JP2017040429A - Method and apparatus for burning silane inclusion gas or silane inclusion waste liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent adhesion or clogging of silicone dioxide [SiO] to a nozzle or a furnace wall.SOLUTION: There is provided a combustion burner operated by fuel and combustion air at an upper part of a combustion furnace to face downward when silane inclusion gas, silane inclusion gas of silane inclusion waste liquid or silane inclusion waste liquid is supplied to the combustion furnace and ignited. There are provided blowing-out nozzles at a position below the combustion burner. The blowing-out nozzles have a flow passage for silane inclusion gas or silane inclusion waste liquid, inert gas flow passage and a combustion air flow passage extending from a central side toward outside, the nozzles are used for blowing out each of fluids from each of flow passages of the blowing-out nozzles to a position below a lower end of a flame generated by the combustion burner.SELECTED DRAWING: Figure 2

Description

The present invention relates to a combustion method and combustion apparatus for silane-containing gas or silane-containing waste liquid discharged from a semiconductor factory or the like.
Here, silane is not only a compound of Si, H, O such as SiH ₄ (monosilane), Si ₂ H ₆ (disilane), Si (CH ₃ O) ₄ (tetramethoxysilane), but also SiH ₂ Cl. ₂ A compound containing Cl such as (dichlorosilane) is also referred to.

  Since the silane-containing gas or the silane-containing waste liquid discharged from a semiconductor factory or the like cannot be discharged out of the system as it is because it contains harmful substances, it must be detoxified. As one means for such detoxification treatment, high-temperature oxidation treatment by spraying a silane-containing gas or a silane-containing waste liquid on a combustion furnace and burning it at a high temperature is frequently used.

  Typically, there is one proposed in Patent Document 1. In this prior art, as shown in FIG. 3, the main burner provided at the center of the top of the furnace has a quadruple tube structure, and the flow path of the gas to be processed from the center to the outside, the inert gas , Primary air flow path, and secondary air flow path are formed.

  Further, a pilot burner is provided on the side portion as necessary to facilitate ignition. In this prior art, the flame of the main burner is provided below the blowing center line from the pilot burner, and an object is to obtain a stable flame.

  On the other hand, a water spray tube is provided at the lower part to cool the water.

Japanese Patent Publication No. 5-48584

The present inventor has examined various prior arts, but could not obtain an appropriate one.
In particular, as in Patent Document 1, when a silane-containing gas blowing channel is incorporated in a main burner, the silane-containing gas is jetted into a flame that exceeds 1000 ° C., so silicon (Si) in silane And silicon dioxide (SiO ₂ ) produced by reacting with oxygen (O ₂ ) or water vapor (H ₂ O) melts or sinters and adheres to the furnace inner wall and nozzle, causing nozzle clogging, or the furnace inner wall It has been found that depending on the deposition, the combustion becomes unstable or causes problems such as blockage in the furnace.

On the other hand, when silane-containing gas or silane-containing waste liquid is burned, it is already known that silicon dioxide (SiO ₂ ) adheres to and clogs the inner wall of the furnace, and there is a technique for taking the following measures.
(1) A plurality of apertures are provided in the furnace wall, air is supplied from the entire furnace wall into the furnace, and the furnace wall surface temperature is kept below the melting and sintering temperature to prevent adhesion and blockage.
(2) Installation of a water cooling jacket on the furnace wall and supplying air from the entire furnace wall into the furnace causes the furnace wall surface temperature (the surface temperature of the steel material constituting the interior of the combustion furnace) to adhere below the melting and sintering temperature. Prevent occlusion.

  However, in the measure (1), the structure of the furnace wall becomes complicated and the cost becomes high. In addition, when the measure (2) is adopted to treat a silane-containing gas containing chlorine (Cl) or a silane-containing waste liquid, hydrogen chloride produced in the furnace by the cooled furnace wall surface as a measure against melting and sintering. (HCl) becomes the dew point or lower (70 to 80 ° C. or lower) and corrosion occurs.

Therefore, a main object of the present invention is to prevent adhesion or blockage of silicon dioxide (SiO ₂ ) to the nozzle and the inner wall of the furnace.

The present invention that has solved the above problems is as follows.
The present invention may be a silane-containing gas or a silane-containing waste liquid.

In the method of burning the silane-containing gas or silane-containing waste liquid of the present invention, the silane-containing gas or silane-containing waste liquid is supplied to the combustion furnace and burned.
At the top of the combustion furnace, a combustion burner with fuel and combustion air is installed downward,
A blowing nozzle is provided at a position below it, and this nozzle has a flow path of silane-containing gas or silane-containing waste liquid, an inert gas flow path, and a combustion air flow path from the center side to the outer side. And
Each fluid is blown out from each flow path of the blowing nozzle to a position below the lower end of the flame generated by the combustion burner.

In the embodiment of the present invention, the silane-containing gas or the silane-containing waste liquid, the inert gas, and the combustion air are blown out from the blowing nozzle toward the high-temperature oxidizing atmosphere in front of the flame of the combustion burner. At this time, the flow of the silane-containing gas or the silane-containing waste liquid is wrapped in the flow of the inert gas. Therefore, the contact between the flow of the silane-containing gas or the silane-containing waste liquid and the flow of the combustion air is blocked, or the contact is hindered, so that the silicon dioxide (SiO ₂ ) is prevented from adhering or blocking at the blowing nozzle.
In addition, the silane-containing gas or the silane-containing waste liquid is supplied below the combustion burner flame without being supplied to the combustion burner flame.

As a result, silicon dioxide (SiO ₂ ) produced by reaction of silicon (Si) in silane with oxygen (O ₂ ) or water vapor (H ₂ O) melts or sinters and adheres to the furnace inner wall and supply nozzle. In addition, it is possible to prevent the adhered matter from growing and clogging.
In addition, according to the present invention, by controlling the combustion state without complicating the structure of the combustion furnace, adhesion or blockage to the nozzle or the inner wall of the furnace is prevented by melting or sintering silicon dioxide (SiO ₂ ). be able to.

The blowout nozzle preferably has a multi-tube structure. From the center side toward the outer side, a silane-containing gas or a silane-containing waste liquid channel, an inert gas channel, or a combustion air channel is preferable.
Such a multi-tube blow-out nozzle can wrap the flow of silane-containing gas or silane-containing waste liquid with the flow of inert gas, as described above.

  Furthermore, when the outlet of the inert gas flow path is the same or forward with respect to the outlet of the flow path of the silane-containing gas or the silane-containing waste liquid, the flow of the silane-containing gas or the silane-containing waste liquid is changed to the inert gas. It becomes possible to inhibit the contact with the flow of combustion air while being wrapped by the flow of gas.

  In order to make this action more reliable, it is more desirable that the outlet of the combustion air channel is located behind the outlet of the inert gas channel.

As described above, silicon dioxide (SiO ₂ ) produced by the reaction of silicon (Si) in silane with oxygen (O ₂ ) or water vapor (H ₂ O) melts or sinters, and the inner wall of the furnace and the supply nozzle It is possible to prevent the adhered material from growing and clogging.

The flow rate of the inert gas at the outlet of the inert gas flow path can be in the range of 2 to 10 m / sec, or 0.3 to 6.0 Nm ³ with respect to 1 kg of the silane-containing gas or the silane-containing waste liquid.

On the other hand, the upper temperature detection with respect to the upper temperature in the furnace by the upper temperature detector provided at a position below the intersection of the center line of the flame by the combustion burner and the directivity line of each fluid from each flow path of the blowing nozzle The operation of raising the temperature in the lower part of the furnace by means of the lower part of the furnace in the furnace located below the furnace is performed.
As this operation, operation which adjusts at least 1 among each supply amount of the inert gas supplied from a blowing nozzle, combustion air, silane containing gas, or a silane containing waste liquid can be mentioned.
It is preferable that the lower temperature in the furnace is lower than 1000 ° C. and 850 ° C. or higher.

The meaning of this is as follows.
The combustion region of the silane-containing gas or the silane-containing waste liquid can be expanded to the lower part of the furnace due to the cooling effect by nitrogen and air, which are inert gases, and the combustion delay effect due to the inhibition of the treatment element by nitrogen.
Therefore, the temperature in front of the combustion burner flame can be suppressed to less than about 1000 ° C., which is the temperature at which silicon dioxide (SiO ₂ ) sinters. As a result, adhesion of silicon dioxide (SiO ₂ ) to the furnace inner wall can be prevented.
Furthermore, when the silane-containing gas or the silane-containing waste liquid is high in calories, the combustion delay effect due to nitrogen is more effective, and the temperature below the furnace becomes higher than the temperature in front of the burner flame. Therefore, melting and sintering of silicon dioxide (SiO ₂ ) can be prevented only by temperature control based on the temperature in the furnace lower part by the furnace lower temperature vessel, and silicon dioxide (SiO ₂ ) adheres and closes on the nozzle and the furnace inner wall. This can be prevented.
In addition, when treating a silane-containing gas or silane-containing waste liquid containing chlorine (Cl), the surface temperature is set to a dew point corrosion temperature by setting the refractory to an appropriate thickness instead of the conventional technique for suppressing the furnace wall surface temperature. It can be maintained at the above temperature (70 to 80 ° C. or higher), and corrosion of the steel material can be prevented.

The apparatus of the present invention is an apparatus for supplying and burning a silane-containing gas or a silane-containing waste liquid to a combustion furnace,
Including a combustion furnace, a combustion burner with fuel and combustion air provided downward in the upper part of the combustion furnace, and a blowout nozzle provided below the combustion burner,
The blowing nozzle has a silane-containing gas or a silane-containing waste liquid passage, an inert gas passage, and a combustion air passage from the center side toward the outer side. is there.
According to the combustion apparatus, the combustion method of the present invention described above can be achieved.

Furthermore, the blowout nozzle has a multi-tube structure, and from the center side toward the outer side, a flow path of silane-containing gas or silane-containing waste liquid, an inert gas flow path, a combustion air flow path,
The outlet of the inert gas flow path is the same as or forward of the outlet of the flow path of the silane-containing gas or the silane-containing waste liquid, and the combustion air flow path with respect to the outlet of the inert gas flow path It is more desirable that the combustion apparatus has a rear outlet located at the rear.

According to the present invention, it is possible to prevent silicon dioxide (SiO ₂ ) from adhering to the blowing nozzle and the inner wall of the furnace.
Specifically, silicon dioxide (SiO ₂ ) produced by the reaction of silicon (Si) in silane with oxygen (O ₂ ) or water vapor (H ₂ O) melts or sinters to the inner wall of the furnace or the blowout nozzle. It is possible to prevent the attached material from growing and clogging.

It is a schematic diagram of the example of a combustion device. It is a longitudinal cross-sectional view for description of the example of combustion in a furnace. It is a longitudinal cross-sectional view of the example of a blowing nozzle.

  Hereinafter, preferred embodiments of a combustion method and combustion apparatus for a silane-containing gas or a silane-containing waste liquid according to the present invention will be described with reference to the drawings. The following description and drawings are merely examples of the embodiment of the present invention, and the contents of the present invention should not be construed as being limited to this embodiment.

(Basic structure of combustion equipment)
FIG. 1 shows an embodiment of a combustion apparatus used in the combustion method of the silane-containing gas or silane-containing waste liquid of the present invention.
The combustion furnace 1 has a vertical cylindrical furnace body 5, and a combustion burner (for example, a vortex burner) 2 is provided at the center of the top, and fuel such as LPG, natural gas, heavy oil, etc. is provided from the combustion burner 2. F is injected into the combustion furnace 1 downward by combustion air (not shown) and burned, and a processing element (silane-containing gas or silane) is placed on the shoulder of the combustion furnace 1 around the combustion burner 2. A plurality of blowing nozzles 3 for spraying the contained waste liquid (G) into the combustion furnace 1 are provided at equal intervals in the circumferential direction and obliquely downward toward the center line of the cylindrical combustion furnace 1.

As shown in FIG. 2, the silane-containing gas or the silane-containing waste liquid G sprayed into the combustion furnace 1 from these nozzles 3 is preferably below the lower end of the combustion flame of the fuel F of the combustion burner 2. It is blown toward. A furnace temperature detector is installed on the furnace wall 5 of the combustion furnace 1. The in-furnace temperature detector is preferably capable of detecting the internal temperature of the combustion furnace and transmitting the detection result to a control unit (not shown), and installing a plurality of in-furnace temperature detectors having different installation heights. It is preferable to do. Based on the detection result, the control unit at least one of a fuel supply amount to the combustion burner, a combustion air amount, a combustion air supply amount to the nozzle 3, an inert gas supply amount, a silane-containing gas or a silane-containing waste liquid supply amount It has a function to adjust. Here, adjustment of the fuel supply amount, the combustion air amount, the combustion air supply amount to the nozzle 3 and the inert gas supply amount may be performed by using flow rate adjusting means such as valves and dampers provided in pipes and ducts of each fluid, This can be done by changing the supply amount from a pump or blower that supplies fluid. In this embodiment, as an in-furnace temperature detector, the upper temperature provided at a position below the intersection X between the center line C2 of the flame B by the combustion burner 2 and the directional line C3 of each element from each flow path of the blowout nozzle 3. A detector Sd and an in-furnace lower temperature detector Su provided at a position below the upper temperature detector Sd were provided.
As another embodiment, only the lower furnace temperature detector Su may be provided.

  The combustion exhaust gas generated by this combustion is supplied to the gas cooler 4 from the lower outlet of the combustion furnace 1, and air is supplied to the combustion exhaust gas for cooling. Thereafter, the gas cooler 4 is supplied to a device such as a bag filter or a detoxification tower and subjected to appropriate processing.

In FIG. 3, the blowing nozzle 3 has a multi-tube structure, and from the center side toward the outer side, a flow path of silane-containing gas or silane-containing waste liquid G, an inert gas flow path, a combustion air flow path, The outlet Ei of the inert gas flow path is the same as or forward of the outlet Eg of the flow path of the silane-containing gas or the silane-containing waste liquid, and the outlet Ei of the inert gas flow path A mode in which the outlet Ec of the combustion air flow path is located rearward is preferable.
The multi-tube structure is suitable for forming an annular cylindrical flow, but in particular, with regard to the inert gas flow path and the combustion air flow path, a large number of them along the axial direction at the annular position. A thin tube may be arranged.

As an example of the operation method, the furnace lower temperature detected by the furnace lower temperature detector Su is higher than the furnace upper temperature detected by the upper temperature detector Sd, or the furnace upper temperature is dioxide dioxide. There is a method of adjusting at least one of the supply amount of combustion air and the supply amount of inert gas to the nozzle 3 so that the temperature is lower than the temperature at which silicon (SiO ₂ ) is melted or sintered.
The supply amount of the inert gas (nitrogen, argon, etc.) is such that the flow rate at the outlet Ei of the inert gas flow path is 2 to 10 m / sec, or 0.3 kg relative to 1 kg of the silane-containing gas or the silane-containing waste liquid G. A range of ˜6.0 Nm ³ (ie, 0.3 to 6.0 Nm ³ / kg) is desirable. Thus, by making the supply amount of the inert gas within a predetermined range, the silane-containing gas or the silane-containing waste liquid and the combustion air are prevented from being mixed in the vicinity of the outlet of the blowout nozzle 3, and the silane-containing waste liquid and the combustion air are mixed. It is possible to prevent silicon dioxide from adhering to the blowout nozzle 3 even when these are mixed. Furthermore, by adopting the supply amount described above, the inert gas becomes one of the combustion delay factors of the silane-containing gas or silane-containing waste liquid, and the combustion of the silane-containing gas or silane-containing waste liquid above the combustion furnace is suppressed. Become.

The in-furnace lower temperature indicated by the in-furnace lower temperature unit Su is less than 1000 ° C. and not less than 850 ° C., more desirably 950 ° C. to 900 ° C.
When it is 1000 ° C. or higher, silicon dioxide is sintered or melted, and the above-described blockage is caused. If it is lower than 850 ° C., an unburned component may be generated.

By the way, there are short burners and long burners as combustion burners, but it is desirable to use a short burner, for example, a vortex burner, because there is an advantage that the height of the furnace body can be shortened.
The length L of the flame B by this vortex burner is substantially in a relationship of about 1.5D with respect to the diameter D of the combustion burner. Based on this, the intersection point X can be determined.

  The installation angle θ of the blow-out nozzle 3 is desirably inclined beyond 0 degree, and in particular, the installation angle θ is preferably 20 degrees to 70 degrees.

Next, examples and comparative examples are shown.
Example 1 and Example 2 are based on the apparatus shown in FIG.2 and FIG.3.
Comparative Example 1 and Comparative Example 2 are examples in which air that flows air through the inert gas flow channel is flowed with respect to Example 1 and Example 2. The results are shown in Table 1.

In Example 1, the combustion Ba - Na - the LPG to 0.37 nm ³ / h, and 10 Nm ³ / h supplied as the combustion air. Silane-containing gas (about 23,860 kJ / kg as the higher heating value) from the center of the blowing nozzle is 2.4 kg / h, nitrogen is 2.6 Nm ³ / h outward from the center, and the furnace lower temperature is outward Was supplied so that the air temperature was about 950 ° C. As a result, the upper temperature in the furnace was 933 ° C., which was lower than the lower temperature in the furnace. At this time, CO was 0 ppm, and it was found that complete combustion was possible at this combustion temperature. Comparative Example 1 is an example in which the nitrogen supplied to the blowing nozzle of Example 1 was replaced with air, and the results were 980 to 1030 ° C., and it was found that there was a combustion delay effect due to nitrogen.

In following examples 2, combustion Ba - Na - the LPG to 0.4 Nm ³ / h, and 10 Nm ³ / h supplied as the combustion air. 2.86 kg / h of silane-containing gas (about 22,200 kJ / kg as the higher heating value) from the center of the blowing nozzle, 2.6 Nm ³ / h of nitrogen outward from the center, and lower temperature in the furnace to the outer side Was supplied so that the air temperature was about 910 ° C. As a result, the upper temperature in the furnace was 878 ° C., which was lower than the lower temperature in the furnace. At this time, CO was 0 ppm, and it was found that complete combustion was possible even at this combustion temperature. Comparative Example 2 is an example in which the nitrogen supplied to the blowing nozzle of Example 2 was replaced with air, and the result was 930 to 980 ° C., and it was found that there was a combustion delay effect due to nitrogen.

Reference examples 1 and 2 are reference data in which silane is simultaneously supplied to a combustion burner and a blow-off nozzle. Reference example 1 is a furnace lower temperature of 845 ° C., CO is 5 ppm, and reference example 2 is CO was generated at a level of about 1 ppm, but a small amount. It was predicted that CO would be further generated at 850 ° C. or lower, and that the lower temperature in the furnace was desirably 850 ° C. to 900 ° C. or higher from the viewpoint of complete combustion.

DESCRIPTION OF SYMBOLS 1 ... Combustion furnace, 2 ... Burner, 3 ... Blowing nozzle, 4 ... Gas cooler, 5 ... Furnace body, G ... Silane containing gas or silane containing waste liquid, 11 ... Inert gas, 12 ... Combustion air, Su ... Upper temperature Detector, Sd ... Upper temperature detector.

Claims (9)

In a method of supplying silane-containing gas or silane-containing waste liquid to a combustion furnace and burning it,
At the top of the combustion furnace, a combustion burner with fuel and combustion air is installed downward,
A blowing nozzle is provided at a position below it, and this nozzle has a flow path of silane-containing gas or silane-containing waste liquid, an inert gas flow path, and a combustion air flow path from the center side to the outer side. And
Each fluid is blown out from each flow path of the blowing nozzle to a position below the lower end of the flame generated by the combustion burner,
A combustion method of a silane-containing gas or a silane-containing waste liquid. The flow rate of the inert gas at the outlet of the inert gas flow path is set to 2 to 10 m / sec, or 0.3 to 6.0 Nm ³ with respect to 1 kg of the silane-containing gas or the silane-containing waste liquid. Of burning silane-containing gas or silane-containing waste liquid. Of the two points that are located below the intersection of the flame center line generated by the combustion burner and the blowing directional line of the blowing nozzle and differ in the vertical direction of the combustion furnace, The silane-containing gas or the silane-containing waste liquid is combusted at a lower position at a combustion temperature higher than the furnace upper temperature or a temperature at which the furnace upper temperature is not higher than a temperature at which silicon dioxide (SiO ₂ ) melts or sinters. The combustion method of the silane containing waste liquid of Claim 1 or 2.   2. The silane-containing gas according to claim 1, wherein an operation for increasing a lower temperature in the furnace by a lower temperature detector in the lower position is performed with respect to an upper temperature in the upper temperature detector provided in the upper position. Or the combustion method of a waste liquid containing silane.   5. The silane according to claim 4, wherein the operation is an operation of adjusting at least one of the supply amounts of inert gas, combustion air, silane-containing gas, or silane-containing waste liquid supplied from a blowing nozzle. Combustion method of contained gas or silane-containing waste liquid.   The combustion method of a silane-containing gas or a silane-containing waste liquid according to claim 1 or 3, wherein the temperature in the lower part of the furnace is lower than 1000 ° C and 850 ° C or higher.   The high heat generation amount of the silane-containing gas or silane-containing waste liquid is 0 kJ / kg or more and 46,000 kJ / kg or less, and the lower temperature in the furnace is supplied from the blowing nozzle so as to be 850 ° C. or more and less than 1000 ° C. 7. The method for combusting a silane-containing gas or silane-containing waste liquid according to claim 6, wherein at least one of the supply amounts of inert gas, combustion air, silane-containing gas or silane-containing waste liquid is controlled. A device for supplying a silane-containing gas or a silane-containing waste liquid to a combustion furnace and burning it,
Including a combustion furnace, a combustion burner with fuel and combustion air provided downward in the upper part of the combustion furnace, and a blowout nozzle provided below the combustion burner,
The blowing nozzle has a flow path of silane-containing gas or silane-containing waste liquid, an inert gas flow path, and a combustion air flow path from the center side to the outer side.
A combustion apparatus for silane-containing gas or silane-containing waste liquid. The blowing nozzle has a multi-tube structure, and from the center side toward the outer side, a flow path of silane-containing gas or silane-containing waste liquid, an inert gas flow path, a combustion air flow path,
The outlet of the inert gas flow path is the same as or forward of the outlet of the flow path of the silane-containing gas or the silane-containing waste liquid, and the combustion air flow path with respect to the outlet of the inert gas flow path The silane-containing gas or silane-containing waste liquid combustion apparatus according to claim 8, wherein the outlet of the silane is located rearward.

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