JPH0452452A - Producing arrangement for uniform gas-flow - Google Patents

Abstract

PURPOSE:To make uniform the blowoff gas-flow and suction gas-flow, which are at low speed (below about 5m/sec) and over a wide area, by a method wherein for a blowoff flow-uniformizing arrangement, a long blowoff pipe is placed in a blowoff box, and toward the downstream side at the upstream side of a blowoff opening, an opening control layer, a filter layer and a honeycomb structure are respectively provided in that order. CONSTITUTION:In a blowoff arrangement 11 for uniform gas-flow, when a gas-flow blown by a blowoff fan 20 is bent about at a right angle, the gas-flow at a blowoff part 21A is apt to concentrate on the end side of a linear flow along the direction blown by the blowoff fan 20, that is, on the far side of the blowoff fan 20. However, a blowoff flow for which both pressure and speed are uniformized can be produced ranging over the longitudinal direction in a blowoff box 21 by the following conditions: That is, a blowoff pipe 23 is provided in the blowoff box 21 and an outlet part 28 on the blowoff pipe 23 is provided on the reverse side of the blowoff part 21A; and baffles (partition) 29 are provided; and the opening degree of the outlet part 28 on the blowoff pipe 23 is formed so as to be made gradually smaller ranging from the near side of an intake 27 on the side of the blowoff fan 20 to the far side thereof.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to the collection and purification of smoking smoke in offices, the collection, collection, and removal of dust such as gas, vapor mist, and fume in factories. The present invention relates to a uniform gas flow forming device suitable for use.

[Prior art] Conventionally, in order to form a uniform gas flow in which the gas pressure and flow velocity are uniform on a plane, The blowout opening of the blowout path is set to gradually decrease from the side closest to the blowout fan to the farthest side, and ■The direction of the flow of the suction fan is bent at right angles to draw in outside air. It has been proposed that the suction opening degree of the suction path is set to gradually increase from the side closer to the suction fan to the side farther from the suction fan.

[Problems to be Solved by the Invention] However, in the prior art, regardless of whether the above-mentioned blowout flow is Alternatively, it becomes extremely difficult to form a low-velocity uniform flow over the entire area of the suction port.

The object of the present invention is to form a uniform flow over a wide area at a low velocity (approximately 5 cm/sec or less) in the blowout flow and/or the suction flow.

[Means for Solving the Problems] The present invention as set forth in claim 1 provides a uniform gas flow system configured by providing a blow-off rectifying device in a blow-off box that blows out the flow of a blow-off fan to the outside from a blow-off port. In the flow forming device, the blow-off rectifying device extends a long blow-off pipe into the blow-off box, and sequentially applies an opening degree control layer, a filter layer, and a honeycomb structure to the blow-off port of the blow-off box from the upstream side to the downstream side. The blowout pipe has an intake port for the flow from the blowout fan at one end, and an outlet for the flow into the blowout box, which is opened on the side substantially opposite to the blowout port. The opening of the pipe is configured to gradually decrease from the side closer to the inlet to the side farther from the inlet, and a plate surrounds the long blowout pipe and partitions the area from the floor of the blowout box to the opening degree control layer in a direction perpendicular to the pipe. The opening degree control layer is arranged so as to partition the flow from the fan's intake port to the inner end of the pipe at an arbitrary interval, and the opening degree control layer controls the opening degree at least in a direction substantially perpendicular to the direction in which the blowout pipe extends. The structure is such that the size is gradually decreased from the side closer to the side to the side farther away.

The present invention according to claim 2 provides a uniform gas flow forming device configured by providing a suction rectifying device in a suction box that sucks outside air from a suction port by the flow of a suction fan, wherein the suction rectifying device It is constructed by extending a long suction pipe inside the box, and the suction pipe has a suction port for the flow to the suction fan at one end, and an inflow port for the flow from inside the suction box on the side substantially opposite to the suction port. The inlet is open, and the degree of opening of the inlet is gradually increased from the side closer to the suction port to the side farther from the suction port.

In the present invention as set forth in claim 3, a blow-off box that blows out the flow of the blow-off fan to the outside from the blow-off port and a suction box that sucks outside air from the suction port by the flow of the suction fan are installed facing each other. In a uniform gas flow forming device configured by providing a blowout rectifier in the blowout box and a suction rectifier in the suction box, the blowout rectifier includes a long blowout pipe extending inside the blowout box. At the same time, the air outlet of the air outlet is constructed by sequentially installing an aperture control layer, a filter layer, and a honeycomb structure from the upstream side to the downstream side, and the air outlet pipe connects the air intake port for the flow from the air blowing fan. provided at one end, an outlet for the flow into the outlet box is opened on the side substantially opposite to the outlet, and the opening degree of the outlet is configured to gradually decrease from the side closer to the inlet to the side farther away from the inlet; A plate that surrounds this long blowout pipe and partitions the area from the floor of the blowout box to the opening degree control layer in a direction perpendicular to the pipe is used to partition the flow from the air intake from the blowout fan to the far end of the pipe at arbitrary intervals. The opening degree control layer is configured such that the opening degree at least in a direction substantially perpendicular to the extending direction of the outlet pipe becomes smaller from the side closer to the outlet tube to the side farther from the outlet tube. It is constructed by extending a long suction pipe inside the box, and the suction pipe has a suction port for the flow to the suction fan at one end, and an inflow port for the flow from inside the suction box on the side substantially opposite to the suction port. The inlet is open, and the degree of opening of the inlet is configured to gradually increase from the side closer to the suction port to the side farther from the suction port.

[Action] According to the present invention as set forth in claim 1, there is the following effect (1).

(1) When blowing by bending the flow direction of the blow-off fan at right angles to the large hole, the blow-out flow from the blow-off port is directed to the end of the straight flow along the blow-out direction of the blow-off fan, in other words, to the far side from the blow-off fan. Easy to concentrate on.

However, in the present invention, "a blow-off pipe is provided in the blow-off box, and the outlet of this blow-off pipe is provided on the side substantially opposite to the blow-off port", and "a baffle (partition plate) is provided".
, and by ``setting the opening degree of the outlet of the outlet pipe to be gradually smaller from the side closer to the intake port on the side of the outlet fan to the side farther away from the outlet,'' the pressure and flow rate are uniform throughout the longitudinal direction of the outlet box. It is possible to form a uniform blowout flow.

Therefore, the flow flowing out from the outlet of the blow-off pipe into the blow-off box tends to concentrate on the terminal end side of the flow along the direction substantially perpendicular to the extending direction of the blow-off pipe, in other words, on the side far from the blow-off pipe.

On the other hand, in the present invention, "the opening degree in the direction substantially perpendicular to the extending direction of the blowout pipe in the opening degree control layer,
By setting the pressure to gradually decrease from the side closer to the outlet pipe to the side farther away from the outlet pipe, the uniform outlet flow formed over the entire longitudinal direction of the outlet box as described above can be It is possible to uniformly flow out to the side of the outlet made of the aperture degree control layer even in the entire area in the direction perpendicular to the direction.

At this time, since the distribution of the aperture in the aperture control layer changes as described above, a high-speed blowout airflow is generated in some parts, and there is no flow in other parts, causing an outflow of the aperture control layer. There is a possibility that vortices will be generated on the side and a large pressure loss will occur. However, in the present invention, since a filter layer made of non-woven fabric or the like is provided on the outflow side of the aperture control layer, the flow flowing out from the aperture control layer is finely redistributed and the generation of the above-mentioned vortices is prevented. However, uniformity of flow can be ensured while reducing pressure loss.

In addition, in order for the uniform flow flowing out from the outlet to reach a long distance, it is necessary to prevent turbulence from occurring at the outlet surface of the outlet to reduce pressure loss. However, in the present invention, since a honeycomb structure is provided at the outlet of the blow-off port, the flow from each honeycomb is made equal to each other, thereby preventing the occurrence of the above-mentioned turbulent flow, reducing pressure loss, and achieving uniformity. You can secure the flight distance of the current.

That is, according to the present invention as set forth in claim 1, it is possible to form a uniform flow over a wide area at a low velocity in the blowout flow.

According to the second aspect of the present invention, the following effect (2) is achieved.

(2) When the direction of the suction fan's flow is bent at right angles for suction, the suction flow to the suction port tends to concentrate on the side closer to the suction fan of the straight flow along the suction direction of the suction fan.

However, in the present invention, ``a suction pipe is provided in the suction box, and the inflow port of this suction pipe is provided on the side substantially opposite to the suction port'', and ``the opening degree of the inflow port of the suction pipe is By setting the fan to increase in size from the side closest to the suction port to the side farthest from it, it is possible to create a suction flow with uniform pressure and flow velocity throughout the entire area inside the suction pipe and, by extension, the entire area of the suction port. .

That is, according to the second aspect of the present invention, it is possible to form a uniform flow over a wide area at a low velocity in the suction flow.

According to the present invention as set forth in claim 3, there is the following effect (3).

(3) A uniform gas flow forming device can be constructed that simultaneously has the effects of (1) and (2) above. That is, according to the present invention as set forth in claim 3, it is possible to form a uniform flow over a wide area at a low velocity in the blowout flow and the suction flow.

[Example] Fig. 1 is a schematic diagram showing a uniform gas flow forming device according to an embodiment of the present invention, Fig. 2 is a sectional view showing a blowing box, and Fig.
FIG. 4 is a front view of the opening degree control plate, FIG. 4 is a perspective view of the blowout pipe, FIG. 5 is a sectional view of the suction box, and FIG. 6 is a perspective view of the suction pipe.

The uniform gas flow forming device 10, as shown in FIG.
It is composed of 2.

- The persistent gas flow blowing device 11 and the uniform gas flow suction device 12 are provided facing each other on both sides of the smoking area, for example, and blow out uniform gas in a plane from the blowing device 11 at low speed. The gas is sucked in uniformly in a plane at low speed by the suction device 12.

However, in implementing the present invention, the basic gas flow blowing device 11 and the uniform gas flow suction device 12 can be used independently.

However, the basic gas flow blowing device 11 is as shown in FIGS.
As shown in the figure, the flow of the blowing fan 20 is
A blow-out rectifying device 22 is provided in a blow-off box 21 configured to blow air from A to the outside.

At this time, the blowout rectifier I22 causes the long blowout pipe 23 to extend inside the blowout box 21, and also causes the blowout box 21 to extend.
An opening degree control plate 24, a filter 25, a filter supporting porous body 25A, and a honeycomb structure 26 are installed in order from the upstream side to the downstream side at the air outlet 21A.

The blow-off pipe 23 has an intake port 27 for the flow from the blow-off fan 20 at one end. Further, the outlet pipe 23 has an outlet 28 for the flow into the outlet box 21 that is opened on the side opposite to the outlet 21A. Further, the blowout pipe 23 is configured such that the opening degree of the outlet 28 is gradually decreased from the side closer to the inlet 27 to the side farther away from the inlet 27. In the present invention, the outlet 28 is constituted by a tapered slit continuous in the longitudinal direction of the blow-off pipe 23 (see Fig. 4).
However, the outlet 28 may be configured with a large number of rectangular slits divided in the longitudinal direction of the blowout pipe 23 (sixth
(see figure).

According to experiments, the opening degree of the outlet 28 is such that the ratio of the large opening degree on the side close to the intake port 27 to the small opening degree on the side far from the intake port 27 is 2 to 5:1, more preferably 3:1. It is better to change it so that

Note that although the flow flowing out from the outlet 28 of the outlet pipe 23 into the outlet box 21 is made substantially uniform in the longitudinal direction of the outlet pipe 23 by setting the opening degree of the outlet 28 described above, Due to this influence, it may flow in the depth direction within the blowout box 21. -Gut gas blowing device 1
1, in order to reliably prevent this, the balloon $I
Around the blow-off pipe 23 in 21, the blow-off pipe 23
Baffles 29 were installed at a plurality of positions along the longitudinal direction to block the above-mentioned flow in the depth direction. These baffles (partition plates) can be installed at arbitrary (or fixed) intervals.

Further, the gas flow blowing device 11 may have a plurality of blowing pipes 23 arranged in parallel inside the blowing box 21.

The opening degree control plate 24 is composed of a perforated plate as shown in FIG. 3, and the opening degree in the direction orthogonal to the extending direction of the blow-off pipe 23 is gradually decreased from the side closer to the blow-off pipe 23 to the side farther from the blow-off pipe 23. It is configured as follows.

The filter 25 is made of nonwoven fabric, crinkled wire mesh, etc., and narrows the flow distribution on the outflow side of the aperture control plate 24 to prevent the generation of vortices and ensures uniform flow while minimizing pressure loss. do.

The honeycomb structure 26 equalizes the flow of air from the air outlet 21A between adjacent honeycombs, prevents turbulence from occurring on the outlet surface, reduces pressure loss, and ensures a uniform flow distance. do.

Note that the honeycomb structure 26 is not limited to a hexagonal hole, but may be a square hole, a round hole, or the like.

Incidentally, the longer the cell length of the honeycomb structure 26, the greater the flying distance of the negative flow. When the cell diameter of the honeycomb structure 26 is 3 mm, if the cell length is 40 mm or more, the uniform flow distance can be extended to 1000 to 2000 mm even at a low speed of 0.2 to 0.51/sec. can.

The filter supporting porous body 25A is made of punch metal, mesh, etc., and the filter 25 and the honeycomb structure 2
6 to prevent the nonwoven fabric or the like that forms the filter 25 from scattering toward the outlet 21A.

Next, as shown in FIG. 1 and FIG.
It is constructed by providing a suction rectifier 32 in a suction box 31 which sucks in outside air from 1A.

At this time, the suction rectifier 32 extends the long suction pipe 33 into the suction box 31, and sequentially connects the filter 34 and the honeycomb structure 35 to the suction port 31A of the suction box 31 from the upstream side to the downstream side. It is configured by installing.

The suction pipe 33 is the suction port 3 for the flow to the suction fan 3o.
6 at one end. Further, the suction pipe 33 has an inlet 37 for the flow from inside the suction box 31 opened on the side opposite to the suction port 31A. Further, the suction pipe 33 is configured such that the opening degree of the inflow port 37 is gradually increased from the side closer to the suction port 36 to the side farther from the suction port 36. In this embodiment, the inlet 37 is composed of a large number of rectangular slits divided in the longitudinal direction of the suction pipe 33 (see FIG. 6). It may be constructed of tapered slits that are continuous in the longitudinal direction (see Fig. 4).

According to experiments, the opening degree of the inlet 37 is such that the ratio of the small opening degree on the side close to the suction port 36 to the large opening degree on the side far from the suction port 36 is 1:14 to 16, more preferably 1:15. It is good to be able to change it so that it becomes .

Note that the root gas flow suction device 12 may have a plurality of suction pipes 33 arranged in parallel within the suction box 31.

The filter 34 is made of non-woven fabric, crinkled wire mesh, etc., and narrows the distribution of the flow sucked in from the suction port 31A, prevents the generation of vortices, and ensures uniformity of the flow while reducing pressure loss. do.

The honeycomb structure 35 equalizes the flow flowing down from the filter 34 side between adjacent honeycombs,
This prevents the occurrence of turbulence at the outlet surface and further ensures flow uniformity. Note that the honeycomb structure 35 is not limited to a hexagonal hole, but may be a square hole, a round hole, or the like.

In addition, in the suction rectifying device 32, an opening degree control layer like the opening degree control plate 24 in the blowout rectifying device 22 is provided on the most upstream side of the suction port 31A (upstream side of the filter 34), and the suction pipe 33 The degree of opening in the direction substantially perpendicular to the extending direction of the suction pipe 33 may be configured to increase sequentially from the side closer to the suction pipe 33 to the side farther from the suction pipe 33.

Next, the operation of the above embodiment will be explained.

(1)-When blowing out air by bending the flow direction of the blowing fan 20 at right angles in the gas flow blowing device fll,
The blowing flow from the blowing outlet 21A is carried out by the blowing fan 20.
It tends to concentrate on the terminal side of the direct flow along the blowing direction, in other words, on the side far from the blowing fan 20.

However, in this embodiment, "the blow-off pipe 23 is provided in the blow-off box 21, and the outlet 28 of the blow-off pipe 23 is provided on the side opposite to the blow-off port 21A", and "the baffle (partition plate) 29, and the opening degree of the outlet 28 of the outlet pipe 23 was adjusted to the intake port 27 on the side of the outlet fan 20.
By setting the pressure to be gradually smaller from the side closer to the side to the side farther away from the air, it is possible to form a blowing flow with uniform pressure and flow velocity over the entire longitudinal direction inside the blowing box 21.

Therefore, the flow flowing out from the outlet 28 of the outlet pipe 23 into the outlet box 21 is concentrated on the end side of the flow along the direction perpendicular to the extending direction of the outlet pipe 23, in other words, on the side far from the outlet pipe 23. easy.

On the other hand, in this embodiment, "opening degree control plate 24
The degree of opening in the direction substantially orthogonal to the extending direction of the blow-off pipe 23 in the blow-off pipe 23 is set to gradually decrease from the side closer to the blow-off pipe 23 to the far side. From the opening degree control plate 24 to the side of the air outlet 21A, so that the uniform air flow formed in the entire longitudinal direction is made uniform also in the entire area in the direction orthogonal to the longitudinal direction inside the air outlet box 21. It can be made to flow out.

At this time, since the distribution of the opening degree on the opening degree control plate 24 changes as described above, a high-speed blowout airflow is generated in some parts, and there is no flow in other parts, so that the opening degree control plate 24 There is a possibility that a vortex may be generated on the outflow side, resulting in a large pressure loss. However, in this embodiment, since the filter 25 made of non-woven fabric or the like is provided on the outflow side of the aperture control plate 24, the flow flowing out from the aperture control plate 24 is finely redistributed and the above-mentioned vortex is eliminated. It is possible to prevent this from occurring and ensure uniformity of flow while minimizing pressure loss.

In addition, in order for the uniform flow flowing out from the outlet 21A to reach a long distance, it is necessary to prevent turbulence from occurring at the outlet surface of the outlet 21A to reduce pressure loss.

However, in this embodiment, since the honeycomb structure 26 is provided at the outlet of the air outlet 21A, the flow from each honeycomb is made equal to each other, preventing the above-mentioned turbulence from occurring, and reducing pressure loss. , - You can secure the flight distance of the flow of guts.

(2) In the root gas flow suction device 12, when the suction fan 3o bends the flow direction at right angles to draw air, the suction flow to the suction port 31A is a linear flow along the suction direction of the suction fan 3o. It is easy to concentrate on the side closer to 30.

However, in this embodiment, "the suction pipe 33 is provided inside the suction box 31, and the inlet port 37 of this suction pipe 33 is provided on the side opposite to the suction port 31A", and "the inlet port 37 of the suction pipe 33 is provided on the side opposite to the suction port 31A" By setting the opening degree of the inlet port 37 of the suction fan 30 to be gradually larger from the side closer to the suction port 36 to the side farther from the suction port 36, the pressure is increased in the entire area inside the suction box 31, and by extension, in the entire area of the suction port 31A. A suction flow with uniform flow velocity can be formed.

(3) Therefore, according to the -like gas flow forming device, - the effect of (1) above by the root gas flow blowing device 11 and the effect of (2) above by the root gas flow suction device 12 are simultaneously achieved. , in the outlet flow and the suction flow,
It is possible to form a uniform dragon over a wide area at low speed.

Hereinafter, specific implementation results of the present invention will be explained.

(a) Outlet rectifier ■ Dimensions of the outlet box 21 are 300 (height) x 170
It was set to 0m11 (length) x 100mm (depth).

■Blowout pipe 23 consisting of one PVC pipe inside the blowout box 21
17 were installed. The diameter of the blow-off pipe 23 was 2 inches.

The blowout pipe 23 is provided with an outlet 28 consisting of a tapered slit, and the opening of the outlet 28 is such that the ratio of the large opening on the side close to the intake port 27 and the small opening on the side far from the intake port 27 is 3:1. It was changed so that

■200 to 450 in the longitudinal direction inside the balloon box 21
Baffles 29 were installed at each wear interval.

(b) Suction rectifier ■ Dimensions of suction box 31: 300mm (height) x 17
00 am (length) x 100 am (depth).

■Suction pipe 33 consisting of three PVC pipes inside the suction box 31
were arranged in parallel. The diameter of the suction pipe 33 was 2 inches. The suction pipe 33 is provided with a large number of inlets 37 consisting of rectangular slits in each of five regions A-H divided in the longitudinal direction (see Fig. 6), and inlets 37 in each region A-E.
The installation structure of No. 7 is as shown in Table 1.

As a result of the experiments described in (a) and (b) above, it was possible to form a uniform flow over a wide area at a low velocity of about 5 cm/see or less in the blowout flow and the suction flow.

[Effects of the Invention] As described above, according to the present invention, it is possible to form a uniform flow over a wide area at a low velocity in the blowout flow and/or the suction flow.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a uniform gas flow forming device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a blowing box, and FIG.
FIG. 4 is a front view of the opening degree control plate, FIG. 4 is a perspective view of the blowout pipe, FIG. 5 is a sectional view of the suction box, and FIG. 6 is a perspective view of the suction pipe. DESCRIPTION OF SYMBOLS 10...- Root gas flow forming device, 11...- Modal gas flow blowing device, 12-...- Root gas flow suction device, 20... Blow-off pipe, 21A... Blow-off port, 21. ...Blowout box, 22...Blowout rectifier, 23...Blowout pipe, 24...Opening degree control board, 25...Filter 26...Honeycomb structure, 27...Intake port, 28 ... Outlet, 30... Suction fan, 31A... Suction port, 31-... Suction box, 32... Suction rectifier, 33-... Suction pipe, 34... Filter 35... - Honeycomb structure, 36... Suction port, 37... Inflow port. Representative Patent Attorney Osamu Shiokawa Figure 2, Figure 3, Figure 4, Figure 5, Figure 6

Claims (3)

[Claims] (1) In a uniform gas flow forming device configured by installing a blow-off rectifying device in a blow-off box that blows the flow of a blow-off fan to the outside from a blow-off port, the blow-off rectifying device includes:
A long blowout pipe is extended inside the blowout box, and an aperture control layer, a filter layer, and a honeycomb structure are sequentially installed at the blowout port of the blowout box from the upstream side to the downstream side. is equipped with an intake port for the flow from the blow-off fan at one end, and an outlet for the flow into the blow-off box is opened on the side substantially opposite to the blow-off port, and the opening degree of the outflow port is adjusted from the side near the inlet. It is constructed so that the size gradually decreases toward the far side, and a plate that surrounds this long blow-off pipe and partitions from the floor of the blow-off box to the opening degree control layer in a direction perpendicular to the pipe allows the flow from the intake of the blow-off fan to the pipe. The opening control layer is arranged so that it is partitioned at arbitrary intervals up to the back end.
A uniform gas flow forming device characterized in that the degree of opening in a direction substantially perpendicular to the extending direction of the blow-off pipe is gradually decreased from a side closer to the blow-off pipe to a side farther from the blow-off pipe. (2) In a uniform gas flow forming device configured by installing a suction rectifier in a suction box that sucks outside air from the suction port by the flow of a suction fan, the suction rectifier has a long suction pipe inside the suction box. The suction pipe has a suction port for the flow to the suction fan at one end, and an inflow port for the flow from inside the suction box is opened on the side substantially opposite to the suction port. 1. A uniform gas flow forming device characterized in that the degree of opening of the gas flow is gradually increased from a side closer to a suction port to a side farther from a suction port. (3) A blowout box that blows the flow of the blowout fan to the outside from the blowout port and a suction box that sucks outside air from the suction port using the flow of the suction fan are installed opposite each other, and the blowout box has a blowout rectifier. In the uniform gas flow forming device, the blow-off rectifier has a long blow-off pipe extending inside the blow-off box, and the blow-off rectifier has a suction rectifier installed in the blow-off box. It is constructed by sequentially installing an aperture control layer, a filter layer, and a honeycomb structure at the mouth from the upstream side to the downstream side, and the blowout pipe has an intake port for the flow from the blowout fan at one end, The outflow port for the flow to the air outlet is opened on the side substantially opposite to the outlet, and the opening degree of the outflow port is configured to gradually decrease from the side closer to the inlet to the side farther from the inlet,
A plate that surrounds this long blowout pipe and partitions the area from the floor of the blowout box to the opening degree control layer in a direction perpendicular to the pipe is used to partition the flow from the air intake from the blowout fan to the far end of the pipe at arbitrary intervals. The opening degree control layer is configured such that the opening degree at least in a direction substantially perpendicular to the extending direction of the outlet pipe becomes smaller from the side closer to the outlet tube to the side farther from the outlet tube. It is constructed by extending a long suction pipe inside the box, and the suction pipe has a suction port for the flow to the suction fan at one end, and an inflow port for the flow from inside the suction box on the side substantially opposite to the suction port. It is open,
A uniform gas flow forming device characterized in that the degree of opening of the inlet port is configured to gradually increase from the side closer to the suction port to the side farther from the suction port.