JP2013015232A - Combustion-type exhaust gas treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustion-type exhaust gas treatment apparatus, capable of performing rapid restoration by easily narrowing down a potential target range of failure cause.SOLUTION: A failure position specification tool 14 is disposed in the middle of a cable 16. In the specification of a failure position, a switch 41 is closed first. At that time, a current supplied from a pilot flame control unit 26 passes through a resistance 45 via a diode 43. Namely, a pseudo current passing through the resistance 45 is input to the pilot flame control unit 26. In this case, when viewed from the pilot flame control unit 26 side, determination is performed as if burning of pilot flame is confirmed. Therefore, even in a case where combustion and damage removing systems may be stopped due to abnormality of pilot flame, a subsequent step such as supply of main fuel is performed based on the recognition that the pilot flame normally exists due to the pseudo current. Since the failure range can be thus narrowed down, rapid restoration can be performed.

Description

  The present invention relates to a combustion-type exhaust gas treatment apparatus, and more particularly to a combustion-type exhaust gas treatment apparatus that enables quick recovery by easily narrowing down a target range that seems to be a cause of failure.

  In the manufacturing process of a semiconductor element, a CVD (Chemical Vapor Deposition) process, an etching process, and the like are performed using a chemical vapor reaction, and various gases are used in a process chamber.

Examples of this gas include silane (SiH ₄ ), which is a semiconductor material gas, and NF ₃ , CF ₄ , C ₂ F ₆ used as a cleaning gas when the inside of a sealed chamber such as a plasma CVD apparatus is cleaned with plasma, for example. , SF ₆ , CHF ₃ , CF ₆ , and the like.

  As shown in the overall configuration diagram of the combustion type exhaust gas treatment system in FIG. 4, a turbo molecular pump 3 and a dry pump 5 are connected in series to the process chamber 1 for evacuation in order to remove these exhaust gases. ing. Then, after the vacuum is drawn to some extent at the start of operation by the dry pump 5, the turbo molecular pump 3 is further evacuated to a required low pressure. However, the turbo molecular pump 3 may be omitted in the case of CVD processing or the like.

The harmful exhaust gas output from the dry pump 5 reaches the central scrubber 11 through the combustion exhaust gas treatment device 6.
The combustion exhaust gas treatment device 6 is generally composed of a combustion device 7 for burning and decomposing gas and a harmful substance removing device 9 for removing a product produced by the decomposition.
At this time, the exhaust gas is guided into the combustion device 7 and the harmful substance removal device 9 while being slightly decompressed by the central scrubber 11.

For example, when silane or nitrogen trifluoride is rendered harmless, silica (SiO ₂ ) powder or hydrofluoric acid (HF) is generated as a product of combustion decomposition. These products are collected in the drain tank in a form dissolved in water.

Here, in the combustion apparatus 7, it is necessary to open the main valve after turning on the seed and supply the main gas fuel to the main burner.
It is automatically determined whether or not the ignition is on (see Patent Document 1). Processing during this period is performed automatically by a sequencer.

JP 2008-89195 A

  By the way, this automatic processing has various factors, for example, when a product adheres to the pilot burner portion that forms the seed fire and the seed fire does not light, or the main gas fuel is not supplied due to clogging of the pipe or the like. In some cases, an error was stopped and the sequencer could not proceed to the next process.

  In such a case, it is difficult to distinguish whether there is a fault in the seed system, or in other systems other than the seed system, and it is possible to visually check whether the seed system is lit. It took time and effort to identify the location of failure and the cause of failure, such as checking whether the pressure and flow rate were normal for all systems.

  The present invention has been made in view of such a conventional problem, and provides a combustion type exhaust gas treatment apparatus that enables quick recovery by easily narrowing down a target range that seems to be a cause of failure. With the goal.

  For this reason, the present invention (Claim 1) includes a flame detection means for detecting the state of a flame in a combustion furnace using a conductive phenomenon, a flame control unit to which a current detected by the flame detection means is input, And a failure location specifying tool for inputting the flame pseudo-current to the flame control unit instead of the current detected by the flame detection means.

  A pseudo current is input to the flame control unit. At this time, when viewed from the flame control unit side, the determination is made as if the flame has been turned on. Therefore, even if there is a problem with the flame device and the system may be stopped due to no flame, the next process is based on the virtual recognition that the flame exists normally due to the pseudo current. Proceed to the step. Therefore, the operation can be confirmed for the entire step including the flame treatment.

  In addition, the present invention (Claim 2) includes a general control unit that proceeds to the next processing step by confirming that the function of confirming the flame condition is normal by the pseudo current. .

  If there is a failure at a location other than the flame treatment, the failure is stopped at that location, so the failure range between the flame facility and the other facilities can be easily distinguished. On the other hand, if the sequence can proceed without problems for the entire steps, it is suspected that there is a cause of failure in the flame treatment. In this way, the failure range can be narrowed down easily, so that quick recovery is possible.

  Further, according to the present invention (Claim 3), the failure location specifying tool includes a resistor and a switch connected in series to the resistor.

  The failure location identification tool can be simply configured.

  Furthermore, the present invention (Claim 4) includes the rectifying element in which the failure location specifying tool is connected in series to the resistor.

  By providing the rectifying element, a pseudo current closer to an actual flame can be obtained.

  Furthermore, the present invention (invention 5) is characterized in that a current flowing through the resistor is 0.1 μA or more.

  Furthermore, the present invention (Claim 6) is characterized in that the current flowing through the resistor is 0.1 μA or more and 1 A or less.

  Sensitive flame detection can be performed by setting it to 0.1 μA or more and 1 A or less.

  Further, according to the present invention (Claim 7), the flame is a seed flame generated by a pilot burner, and the exhaust gas is burned and decomposed by burning fuel and air supplied from the main burner based on the flame. The combustion furnace and the harmful substance removing device for dissolving the product generated in the combustion furnace in water are provided.

  Even a complex system such as a combustion exhaust gas treatment system can be easily maintained by narrowing down the target area of the failure location.

  As described above, according to the present invention, by confirming the presence of the flame with the flame pseudo-current, it is configured to automatically proceed to the next processing step with no abnormality for the flame. The operation can be confirmed for all the steps.

  If there is a failure at a location other than the flame treatment, the failure is stopped at that location, so the failure range between the flame facility and the other facilities can be easily distinguished. On the other hand, if the sequence can proceed without problems for the entire steps, it is suspected that there is a cause of failure in the flame treatment. In this way, the failure range can be narrowed down easily, so that quick recovery is possible.

Configuration diagram of an embodiment of the present invention A figure showing the state of the fire monitoring Configuration diagram of seed fire pseudo-circuit Overall configuration diagram of the abatement system

Hereinafter, embodiments of the present invention will be described. FIG. 1 shows a configuration diagram of an embodiment of the present invention. In FIG. 1, a combustible gas (SiH ₄ or the like) generated in the process chamber 1 or a gas to be treated such as a cleaning gas is introduced into the combustion furnace 23 of the combustion apparatus 7 through the suction port 21 together with fuel and air. ing. The combustion furnace 23 is formed in a cylindrical shape.

  At the top of the combustion furnace 23, a pilot burner 22 for seed fire is arranged. The fire type of the pilot burner 22 is monitored by a fire control unit (Burner Control Unit) 26 corresponding to the flame control unit. The frame rod 18 is disposed so as to come into contact with the seed fire. A cable 16 is laid from the seed fire control unit 26, and ends of the cable 16 are connected to the metal housings of the frame rod 18 and the pilot burner 22, respectively.

  When an AC voltage is applied between the flame rod 18 and the pilot burner 22 from the seed fire control unit 26 side, a current proportional to the flame intensity is generated. This electric current is detected by the seed fire control unit 26.

  Further, a failure location specifying tool 14 indicated by a dotted frame in FIG. The failure location specifying tool 14 is connected between the positive electrode and the negative electrode of the cable 16, and a switch 41, a diode 43, and a resistor 45 are connected in series.

  The flame ignited by the seed flame is a high-temperature combustion flame. That is, it is configured to increase the detoxification efficiency by high-temperature combustion by increasing the mixing ratio of fuel and oxygen to the gas to be treated than usual. The seed fire control unit 26 is also controlled by a main PLC 28 (Programmable Logic Controller) corresponding to the overall control unit.

A main fuel nozzle 24 for supplying a mixed gas of main fuel and air is disposed below the position where the pilot burner 22 is disposed.
In the combustion furnace 23, exhaust gas and fine particle dust are burned at a high temperature of about 1000 ° C. to be chemically decomposed.
For example, when silane which is a semiconductor material gas is burned and decomposed, SiO ₂ powder is generated as fine particle dust.

  A conical cooling unit 25 is disposed at the lower stage of the combustion furnace 23. Water 27 is supplied to the cooling unit 25, and high-temperature exhaust gas generated by combustion decomposition is cooled to about several tens of degrees Celsius by the water 27. The water 27 is discharged to the pipe 29 through the bottom opening of the cooling unit 25 together with the exhaust gas.

  Further, a cylindrical water scrubber 31 corresponding to the harmful substance removing device 9 is erected on the pipe 29 so as to be aligned with the combustion device 7. An opening leading to the pipe 29 is formed at the bottom of the water scrubber 31 through which exhaust gas and particulate dust to be removed are introduced.

  The exhaust gas and fine particle dust introduced into the water scrubber 31 rises inside the water scrubber 31. At this time, treated water such as water (scrubber) is directed downward from the shower nozzle 32 provided in the upper space in the water scrubber 31. Water) is sprayed in the form of a mist.

  The mist-like treated water sprayed from the shower nozzle 32 comes into contact with the exhaust gas and fine particle dust in the water scrubber 31 while falling by its own weight, thereby collecting them. The collected treated water flows into the pipe 29 from the bottom of the water scrubber 31 and flows down the inner wall of the drain pipe 33 into the drain tank 35. The shower nozzle is also provided in the pipe 29, and the treated water 37 is sprayed also in the pipe 29.

  A discharge port 39 is provided in the upper part of the water scrubber 31, and the gas purified by the water scrubber 31 is discharged from the discharge port 39 to the atmosphere via a factory pipe (not shown).

  The treated water in the drain tank 35 is discharged from a drain port (not shown) and then pumped to the water supply tank of the shower nozzle 32 by a pump and reused as treated water sprayed from the shower nozzle 32. In this way, in the treated water circulation system that reuses treated water, exhaust gas concentration and dust concentration in the circulated treated water are monitored by a sensor (not shown), and the treated water is repeatedly used until the concentration reaches a predetermined concentration. .

The main PLC 28 monitors the pilot burner 22 via the seed fire control unit 26, monitors the flow rate of the gas, fuel, air and water to be processed, the pressure in the combustion furnace 23, the back pressure of the water scrubber 31, and the process The on-off control of the gas, fuel, air, and water flow rate adjustment valves and the monitoring of the temperature in the combustion furnace 23 are performed.
As described above, the harmful substance removing device 9 has been described by taking the water scrubber of the wet dust collector as an example, but may be a dry dust collecting system such as a bag filter.

Next, the operation of the embodiment of the present invention will be described.
During normal operation, the switch 41 of the failure location specifying tool 14 is open.
The gas to be treated introduced from the suction port 21 is introduced into the combustion furnace 23. The gas to be treated is ignited by the pilot burner 22, and is combusted and decomposed by a mixed gas of main fuel and air introduced from the main fuel nozzle 24.

  At this time, as shown in FIG. 2, the current flowing between the frame rod 18 and the casing of the pilot burner 22 is input to the fire control unit 26, and the fire is turned on in the fire control unit 26. It is confirmed.

  Exhaust gas and particulate dust generated as a result of combustion decomposition are collected in the pipe 29 in a form dissolved in water sprayed in the cooling unit 25 and the pipe 29 and partly introduced into the water scrubber 31. . The exhaust gas and fine particle dust are collected in the pipe 29 in a form dissolved in the sprayed water even when rising inside the water scrubber 31.

Next, a recovery method when an alarm is detected in the main PLC 28 and the combustion / detoxification system is stopped will be described.
The cause of this system stop can be considered variously due to, for example, a fire, a flow rate, a pressure, a valve, and a temperature. For this reason, when the system stops, the target range that seems to be the cause of failure is narrowed down by the following method.

  In order to identify the failure location, first, the switch 41 shown in FIG. 3 is closed. At this time, the current supplied from the seed fire control unit 26 flows through the resistor 45 via the diode 43. That is, the pseudo current flowing through the resistor 45 is input to the seed fire control unit 26.

  However, the diode 43 is provided in order to simulate the rectifying action that is a characteristic of the flame, and the diode 43 can be omitted if the characteristic of the flame is ignored. is there. The flame current is 0.1 μA or more, preferably 0.1 μA or more and 1 A or less.

  At this time, when viewed from the side of the seed fire control unit 26, the determination is made as if it was confirmed that the seed fire was turned on. Therefore, even if there is a problem with the seed igniter and the combustion / detoxification system may be stopped due to the absence of the seed igniter, the seed igniter is normally present due to the pseudo-current. Based on the virtual recognition, the process proceeds to the next main fuel supply step.

  Therefore, the operation can be confirmed for the entire steps including the pilot process. If there is a failure at a location other than the pilot fire treatment, the failure is stopped at that location, so that it is possible to easily distinguish the failure range between the pilot fire treatment and other facilities. On the other hand, if the sequence can proceed without problems for the entire steps, it is suspected that there is a cause of failure in the seed fire treatment. In this way, the failure range can be narrowed down easily, so that quick recovery is possible.

  As shown in FIG. 1, an on / off signal 47 to the switch 41 may be transmitted from the main PLC 28. Then, an on / off signal 47 is transmitted when there is an abnormality in the system or periodically. In this case, it is possible to automatically determine the failure range without human intervention. For this reason, efficient maintenance such as dispatching workers who are familiar with the seed fire is possible only when the seed fire device is abnormal.

DESCRIPTION OF SYMBOLS 1 Process chamber 3 Turbo molecular pump 5 Dry pump 6 Combustion type exhaust gas treatment device 7 Combustion device 9 Hazardous substance removal device 11 Central scrubber 14 Fault location identification tool 16 Cable 18 Flame rod 21 Inlet 22 Pilot burner 23 Combustion furnace 24 Main fuel nozzle 25 Cooling unit 26 Seeker control unit 27, 37 Water 28 Main PLC
29 Piping 31 Water scrubber 32 Shower nozzle 35 Drain tank 41 Switch 43 Diode 45 Resistance 47 ON / OFF signal

Claims (7)

Flame detection means for detecting the state of the flame of the combustion furnace using a conductive phenomenon;
A flame control unit to which the current detected by the flame detection means is input;
A combustion type exhaust gas treatment apparatus comprising: a failure location specifying tool for inputting a pseudo-current of the flame to the flame control unit instead of the current detected by the flame detection means.   The combustion exhaust gas according to claim 1, further comprising an overall control unit that proceeds to a next processing step by confirming that the function of confirming the state of the flame is normal by the pseudo current. Processing equipment.   The combustion type exhaust gas treatment apparatus according to claim 1 or 2, wherein the failure location specifying tool includes a resistor and a switch connected in series to the resistor.   The combustion type exhaust gas treatment apparatus according to claim 3, wherein the failure location specifying tool includes a rectifying element connected in series with the resistor.   The combustion-type exhaust gas treatment apparatus according to claim 3 or 4, wherein a current flowing through the resistor is 0.1 µA or more.   6. The combustion exhaust gas treatment apparatus according to claim 3, wherein the current flowing through the resistor is 0.1 μA or more and 1 A or less. The flame is a pilot fire generated by a pilot burner,
The combustion furnace for burning and decomposing exhaust gas by burning fuel and air supplied from a main burner based on the seed fire;
The combustion exhaust gas treatment apparatus according to any one of claims 1 to 6, further comprising a harmful substance removal device that dissolves a product produced in the combustion furnace in water.

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