JP2024061182A - Exhaust Gas Treatment Equipment - Google Patents

Abstract

[Problem] To provide an exhaust gas treatment facility that operates stably for a long period of time and can extend the life of the filter replacement. [Solution] In an exhaust gas treatment facility 10 that includes a detoxification device 11, 21 that detoxifies harmful components in exhaust gas, a filter unit 31 that separates powder contained in the exhaust gas discharged from the detoxification device 11, 21, and an exhaust gas pipe L1 that runs from the detoxification device 11, 21 to the filter unit 31, an atmospheric intake valve 12, 22 is provided at the outlet of the detoxification device 11, 21, and a control unit that controls the opening and closing of the atmospheric intake valve 12, 22 controls the atmospheric intake valve 12, 22 in the direction of closing when it detects an increase in the differential pressure between the upstream and downstream sides of the filter unit 31. [Selected Figure] Figure 1

Description

The present invention relates to exhaust gas treatment equipment, and more specifically to equipment for treating exhaust gas containing harmful components discharged from various electronic device manufacturing equipment such as semiconductor manufacturing equipment.

Various process gases and cleaning gases are used in manufacturing equipment for various electronic devices, such as semiconductors. Since the process gases and cleaning gases (hereafter referred to as exhaust gases) contain harmful components, they are sent via pump to a detoxification device where they are rendered harmless. Powder generated during the detoxification process is separated and removed before being exhausted to the outside.

In this type of exhaust gas treatment equipment, there are proposals to install multiple filter units that separate and remove powder, and to achieve stable operation by switching between the filters in use and the filters to be maintained (e.g., Patent Document 1), and to use metal piping with an epoxy resin baked coating on the inner periphery of the piping to prevent powder from accumulating on the exhaust gas piping from the abatement device to the filter units (e.g., Patent Document 2).

JP 2003-21315 A JP 2016-017678 A

However, there is a demand for an exhaust gas treatment facility that can prevent blockage (clogging) of filters and extend the filter replacement life without installing multiple filter units, such as the exhaust gas treatment facility shown in Patent Document 1.

Therefore, the present invention aims to provide an exhaust gas treatment facility that can operate stably for a long period of time and extend the filter replacement life.

In order to solve the above problems, the first aspect of the present invention is an exhaust gas treatment facility that includes a detoxification device that detoxifies harmful components in exhaust gas, a filter unit that separates powder contained in the exhaust gas discharged from the detoxification device, and an exhaust gas pipe leading from the detoxification device to the filter unit, and is characterized in that the outlet of the detoxification device is provided with an air intake valve, and a control unit that controls the opening and closing of the air intake valve controls the air intake valve to close when it detects an increase in the differential pressure between the upstream and downstream sides of the filter unit.

The second invention of the present invention is an exhaust gas treatment facility including a detoxification device that detoxifies harmful components in exhaust gas, a filter unit that separates powder contained in the exhaust gas discharged from the detoxification device, and an exhaust gas pipe leading from the detoxification device to the filter unit, and is characterized in that an air intake valve is provided at the outlet of the detoxification device, and a control unit that controls the opening and closing of the air intake valve receives a gas usage signal from a manufacturing device that outputs exhaust gas to the detoxification device, and controls the air intake valve in a direction to close when the signal is not a signal indicating that a gas that generates powder is being used during the detoxification process of the detoxification device.

The third invention of the present invention is an exhaust gas treatment facility including a detoxification device that detoxifies harmful components in exhaust gas, a filter unit that separates powder contained in the exhaust gas discharged from the detoxification device, and an exhaust gas pipe leading from the detoxification device to the filter unit, and is characterized in that an air intake valve is provided at the outlet of the detoxification device, and a control unit that controls the opening and closing of the air intake valve controls the air intake valve in a direction to close when it detects that the combustion mode of the detoxification device during detoxification processing is not one that generates powder.

The exhaust gas piping is provided at its end opposite to the end connected to the filter unit with an atmospheric air introduction valve for adjusting the transport speed, which introduces atmospheric air to adjust the transport speed. The control unit controls the atmospheric air introduction valve for adjusting the transport speed in an opening direction when it detects a decrease in the differential pressure between the upstream and downstream sides of the filter unit. Furthermore, a plurality of the abatement devices may be provided.

According to the first invention, when an increase in the differential pressure between the upstream and downstream sides of the filter unit is detected, the atmospheric intake valve is controlled in the direction of closing, thereby reducing the overall ventilation air volume, preventing powder from re-adhering to the filter unit, and restoring the differential pressure. By restoring the differential pressure in this way, it is possible to extend the period until the differential pressure reaches the guideline for filter replacement.

In addition, according to the second and third inventions, the load state of the generated powder is constantly recognized, and the differential pressure is restored in a situation where no powder is generated, which allows for more stable operation and extends the life of parts that need replacing.

In addition, by providing an air intake valve for adjusting the transport speed, the powder transport speed in the exhaust gas piping can be constantly maintained, enabling stable operation.

1 is an explanatory diagram showing an example of an exhaust gas treatment facility according to the present invention; 4 is a graph showing the change in filter differential pressure ΔP over the number of days in continuous operation according to one embodiment of the exhaust gas treatment equipment of the present invention and in normal continuous operation.

Figure 1 is an explanatory diagram showing one embodiment (example) of the exhaust gas treatment equipment of the present invention. The exhaust gas treatment equipment 10 in this example is roughly composed of a plurality of detoxification devices 11, 21 that perform detoxification of gas discharged from various electronic device manufacturing equipment 1 such as semiconductors via a dry pump 2, a filter unit 31 that separates powder contained in the exhaust gas discharged from the detoxification devices 11, 21, and an exhaust gas pipe L1 that runs from the detoxification devices 11, 21 to the filter unit 31.

The electronic device manufacturing equipment 1 is, for example, a process chamber for semiconductor manufacturing, and various gases are used depending on the type and process of film formation, and exhaust gases corresponding to those gases are discharged. These gases discharged from the electronic device manufacturing equipment 1 are sucked into the dry pump 2 and sent to the decontamination equipment 11.

The abatement device 11 is of the so-called water-cooled thermal decomposition type, and is equipped with a decomposition section 11a, a tank section 11b, and a scrubber section 11c. The decomposition section 11a thermally decomposes harmful components in the exhaust gas, and has a double-cylinder structure consisting of an inner cylinder and an outer cylinder, with a burner inside the inner cylinder. A fuel supply pipe (not shown) and a combustion-supporting fluid supply pipe (not shown) are arranged in the burner, and when the fuel supplied from the fuel supply pipe is mixed with the combustion-supporting fluid supplied from the combustion-supporting fluid supply pipe and combusted, the exhaust gas supplied from the dry pump 2 is thermally decomposed.

The exhaust gas treated in the decomposition section 11a and the powder generated during the treatment are discharged to the tank section 11b provided below the decomposition section 11a. The tank section 11b is a cooling water tank in which cooling water is stored up to an intermediate height in a sealed state, and is provided with an exhaust port at the top to which the scrubber section 11c described below is connected. In the tank section 11b, the gas discharged from the decomposition section 11a comes into contact with the cooling water and is cooled, and some of the powder (secondary product) is captured by the cooling water. Although not shown, the tank section 11b is provided with a water supply path and a drainage path for introducing new cooling water to replace the water while maintaining a constant amount of stored cooling water.

The scrubber section 11c is provided on the top of the tank section 11b, and is filled with a filler material and has a spray nozzle above the filler material. In the scrubber section 11c, impurities in the gas cooled by the cooling water in the tank section 11b are captured by the filler material, and then the gas is washed with cleaning water sprayed from the spray nozzle to remove water-soluble components.

The exhaust gas discharged from the scrubber section 11c contains a relative humidity of almost 100% and a small amount of mist due to the water spray from the spray nozzle, and some powder still remains. If the powder with a high moisture content or the moisture mist is entrained in the exhaust gas, the adhesion force on the filter surface of the filter unit 31 described later will be large, and it may be difficult to remove the powder from the filter surface even by backwashing. For this reason, an air intake valve 12 for drawing in air for drying is provided at the outlet (rear stage of the abatement device) of the scrubber section 11c before merging with the exhaust gas pipe L1. The air intake valve 12 is a control valve whose opening can be adjusted to adjust the flow rate of the air introduced. The air introduced from the air intake valve 12 is used not only for drying as described above, but also for transporting the powder in the exhaust gas pipe L1.

The decontamination device 21 has the same configuration as the decontamination device 11, and includes a decomposition section 21a, a tank section 21b, and a scrubber section 21c, and an air intake valve 22 is provided at the outlet of the scrubber section 21c.

The filter unit 31 has multiple bag filters 31a installed inside. The exhaust gas introduced into the filter unit 31 from the exhaust gas pipe L1 passes from the primary side to the secondary side of the bag filter 31a, and powder and other particles contained in the exhaust gas adhere to and accumulate on the primary side surface of the bag filter 31a. The exhaust gas that has passed through the bag filter 31a is discharged to the outside of the exhaust gas treatment equipment 10 by the exhaust pump 3.

In addition, to backwash the powder and other particles adhering to the bag filter 31a, the backwash valve 31b is constantly opened and closed at regular intervals, and the air is blown from the secondary side to the primary side of the bag filter 31a, causing the powder and other particles adhering to the primary surface of the bag filter 31a to detach and fall into the powder discharge section (hopper) 31c.

In the exhaust gas treatment equipment 10 of this embodiment, the difference in pressure (filter differential pressure ΔP) measured by the pressure gauge P1 on the upstream side of the filter unit 31 and the pressure gauge P2 on the downstream side is detected by a control unit (not shown). As exhaust gas treatment continues in the exhaust gas treatment equipment 10, clogging of the bag filter 31a progresses and the filter differential pressure ΔP gradually increases. When it reaches 1.0 kPa, it is time to replace the filter.

In addition, an air intake valve 41 for adjusting the conveying speed is provided at the end of the exhaust gas pipe L1 opposite the end connected to the filter unit 31, which introduces air to adjust the conveying speed.

Here, if the amount of airflow from the exhaust gas pipe L1 to the filter unit 31 is large, the powder particles removed by backwashing may re-adhere to the primary surface of the bag filter 31a.

Therefore, in the exhaust gas treatment equipment 10 in this embodiment, when the control unit detects an increase in the filter differential pressure ΔP during continuous operation of the exhaust gas treatment (for example, when an increase of 0.9 to 1.0 kPa is detected), the control unit automatically controls the atmospheric intake valves 12, 22 installed downstream of the detoxification devices 11, 21 to temporarily reduce the opening. In this way, by reducing the opening of the atmospheric intake valves 12, 22, the overall ventilation air volume is reduced, re-adhesion to the primary side surface of the bag filter 31a is prevented, and the differential pressure is restored. In addition, the atmospheric intake valves 12, 22 whose opening has been reduced may be timer-controlled to return to their original opening after, for example, 10 to 60 minutes have elapsed, depending on the number of bag filters 31a. At this time, if the differential pressure recovery cannot be confirmed, the atmospheric intake valves 12, 22 may be controlled again to reduce the opening.

Figure 2 is a graph showing the change in filter differential pressure ΔP over time in normal continuous operation and when control is implemented with the addition of a differential pressure recovery function according to the embodiment of the present invention described above. In the case of normal continuous operation, plotted with black triangles, it took about 240 days to reach the replacement guideline of 1.0 kPa. In the case of the embodiment of the present invention, plotted with black circles, it took about 330 days to reach the filter differential pressure guideline for replacement, enabling stable operation and extending the life of parts that can be replaced.

Next, a modified example (modified example 1) of the control of the exhaust gas treatment facility 10 of the present invention will be described. In the electronic device manufacturing apparatus 1, various gases are used depending on the type and process, and exhaust gas corresponding to the gas is discharged. In the process steps for manufacturing semiconductors and liquid crystal panels, special gases such as silane gas (SiH ₄ ) and tungsten hexafluoride (WF ₆ ) are used as process gases. When these flammable special gases are treated by the abatement device 11, powder (secondary product) is generated.

On the other hand, when a persistent gas such as nitrogen trifluoride (NF ₃ ) used in the cleaning process is treated by the detoxification device 11, the generation of powder is slight.

The electronic device manufacturing apparatus 1 transmits a gas usage signal indicating which gas is being used in which process to the control unit of the exhaust gas treatment equipment 10. Examples of gas usage signals include a signal (DEPO signal) indicating that a film formation process (process step) that generates powder is being performed in the decontamination device 11, and a signal (CLN signal) indicating that a cleaning process is being performed.

If powder is being generated in the abatement device 11, the load of the powder generation will be generated, and so differential pressure recovery control as in the above embodiment will have little effect. However, if the control unit confirms that no powder is being generated, the opening of the atmospheric intake valves 12, 22 can be automatically controlled to reduce, thereby reducing the overall ventilation air volume and enabling differential pressure recovery.

When the control unit confirms that no powder is being generated, it means, for example, that in a case where both the DEPO signal and the CLN signal can be received, neither signal is input. Also, if only the CLN signal can be received, the CLN signal input is sufficient since it means that at least a large amount of powder is not being generated and the load is light (this may be considered to be a case where the signal is not one that uses the gas that generates the powder of the present invention).

In the embodiment, when an increase in the filter differential pressure ΔP is detected, the opening of the atmospheric intake valves 12, 22 is controlled, but as time passes and the filter becomes increasingly clogged, it becomes difficult to remove the powder by backwashing, and sufficient effects may not be obtained. In variant 1, the steady load state of the generated powder is recognized by the input signal from the electronic device manufacturing equipment 1, and differential pressure recovery control is added, making it possible to further stabilize operation and extend the life of parts replacement.

In addition, many models of abatement devices 11, 21 are capable of switching the combustion mode based on the gas usage signal of electronic device manufacturing equipment 1 in order to optimize the operating conditions (combustion mode) from the perspective of energy conservation. Therefore, instead of controlling based on the gas usage signal of electronic device manufacturing equipment 1 as in variant 1, as variant 2, it is also possible to control the opening degree of atmospheric intake valves 12, 22 by the control unit based on the combustion mode of the abatement device.

As for the combustion mode, for example, there is an idle mode in which only a small ignition burner is on (fuel consumption of about 1 L/min) when the gas to be treated is not flowing, and when the gas to be treated starts to flow, it switches to a low energy mode or a high energy mode.

The low energy mode is a mode when treating flammable gases such as silane gas (SiH ₄ ) and tungsten hexafluoride (WF ₆ ), which can be detoxified with 60-70% of the fuel consumption.

The high energy mode is a mode in which, for example, persistent gases such as nitrogen trifluoride (NF ₃ ) that cannot be treated unless 100% of the fuel is used are treated.

Therefore, in the idle mode and high energy mode, no powder is generated during processing by the abatement device (in the high energy mode, a small amount of powder is generated, as in the case of the CLN signal input in the first modification, but this mode may be considered a mode that is not a combustion mode that generates powder according to the present invention). Therefore, in the second modification, when the control unit confirms that no powder is being generated based on the combustion mode of the abatement device, the opening of the atmospheric intake valves 12, 22 may be automatically controlled in a direction to reduce the overall ventilation air volume, thereby allowing the pressure difference to be restored.

In addition, in any of the embodiment, variant 1, and variant 2, when both decontamination devices 11, 21 are operating, the powder transport speed in the exhaust gas pipe L1 is sufficient. However, if either of them stops, the powder transport speed in the exhaust gas pipe L1 decreases, and there is a risk of powder accumulating on the exhaust gas pipe L1.

When there are two abatement devices and one filter unit, the operating value of the filter differential pressure ΔP during normal operation is 0.6-0.8 kPa. Here, if one of the abatement devices stops, the filter differential pressure ΔP drops to about 0.3 kPa.

In this way, when the control unit detects that the filter differential pressure ΔP has dropped to a level where it is determined that the powder transport speed in the exhaust gas pipe L1 is not being obtained sufficiently, it is preferable to open the atmospheric intake valve 41 for adjusting the transport speed in the exhaust gas pipe L1 and control the filter differential pressure ΔP to return to approximately 0.6 kPa and ensure the transport speed.

The degree of decrease in the filter differential pressure ΔP at which the conveying speed adjustment atmosphere intake valve 41 should be opened can be preset based on the abatement device, the number of filter units, etc.

The following Table 1 shows examples of the air flow rate at each location of the exhaust gas treatment equipment 10 during normal operation, during differential pressure recovery control in Example 1 and Modifications 1 and 2, and when the filter differential pressure ΔP drops and the atmospheric intake valve 41 for adjusting the transport speed is opened.

Q1 is the flow rate of exhaust gas after the abatement process in the abatement device 11, Q2 is the flow rate of air taken in through the atmospheric intake valve 12, Q3 is the flow rate of exhaust gas after the abatement process in the abatement device 21, Q4 is the flow rate of air taken in through the atmospheric intake valve 22, and Q5 is the flow rate of air taken in through the atmospheric intake valve 41 for adjusting the transport speed.

In the above embodiment, the exhaust gas treatment equipment has two detoxifiers and one filter unit, but the number of each is not particularly limited. The detoxifier is not limited to the water-cooled thermal decomposition type, and any known type capable of detoxifying harmful components in exhaust gas, such as a heater type or plasma type, may be used.

1...Electronic device manufacturing equipment, 2...Dry pump, 3...Exhaust pump, 10...Exhaust gas treatment equipment, 11, 21...Detoxification equipment, 11a, 21a...Decomposition section, 11b, 21b...Tank section, 11c, 21c...Scrubber section, 12, 22...Atmospheric intake valve, 31...Filter unit, 31a...Bag filter, 31b...Backwash valve, 31c...Powder discharge section, 41...Atmospheric intake valve for adjusting conveying speed

Claims (5)

An exhaust gas treatment facility including a detoxification device that detoxifies harmful components in exhaust gas, a filter unit that separates powder contained in the exhaust gas discharged from the detoxification device, and an exhaust gas piping that runs from the detoxification device to the filter unit,
An atmosphere intake valve is provided at an outlet of the abatement device,
The control unit which controls the opening and closing of the atmospheric intake valve controls the atmospheric intake valve to close when it detects an increase in the differential pressure between the upstream and downstream sides of the filter unit. An exhaust gas treatment facility including a detoxification device that detoxifies harmful components in exhaust gas, a filter unit that separates powder contained in the exhaust gas discharged from the detoxification device, and an exhaust gas piping that runs from the detoxification device to the filter unit,
An atmosphere intake valve is provided at an outlet of the abatement device,
The control unit which controls the opening and closing of the atmospheric intake valve receives a gas usage signal from a manufacturing device which outputs exhaust gas to the decontamination device, and controls the atmospheric intake valve in the direction of closing if the signal does not indicate that a gas which generates powder is being used during the decontamination process. An exhaust gas treatment facility including a detoxification device that detoxifies harmful components in exhaust gas, a filter unit that separates powder contained in the exhaust gas discharged from the detoxification device, and an exhaust gas piping that runs from the detoxification device to the filter unit,
An atmosphere intake valve is provided at an outlet of the abatement device,
An exhaust gas treatment facility characterized in that a control unit that controls the opening and closing of the atmospheric intake valve controls the atmospheric intake valve to close when it detects that the combustion mode during the detoxification process of the decontamination device is not one that generates powder. an air introduction valve for adjusting a conveying speed, which introduces air in order to adjust a conveying speed, is provided at an end of the exhaust gas pipe opposite to the end connected to the filter unit;
4. The exhaust gas treatment facility according to claim 1, wherein the control unit controls the transport speed adjusting atmospheric intake valve in an opening direction when it detects a decrease in the differential pressure between the upstream side and the downstream side of the filter unit. The exhaust gas treatment facility according to claim 4, characterized in that a plurality of the abatement devices are provided.

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