JP2005106418A - Method for supplying waste gas, and backfire preventing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for supplying waste gas, in which waste gas of high concentration can be safely supplied to a waste gas processing device, and in which backfire phenomenon can be securely prevented while effectively utilizing waste gas processing waste heat. <P>SOLUTION: Waste gas of explosion-range concentration including combustible components discharged from a manufacturing device 12 is sent through a vapor-filled range 28a positioned between the manufacturing device 12 and the waste gas processing device 14 in which vapor V generated by use of processing waste heat in the processing device 14 is filled. It is thus supplied to the processing device 14 with the vapor V. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a high-concentration flammable component in an explosion range discharged from a production apparatus (usually above the lower explosion limit, hereinafter described as being above the lower explosion limit, but also including the case below the upper explosion limit) In some cases, the present invention relates to an exhaust gas supply method used in a detoxifying device for explosive exhaust gas containing dust and a backfire prevention device.

In the industry, various products are manufactured using various gases, and exhaust gas is generated as a by-product, and the treatment to make it harmless (for example, high-temperature heating gas) is done with the exhaust gas treatment device. Done and released into the atmosphere. In some of the manufacturing facilities, exhaust gas exhausted from the manufacturing equipment may contain exhaust gas containing H ₂ and explosive combustible components in a wide concentration range, such as SiH ₄ . Explosive accidents may occur due to improper treatment.

  As countermeasures, in many cases, a large amount of nitrogen is immediately mixed into the exhaust gas containing high concentrations of these explosive combustible components at the exhaust port of the production apparatus, and the exhaust gas is diluted after the combustible components are diluted below the lower limit of explosion. The method of processing by processing was adopted.

  This method is very safe because the combustible components are diluted below the lower limit of explosion, but the exhaust gas treatment air volume swells many times the amount of exhaust gas discharged from the manufacturing equipment. However, there was a problem that the processing cost was increased.

  On the other hand, in addition to the above-mentioned measures, conventionally, there has been proposed a technique for preventing backfire from a combustor or the like by providing a water-sealed safety device that diffuses exhaust gas into water and allows water to pass through ( For example, see Patent Document 1.)

  However, this technique for providing a water seal safety device has a problem in that it is difficult to cope with a wide range of explosion phenomena because there is a limit to the difference in water seal level.

  Therefore, there is a demand for measures that can cope with a wide range of explosion phenomena at a relatively low cost.

  As a technology corresponding to this, as shown in FIG. 5, the flashback prevention material (5a) filled with a backfire prevention material (5a) such as a mesh between the manufacturing device (1) and the exhaust gas treatment device (3) has already been provided. A technique for installing the device (5) has been proposed. As a result, the exhaust gas supply pipe arranged between the manufacturing device (1) and the exhaust gas treatment device (3) due to a flame used for the thermal decomposition of the exhaust gas (G) in the exhaust gas treatment device (3). Even if a reverse flow is attempted through (7), the backfire prevention material (5a) prevents backfire, and even if flammable gas is accumulated inside the production equipment (1), the production equipment (1) will explode. Can be effectively prevented.

However, in the case where such a backfire prevention device (5) is provided, it is effective when the exhaust gas (G) is composed of only a gaseous component, but in the exhaust gas (G) such as a semiconductor manufacturing device. When a large amount of dust is included, the backfire prevention material (5a) is clogged, and there is a problem that frequent maintenance must be performed. The maintenance of the exhaust gas supply pipe (7) containing such explosive combustible components is extremely dangerous, and it is preferable to make the maintenance as free as possible.
JP 2003-194479 A (FIG. 1)

  Therefore, the main problem of the present invention is that in the case of performing the detoxification treatment of the exhaust gas containing the dust and the high concentration combustible component as described above, the maintenance-free exhaust gas containing the high concentration combustible component is required. An object of the present invention is to provide a method for supplying exhaust gas that can be safely supplied as it is to an exhaust gas treatment device, can prevent the occurrence of a flashback phenomenon, and can also save energy, and a flashback prevention device used in this method.

  The exhaust gas supply method according to claim 1 is described as follows: “Exhaust gas (G) containing a combustible component having a concentration within an explosion range (generally the lower explosion limit or more) discharged from the manufacturing apparatus (12) 14), the exhaust gas (G) is located between the production apparatus (12) and the exhaust gas treatment apparatus (14), and the residual heat from the exhaust gas treatment apparatus (14) is used. After passing through the steam-filled region (28a) filled with the generated steam (V), it is supplied to the exhaust gas treatment device (14) together with the steam (V). "

  The invention described in claim 2 relates to a backfire prevention device (10) for carrying out the detoxification treatment of the exhaust gas (G) according to claim 1, and “combustibility of concentration in the explosion range”. A steam-filled region that is provided between the production device (12) that discharges exhaust gas (G) containing components and the exhaust gas treatment device (14) that removes exhaust gas (G) and is filled with water vapor (V) inside ( 28a) is formed and the tubular main body (28) through which the exhaust gas (G) passes, and the residual heat generated when the exhaust gas (G) is pyrolyzed by being attached to the exhaust gas treatment device (14). And a water vapor generating means (30) for generating water vapor (V) and supplying the water vapor to the water vapor filling region (28a) ”.

  In these inventions, when the exhaust gas (G) from the production apparatus (12) reaches the water vapor filled region (28a), the component molecules constituting the exhaust gas (G) and the water vapor in the water vapor filled region (28a) [that is, The water molecules floating in the steam-filled area (28a)] (V) mix evenly, and for some reason, air (exactly oxygen) is present in the exhaust gas (G) in the exhaust gas supply pipe (26). Even if it is mixed, the bond between the combustible component in the exhaust gas (G) and the mixed oxygen is inhibited by the steam (V), and the temperature rise suppression effect by the steam (V) is also added to the exhaust gas from the production device (12). The occurrence of flashback in the exhaust gas supply pipe (26) leading to the treatment device (14) can be effectively prevented. Since water vapor (V) is used to prevent backfire, even if dust is actually contained in the exhaust gas (G), clogging does not occur and maintenance is free. In other words, the method of the present invention is particularly effective for preventing backfire of dust-containing exhaust gas.

  In addition, since the steam (V) is generated by using the residual heat from the exhaust gas treatment device (14), a sufficient amount of steam (V) to be supplied to the steam filling region (28a) can be generated. Further, energy saving can be promoted as compared with the case where a steam device (V) is generated by installing a separate heater device or the like.

    The invention according to claim 3 is the backfire prevention device (10) according to claim 2, wherein “the spiral plate (32), the baffle plate (50) or the porous plate (52 ), And the like.

  Thus, the resistance increase of the spiral plate (32), the baffle plate (50) or the porous plate (52) in the water vapor filling region (28a) [that is, the internal space of the main body (28) of the backfire prevention device (10)] When the intermediate member is installed, the exhaust gas (G) and the water vapor (V) are agitated and mixed sufficiently in the water vapor full area (28a), and the passage time in the water vapor full area (28a) becomes long and the water vapor As a result, the effect of suppressing the temperature rise of the exhaust gas (G) can be improved and the effect of preventing backfire can be further enhanced.

  According to the present invention, since the steam-filled region through which the exhaust gas passes is provided between the manufacturing apparatus and the exhaust gas treatment device, the component molecules constituting the exhaust gas and the steam are uniform when the exhaust gas reaches the steam-filled region. The combination of flammable component molecules with oxygen mixed into the exhaust gas for some reason is blocked by water vapor, and the temperature rise suppression effect by water vapor is also added, so the concentration of flammable components in the exhaust gas is at the lower explosion limit. Even if it is the above, backfire generation | occurrence | production within the exhaust gas supply piping from a manufacturing apparatus to an exhaust gas treatment apparatus can be prevented effectively.

  In particular, since steam is generated by using the residual heat of the exhaust gas treatment apparatus, a sufficient amount of steam to be supplied to the steam-filled region can be generated, and a heater device or the like is separately installed to generate steam. Energy saving can be promoted compared to the case of generating.

  And by installing an intermediate member for increasing resistance in the steam-filled region, the exhaust gas and steam are stirred and mixed sufficiently, and the passage time in the steam-filled region becomes longer, thereby improving the backfire prevention effect. There is an advantage that can be.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a first embodiment of a flashback prevention device 10 according to the present invention. In FIG. 1, the manufacturing apparatus (12) is a semiconductor manufacturing apparatus such as CVD, and as an exhaust gas (G) of a semiconductor manufacturing process, a combustible component having explosive properties in a wide range of concentrations such as H ₂ and SiH _{4 and the} like. In some cases, exhaust gas (G) with a large amount of fine dust is discharged. Of course, the manufacturing apparatus (12) is not limited to a semiconductor manufacturing apparatus, but includes all apparatuses that discharge exhaust gas containing explosive combustible components as exhaust gas.

  In the case of Example 1 shown in FIG. 1, the exhaust gas treatment device (14) is generally used to thermally decompose the exhaust gas (G) introduced into the exhaust gas decomposition treatment tower (16) and the exhaust gas decomposition treatment tower (16). Combustion heater (18), rear scrubber (20), wiring system, instruments, exhaust fan (22) and water tank (24), each connected by piping and wiring, in one compact cabinet It is stored in.

  The production device (12) and the exhaust gas treatment device (14) are connected by an exhaust gas supply pipe (26), and a backfire prevention device (10) is disposed in the middle thereof.

  As shown in FIG. 1, the backfire prevention device (10) includes a cylindrical main body (28) provided on the exhaust gas supply pipe (26) between the production device (12) and the exhaust gas treatment device (14). And water vapor generating means (30) provided on the exhaust gas outlet (16b) side of the exhaust gas decomposition treatment tower (16).

  Here, a water vapor filling region (28a) for filling water vapor is formed in the internal space of the main body (28), and the water vapor filling region (28a) is provided with a spiral plate (32). In this embodiment, the main body (28) of the backfire prevention device (10) is shown as being cylindrical, but the shape of the main body (28) is cylindrical, that is, the inside is hollow. Any shape such as a rectangular tube may be used as long as it can form the water vapor filling region (28a) therein.

  The water vapor generating means (30) generates water vapor using the heat of the high temperature exhaust gas (G) discharged after pyrolysis in the exhaust gas decomposition treatment tower (16) [namely, residual heat of treatment]. As shown in FIG. 2, a cylindrical tank (34) connected to the exhaust gas outlet (16b) of the exhaust gas decomposition treatment tower (16) and sealed at the upper and lower surfaces, and water (W) from the outside are supplied to the tank (34). A water supply pipe (36) supplied into the tank, one or more heat exchange tubes (38) attached so as to penetrate the upper and lower surfaces of the tank (34), and an upper surface and a water surface of the tank (34). A steam supply pipe (40) for supplying the steam (V) generated in the tank (34) to the inside of the main body (28) of the backfire prevention device (10) [that is, the steam filling region (28a)] And a pipe (42) for supplying an inert gas (N) such as nitrogen gas into the tank (34) in order to push the steam (V) generated in the tank (34) into the steam supply pipe (40). And the inside of the tank (34) is heated by exhaust gas heat. And comprising a heater (44) for heating the water (W) in the initial stage up to the.

  The heat exchange cylinder (38) takes in the hot exhaust gas (G) pyrolyzed in the exhaust gas decomposition treatment tower (16) from the upper end opening (38a) and exchanges heat with water (W) in the tank (34). Thus, water vapor (V) is generated in the tank (34).

  The heater (44) is operated during a period (that is, at the initial stage) until the temperature in the exhaust gas decomposition treatment tower (16) is sufficiently raised to about 700 ° C. to 1300 ° C. by the combustion heater (18). The water (W) in) is heated.

  In the above configuration, the exhaust gas (G) containing a combustible component having a concentration exceeding the lower explosion limit discharged from the manufacturing device (12) is introduced into the main body (28) from the bottom of the backfire prevention device (10). . Since the flashback prevention device (10) is connected to the exhaust gas treatment device (14), the direction toward the exhaust gas treatment device (14), that is, in the case of FIG. 1, from the bottom of the main body (28) to the ceiling portion. The airflow is spiraling along the spiral plate (32).

  On the other hand, in the exhaust gas treatment device (14), at the initial stage until the inside of the exhaust gas decomposition treatment tower (16) is sufficiently heated by the combustion heater (18), the tank (34) is formed by the heater (44) in the steam generation means (30). The water (W) in) is heated to generate water vapor (V), and this water vapor (V) is supplied into the main body (28) of the backfire prevention device (10). Then, when the temperature in the exhaust gas decomposition treatment tower (16) rises by the combustion heater (18) and the exhaust gas (G) is in an operating state capable of thermal decomposition, the heater (44) is cut off and the exhaust gas treatment is performed. The water (W) in the tank (34) is heated by the residual heat of the pyrolysis treatment of the exhaust gas (G) supplied to the device (14), and the water vapor (V) generated accordingly is supplied in the main body (28). Is done. Thereby, the internal space of the backfire prevention device (10) is filled with water vapor (V) as the water vapor full area (28a).

  The exhaust gas (G) introduced into the bottom of the flashback prevention device (10) rises spirally along the spiral plate (32) together with a large amount of water vapor (V) and is sufficiently mixed therebetween. In this state, the exhaust gas (G) is supplied to the exhaust gas decomposition treatment tower (16) of the exhaust gas treatment device (14) together with the water vapor (V) through the ceiling, and is thermally decomposed by the exhaust gas treatment device (14).

The combustion part (16a) inside the exhaust gas decomposition treatment tower (16) is maintained at a high temperature of about 700 to 1300 ° C. by the combustion heater (18) (for example, in the case of silane; SiH ₄ , 700 to 900 ° C., In the case of NF ₃ , 900 to 1100 ° C., and in the case of WF ₆ , 700 to 900 ° C.). The exhaust gas (G) introduced into the combustion part (16a) is reliably pyrolyzed by the outside air containing oxygen supplied from the outside into the exhaust gas decomposition treatment tower (16) from the outside as necessary, and the rear scrubber ( 20), after the temperature is reduced by spraying (20a) in the rear scrubber (20) (if dust is generated by the thermal decomposition, it is removed at the same time) and then released into the atmosphere by the exhaust fan (22) Is done. Pumping water to the spray (20a) is performed by a pumping pump (48) that supplies water from the water tank (24) to the spray (20a).

  As described above, in the exhaust gas decomposition treatment tower (16), the exhaust gas (G) is completely pyrolyzed, but sometimes air is mixed into the exhaust gas supply pipe (26) for some reason and backfired. There may be a situation where the phenomenon occurs. At this time, if the backfire prevention device (10) is not equipped, the combustion part of the exhaust gas treatment device (14) is connected through the exhaust gas supply pipe (26) connecting the production device (12) and the exhaust gas treatment device (14). The flame of (16a) flows into the manufacturing device (12), ignites the combustible gas accumulated inside, and causes an explosion in the manufacturing device (12) (especially the explosion range is wide in a range such as hydrogen). However, in the flashback prevention device (10) of the present invention, even if such a state occurs, the steam (V) is flammable as described above. Since it enters between the component molecule and the auxiliary combustible component molecule, even if the concentration of the combustible component falls within the explosion range, the flashback phenomenon can be prevented.

  In other words, when exhaust gas (G) containing a high concentration of explosive combustible components exceeding the lower explosion limit is introduced into the backfire prevention device (10), as described above, the exhaust gas (G ) Completely mixes with water vapor (V) at the molecular level, and even if oxygen is mixed into the exhaust gas (G) for some reason, the rapid oxidative bond between oxygen and flammable components is hindered, causing an explosive combustion phenomenon. Will not cause. In other words, even if a flashback phenomenon occurs between the exhaust gas treatment device (14) and the outlet of the flashback prevention device (10), this flame is not flashback prevention device (10). It is extinguished within and does not reach the entrance of the backfire prevention device (10).

  In particular, in the present invention, the steam (V) supplied into the backfire prevention device (10) is generated by using the residual heat generated when the exhaust gas (G) is pyrolyzed in the exhaust gas decomposition treatment tower (16). Therefore, it is possible to generate a sufficient amount of water vapor to be supplied to the water vapor filling region (28a) in the main body (28) of the backfire prevention device (10), and to achieve effective use of residual heat, that is, energy saving. Can do.

  In the above-described embodiment, the case where the exhaust gas (G) is introduced from the bottom of the flashback prevention device (10) is shown, but of course, the present invention is not limited to this, and the flashfire prevention device (10) You may make it introduce from the ceiling part.

  Further, as described above, the exhaust gas (G) pyrolyzed inside the exhaust gas decomposition treatment tower (16) exchanges heat with water (W) in the tank (34) when passing through the heat exchange cylinder (38). The steam (V) is generated in the tank (34). The temperature of the exhaust gas (G) is as high as about 700 ° C to 1300 ° C, and therefore, the exhaust gas (G) pyrolyzed particularly at a temperature around 1300 ° C. When the water passes through the heat exchange cylinder (38), the water in the tank (34) becomes water vapor one after another, and the amount of water in the tank (34) may decrease at a stretch. In such a case, when the water in the tank (34) runs out, the water vapor generating means (30) is in an empty state, and the means (30) is damaged by heat. For this reason, a cooling device (not shown) is attached to the tank (34) of the water vapor generating means (30) to control the amount of water vapor generated so that all water in the tank (34) is not evaporated. Good.

  Furthermore, if the exhaust gas (G) contains dust, a front scrubber functionally similar to the backfire prevention device (10) is provided in the front stage of the exhaust gas treatment device (14). By providing the water vapor filling region (28a), it is possible to function as a backfire prevention device (10).

  FIG. 3 is an example in which a plurality of baffle plates (50) are used, and FIG. 4 is an example in which a plurality of porous plates (52) such as a metal net or punching metal are provided inside.

  In the case of the spiral plate (32) in FIG. 1 and the baffle plate (50) in FIG. 3, the internal exhaust gas passage is lengthened to achieve sufficient mixing of water vapor (V) and exhaust gas (G). On the other hand, in the case of the porous plate (52) of FIG. 4, the water is sufficiently adhered to the entire porous plate (52), and the contact between the water and the gas can be improved. Therefore, the dust collecting effect is great. In addition, since the porous plate (52) itself has a backfire prevention function, it has an excellent backfire prevention effect in cooperation with the backfire prevention effect of the water vapor (V). Although there is concern about clogging of the porous plate (52) due to dust, water vapor (V) is constantly supplied from the upper surface to the porous plate (52), and this water vapor (V) is 52) is cooled and becomes water droplets, and since these water droplets are constantly flowing downward from the upper porous plate (52), the porous plate (52) is always washed and clogged. Does not occur.

It is a block diagram of 1st Example of the backfire prevention apparatus which concerns on this invention. It is a partially broken perspective view which shows the water vapor | steam production | generation means in a backfire prevention apparatus. It is a block diagram of 2nd Example of the backfire prevention apparatus which concerns on this invention. It is a block diagram of 3rd Example of the backfire prevention apparatus which concerns on this invention. It is a block diagram which shows the conventional backfire prevention apparatus.

Explanation of symbols

(10) ... Backfire prevention device
(12) ・ ・ ・ Production equipment
(14) ・ ・ ・ Exhaust gas treatment equipment
(16) ... Exhaust gas decomposition treatment tower
(18) ... Combustion heater
(20) ・ ・ ・ Rear scrubber
(22) ... Exhaust fan
(24) ... Water tank
(26) ... Exhaust gas supply piping
(28) ・ ・ ・ Main body (of backfire prevention device)
(28a) ・ ・ ・ Water vapor filling area
(30) ... Water vapor generating means
(32) ... Spiral plate
(34) ・ ・ ・ Tank
(36) ... Water supply piping
(38) ... Heat exchange tube
(40) ... Steam supply piping
(42) ... Piping
(44) ・ ・ ・ Heater
(48) ・ ・ ・ Pumping pump
(50) ... Baffle plate
(52) ... Porous plate

Claims (3)

In a method for detoxifying exhaust gas containing a combustible component having an explosive range concentration discharged from a manufacturing device with an exhaust gas treatment device,
The exhaust gas is positioned between the manufacturing apparatus and the exhaust gas treatment apparatus, and after passing through a water vapor filling region filled with water vapor generated by using the residual heat of the exhaust gas treatment apparatus, together with the water vapor An exhaust gas supply method for supplying to the exhaust gas treatment apparatus. Provided between a manufacturing apparatus that discharges exhaust gas containing a combustible component with an explosive range concentration and an exhaust gas treatment apparatus that removes the exhaust gas, a steam-filled region filled with steam is formed inside, and the exhaust gas is A cylindrical body passing through,
It is attached to the exhaust gas treatment apparatus, and comprises steam generation means for generating steam using residual processing heat generated when the exhaust gas is thermally decomposed and supplying the steam to the steam-filled region. Backfire prevention device to do.   The backfire prevention device according to claim 2, wherein an intermediate member for increasing resistance, such as a spiral plate, a baffle plate, or a porous plate, is installed in the water vapor filling region.

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