JP4528141B2 - Flame retardant decomposition burner - Google Patents

Description

The present invention relates to a flame retardant material decomposition burner, and in particular, a fluorocarbon (CF ₄ , SF ₆₎ contained in a process exhaust gas discharged in a semiconductor manufacturing process, a liquid crystal manufacturing process, a solar cell manufacturing process, a gas processing process in a waste transformer, or the like. , NF ₃ , SiF _4, etc.) and the like.

  Many kinds of harmful substances are contained in process exhaust gas discharged from a semiconductor manufacturing process, a liquid crystal manufacturing process, a solar cell manufacturing process, a gas processing process in a waste transformer, or the like. Various exhaust gas treatment apparatuses have been proposed to detoxify such harmful substances and release them into the atmosphere. For example, in Patent Document 1, an exhaust gas combustion nozzle having a combustion cylinder composed of an outer cylinder and an inner cylinder, and having an exhaust gas passage and a fuel gas supply passage arranged concentrically around the exhaust pipe at the bottom of the inner cylinder. And a means for supplying combustion-supporting gas having a pressure equal to or higher than atmospheric pressure into the inner cylinder is described. In this device, a flame is formed so as to surround the exhaust gas flow path, and a flame-supporting gas having a pressure higher than the atmospheric pressure is blown into the flame, thereby facilitating flame retardant harmful substances such as PFC in the process exhaust gas. It is made to burn and decompose.

  Further, as a flame retardant substance decomposition burner 1 that is further downsized and simplified in structure, the present inventors have shown one end of the combustion cylinder 2 as shown in a plan view in FIG. 5a and a sectional view in FIG. 5b. Is closed by a blocking wall 3, and a process exhaust gas introduction nozzle 40 for ejecting a process exhaust gas containing a flame retardant is attached to the blocking wall 3 so as to coincide with the central axis L of the combustion cylinder 2, and the central axis L A plurality of combustion burners 50 are attached at positions on concentric circles from each other, and the plurality of combustion burners 50 are axially arranged so that the respective jet flames f can converge at substantially the same point on the central axis L of the combustion cylinder 2. A flame-retardant material decomposition burner 1 that has been attached with an inclination is already proposed (see Patent Document 2).

In this flame retardant material decomposition burner 1, the flames f emitted from the plurality of combustion burners 50 converge at substantially the same point on the central axis L of the combustion cylinder 2, so that there is a high temperature around the area where the flame converges. A combustion region S is formed. Since the process exhaust gas from the process exhaust gas introduction nozzle 40 surely passes through the region S, the combustion decomposition treatment of the flame retardant substance in the exhaust gas proceeds effectively, and CF ₄ having a high combustion decomposition temperature or Even with SF ₆ , a high decomposition rate can be obtained.

JP 2003-170020 A JP 2003-202108 A

  The flame retardant substance decomposition burner described in Patent Document 2 desirably has a slower flow rate of the process exhaust gas introduced from the nozzle as described in the document. Thereby, the residence time of the gas to be treated in the high-temperature combustion region is increased, and high combustion decomposition efficiency for the flame-retardant material can be obtained. When the flow velocity becomes too large, the process exhaust gas passes through the converging flame as if it is opened, and the combustion decomposition efficiency is lowered.

  For example, the present inventors have continuously conducted an experiment in which a process exhaust gas discharged from a semiconductor manufacturing process is subjected to a combustion decomposition process using a flame retardant substance decomposition burner described in Patent Document 2. One or a small number of flame retardant substances discharged from a plurality of semiconductor manufacturing apparatuses installed in parallel, or a process exhaust gas discharged from each semiconductor manufacturing apparatus having a plurality of chambers per chamber If the decomposition burner is used for processing, the amount of process exhaust gas to be processed increases, the flow rate of the process exhaust gas fed from the process exhaust gas introduction nozzle 40 into the combustion chamber increases, and the converged flame is processed as described above. I experienced exhaust gas passing through in an open manner.

  When the processing amount of process exhaust gas is small, the process exhaust gas discharged from each of a plurality of semiconductor manufacturing apparatuses or a plurality of chambers is combined into one by a halfway pipe, and a combustion cylinder of a flame retardant substance decomposition burner However, there is a case where the process exhaust gas does not open the converged flame. However, combining process exhaust gases from different semiconductor manufacturing equipment or different chambers before entering the combustion cylinder is dangerous when components in each process exhaust gas are different. There must be.

  As a solution, a plurality of process exhaust gas introduction nozzles 40 are concentrically added and attached to the blocking wall 3 in parallel with the process exhaust gas introduction nozzles 40, that is, in a direction parallel to the central axis L of the combustion cylinder 2. Also tried to disperse and introduce process exhaust gas. In this case, the flow rate of the process exhaust gas is reduced due to the dispersion, and the phenomenon that the process exhaust gas passes through the converging flame so as to push open can be eliminated.

  However, a part of the process exhaust gas flowing from the process exhaust gas introduction nozzle additionally arranged concentrically passes through the peripheral region of the converged flame, that is, the low temperature region along the wall surface of the combustion cylinder 2. Therefore, we experienced that the combustion decomposition efficiency decreased. By introducing more fuel and raising the temperature in the low temperature region of the combustion cylinder, the desired combustion decomposition efficiency can be achieved, but the fuel efficiency becomes extremely poor and the temperature of the combustion cylinder wall surface increases. It was not a realistic solution because it promoted thermal degradation of refractory materials.

  The present invention has been made in view of the above circumstances. For example, a large amount of process exhaust gas discharged from a semiconductor manufacturing process, a liquid crystal manufacturing process, a solar cell manufacturing process, a gas processing process in a waste transformer, or the like, High even if it is discharged from a plurality of manufacturing or processing apparatuses installed in parallel, or discharged from each manufacturing or processing apparatus having a plurality of chambers in one unit An object of the present invention is to provide a further improved flame retardant decomposition burner that can be safely detoxified with combustion decomposition efficiency.

  A flame retardant material decomposition burner according to the present invention comprises a combustion cylinder whose one end is closed by a closing wall, and a plurality of combustion burners attached to the closing wall at a position substantially concentrically from the central axis of the combustion cylinder. And the plurality of combustion burners are attached with inclined axes so that the respective jet flames can converge at substantially the same point on the central axis of the combustion cylinder, and the blocking wall has a plurality of difficulty walls. A plurality of process exhaust gas introduction ports including a flammable substance, the plurality of process exhaust gas introduction ports so that an extension line of an axis thereof can intersect with the ejection flame in the vicinity of the convergence point of the ejection flame or downstream thereof. It is characterized by being attached with an inclined axis.

  The flame retardant material decomposition burner according to the present invention basically includes only a combustion cylinder, a process exhaust gas introduction port, and a combustion burner, and is designed to have a very simple configuration and a short overall length. be able to. Therefore, similarly to the flame-retardant substance decomposition burner described in Patent Document 2, it is possible to easily install a process exhaust gas treatment facility under the floor of a semiconductor manufacturing factory or the like. In addition, the flames from the plurality of combustion burners arranged almost concentrically are converged at approximately the same point on the central axis of the cylinder, so that the high temperature combustion region is around the region where the flame converges. Is formed in the same manner as the flame retardant decomposition burner described in Patent Document 2.

In the flame retardant material decomposition burner of the present invention, the process wall further includes a plurality of process exhaust gas introduction ports on the closed wall, and an extension line of an axis thereof is a jet flame near or near the convergence point of the jet flame. The axis is inclined so as to intersect. As a result, the process exhaust gas containing the flame-retardant material from each process exhaust gas introduction port is ejected toward the high temperature combustion area formed around the area where the flame converged, and entered from the outer edge of the flame into it. Therefore, the combustion decomposition of the flame retardant material such as chlorofluorocarbon mixed in the process exhaust gas effectively proceeds. In our experiments, NF ₃ was burned and decomposed, and a decomposition rate of 99% or more was obtained.

  Even when the amount of process exhaust gas to be processed is large, the entire amount of process exhaust gas can be injected from the outer edge of the flame toward the inside of the flame, so that a phenomenon occurs in which the process exhaust gas passes through the converging flame as it opens. And combustion decomposition efficiency does not decrease. In addition, the phenomenon that the process exhaust gas flows down along the wall surface region of the combustion cylinder, that is, through the low temperature region of the combustion chamber can be eliminated. .

  Even when processing exhaust gas discharged from each chamber from a plurality of manufacturing or processing apparatuses installed in parallel or from a single manufacturing or processing apparatus having a plurality of chambers is processed simultaneously, the manufacturing or processing apparatus or chamber By installing as many process exhaust gas introduction ports as possible, it is possible to prevent the process exhaust gases from merging upstream of the combustion cylinder, so that the danger due to mixing of process exhaust gases can be eliminated.

  In the flame retardant material decomposition burner of the present invention, the optimum inclination angle of the combustion burner axis with respect to the combustion cylinder center axis is determined experimentally under given processing conditions. In the experiment, it is preferable from the practical sense that the angle is in the range of 15 to 50 degrees, more preferably 30 to 45 degrees with respect to the central axis of the combustion cylinder. When the inclination angle is larger than 50 degrees, the flame is too close to the back surface of the closed wall, and thermal damage of the refractory material is likely to proceed. When the inclination angle is smaller than 15 degrees, the flame is too close to the inner surface of the combustion cylinder, and thermal damage of the refractory material is likely to proceed.

  In the flame-retardant material decomposition burner according to the present invention, a plurality of process exhaust gas introduction ports are attached to a closed wall so that the extension lines of all the axes converge at substantially the same point on the central axis of the combustion cylinder. Is a preferred form. By adopting this form, mixing of the process exhaust gas ejected from the plurality of process exhaust gas introduction ports and the formed ejection flame is further ensured, and high combustion decomposition efficiency is obtained.

  In the flame-retardant material decomposition burner according to the present invention, the flow rate of the process exhaust gas ejected from the process exhaust gas introduction port is basically arbitrary, and when the flow rate is large, even if the fuel consumption increases accordingly, the flow rate is increased. As a result, the combustion decomposition efficiency does not decrease. Therefore, in the flame retardant substance decomposition burner according to the present invention, the degree of freedom in designing the combustion cylinder and the process exhaust gas introduction port is increased, and by adopting the flame retardant substance decomposition burner according to the present invention, for example, semiconductor manufacturing The degree of freedom in designing the process exhaust gas treatment equipment in the process, liquid crystal production process, solar cell production process, or gas treatment process in the waste transformer can be increased.

  By using the flame retardant decomposition burner according to the present invention, a large amount of process exhaust gas containing a flame retardant discharged in a semiconductor manufacturing process, a liquid crystal manufacturing process, a solar cell manufacturing process, a gas treatment process in a waste transformer, etc. Even if it is discharged for each chamber from a plurality of manufacturing or processing apparatuses installed in parallel or a manufacturing or processing apparatus having a plurality of chambers in one unit, it is safe and harmless with high combustion decomposition efficiency Can be processed.

  One form of the flame-retardant substance decomposition burner according to the present invention will be described with reference to the drawings. FIG. 1 shows an example of a flame retardant substance decomposition burner 1, FIG. 1 a is a plan view, and FIG. 1 b is a cross-sectional view taken along line bb in FIG. The burner 1 includes a cylindrical combustion cylinder 2 and a closing wall 3 that closes one end of the combustion cylinder 2. The combustion cylinder 2 has an exterior body 22 having a flange 21 formed at the upper end, and the inner peripheral surface of the exterior body 22 is covered with an appropriate fireproof material 23 like a double-layered firebrick. Conventionally, the lower open end of the combustion cylinder 2 is connected to a suction blower or a water scrubber or the like through an appropriate pipe line as in this type of burner.

  The closing wall 3 has an exterior body 32 in which a flange 31 is formed at the lower end, and the interior of the exterior body 32 is filled with refractory materials 33 stacked in multiple stages. The blocking wall 3 is hermetically integrated with the combustion cylinder 2 by superimposing the flange 31 on the flange 21 of the combustion cylinder 2 and bolting, so that the upper end side of the combustion cylinder 2 is closed. The

  A plurality of combustion burners 50 are attached to the blocking wall 3 at positions that are concentric with the central axis L of the combustion cylinder 2 at equal intervals. In the example shown in the figure, four combustion burners 50 are attached at intervals of 90 degrees, but two or more are optional. Each combustion burner 50 is inclined at a predetermined angle α (preferably in a range of 15 to 50 degrees) so that an extension line of the axis L1 intersects at substantially the same point P1 on the center axis L of the combustion cylinder 2. As a result, as shown in FIG. 2, each jet flame f converges at substantially the same point P1a on the central axis L of the combustion cylinder 2. A high-temperature combustion region S is formed around the region where the flame has converged. The plurality of combustion burners 50 are positioned substantially concentrically from the center axis L of the combustion cylinder 2 on condition that the jet flame f converges at substantially the same point on the center axis L of the combustion cylinder 2. It suffices if they are arranged.

  Further, a plurality of process exhaust gas introduction ports 60 are attached to the blocking wall 3 at positions that are concentric with the central axis L of the combustion cylinder 2 at equal intervals. In the illustrated example, four process exhaust gas introduction ports 60 are attached at intervals of 90 degrees so as to be intermediate positions between the combustion burners 50 and 50, respectively. Each exhaust gas introduction port 60 has its axis L2 so that the extension line of the axis L2 intersects the ejection flame f in the vicinity of the convergence point P1a (FIG. 2) of the ejection flame f or at the downstream position P2 thereof. It is attached to the blocking wall 3 in an inclined posture.

  Preferably, each exhaust gas introduction port 60 has a predetermined angle β (preferably between 15 degrees and 50 degrees) such that the extension line of the axis L2 intersects at substantially the same point P2 on the center axis L of the combustion cylinder 2. It is attached with an inclination in the range). However, as described above, if the extension line of the axis L2 of the exhaust gas introduction port 60 intersects the ejection flame f in the vicinity of the convergence point P1a (FIG. 2) of the ejection flame f or at a position downstream thereof. Good. In any case, by arranging the axis L2 of the exhaust gas introduction port 60 to be inclined, the process exhaust gas from the exhaust gas introduction port 60 enters the flame f from the outer edge of the flame f as shown in FIG. Then, it enters the high-temperature combustion region S formed around the region where the flame converges, and the combustion decomposition treatment of the flame-retardant substance such as chlorofluorocarbon mixed in the process exhaust gas effectively proceeds.

  An appropriate number of the exhaust gas introduction ports 60 is selected in consideration of the amount of process exhaust gas to be processed, the diameter of the exhaust gas introduction port 60, and the like, but it is preferably two or more. In addition, the inclination angle β of the axis L2 of each exhaust gas introduction port 60 is an equal angle on condition that the extended line intersects with the ejection flame f in the vicinity of the convergence point P1a of the ejection flame f or at a position downstream thereof. May be different. In addition, it is not essential that each exhaust gas introduction port 60 is arranged at a position concentrically with the central axis L of the combustion cylinder 2, and some exhaust gas introduction ports 60 are arranged at different distances from the central axis L. May be.

  In the combustion decomposition process of the process exhaust gas, a fuel such as city gas, propane gas and hydrogen and a premixed gas of oxidant such as oxygen and air are supplied from the combustion burner 50. Although not shown, the fuel and the oxidant may be supplied separately and blown out from the blowing nozzle, and then the mixed gas may be formed. For example, process exhaust gas from a semiconductor manufacturing apparatus or the like is guided to the process exhaust gas introduction port 60 and jets process exhaust gas at a predetermined flow rate into the combustion cylinder 2. As described above, the four jet flames f from the four combustion burners 50 converge at substantially the same point on the central axis L of the combustion cylinder 2 and form a high-temperature combustion region S in the vicinity thereof. . The process exhaust gas ejected into the combustion cylinder 2 is blown into the high-temperature combustion region S from the outer edge of the flame f, and in the process of passing therethrough, the combustion decomposition treatment of the flame-retardant substance effectively proceeds. Process exhaust gas that has been subjected to combustion decomposition treatment flows out from the lower end of the combustion cylinder 2.

  Examples and comparative examples will be described.

[Example 1]
A flame retardant material decomposition burner 1 having the form shown in FIG. 1 was prepared. The inclination angle α of the axis L1 of each combustion burner 50 and the inclination angle β of the axis L2 of the process exhaust gas introduction port 60 are both 30 degrees. In addition, each exhaust gas introduction port 60 has an extension line of the axis L2 at substantially the same position as the convergence point P1a of the ejection flame f and intersects at substantially the same point on the central axis L of the combustion cylinder 2. Set.

Two types of gas to be treated (N ₂ dilution gas) containing 1 SLM and 10 SLM of NF ₃ were jetted from the process exhaust gas introduction port 60 into the combustion cylinder 2 at different flow rates. Methane (CH ₄ ) was used as the fuel, and air was used as the oxidant. The combustion decomposition treatment was performed, and the fuel flow rate (CH ₄ flow rate SLM) required for the NF ₃ concentration at the outlet to be equal to or lower than the working environment reference value (10 ppm) was measured. The result is shown as “when there are multiple ports” in the graph shown in FIG.

[Comparative Example 1]
The same measurement was performed using a flame retardant material decomposition burner of the form shown in FIG. The other structure of the burner was the same as that of the flame-retardant material decomposition burner of Example 1 except that the process exhaust gas introduction nozzle 40 was attached so as to coincide with the central axis L of the combustion cylinder 2. The result is shown as “when 1 port (center)” in the graph shown in FIG.

[Discussion]
As shown in the graph of FIG. 4, when the gas flow to be processed is about 100 SLM, that is, when the flow rate is low, the fuel flow (fuel consumption) required for the required combustion decomposition is the same as that of the burner of the example. The burner is substantially the same, but it can be seen that the fuel consumption of the burner of the embodiment (that is, the burner according to the present invention) decreases as the flow rate of the gas to be processed increases. As described above, in the burner of the form shown in FIG. 5, the non-process gas passes through the converging flame so as to push it open. It shows that more fuel needs to be input to maintain. This demonstrates the effectiveness of the burner according to the present invention.

[Example 2]
Using the flame-retardant material decomposition burner 1 used in Example 1, a gas to be treated (N ₂ dilution gas) containing NF ₃ is supplied from the process exhaust gas introduction port 60 under three conditions of flow rates of 100 SLM, 300 SLM, and 500 SLM. It was ejected into the body 2. Methane (CH ₄ ) was used as the fuel, and air was used as the oxidant. The combustion decomposition treatment was performed, and the NF ₃ concentration (ppm) and the decomposition rate (%) at the outlet were measured. At the same time, the required fuel consumption (SLM) was measured. The results are shown in Table 1 as “30 °”.

[Comparative Example 2]
As shown in FIG. 3, the other configurations are the same, but each process exhaust gas introduction port 60 a is arranged such that its axis L 2 is parallel to the center axis L of the combustion cylinder 2. Made. The distance from the central axis L of the exhaust gas introduction port outlet was the same as that of the flame-retardant substance decomposition burner 1 used in Example 2. The combustion decomposition treatment was performed under the same conditions as in Example 2. The results are shown in Table 1 as “0 °”.

[Discussion]
As shown in Table 1, in the case of a flow rate of 100 SLM, by using the flame retardant material decomposition burner according to the present invention, the NF ₃ which is 99% higher than that of the comparative example while having the same fuel consumption (10 SLM). The decomposition rate is obtained, and the effectiveness of the present invention is shown. In the case of the flow rates of 300 SLM and 500 SLM, almost the same decomposition rate of NF ₃ is obtained in the example and the comparative example. However, in order to obtain the same decomposition rate, there is a large difference in fuel consumption. However, the effectiveness of the present invention is shown.

1 shows one embodiment of a flame retardant substance decomposition burner according to the present invention, FIG. 1a is a plan view, and FIG. 1b is a sectional view taken along line bb of FIG. 1a. The figure which shows typically the entering state of the process exhaust gas with respect to the ejection flame in the flame-retardant substance decomposition burner by this invention. It is a figure which shows the flame-retardant substance decomposition | disassembly burner used in the comparative example 2, FIG. 3a is a top view, FIG. 3b is sectional drawing by the bb line of FIG. Graph showing NF ₃ concentration working environmental standards in nitrogen gas containing NF ₃ fuel flow required to the (10 ppm) or less (CH ₄ flow SLM). It is a figure which shows the conventional flame retardant substance decomposition burner, FIG. 5a is a top view, FIG. 5b is sectional drawing by the bb line of FIG. 5a.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Flame retardant material decomposition burner, 2 ... Cylindrical combustion cylinder, 3 ... Blocking wall, L ... Center axis of combustion cylinder, 50 ... Combustion burner, L1 ... Axis of combustion burner, α ... Axis of combustion burner , F ... flame, 60 ... process exhaust gas introduction port, L2 ... process exhaust gas introduction port axis, β ... process exhaust gas introduction port axis inclination angle

Claims (4)

  A combustion cylinder whose one end is closed by a closed wall, and a plurality of combustion burners attached to the closed wall at positions substantially concentrically from the central axis of the combustion cylinder, each of the plurality of combustion burners being It is attached with an inclined axis so that the erupting flame can converge at substantially the same point on the central axis of the combustion cylinder, and the closed wall has a process exhaust gas introduction port containing a plurality of flame retardant substances. The plurality of process exhaust gas introduction ports are attached with an inclined axis so that an extension of the axis can intersect with the jet flame near the convergence point of the jet flame or downstream thereof. Features a flame retardant decomposition burner.   The flame-retardant material decomposition burner according to claim 1, wherein the inclination angle of the axis of each combustion burner is in the range of 15 to 50 degrees with respect to the central axis of the combustion cylinder.   The plurality of process exhaust gas introduction ports are attached to the blocking wall with the axis inclined so as to intersect at substantially the same position on the central axis of the combustion cylinder. Flame retardant decomposition burner.   The process exhaust gas to be treated is a process exhaust gas containing CFCs discharged from a semiconductor manufacturing process, a liquid crystal manufacturing process, a solar cell manufacturing process, or a gas processing process in a waste transformer. A flame retardant decomposition burner according to the above.

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