through which powder passes or is generated, and a valve plate slides in a direction substantially transverse to a valve seat disposed on the opening side of a cylindrical body defining the passage. In the powder cutoff valve device for separating / seating and opening / closing the passage, each of the valve plate and the valve seat has an annular seal surface that is in sliding contact with each other when the valve plate slides and separates / seats. The valve seat includes an annular accommodation area that faces a sealing surface of the valve plate when the valve plate is seated, and is accommodated in the accommodation area such that a front surface of the valve seat is recessed from the sealing surface of the valve seat in a predetermined manner. And an annular elastic body that is elastically deformed when gas is supplied and pressurized, and by supplying gas to the back side of the elastic body in the accommodation area in conjunction with opening and closing of the passage. Pressurize to a specified level and discharge the gas from the back side. Powder shutoff valve device characterized by and a gas supply / recovery means for removing the pressure. 2. The powder shutoff valve device according to claim 1, wherein the powder is ash. 3. The powder cutoff valve device according to claim 1, wherein the passage is a dust transport passage for transporting dust, and the powder is dust generated from the dust. 4. The gas supply / recovery means supplies the gas when the valve plate is seated on the valve seat to pressurize the gas in a predetermined manner, and immediately before the valve plate starts to separate from the valve seat. The powder cutoff valve device according to claim 1, wherein the powder cutoff valve device is discharged. 5. The powder cutoff valve device according to claim 1, wherein the elastic body is provided with a notch on a front surface thereof to promote elastic deformation. 6. The method according to claim 1, wherein at least one of the sealing surfaces is made of a wear resistant material.
The powder shutoff valve device according to any one of claims 1 to 5. 7. The powder according to claim 1, further comprising a pressing unit that presses the valve plate toward the valve seat when the valve plate is seated. Shut-off valve device.