JP2001227783A - Combustible gas diluting and discharging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustible gas diluting and discharging method in which combustible gas discharged from a reaction furnace is not directly forcedly sucked nor discharged, but even when the combustible gas is generated at random, this can be always met and discharged, and the combustible gas to be discharged can be simultaneously treated relative to a plurality of reaction furnaces and diluted to an explosion limit or lower and discharged. SOLUTION: Combustible gas is guided to an inducing air passage 9 by gas piping 7. The combustible gas is induced and discharged from an outlet opening part of the gas piping opened to the downstream side of the passage in accordance with the flow velocity of air in the passageway.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to forcing a relatively small flow rate and high concentration of flammable gas discharged from a manufacturing process in a normal temperature to high temperature reduction reactor in a closed reducing atmosphere by a direct blower. The present invention relates to a method for diluting and discharging a combustible gas that dilutes and discharges indirectly and safely and efficiently using the flow velocity of air in an air flow path without discharging.

[0002]

2. Description of the Related Art In a semiconductor manufacturing process such as a normal-pressure CVD furnace, a reactor 2 is installed in a clean room 1 and hydrogen gas is supplied from a gas pipe 4 connected to the reactor 2 as schematically shown in FIG. Exhaust gas containing exhaust gas (not shown)
And a method of sucking / discharging with the blower 3 through the air. In the abatement cylinder, unreacted raw material gas and reaction products are removed, and hydrogen gas, which is a flammable gas having a relatively small flow rate but high concentration, is discharged through the blower 3.

[0003] Since high-concentration hydrogen gas has the danger of burning and explosion due to static electricity or slight impact, the gas pipe 4
The diluent gas is introduced from the diluent gas introduction pipe 5 to dilute the diluent gas below the lower explosion limit and then discharged by the blower 3. The diluent gas used here may be an inert gas such as nitrogen or helium, but air is generally used because a large amount is required.

On the other hand, flammable gas is discharged from the reactor at almost no pressure. However, in order to prevent a resistance or a pulsating flow that obstructs the flow at the time of the discharge, that is, a back pressure fluctuation, as a blower, Using a roots-type blower, a considerably high negative pressure is applied for forced suction. This is because if the back pressure is generated, the flammable gas stays in the gas pipe and is dangerous.

[0005] Roots-type blowers are characterized by being able to discharge even a gas having a low specific gravity without leakage, to prevent fluctuations in back pressure, to have a long durability, and to have high functional stability and safety.

[0006] Further, since the generation time, amount, concentration, etc. of the exhaust gas from the reactors are random due to the production cycle, when a plurality of reactors are targeted, one for each reactor.
It is necessary to take forced exhausting means including a roots blower on a one-to-one basis.

As described above, a relatively small amount and high concentration of flammable gas discharged from the reactor is introduced into the gas pipes individually connected to each reactor by means of a Roots-type blower, and air is exploded. It is forcibly sucked and discharged while diluting below the limit.

[0008]

As described above, the Roots-type blower used for sucking and discharging the combustible gas discharged from the reactor requires high noise due to its structure. In addition, the necessity of one-to-one correspondence with the reactor, and the suction and discharge of combustible gas,
The sealing technology for gas leakage from the bearing is difficult, and it is necessary to perform a special water-sealed bearing.

Further, as a diluent gas for preventing explosion,
A large amount of air is introduced into the suction side of the blower, but due to insufficient dilution ratio, there is a danger of static electricity ignition or shock explosion in the blower. is necessary.

Therefore, especially when a plurality of reactors are installed, a great expense and labor are required for equipment, power, installation space, maintenance and the like.

Therefore, an object of the present invention is to eliminate the method of directly forcibly sucking and discharging the combustible gas discharged from the reaction furnace, and to randomly generate the combustible gas discharged from the reaction furnace. Can always respond and make discharge possible,
Back pressure fluctuation does not occur and safety is high. For multiple reactors, combustible gas discharged from multiple gas pipes that correspond one-to-one is treated collectively and diluted to the explosion limit or less. It is an object of the present invention to provide a method for diluting and discharging a flammable gas which can be discharged, does not require much expense and labor, and has no influence on a product in a reaction furnace.

[0012]

According to the method for diluting and discharging flammable gas of the present invention, a flammable gas to be discharged is introduced into a flow path of air to be extracted through a gas pipe, and an air flow rate in the flow path is reduced. Thus, flammable gas is attracted and discharged from the outlet opening of the gas pipe.

Here, the air flow path to be referred to is composed of an air blower and a connection duct. The air blower is
Since it only sucks air, it is not necessary to stick to its bearings, etc. structurally, and any air flow rate required and the amount of air that dilutes below the explosion limit of the flammable gas to be discharged can be used. Such a blower may be used. Preferably,
A low-noise type is preferable in consideration of the surrounding environment.

However, it is necessary to provide a protection net on the suction side to prevent foreign matter from entering, and to protect the rotor by installing a rain box to prevent the protection of the blower and a silence box for further noise suppression. Safety measures are taken. Also, a dust filter or a medium-performance filter is provided on the suction side, and protective measures are taken to prevent malfunction due to dust adhesion to sensors.

As described above, according to the present invention, when the flammable gas to be discharged is guided into the flow path of the convection air by the gas pipe, the convection air flowing through the flow path causes the outlet opening of the gas pipe to be opened. A vortex is formed in the gas pipe, creating a negative attractive pressure in the gas pipe. Therefore, the flammable gas is attracted and diluted from inside the gas pipe, and the flammable gas is spontaneously attracted because the gas pipe always receives a negative attraction pressure. There is no. Thus, a relatively small amount of highly combustible gas discharged from the reactor is
It is indirectly attracted and diluted by the inviting air flowing in the inviting air flow path, and is safely and quickly discharged without interruption. Therefore, it is not necessary to take a method of forcibly sucking and discharging the combustible gas discharged from the reaction furnace using a roots-type blower as in the related art, and the combustible gas discharged from the reaction furnace is randomly generated. Even if it occurs, it can be constantly discharged and no back pressure fluctuation occurs.

Further, since the above-mentioned air-inducing channel is set on the discharge side of the air blower, if the air-inducing channel is set on the suction side of the air blower as in the prior art,
Although the burden for avoiding the danger increases, in the present invention, there is no such danger, no back pressure fluctuation occurs, and the safety is enhanced.

Further, in the present invention, the flammable gas discharged from a plurality of manufacturing steps is led to a common air flow path via gas pipes connected to the respective manufacturing steps, and the flammable gas from each gas pipe is ignited. Sexual gas can be collectively attracted.

[0018] In this case, even if a plurality of gas pipes are collectively arranged in the common air flow path, the attraction pressure generated in the outlet opening of each gas pipe does not change. Also, the opening surface of each gas pipe is arranged on the same cross section of the quoted air flow path,
The positions may be shifted to effectively secure the air flow path. Thus, according to the present invention, a single blower can cope with a plurality of reaction furnaces, and from the viewpoint of maintenance,
Power costs, installation area, equipment costs, maintenance man-hours, etc. can be significantly reduced.

Further, in the present invention, the amount of air to be supplied to the air flow passage is set to an amount that dilutes the flammable gas attracted and discharged from the gas pipe to a lower explosion limit or less.

In this way, the flammable gas from the reactor is attracted to the reference air and diluted at the same time as the explosion limit or less, so that the flammable gas can be diluted and discharged without any back pressure fluctuation. .

In the present invention, the direction of the air flow channel may be either a vertical flow or a horizontal flow, but the outlet opening of the gas pipe is directed downstream toward the center of the air flow channel. Opening is most likely to form a vortex. In addition, the shape of the outlet opening of the gas pipe may be any shape as long as it induces the attraction pressure by the vortex.
Although a straight pipe having no end face width may be used, if the outlet opening of the gas pipe has an end face width, the attraction pressure can be increased by a vortex formed based on the end face width.

By the way, as the air flow velocity in the air passage increases, the attraction pressure generated at the outlet opening of the gas pipe increases. However, as the air velocity increases, the pressure loss and the air induction in the air passage increase. The fluctuation range of the pressure becomes large. As described above, the magnitude of the induced pressure generated at the outlet opening of the gas pipe in the air flow path to be quoted has a close relationship with the air flow rate and the width of the end face of the outlet opening of the gas pipe. Therefore, the end face width of the outlet opening of a practical gas pipe is experimentally set.

Therefore, according to the present invention, the flammable gas from the reaction furnace is prevented from air from the reaction furnace by an appropriate gas attraction effect by effectively utilizing the end face width of the outlet opening of the gas pipe and the range of the convection air flow velocity. When the specific gravity is small, the air can be drawn into the air flow path at a low pressure, and when the specific gravity is large, the air can be drawn into the air flow path under a high pressure.
Further, it is possible to widely cope with a pipe resistance pressure loss from the reactor to the gas pipe opening. Also, if the exhaust gas from the reactor involves flammable gas and harmful substances, after inviting and discharging into the air flow channel, the air flow channel is connected to the detoxification tower for detoxification. It is also possible.

[0024]

Embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a schematic block diagram of an experimental apparatus to which the method for diluting and discharging flammable gas according to the present invention is applied. The method for attracting flammable gas in this device is to guide flammable gas generated from a plurality of gas generating sources into a quoting air flow path through a gas pipe to attract gas in each gas pipe by an air flow velocity. In FIG. 1, instead of inducing the combustible gas discharged from the gas generating source 6, air is attracted, and the difference in the attracting effect due to the end face width and shape of the outlet opening of the gas pipe 7 is shown in FIG. The experimental apparatus for examining the above is shown. In FIG. 1, the illustration of the broken line portion of the gas pipe 7 up to the opening end face is omitted.

In FIG. 1, the case where air is pushed in instead of flammable gas to exhaust the air is based on the assumption that the exhaust gas from the reactor flows into the gas pipe at a positive pressure. Accordingly, each gas pipe 7 is connected to the header pipe 8 on the discharge side of the air blower, a flow meter is provided in each gas pipe 7 to supply a predetermined amount of air, and the pressure in each gas pipe is measured by a Manostar gauge (shown in FIG. (Omitted).

Further, the six gas pipes 7 in FIG.
Gas-inducing dilution box 10 inserted in the inviting air passage 9
Is connected to an L-shaped gas pipe 7a attached through a flange 7b, and the open end of the L-shaped gas pipe 7a is opened in the duct toward the outlet side 9a of the air passage 9 to be drawn. Let me. 2 (a), 2 (b) and 2 (c) show the structure of the gas-induced dilution box 10, and FIG. 2 (a) is a plan view and FIG.
2B is a longitudinal sectional view, and FIG. 2C is a side view.

In the above configuration, the amount of air to be drawn passes through the air flow path 9 while being adjusted by the air blower 11 and the damper 12. Here, the influence of the width and the shape of the opening end face of the L-shaped gas pipe 7a on the attraction effect is shown in the following experimental examples.

The inner diameter of the air passage 9 used for the experiment was 510 mm, and the gas pipe 7 and the L-shaped gas pipe 7a were used.
Is a synthetic resin tube having an inner diameter of 40 mm and an outer diameter of 48 mm.

The shape of the open end of the gas pipe 7a is as follows.
With respect to the shapes 1 to 8 as shown in FIG. 3, the end face width W from the outer diameter of the gas pipe to the end edge of the end face of the opening in each shape is as follows.

Shape 1: A state in which the end of the gas pipe has cut the pipe (W = 0 mm).

Shape 2: A shape in which the outer periphery of the end of the gas pipe is tapered to narrow toward the tip (W = 0 mm).

Shape 3: A gas pipe provided with a flange having an outer diameter of 63 mm at the end thereof (W = 7.5 mm).

Shape 4: A gas pipe provided with a flange having an outer diameter of 57 mm at the end thereof (W = 4.5 mm).

Shape 5: Outer diameter 57 provided at end of gas pipe
mm flange with a tapered lower surface (W = 4.5
mm).

Shape 6: Inner diameter 6 of pipe end at end of gas pipe
5 mm, provided with a large-diameter portion having an outer diameter of 73 mm (W = 0 mm).

Shape 7: A gas pipe provided with a tapered portion at the end where the outer circumference with an outer diameter of 80 mm expands toward the tip (W =
16mm).

Shape 8: A gas pipe provided with a flange having an outer diameter of 84 mm at the end thereof (W = 34 mm).

With respect to each of the above shapes 1 to 8, the air flow rate in the air flow passage 9 on the discharge side of the air flow blower 11 is changed to 4 to 30 m / s by the air blower 11 to generate gas in each gas pipe 7a. The attraction pressure Pa was measured. However, for the shape 7, the air flow rate was changed to 4 to 35 m / s.

In the experimental example, how much the induced pressure actually occurs in the gas pipe is determined by changing the air velocity of the quoted air flow path 9 and changing the gas pipe 7a installed in the quoted air flow path 9. With respect to the difference between the shape of the opening and the difference in the end face width W of the opening end face, the attraction pressure effect was examined.

Note that the quoted air flow velocity is an effective velocity calculated using a cross-sectional area obtained by subtracting the sum of the cross-sectional area of the outer diameter of the opening of the gas pipe from the sectional area of the quoted air flow path.

The air pushing amount is set to 0 L / min, 25 L / min,
Although it was changed to 50 L / min, the pushing dynamic pressure hd and the flowmeter pressure loss h
c affects the induced pressure measurement. Dynamic pressure is 0,0.1,
0.3 Pa and the flowmeter pressure loss changed to 2.7, 4.3, and 6.7 Pa.

Naturally, the measured value hs' is a value including the influence.
hs ′ = hs−hc + hd. However, when the pressure hs = hs ′ + hc−hd actually induced in the air flow path, regardless of the amount of air being pushed in, the constant attraction under the conditions of each W described above. Pressure was obtained. The pressure hs in the gas pipe based on the result of this experiment is the induced pressure actually generated in the air flow path.

1. It can be seen that the attraction pressure increases as the quoted air flow velocity increases, and the degree of increase in the attraction pressure increases with the end face width W, so that the effect of the vortex becomes more remarkable. However, when the end face width W exceeds 7.5 mm, the attraction pressure gradually decreases,
At W = 34 mm, the attraction pressure is lower than that of a straight tube of W = 0 mm (see FIG. 4). The end face width W at the limit for exhibiting the attraction pressure equivalent to W = 0 mm was 31 mm.

This indicates that the vortex is violently formed even at the end face of the opening of W = 7.5 mm or more, but the attraction effect becomes difficult to reach the inner diameter of the gas pipe as the end face width increases. , W = 31 mm or more, on the contrary, the end face width hinders the attraction pressure. However, it is possible to compensate for the decrease in the attraction pressure by increasing the attraction air flow velocity. The range in which the attraction pressure is most effectively generated is W = 7.5.
mm. The effect of the end face width W = 4.5 to 16 mm is W
= 20 mm for 20 mm.

[0046]

[Table 1]

The relationship between the induced air flow rate and the induced pressure tended to increase in an S-shaped curve. Shape 3
FIG. 5 shows the trend in the case of.

The flow rate of the air to be quoted is as follows: Shape 7 (W = 16 m
In m), when the fluctuation range of the attraction pressure was observed by the change in the air flow velocity, when it exceeded 30 m / s, the fluctuation of the attraction pressure became undesirably large.

[0049]

[Table 2]

2. When the influence of the attraction pressure due to the shape of the gas pipe 7a was compared between the shapes 1, 2, and 6 having no end face width W, the size of the inner diameter was not affected, and the vortex flow was formed in the shape 2 having the acute end. And the attraction pressure was significantly reduced.

[0051]

[Table 3]

3. As a shape comparison having an end face width W, the induced pressure due to the difference in the cross-sectional shape of the end face at an air flow velocity of 15 m / s was compared. However, the effect was not affected. Can be. In addition, as can be seen from the comparison between the shapes 4 and 5, the suction pressure difference is derived from the end face width.

[0053]

[Table 4]

FIG. 6 is a schematic configuration diagram showing an embodiment of a gas dilution and discharge apparatus to which the method for diluting and discharging a combustible gas of the present invention is applied.

This gas dilution and discharge device includes a plurality of reactors 1
Introduced air blower 1 with gas pipe 7 connected to each
The flammable gas is introduced into the quotation air flow path 9 on the discharge side of No. 1;
The flammable gas is attracted from each gas pipe 7 by the flow of the convection air flowing through the flow passage 9 to be diluted and discharged. In FIG. 6, the broken line portion of the gas pipe 7 does not show the illustration up to the opening end face in the gas-inducing dilution box 10.

The invitation air blower 11 is a centrifugal blower, and is installed in a rain-and-muff box 14. A sound absorbing material 15 is attached to the inner surface of the sound deadening box 14, and bellows 16 are provided at a suction port and a discharge port of the blower 11 to prevent transmission of vibration and noise of the blower 11 to the outside. A chamber 17 is provided on the air inlet side of the rainproof sound deadening box 14, and a dust filter 19,
A medium-performance filter 20 is provided to protect the sensors, and a net 21 is provided at the entrance of the rain-and-noise box 14 to take measures to prevent dust and foreign matter from being sucked into the blower 11. The amount of air to be drawn from the blower 11 to the flow path 9 is adjusted by a damper 12. The attraction air flow path 9 has a silencer 22 at a base end, a gas attraction dilution box 10 connected to each of the reactors 13 by a gas pipe 7, and an exhaust with a tip bent in a horizontal direction to prevent rainwater inflow. A duct 23 and a silencer 22
Is connected to an emergency inert gas inlet 24,
Inside the exhaust duct 23, air volume, temperature and gas concentration sensors 25 are provided.

In the gas attraction dilution box 10, the gas pipes 7a respectively connected to the plurality of reaction furnaces 13 are arranged at the same height and at equal intervals, with their open ends facing downstream. A practical form of the open end of the gas pipe 7a is as shown in FIGS. 7A to 7F. In the shape of FIG. 7C, the number of the end face protrusions is not limited to two, and a plurality of end face protrusions are possible.

In the gas diluting / discharging device described above, a necessary attraction force is generated in accordance with the flow rate of the dilution air in the drawing air passage 9 by the drawing air blower 11.

If the amount of dilution air is insufficient, the exhaust duct 23
Even if the gas concentration sensor 25 detects the excess concentration of hydrogen in the exhaust gas, the inert gas is immediately supplied from the inert gas inlet 24 on the upstream side until the concentration becomes equal to or less than the concentration set point of the gas concentration sensor 25, and hydrogen is supplied. The gas concentration can be maintained at a safe concentration. With such sensor control, explosion-proof measures are taken to maintain safety. In addition, by controlling the number of revolutions of the quotation air blower 11 by inverter control, the amount of dilution air can be increased or decreased within the allowable range of the convection pressure by interlocking with the gas concentration sensor 25 to keep the set point or less. It is possible. Furthermore, an emergency measure can be taken by installing a temperature sensor on the downstream side and detecting an abnormal temperature such as ignition combustion by a detection alarm or the like. An air flow sensor is also installed on the downstream side to manage whether the attraction pressure of combustible gas and the amount of air to be quoted are maintained in an appropriate state.

The above-mentioned gas diluting and discharging apparatus is combined with a plurality of epitaxial furnaces, which are reaction furnaces. In order to attract and discharge a total of 600 L / min of gas during operation of these furnaces, the gas pipe has an inner diameter of 45 mm and an end face width W. = 10.7 mm, shape 3 type was used, and the air flow rate at which the hydrogen gas concentration after dilution was 1% or less was 130 m ³ / min. Air flow rate 11.5m / s, duct inner diameter 4
When it was set to 90φ, the induced pressure showed 38 Pa, the hydrogen gas concentration sensor value indicated 0.5 to 0.6%, and there was no adverse effect on the epitaxial wafer, and a high level was obtained.

Further, as an advantage in maintenance, a roots-type blower is conventionally installed for each reactor in a one-to-one relationship. One blower can handle multiple reactors at a time, reducing power costs by 1/10, installation area by 1/4, and equipment costs by 1
/ 4, maintenance man-hour is reduced to 1/4, and operation noise is reduced to 10m with a conventional Roots type blower.
While there was a noise of 70 dB or more at the point, the centrifugal blower applied to the present invention also reduced the noise to 51 dB or less at the point of 10 m.

It should be noted that the gas dilution and discharge apparatus of the present invention can also be applied to flammable gas discharged from a reduced pressure CVD furnace, reduction reaction process equipment such as metal purification, etc., in addition to the above.

[0063]

As described above, according to the present invention, the flammable gas is drawn from the reaction furnace by the inviting air flowing in the inviting air flow path to dilute the flammable gas. In order to increase the attractive force by providing an end face width at the gas pipe opening for discharging the reactive gas and to perform attractive dilution for energy saving, it is not necessary to provide a dilution discharge means for each reactor and to perform suction. The dilution discharge device can cope with dilution discharge of combustible gas from a plurality of reactors.

In addition, by maintaining a sufficient vacuum and a negative pressure in the gas pipe connected to each reactor by the suction pressure, high safety is ensured, and diluting and discharging to a level lower than the lower limit of the explosion smoothly. Can be. In addition, since the quoted air flow path is set on the discharge side of the blower, the combustible gas does not pass through the blower, so that the safety of the gas dilution and discharge device to which the present invention is applied is enhanced, and a special blower is required. No,
Noise control is also easier.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an experimental apparatus to which a method for diluting and discharging combustible gas according to the present invention is applied.

FIGS. 2A and 2B show a gas-inducing dilution box constituting an air-inducing air flow path of the present invention, wherein FIG. 2A is a plan view, FIG. 2B is a longitudinal sectional view, and FIG.

FIG. 3 is a cross-sectional view of a tip portion of a gas pipe used in an experiment of an operation principle of the present invention.

FIG. 4 is a graph showing a relationship between an end face width of a gas pipe and an induced pressure generated in the gas pipe.

FIG. 5 is a graph showing a relationship between a flow rate of air to be drawn in a flow path of air to be drawn and an induced pressure generated in a gas pipe. It is a graph which shows the relationship between the end face width of a gas pipe, and an induced pressure.

FIG. 6 is a schematic configuration diagram of a gas dilution and discharge device to which the flammable gas dilution and discharge method of the present invention is applied.

7 (a) to 7 (f) are cross-sectional views of the tip of a gas pipe showing a practical gas pipe.

FIG. 8 is a schematic view of a conventional flammable gas dilution and discharge device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Clean room 2 Reactor 4 Gas pipe 3 Blower 5 Dilution gas introduction pipe 6 Gas generation source 7 Gas pipe 7a Gas pipe 7b Flange 8 Header pipe 9 Air flow path 9a Exit side 10 Gas induction dilution box 11 Air air blower 12 Damper 13 Reactor 14 Rain-proof silencing box 15 Sound-absorbing material 16 Bellows 17 Chamber 18 Air inlet 19 Dust filter 20 Medium performance filter 21 Net 22 Silencer 23 Exhaust duct 24 Inert gas inlet 25 Gas concentration sensor, temperature sensor, air Flow sensor, etc. W Gas pipe end face width

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshikazu Sogabe 2-4-1 Iwamotocho, Chiyoda-ku, Tokyo Inside Seiko Kakoki Co., Ltd. Tokyo Sales Office (72) Inventor Kazuto Yamazaki Mizudo, Amagasaki City, Hyogo Prefecture 4-1-1, Machi-cho Seiko Kakoki Co., Ltd. Environmental Equipment Business Headquarters (72) Inventor Hideo Sugiyama 3-13-33 Kugachi, Amagasaki-shi, Hyogo Seiko Kakoki Co., Ltd. Research Laboratory (72) Inventor Tsukada Noya 5-1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture Inside the Hidaka Factory, Hitachi Cable Co., Ltd. (72) Inventor Masaaki Sasaki 5-1-1, Hidaka-cho, Hitachi City, Ibaraki Prefecture Hidaka Factory, Hitachi Cable, Ltd. Inside

Claims (5)

[Claims] 1. A flammable gas to be discharged is guided into an air flow passage via a gas pipe, and the flammable gas is attracted and discharged from an outlet opening of the gas pipe by an air flow velocity in the flow path. A method for diluting and discharging flammable gas, comprising: 2. The method for diluting and discharging flammable gas according to claim 1, wherein the air flow path is set on the discharge side of the air blower. 3. The flammable gas discharged from a plurality of manufacturing steps is led to a common air flow path via gas pipes connected to the respective manufacturing steps, and the flammable gas from each gas pipe is collectively collected. 2. Attraction and discharge
Or the flammable gas dilution and discharge method according to 2. 4. The method according to claim 1, wherein the amount of air to be quoted is set to an amount that dilutes the flammable gas attracted and discharged from the gas pipe to a value lower than the lower explosion limit. 3. The method for diluting and discharging flammable gas according to item 1. 5. The gas pipe according to claim 1, wherein the outlet opening of the gas pipe has an end face width, and a vortex is formed based on the end face width, and the attraction pressure is increased by the vortex. The method for diluting and discharging flammable gas according to the above section.