WO2024024287A1 - Gas treatment method and gas treatment system - Google Patents

Abstract

Provided are a gas treatment method and a gas treatment system with which it is possible to recover from any reduction in VOC treatment performance without requiring wiping work or the like by a worker.　This method includes: a step (A) in which a gas being treated is introduced into a treatment space that constitutes part of a flow path in a state in which a discharge lamp is lit, the discharge lamp being disposed within the treatment space and emitting UV light having a main emission wavelength of 200 nm or lower; and a step (B) in which a purified gas that contains oxygen but substantially does not contain VOCs is introduced into the treatment space in a state in which the discharge lamp is lit after step (A) is implemented.

Description

Gas treatment method, gas treatment system

The present invention relates to a gas processing method and a gas processing system, and particularly to a gas processing method and a gas processing system for processing gas containing VOC (Volatile Organic Compounds).

Conventionally, a technique has been proposed for purifying a gas to be treated using a low-pressure mercury lamp. For example, Patent Document 1 listed below describes using a low-pressure mercury lamp that emits ultraviolet light with a wavelength of 185 nm or 254 nm to decompose and remove impurities and bacteria in a gas to be treated. More specifically, it is described that ozone (O ₃ ) gas is generated using ultraviolet light with a wavelength of 185 nm, and that impurities and malodorous substances are decomposed by this ozone gas.

By the way, the following Patent Document 2 discloses a xenon excimer lamp that emits light with a narrow emission band width centered around a wavelength of 172 nm, which is a shorter wavelength than the above-mentioned low-pressure mercury lamp.

JP2006-204683A Japanese Patent Application Publication No. 2007-335350

Excimer lamps such as those disclosed in Patent Document 2 have conventionally been used for the purpose of removing organic substances in the manufacturing process of semiconductors and liquid crystal panels. That is, until now, excimer lamps have typically been used in strictly controlled clean environments.

The present inventors are considering a gas processing device that can efficiently generate ozone by using this excimer lamp instead of the low-pressure mercury lamp as described in Patent Document 1.
In particular, when the gas to be treated contains oxygen, highly reactive O( ^1D ) is generated by irradiation with short wavelength light emitted from an excimer lamp, and when the gas contains water. Since hydroxyl radicals (.OH) are generated, it is expected that the ability to decompose VOCs contained in the gas to be treated will be improved.

By the way, the inventors of the present invention have conducted extensive research into using excimer lamps to treat gases containing VOCs, and have found that as the treatment continues, contaminants adhere to the surface of the excimer lamp. A new problem was discovered: the illumination intensity of the ultraviolet light emitted from excimer lamps decreases. Such a situation is undesirable because it reduces the ability of the gas treatment device to treat VOCs over time.

If contaminants adhere to the surface of the excimer lamp, it may be possible to restore the VOC processing ability by periodically wiping off the contaminants. However, it is not realistic to regularly wipe down the excimer lamps of all gas treatment equipment installed in the exhaust ducts of experimental facilities and factories, as it requires a great deal of labor and time. isn't it.

In view of the above-mentioned problems, an object of the present invention is to provide a gas treatment method and a gas treatment system that can recover from a decrease in VOC processing capacity without requiring wiping work or the like by an operator.

The gas treatment method of the present invention includes:
A gas treatment method for treating a target gas containing VOCs and oxygen, the method comprising:
Introducing the gas to be treated into the processing space while lighting a discharge lamp that emits ultraviolet light with a main emission wavelength of 200 nm or less, which is arranged in the processing space that forms part of the flow path. A step (A) of
After carrying out the step (A), a step (B) of introducing a clean gas containing oxygen and substantially no VOC into the processing space while the discharge lamp is lit; It is characterized by including.

In this specification, the "main emission wavelength" refers to a wavelength range Z(λ) of ±10 nm for a certain wavelength λ, which is defined as a wavelength range Z(λ) of 40% or more of the total integrated intensity within the emission spectrum. refers to the wavelength λi in the wavelength range Z(λi) showing the integrated intensity of .

In this specification, "substantially not containing VOC" is intended to include not only cases where the VOC concentration is 0 ppm but also cases where the VOC concentration is less than 50 ppm. Regarding the clean gas, the VOC concentration is preferably less than 25 ppm, more preferably 10 ppm or less.

It is assumed that the contaminants adhering to the surface of the discharge lamp are intermediate products derived from VOCs and mainly generated by irradiation with ultraviolet light in step (A). The intermediate product is a substance produced during the process in which VOCs are decomposed into final products such as water and carbon dioxide, mainly by ozone and radicals.

Therefore, the present inventors created an environment in which the ozone generated in the processing space is more likely to react with the pollutants attached to the surface of the discharge lamp than with the VOCs contained in the gas to be processed, and remove the pollutants as a final product. We conducted extensive research on a method to clean the surface of a discharge lamp by decomposing it into its products.

If a discharge lamp with contaminants attached to its surface is turned on while clean gas is introduced, it will not be possible to irradiate ultraviolet light at the desired intensity, but the oxygen contained in the clean gas will be exposed to ultraviolet light. irradiation to produce ozone within the processing space. The clean gas is substantially free of VOCs. Therefore, the ozone easily reacts with contaminants adhering to the surface of the discharge lamp.
In other words, the pollutants that have accumulated on the surface of the discharge lamp are gradually decomposed into the final products, water and carbon dioxide, by the ozone generated within the processing space, and are then removed outside the processing space. is discharged to.

Therefore, by using the above method, contaminants attached to the surface of the discharge lamp can be removed simply by switching the gas to be introduced, without requiring wiping work or the like.
Then, the amount of ultraviolet light emitted from the discharge lamp is restored so as to approach the state before processing the gas to be processed.

Note that in the above method, step (A) and step (B) do not need to be performed continuously. For example, after carrying out step (A), the discharge lamp is turned off and a predetermined flow rate of clean gas is introduced into the processing space with the discharge lamp turned off, and then the discharge lamp is turned on and step (B) is carried out. It does not matter if a method of implementing this is adopted. In addition, after carrying out step (A), a method of carrying out step (B) after passing through a step of lighting a discharge lamp while completely stopping the introduction of gas into the processing space, and a method of carrying out step (B). After that, a method may be adopted in which a step is performed in which the discharge lamp is turned on while the introduction of gas into the processing space is temporarily completely stopped.

Furthermore, the gas to be processed introduced into the processing space in step (A) may be a mixed gas in which clean gas is mixed with the gas taken in from the exhaust port of the laboratory etc. and introduced from the duct. I do not care.

In the above gas treatment method,
The step (A) and the step (B) may be performed by lighting an excimer lamp, which is a type of discharge lamp, in which a luminescent gas containing xenon (Xe) gas is sealed in the tube. I do not care.

The wavelength range of the optical absorption band of oxygen is mainly within the range of 100 nm or more and 240 nm or less, and ozone is generated by irradiating oxygen molecules with ultraviolet light in this wavelength range. An excimer lamp whose tube body is filled with a luminescent gas containing xenon (Xe) gas is a discharge lamp that emits ultraviolet light with a main emission wavelength of around 172 nm and a narrow emission band width.

In other words, in the excimer lamp with this configuration, most of the emitted ultraviolet light is absorbed by oxygen and water and used for ozone generation, so there is relatively little wasted ultraviolet light, and it can be used as a discharge lamp for the above method. suitable.

In the above gas treatment method,
The step (B) may be a step in which air is introduced into the processing space as the clean gas.

Generally, air contains oxygen and water. When air is irradiated with ultraviolet light having a main emission wavelength of 200 nm or less, highly reactive O( ¹ D) and hydroxyl radicals (.OH) are generated, as described above. That is, by using the above method, in addition to the decomposition treatment effect of ozone, a high decomposition treatment effect of hydroxyl radicals can be obtained for VOCs and pollutants adhering to the surface of the discharge lamp.

Note that the above method may include, for example, a step of introducing mist-like water into the processing space using a humidifier or the like in order to obtain a high decomposition treatment effect by hydroxyl radicals.

The above gas treatment method is
The method may be such that the step (B) is performed after a predetermined period of time has elapsed after starting the step (A).

In addition, the above gas treatment method is
In the step (A), the step (B) may be performed after the total flow rate of the gas to be processed that has passed through the processing space becomes equal to or greater than a predetermined threshold.

If step (A) is continued for a long period of time, there is a possibility that too much contaminant will accumulate on the surface of the discharge lamp, resulting in a state in which almost no ultraviolet light can be emitted. If almost no ultraviolet light is emitted from the discharge lamp, no matter how much clean gas is introduced into the processing space in step (B), ozone will not be generated and the pollutants attached to the surface of the discharge lamp will not be decomposed.

Furthermore, contaminants that have not been treated in any way for a long period of time may stick to the surface of the discharge lamp and become hardly decomposed even when exposed to ozone or hydroxyl radicals.

Furthermore, if a large amount of VOC is expected to be introduced in a short period of time, a large amount of contaminants will suddenly adhere to the surface of the discharge lamp, making it difficult to continue process (A) for a long period of time. Even if this is not done, there is a possibility that the discharge lamp will be unable to emit ultraviolet light.

Therefore, by using the above method, it is possible to finish the implementation of step (A) and perform step (B) before the discharge lamp falls into the above-mentioned state, and the discharge lamp can be more reliably removed. The amount of emitted ultraviolet light can be recovered.

The gas treatment system of the present invention includes:
a casing in which a processing space is formed in which a processing target gas containing VOCs and oxygen is taken in and processed;
a discharge lamp disposed in the processing space that emits ultraviolet light with a wavelength of 200 nm or less; and the processing space contains the gas to be processed, or the processing space contains oxygen and does not substantially contain VOCs. an inlet for taking in the first clean gas;
an outlet for discharging the gas that has passed through the processing space;
It is characterized by comprising a switching unit that selectively switches between introducing the gas to be treated and introducing the first clean gas into the inlet.

The "switching part" here is a mechanism that realizes switching between introducing the processing target gas into the processing space and introducing the first clean gas. A three-way valve installed at the connection point between the flow path to be used and the flow path through which the first clean gas flows, a control valve that opens and closes the flow path, and a control valve installed directly at or around the opening of the gas processing device. Corresponds to shutters, louvers, etc. Further, the switching section may be configured by combining a plurality of these mechanisms.

In the above gas processing system,
The discharge lamp may be an excimer lamp in which a luminescent gas containing xenon (Xe) gas is enclosed in a tube.

In the above gas processing system,
The first clean gas may be air.

The above gas processing system is
The housing is provided with a plurality of processing spaces, the introduction port, and the discharge port, and when the switching unit switches to introduce the gas to be processed into the introduction port, the switching unit switches the processing space to the other gas to be processed. It may be configured to switch so as to introduce the first clean gas into the opening.

In addition, the above gas processing system is
A plurality of gas treatment devices each having the housing, the discharge lamp, the inlet, and the discharge port are provided, and the switching unit is configured to switch the opening of one of the plurality of gas treatment devices. It may be configured such that when the gas to be treated is switched to be introduced into the gas treatment section, the first clean gas may be introduced into the opening of another gas treatment device.

The above gas processing system is
a control unit that performs switching control of the switching unit;
and a timer that measures the time that has elapsed since the control unit controlled the switching unit and started introducing the gas to be processed into the inlet,
When the timer detects that a predetermined time has elapsed, the control unit may be configured to perform control to switch the switching unit to guide the first clean gas to the inlet.

The above gas processing system is
a control unit that performs switching control of the switching unit;
The control unit controls the switching unit to start introducing the process target gas into the inlet, and then includes a flow meter that measures the flow rate of the process target gas flowing through the processing space. ,
When the flow meter detects that the total flow rate of the gas to be treated that has flowed through the treatment space is equal to or higher than a predetermined threshold, the control unit guides the first clean gas to the inlet. The switching unit may be configured to execute control for switching the switching unit.

According to the present invention, a gas treatment method and a gas treatment system are realized that can recover from a decrease in VOC processing capacity without requiring wiping work or the like by an operator.

1 is a drawing schematically showing an embodiment of a gas processing system. 2 is an enlarged view of the configuration around the gas treatment device in FIG. 1. FIG. FIG. 2 is a side cross-sectional view schematically showing the configuration of a gas processing device. It is a drawing showing a state in which a gas to be treated is introduced into the gas treatment device. It is a drawing showing a state where air is introduced into the gas treatment device. It is a flowchart showing the operation process of the gas treatment device. 1 is a drawing schematically showing the configuration of an excimer lamp used in a verification experiment. 6A is a drawing when the excimer lamp shown in FIG. 6A is viewed from a direction rotated by 90 degrees around the tube axis. 2 is a diagram schematically showing how the illuminance of ultraviolet light emitted from an excimer lamp is measured. It is a graph which shows the time change of the illuminance maintenance rate of each sample. 1 is a diagram schematically showing a state in operation of an embodiment of a gas processing system. 1 is a diagram schematically showing a state in operation of an embodiment of a gas processing system. 1 is a drawing schematically showing an embodiment of a gas processing system. 1 is a drawing schematically showing an embodiment of a gas processing system. 1 is a diagram schematically showing the configuration and operation of an embodiment of a gas processing system. 1 is a diagram schematically showing the configuration and operation of an embodiment of a gas processing system. FIG. 2 is a drawing schematically showing a configuration around a gas processing device in another embodiment of the gas processing system. 7 is a drawing schematically showing the configuration and operation of another embodiment of a gas processing system. 7 is a drawing schematically showing the configuration and operation of another embodiment of a gas processing system. FIG. 3 is a diagram schematically showing a gas treatment device in another embodiment of the gas treatment system. 13B is a drawing of the gas treatment device of FIG. 13A when viewed toward the opening. FIG.

Hereinafter, the gas processing method and gas processing system of the present invention will be explained with reference to the drawings. It should be noted that the following drawings are all schematically illustrated, and the dimensional ratios and numbers on the drawings do not necessarily match the actual dimensional ratios and numbers.

[First embodiment]
FIG. 1 is a diagram schematically showing the overall configuration of the gas treatment system 1, and FIG. 2 is an enlarged diagram of the configuration around the gas treatment apparatus 10 in FIG. As shown in FIG. 1, the gas processing system 1 of the first embodiment is described as a so-called general ventilation system that processes gas to be processed containing VOCs present in a laboratory 3 of a building 2.

Note that specific examples of the building 2 include facilities that require environmental management regarding VOCs, such as chemical factories, research laboratories and university laboratories, and medical facilities.

The gas processing system 1 includes a gas processing device 10, a first flow path 11, a second flow path 12, a third flow path 13, and a switching section 14, as shown in FIGS. 1 and 2. Although FIG. 1 shows a gas processing system 1 equipped with one of these, in reality, each is required depending on the size and structure of the building 2, the number of laboratories 3, etc. Only a few are installed.

The first flow path 11 is connected to a duct opening 4 provided in the laboratory 3, and is a flow path through which the gas to be treated G1 containing oxygen, water, and VOC generated in the laboratory 3 flows. . In addition, a fan for blowing air is provided in the duct opening 4 or the first flow path 11 to ensure that the gas G1 to be treated flows in a predetermined direction and to prevent VOCs from flowing back into the laboratory 3 side. It doesn't matter if you stay there. Further, although not shown in FIG. 1, the laboratory 3 may be provided with a ventilation port for taking in as much outside air as the gas taken in through the duct opening 4.

The second flow path 12 is connected to an intake port 2a for taking in air G2, which is a clean gas (first clean gas) that contains oxygen and water and does not substantially contain VOCs, from the outside of the building 2, This is a flow path through which air G2 flows. Note that a fan for blowing air may be provided in the intake port 2a or the second flow path 12 so that the air G2 is taken in and flows reliably in a predetermined direction.

The third flow path 13 is a flow path connected to the exhaust port 2b for exhausting the treated gas G3 discharged from the gas treatment device 10 to the outside of the building 2. Similarly to the above, a blowing fan may be provided in the exhaust port 2b or the third flow path 13 so that the treated gas G3 is discharged from the exhaust port 2b.

The switching unit 14 is a mechanism that selectively switches between introducing the process target gas G1 and introducing the air G2. Note that the switching unit 14 in the first embodiment is a three-way valve disposed at the connection point between the first flow path 11 and the second flow path 12, but for example, it may be a control valve that opens and closes the flow path, a shutter, a louver, The above mechanism may be implemented using a damper or the like, or a combination thereof.

(Gas treatment device 10)
FIG. 3 is a drawing schematically showing the configuration of the gas treatment device 10. As shown in FIG. As shown in FIG. 3, the gas treatment apparatus 10 in the first embodiment includes a housing 20, a discharge lamp 21, and a control section 22. FIG. 4A is a drawing showing a state in which the gas to be processed G1 is introduced into the gas processing apparatus 10, and FIG. 4B is a drawing showing a state in which air G2 is introduced into the gas processing apparatus 10.

The housing 20 is provided with an inlet 20a and an outlet 20b on opposing sides, and the inlet 20a and the outlet 20b are connected on the inside, and the gas to be processed G1 or the air G2 is inside. A processing space 20c into which the gas is introduced is formed. Further, in the case 20 of the first embodiment, a space 20d in which the control unit 22 is housed is formed as a clean space separate from the processing space 20c.

The discharge lamp 21 is disposed within a processing space 20c formed within the housing 20, and irradiates ultraviolet light to the gas G1 or air G2 to be processed that flows in from the inlet 20a. The discharge lamp 21 in the first embodiment is an excimer lamp whose tube body is filled with luminescent gas containing xenon (Xe) gas, and when powered and turned on, emits ultraviolet light having a main emission wavelength of 172 nm. It is.

Note that the discharge lamp 21 may be any light source that can emit ultraviolet light with a main emission wavelength of 200 nm or less; for example, it may be an excimer lamp in which argon (Ar) gas and fluorine (F) gas are sealed in a tube as luminous gases. A deuterium lamp, an excimer laser, an _F2 laser, etc. may be employed as the lamp or another light source. Regarding excimer lamps, there are shapes called single-tube or double-tube where the electrodes are arranged concentrically, and shapes where the tube has a rectangular cross section and the electrodes are arranged opposite each other through the tube. There is a shape called a flat tube shape in which excimer lamps are arranged, but any shape of excimer lamp may be used.

In the first embodiment, as shown in FIG. 3, a part of the processing space 20c is configured to be narrow. Since ultraviolet light with a wavelength of 200 nm or less is easily absorbed by oxygen, it can only travel about 10 mm in the processing space 20c. Therefore, the above-mentioned configuration is adopted in order to make it easier for the gas G1 to be treated and the air G2 to flow near the discharge lamp 21.

The control section 22 includes an inverter 22a, an introduced gas control section 22b, and a timer 22c. The inverter 22a is an electric circuit that generates power for lighting the discharge lamp 21 from power supplied from an external power source (not shown). Electric power generated by the inverter 22a is supplied to the discharge lamp 21 via a power supply line 22d. In reality, there are two feeder lines 22d, one for the positive electrode and one for the negative electrode, but in FIG. Only the electric wire 22d is shown.

The introduced gas control unit 22b outputs a signal d1 that starts the lighting operation of the discharge lamp 21 to the inverter 22a, as shown in FIG. 4A. Further, the introduced gas control section 22b outputs a signal d2 to the switching section 14 to control the introduction of the processing target gas G1 into the processing space 20c. Note that in FIGS. 3 to 4B, communication between the introduced gas control section 22b and the switching section 14 is schematically illustrated, but in the first embodiment, communication between the introduced gas control section 22b and the switching section 14 is shown schematically. is configured to enable wireless communication. Note that the introduced gas control section 22b and the switching section 14 may be configured to be connected by a cable and communicate by wire. Note that the communication between the introduced gas control section 22b and the switching section 14 may be configured to enable two-way communication. For example, the switching section 14 may indicate that the switching of the flow path is completed by controlling the introduced gas. It may be configured to output a signal to notify the section 22b.

The timer 22c measures the elapsed time immediately after the predetermined control is executed, and outputs a signal d3 or a signal d5 to the introduced gas control section 22b. Note that if there is no particular need to measure time, such as when a person operates the control unit 22 to control the switching unit 14 at an arbitrary timing, the gas treatment device 10 does not need to include the timer 22c. .

(Gas treatment method)
Next, how the gas processing system 1 operates will be explained with reference to FIG. 5. Note that FIG. 5 referred to in the description here is a flowchart showing the operation process of the gas treatment apparatus 10.

As shown in FIG. 4A, the introduced gas control section 22b outputs a signal d2 to the switching section 14 (step S1).

When the gas processing system 1 starts operating after step S1, the introduced gas control section 22b outputs the signal d1 to the inverter 22a, and the introduction of the processing target gas G1 into the processing space 20c is started ( Step S2).

Step S2 may be executed earlier than Step S1, and furthermore, Step S1 and Step S2 may be executed simultaneously, but the processing target gas G1 introduced immediately after the switching unit 14 is controlled is In order to ensure reliable processing, it is preferable that step S2 be performed several seconds after step S1. In addition, in whichever procedure is carried out, it is realized that the gas G1 to be treated is introduced into the treatment space 20c while the discharge lamp 21 is turned on in step (A).

After performing step S2, the timer 22c measures the elapsed time from immediately after completing step S2 (step S3). Note that, as described above, it is assumed that the order of step S1 and step S2 is reversed or that step S1 and step S2 are executed simultaneously, but this timer 22c Measure the elapsed time immediately after all of these are completed.

When the timer 22c detects that a predetermined time has elapsed since step S2 was performed, the timer 22c outputs a signal d3 to the introduced gas control section 22b (step S4). The timing at which the timer 22c outputs the signal d3 in step S4 is determined based on the type of VOC contained in the gas G1 to be treated on the surface of the discharge lamp 21 and the gas G1 to be treated introduced into the gas treatment apparatus 10. It is arbitrarily set depending on the concentration of VOCs, etc. In the first embodiment, the timing is set 100h after step S2 is completed.

The introduced gas control unit 22b, which has received the signal d3 from the timer 22c in step S4, outputs the signal d4 to the switching unit 14, as shown in FIG. 4B (step S5). By carrying out this step S5, introduction of air G2 into the processing space 20c is started.

Note that the control unit 22 is configured to temporarily stop the discharge lamp 21 while this step S5 is being carried out, and after the introduction of the air G2 has started, to turn on the discharge lamp 21 again. Good too. In either case, it is possible to introduce air G2 (first clean gas), which is a clean gas, into the processing space 20c while the discharge lamp 21 is lit in step (B). be done.

After performing step S5, the timer 22c measures the elapsed time from immediately after completing step S5 (step S6).

When the timer 22c detects that a predetermined time has elapsed immediately after the completion of step S5, the timer 22c outputs a signal d5 to the introduced gas control section 22b (step S7). Note that the timing at which the timer 22c outputs the signal d5 in step S7 is set at an arbitrary time when it is assumed that the contaminants accumulated on the surface of the discharge lamp 21 have been removed to some extent; however, in the first embodiment, was set to 20h.

In step S7, the introduced gas control section 22b, which has received the signal d5 from the timer 22c, outputs the signal d1 to the switching section 14, as shown in FIG. 4A, and performs the operation of step S2.

Thereafter, as shown in FIG. 5, steps S2 to S7 are repeated until the operation of the gas treatment apparatus 10 is stopped. The timing of stopping the operation of the gas treatment device 10 is arbitrary, but in order to prevent contaminants from sticking to the surface of the discharge lamp 21 before restarting the operation, it is possible to stop the operation of the gas treatment device 10 immediately after step S7 is performed. It is preferable that

[Verification experiment]
Here, a verification experiment was conducted to confirm whether by lighting the discharge lamp while flowing air G2, the VOC-derived contaminants attached to the surface would be removed and the amount of ultraviolet light L1 emitted from the discharge lamp would be restored. The details of the verification experiment will be explained below.

(conditions)
FIG. 6A is a drawing schematically showing the configuration of an excimer lamp 60 used in this verification as a discharge lamp, and FIG. 6B is a drawing showing the excimer lamp 60 shown in FIG. 6A viewed from a direction rotated by 90 degrees around the tube axis. This is a drawing when FIG. 7 is a diagram schematically showing how the illuminance of ultraviolet light emitted from the excimer lamp 60 is measured.

As shown in FIGS. 6A and 6B, the excimer lamp 60 used in this verification is a so-called flat tube-shaped excimer lamp in which electrodes 62 are arranged to face each other with a tube body 61 interposed therebetween. Although not shown, the excimer lamp 60 has a rectangular cross section when cut along a plane perpendicular to the tube axis 61a. Further, the length of the excimer lamp 60 in the direction of the tube axis 61a is 158 mm, and the length of each side of the electrode 62 is 12 mm x 95 mm.

In this verification, four sample data (#1 to #4) were obtained using four excimer lamps created with the same specifications.

This verification is performed by implementing the above-mentioned steps S1 to S6 using the gas treatment device 10 of the first embodiment, and checking the illuminance maintenance rate every 20 hours after starting step S6. Ta. Note that the "illuminance maintenance rate" here refers to the illuminance when the discharge lamp 21 is turned on at a predetermined timing in a state before the treatment target gas G1 is introduced into the treatment space 20c. It is defined as the ratio of illuminance when the light is turned on and measured using the same method.

Note that the illuminance of the excimer lamp 60 is obtained by measuring the center portion 61b of the excimer lamp 60 shown in FIG. 6A with an illuminance meter 63 placed at a position 3 mm apart from the excimer lamp 60, as shown in FIG. did.

The gas G1 to be treated was adjusted so that the concentration of m-xylene, which is a type of VOC, was 80 ppm. Further, during step S3, the gas G1 to be processed is introduced into the processing space 20c at a flow rate of 0.4 m ³ /min, and during step S6, the gas G1 to be processed is introduced into the processing space 20c at a flow rate of 0.4 m ³ /min. Air G2 was introduced into the chamber.

In this verification, four sample data were obtained using four excimer lamps created with the same specifications.

(result)
FIG. 8 is a graph showing temporal changes in the illuminance maintenance rate of each sample. In the graph shown in FIG. 8, the horizontal axis shows the elapsed time when the time when step S6 was started is 0h, and the vertical axis shows the illuminance maintenance rate. As shown in FIG. 8, as time passes immediately after starting step S6, the illuminance maintenance rate increases, that is, the amount of ultraviolet light emitted from the excimer lamp 60 recovers. is confirmed.

Regarding sample #1 in FIG. 8, the illuminance maintenance rate at the time when step S6 is started is higher than that of the other samples. This is presumably because the amount of contaminants adhering to the central portion 61b of the excimer lamp 60 shown in FIG. 6A was relatively small.

Although the number of samples was 1, when we conducted a verification experiment with a gas to be treated containing toluene, which is a type of VOC, under similar conditions, we found that contaminants adhered to the surface of the excimer lamp 60. It was confirmed that the amount of emitted ultraviolet light was recovered.

As described above, according to the gas processing method and gas processing system 1, the pollutants attached to the surface of the discharge lamp 21 can be removed by simply switching the gas introduced into the processing space 20c without requiring wiping work or the like. can do. Then, the amount of ultraviolet light emitted from the discharge lamp 21 is restored so as to approach the state before processing the gas G1 to be processed.

Note that the switching of the gas introduced into the gas processing device 10 may be configured to be executed at a predetermined time by a timer 22c included in the gas processing device 10, It may be configured to switch based on ON/OFF of a draft chamber, detection of an increase in VOC concentration by a gas sensor, detection of the presence of a person by a human sensor, etc.

Furthermore, the switching of the switching unit 14 may be realized by a person manually operating the switching unit 14 without the gas processing device 10 having the introduced gas control unit 22b and the timer 22c.

In addition, we have described a method for switching the gas introduced into the gas treatment device 10 by switching between connecting it to the duct opening 4 and connecting it to the intake port 2a. The configuration may be such that only the following steps are performed. In other words, when the gas to be treated G1 is introduced into the gas processing apparatus 10, the air G2 may be introduced from the intake port 2a at the same time. The gas to be treated G1 is a gas containing VOCs and oxygen, and is a mixed gas made by mixing the gas containing VOCs generated in the laboratory 3 and fresh air taken in from outside the building 2. However, if the gas contains VOC and oxygen, it corresponds to the gas to be processed G1.

If the concentration of VOCs in the laboratory 3 increases, it may have a negative effect on the health of workers, so while adjusting the amount of air G2 taken in, it is necessary to constantly bring in fresh air from outside the building 2. preferable.

[Second embodiment]
The configuration of the second embodiment of the gas processing system 1 of the present invention will be described focusing on the differences from the first embodiment.

9A and 9B are drawings schematically showing the operating state of the second embodiment of the gas processing system 1. As shown in FIGS. 9A and 9B, in the gas processing system 1 of the second embodiment, a gas processing device 10 is connected to an exhaust port 5a of a draft chamber 5 installed in a laboratory room 3 via a flow path 31. It is described as a so-called local ventilation system.

More specifically, for example, during the day when an experiment is being conducted in the laboratory 3, the gas to be treated G1 containing VOC generated in the draft chamber 5 is transferred to the gas treatment device 10 via the flow path 31. be introduced. Then, during late nights, holidays, and the like when experiments are not conducted, the clean air in the laboratory 3 is directly introduced into the gas processing apparatus 10 via the flow path 31.

FIGS. 9C and 9D are drawings schematically showing a second embodiment of the gas processing system 1, which has a different configuration from FIGS. 9A and 9B. As shown in FIG. 9C, the gas processing system 1 may be configured as a system that maintains the inside of the laboratory 3 in a clean environment using a draft chamber 5 in which the gas processing device 10 is mounted.

Further, as shown in FIG. 9D, the gas processing system 1 is a system in which a gas processing device 10 is placed in the laboratory 3 as an air cleaner in addition to the draft chamber 5, and maintains the laboratory 3 in a clean environment. It does not matter if it is configured as .

Similar to the gas processing system 1 shown in FIGS. 9A and 9B, the gas processing system 1 shown in FIG. 9C contains VOCs generated in the draft chamber 5 during the day when experiments are conducted in the laboratory 3. A gas to be treated G1 is introduced into the gas treatment apparatus 10. Then, during late nights, holidays, and the like when experiments are not conducted, clean air G2 within the laboratory 3 is introduced into the gas processing apparatus 10. In addition, in FIGS. 9C and 9D, for convenience of illustration, the gas to be processed G1 and the air G2 are illustrated as being the same gas, but in reality, the experiment is being conducted in the laboratory 3. In this case, the gas to be processed is G1, and if the experiment is not being conducted in the laboratory 3, or if the doors and windows are opened for ventilation and the laboratory 3 is a relatively clean space, it is air. It has become G2.

The gas treatment apparatus 10 is controlled so that the discharge lamp 21 is lit while the gas to be treated G1 is flowing in and while the clean air G2 is flowing in. Through this control, the dirt that adheres to the surface of the discharge lamp 21 when processing the target gas G1 is decomposed by ozone and hydroxyl radicals generated from the oxygen and water contained in the air G2, and the discharge lamp 21 is gradually decomposed. removed from the surface of 21. Therefore, the amount of ultraviolet light emitted from the discharge lamp 21 is restored so as to approach the state before processing the gas G1 to be processed.

[Third embodiment]
The configuration of the third embodiment of the gas processing system 1 of the present invention will be described with a focus on the parts that are different from the first embodiment and the second embodiment.

10A and 10B are drawings schematically showing the configuration and operation of the third embodiment of the gas processing system 1. FIG. As shown in FIGS. 10A and 10B, the third embodiment of the gas treatment system 1 includes two gas treatment devices (10a, 10b) connected in series and three three-way valves (14a, 14a, 14a). The switching unit 14 is configured such that the direction in which the gas to be treated G1 is introduced into the gas treatment apparatus (10a, 10b) is alternately switched.
By switching the direction in which the gas to be treated G1 is introduced, in the gas treatment apparatus 10, although the configuration of the apparatus does not change, the inlet 20a into which the gas to be treated G1 is introduced and the inlet 20a where the gas to be treated G3 is introduced, and the direction in which the treated gas G3 is discharged are changed. This means that the discharge port 20b is replaced with the discharge port 20b.

The operation of this configuration will be explained in detail. First, when the gas processing system 1 starts operating, the three-way valves (14a, 14a, 14a) are switched so that the gas G1 to be processed flows through the path as shown in FIG. 10A. Note that the three-way valves (14a, 14a, 14a) may be controlled by a control unit (not shown) provided in any of the gas treatment apparatuses 10 or a separately provided control unit (not shown), It does not matter if the user manually switches the switch.

In such a state, the gas processing device 10b first takes in the gas to be treated G1, processes the gas to be treated G1, and discharges the treated gas G3, which is a clean gas.

Note that the oxygen contained in the gas to be treated G1 is not entirely converted into ozone in the gas treatment device 10b, and at least a portion thereof is exhausted as is. Moreover, the ozone generated in the gas processing apparatus 10b reacts with the gas to be processed and is decomposed, and a part of the ozone becomes oxygen. Therefore, the processed gas G3 discharged from the gas processing device 10b is a clean gas containing oxygen.

Then, the treated gas G3, which is a clean gas discharged from the gas treatment device 10b, is introduced into the gas treatment device 10a. At this time, if VOC-derived contaminants are attached to the surface of the discharge lamp 21 included in the gas treatment device 10a, the contaminants are decomposed and removed. That is, the amount of ultraviolet light emitted from the discharge lamp is recovered.

When the above operation is started and a predetermined time has elapsed, the three-way valves (14a, 14a, 14a) are switched, and as shown in FIG. 10B, the gas treatment device 10a takes in the gas G1 to be treated, and The treated gas G3, which is a clean gas, is discharged.

Then, the treated gas G3, which is a clean gas discharged from the gas treatment device 10a, is introduced into the gas treatment device 10b. This time, the VOC-derived contaminants adhering to the surface of the discharge lamp 21 included in the gas treatment device 10b are decomposed and removed. That is, the amount of ultraviolet light emitted from the discharge lamp is recovered.

Thereafter, the state shown in FIG. 10A and the state shown in FIG. 10B are alternately repeated until the operation of the gas treatment system 1 is stopped, thereby maintaining the clean state of the surface of the discharge lamp of the gas treatment device (10a, 10b). is maintained.

[Another embodiment]
Another embodiment will be described below.

<1> FIG. 11 is a drawing schematically showing the configuration around the gas processing device 10 in another embodiment of the gas processing system 1. As shown in FIG. 11, the control unit 22 of the gas treatment device 10 does not include a timer 22c, and is configured such that the introduced gas control unit 22b receives the signal d6 output from the flow meter 40 provided on the upstream side. It doesn't matter if it is done. The introduced gas control section 22b may be configured to control the switching section 14 after the total flow rate after starting the introduction of the processing target gas G1 reaches a predetermined threshold value or more.

With this configuration, even if a large amount of gas G1 to be treated is temporarily introduced and a large amount of contaminants adhere to the surface of the discharge lamp 21 in a short period of time, cleaning can be performed without waiting for a predetermined period of time to pass. It is possible to switch to gas introduction.

In addition, in this embodiment, it additionally includes a storage unit that stores time-series data of the flow rate of the gas to be processed G1 measured by the flow meter 40, and a storage unit that contains the data and can be read by an external device such as a smartphone or a PC. It is also possible to include a communication unit that generates and outputs a wireless signal. Furthermore, with this configuration, it is possible to detect an abnormality in the discharge lamp 21 and predict when it will be replaced.

Further, parameters other than the elapsed time since the introduction of the gas G1 to be treated and the total flow rate may be used to control the switching unit 14. Specifically, the parameters include the concentration of VOC contained in the treated gas G3, the difference between the pressure of the gas flowing through the inlet and the pressure of the gas flowing through the outlet, or based on these. The calculated Cv value etc. can be adopted.

<2> FIGS. 12A and 12B are drawings schematically showing the configuration and operation of yet another embodiment of the gas processing system 1. As shown in FIGS. 12A and 12B, the gas processing system 1 includes two gas processing apparatuses (10a, 10b) connected in parallel and a switching section consisting of four control valves (14b, 14b, 14b, 14b). 14, the gas to be treated G1 and the air G2 are alternately introduced into the respective gas treatment apparatuses 10.

With the above configuration, the recovery process for the discharge lamp 21 can also be performed without always stopping the process of the process target gas G1 in either of the gas processing apparatuses (10a, 10b). In this embodiment of the gas processing system 1, two gas processing devices are installed, but three or more gas processing devices may be installed in order to increase the gas processing capacity. In addition, if at least one of the plurality of gas treatment devices is a device that can prevent VOCs from being released to the outside only until the recovery treatment of the discharge lamp 21 is completed, for example, activated carbon may be used in the flow path. It may be a filled device or a device that burns VOCs.

FIG. 13A is a diagram schematically showing the gas treatment device 10 in yet another embodiment from FIGS. 12A and 12B, and FIG. 13B is a diagram schematically showing the gas treatment device 10 in FIG. 13A as viewed toward the opening. This is a drawing when Note that in FIG. 13B, the space 20d is omitted for convenience of illustration.

As shown in FIG. 13A, the gas processing apparatus 10 includes a plurality of processing spaces (20c, 20c) and an inlet 20a and an outlet 20b corresponding to each of the processing spaces. The gases (G1, G2) introduced into the respective processing spaces (20c, 20c) may be switched by controlling the processing spaces (20c, 20c) to be exchanged.

With the configuration shown in FIGS. 13A and 13B, the discharge can be performed without increasing the size of the entire system and without stopping the processing of the gas G1 to be processed in either processing space (20c, 20c). A recovery process for the lamp 21 can also be performed. In addition, in the gas processing apparatus 10 having the above configuration, switching of the gases (G1, G2) introduced into the processing space (20c, 20c) is performed only within the gas processing apparatus 10, so that there are many control valves and shutters. There is no need to construct a complicated gas flow path using, etc.

<3> In each of the embodiments described above, air taken in from outside the building 2 is used as the clean gas introduced into the gas treatment device 10, but the clean gas does not contain oxygen. , any gas other than air may be used as long as it does not substantially contain VOC. For example, gas with a high oxygen concentration may be introduced directly from an oxygen cylinder, or air taken from a space within the building 2 where a clean environment is maintained may be introduced.

Furthermore, in order to generate hydroxyl radicals that exhibit higher reactivity than ozone, the gas treatment system 1 is equipped with a humidifying means such as a humidifier so that water is included in the clean gas introduced into the gas treatment device 10. It doesn't matter if you are prepared.

<4> The configuration included in the gas processing system 1 described above is just an example, and the present invention is not limited to each illustrated configuration.

1: Gas processing system 2: Building 2a: Intake port 2b: Exhaust port 3: Laboratory 4: Duct port 5: Draft chamber 5a: Exhaust port 10, 10a, 10b: Gas processing device 11: First flow path 12: First flow path Two channels 13: Third channel 14: Switching section 14a: Three-way valve 14b: Control valve 20: Housing 20a: Inlet 20b: Discharge port 20c: Processing space 20d: Space 21: Discharge lamp 22: Control section 22a: Inverter 22b: Introduced gas control unit 22c: Timer 22d: Power supply line 31: Flow path 40: Flowmeter 60: Excimer lamp 61: Tube body 61a: Tube axis 61b: Center portion 62: Electrode 63: Illuminance meter G1: Processing target gas G2: Air G3: Treated gas L1: Ultraviolet light

Claims (12)

1. A gas treatment method for treating a target gas containing VOCs and oxygen, the method comprising:
   Introducing the gas to be treated into the processing space while lighting a discharge lamp that emits ultraviolet light with a main emission wavelength of 200 nm or less, which is arranged in the processing space that forms part of the flow path. A step (A) of
   After carrying out the step (A), a step (B) of introducing a clean gas containing oxygen and substantially no VOC into the processing space while the discharge lamp is lit; A gas processing method characterized by comprising:
2. The step (A) and the step (B) are characterized in that they are carried out by lighting an excimer lamp, which is a type of discharge lamp, and whose tube body is filled with a luminescent gas containing xenon (Xe) gas. The gas treatment method according to claim 1.
3. The gas processing method according to claim 1, wherein in the step (B), air is introduced into the processing space as the clean gas.
4. The gas processing method according to any one of claims 1 to 3, wherein the step (B) is performed after a predetermined time has elapsed after starting the step (A).
5. Claim 1, wherein in the step (A), the step (B) is carried out after the total flow rate of the gas to be treated that has passed through the treatment space becomes equal to or greater than a predetermined threshold. 3. The gas treatment method according to any one of items 3 to 3.
6. a casing in which a processing space is formed in which a processing target gas containing VOCs and oxygen is taken in and processed;
   a discharge lamp disposed in the processing space that emits ultraviolet light with a wavelength of 200 nm or less; and the processing space contains the gas to be processed, or the processing space contains oxygen and does not substantially contain VOCs. an inlet for taking in the first clean gas;
   an outlet for discharging the gas that has passed through the processing space;
   A gas processing system comprising: a switching unit that selectively switches between introducing the gas to be treated and introducing the first clean gas into the inlet.
7. 7. The gas processing system according to claim 6, wherein the discharge lamp is an excimer lamp in which a luminescent gas containing xenon (Xe) gas is enclosed in a tube.
8. The gas processing system according to claim 6, wherein the first clean gas is air.
9. The housing is provided with a plurality of processing spaces, the introduction port, and the discharge port, and when the switching unit switches to introduce the gas to be processed into the introduction port, the switching unit switches the processing space to the other gas to be processed. 7. The gas treatment system of claim 6, wherein the gas treatment system is switched to introduce the first clean gas into an opening.
10. A plurality of gas treatment devices each having the housing, the discharge lamp, the inlet, and the discharge port are provided, and the switching unit is configured to switch the opening of one of the plurality of gas treatment devices. 7. The gas processing system according to claim 6, wherein when the gas to be treated is switched to be introduced into the opening of the other gas processing device, the first clean gas is switched to be introduced into the opening of another gas processing device.
11. a control unit that performs switching control of the switching unit;
    and a timer that measures the time that has elapsed since the control unit controlled the switching unit and started introducing the gas to be processed into the inlet,
    Claims 6 to 10, wherein when the timer detects that a predetermined time has elapsed, the control unit executes control to switch the switching unit so as to guide the first clean gas to the inlet. The gas treatment system according to any one of the above.
12. a control unit that performs switching control of the switching unit;
    The control unit controls the switching unit to start introducing the process target gas into the inlet, and then includes a flow meter that measures the flow rate of the process target gas flowing through the processing space. ,
    When the flow meter detects that the total flow rate of the gas to be treated that has flowed through the treatment space is equal to or higher than a predetermined threshold, the control unit guides the first clean gas to the inlet. The gas processing system according to any one of claims 6 to 10, wherein control for switching the switching unit is executed.