JP2008183533A - Concentration dilution method for volatile organic gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a concentration dilution method for volatile organic gas with a small-sized adsorption layer without discharging volatile organic gas left in a high concentration state of volatile organic compounds in the gas. <P>SOLUTION: A passing-through direction switching means 5 switches the passing-through direction (hereafter a first direction) of the volatile organic gas passing through the adsorption layer 3 from a supply line 2 and discharged from a discharge line 4, to a reverse direction (hereafter a second direction). The volatile organic gas switched in the passing direction passes through the adsorption layer 3 from the discharge line 4 and flows to the supply line 2, then returns to the discharge line 4 via a return line 6. The passing-through direction switching means 5 switches the passing-through direction of the volatile organic gas switched in the passing direction to the second direction to the first direction, the volatile organic gas is passed from the discharge line 4 to the return line 6, a part of the supply line 2 from a communication point of the return line 6 to the adsorption layer 3, the adsorption layer 3 and the discharge line 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a volatile organic gas concentration dilution method for diluting the concentration of a volatile organic compound in a volatile organic gas by passing the volatile organic gas through an adsorption layer.

  As a conventional invention, the sterilization gas containing ethylene oxide and the like discharged from the sterilizer after sterilization work and the aeration gas discharged from the sterilizer after the sterilizer is replaced with clean air are burnt and detoxified. Therefore, by passing these gases (hereinafter referred to as volatile organic gases) through the adsorption layer and adsorbing the volatile organic compounds contained in the gas onto the adsorbent of the adsorption layer, the concentration becomes a concentration that allows combustion treatment. Some of them are reduced (see Patent Document 1).

Japanese Patent Laid-Open No. 08-215541

  In the conventional invention, since the volatile organic gas once passed through the adsorption layer is supplied to the combustion processing apparatus as it is, when the total amount (supply amount) of the volatile organic compound contained in the gas exceeds the adsorbable amount of the adsorption layer, A volatile organic compound having a high concentration is discharged from the adsorption layer. When this concentration becomes higher than the combustible concentration, there arises a situation where the volatile organic gas cannot be sufficiently detoxified by the combustion treatment even if the volatile organic gas is supplied to the combustion treatment apparatus. In order to prevent such a situation from occurring, in the conventional invention, a large adsorbing layer that is sufficiently safe for the total amount of volatile organic compounds contained in the volatile organic gas supplied from the sterilizer must be provided. Don't be.

  An object of the present invention is to provide a method for diluting the concentration of a volatile organic gas that can reduce the size of an adsorption layer without discharging the volatile organic compound in the volatile organic gas in a high state.

  The invention according to claim 1 is a volatilization method for diluting the concentration of the volatile organic compound by passing the volatile organic gas through an adsorption layer having an adsorbent that adsorbs the volatile organic compound contained in the volatile organic gas. A concentration diluting method of a volatile organic gas, wherein the volatile organic gas is passed through the adsorption layer in a first direction in a first direction, and the second direction is opposite to the first direction. A second direction passing step for passing the volatile organic gas through the adsorption layer, and the volatile organic gas is passed through the adsorption layer at least once in the first direction passing step and the second direction passing step. .

  The invention according to claim 2 is the first direction detection step of detecting the concentration of the volatile organic compound in the volatile organic gas that has passed through the adsorption layer in the first direction in the invention according to claim 1. A second direction detecting step for detecting a concentration of the volatile organic compound in the volatile organic gas that has passed through the adsorption layer in the second direction; and the volatile organic detected by the first direction detecting step. When the concentration of the volatile organic compound in the gas is higher than a predetermined concentration, the first switching step for switching from the first direction passing step to the second direction passing step and the second direction detecting step detects the first direction switching step. When the concentration of the volatile organic compound in the volatile organic gas is higher than a predetermined concentration, the second direction passage step to the first direction passage step. And a second switching step of switching to flop.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the adsorption is performed when the concentration of the volatile organic compound in the volatile organic gas before passing through the adsorption layer is lower than a predetermined concentration. And a detour step of diverting the volatile organic gas before passing through the bed from the adsorption layer.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein before the first direction passing step, after the first direction passing step, before the second direction passing step, the first A dilution gas is supplied to the volatile organic gas at least at any point after the two-way passing step.

  The invention according to a fifth aspect is the invention according to any one of the first to fourth aspects, wherein the adsorption layer is composed of a plurality of adsorption layers, and the volatile organic gas is adsorbed in the first direction passing step. A layer is passed in the first direction, and in the second direction passing step, the volatile organic gas is passed through the adsorption layers in the second direction.

  In the present invention, the number of times the volatile organic gas is passed through the adsorption layer is not limited to one time as in the past, and the volatile organic gas is volatile any number of times until the concentration of the volatile organic compound in the volatile organic gas is sufficiently diluted. Organic gas can be passed through the adsorption layer. For this reason, the adsorption efficiency per adsorption layer is higher than in the prior art, and the adsorption layer can be downsized without being discharged while the concentration of the volatile organic compound in the volatile organic gas remains high.

  Furthermore, in the present invention, the amount of heat required to raise the temperature in the adsorption layer is reduced by the amount that the adsorption layer can be made smaller than before. For this reason, the temperature in the adsorption layer is easily increased only by the amount of heat generated when the volatile organic compound in the volatile organic gas is adsorbed on the adsorbent. Since the desorption rate of the volatile organic compound from the adsorbent increases as the temperature in the adsorption layer increases, the volatile organic compound from the adsorbent when the temperature in the adsorption layer increases as described above. Can be removed quickly, and the reuse efficiency of the adsorption layer can be improved.

  Here, the processing amount of the volatile organic gas is determined by an integrated value of the concentration of the volatile organic compound in the volatile organic gas discharged from the discharge path and the flow rate of the volatile organic gas. Therefore, the treatment amount of the volatile organic gas can be increased when the concentration of the volatile organic compound in the discharged volatile organic gas is as high as possible within the range where the combustion treatment is possible. The preferred embodiment of the present invention does not switch the passing direction of the volatile organic gas to the adsorption layer until the concentration of the volatile organic compound in the volatile organic gas becomes higher than a predetermined concentration. For this reason, the processing amount of the volatile organic gas can be improved by increasing the concentration of the volatile organic compound in the discharged volatile organic gas to the vicinity of the predetermined concentration.

  In a preferred embodiment of the present invention, the concentration of the volatile organic compound in the volatile organic gas is maintained near a predetermined concentration by supplying the dilution gas. Thereby, the processing amount of a volatile organic compound can be increased.

  In a preferred embodiment of the present invention, when the concentration of the volatile organic compound in the volatile organic gas newly supplied to the adsorption layer is lower than a predetermined concentration, the volatile organic gas is bypassed from the adsorption layer. . For this reason, only the volatile organic gas whose concentration of the volatile organic compound is higher than the predetermined concentration is intensively passed through the adsorption layer, so that the processing efficiency of the volatile organic gas can be improved.

  In a preferred embodiment of the present invention, by using a plurality of adsorption layers, the number of adsorbents per adsorption layer is reduced, that is, the adsorption layer can be reduced in size compared to the case of using a single adsorption layer. Since the adsorbent is reduced in size, the time for increasing the concentration of the volatile organic compound that has passed through the adsorbing layer to a predetermined concentration is shortened, and the processing amount according to the present invention can be rapidly improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view schematically showing an example of a concentration diluting apparatus 1 used by the concentration dilution method for volatile organic gas of the present invention.
The concentration dilution apparatus 1 includes a supply path 2, an adsorption layer 3, and a discharge path 4 as basic configurations, and allows volatile organic gas to pass from the supply path 2 to the discharge path 4 through the adsorption layer 3. The supply path 2 communicates with a volatile organic gas storage container (not shown) and the adsorption layer 3, and supplies the volatile organic gas from the volatile organic gas storage container to the adsorption layer 3. The adsorption layer 3 has an adsorbent that adsorbs a volatile organic compound contained in the volatile organic gas, and reduces the concentration of the volatile organic compound in the supplied volatile organic gas. Examples of the adsorbent include activated carbon, zeolite, silica, alumina, and porous adsorbent. The discharge path 4 communicates with the adsorption layer 3 and a combustion treatment device (not shown), and discharges volatile organic gas from the adsorption layer 3 to the combustion treatment device.

  The concentration dilution apparatus 1 further includes a passage direction switching means 5, a return path 6, a dilution gas supply means 7, and a bypass 8. The passing direction switching means 5 switches the passing direction of the volatile organic gas passing through the adsorption layer 3. The return path 6 communicates with the supply path 2 and the discharge path 4 and bypasses the adsorption layer 3. The dilution gas supply means 7 supplies dilution gas (for example, air) to the supply path 2 and the discharge path 4 via the return path 6. The bypass circuit 8 bypasses the adsorption layer 3, communicates with the upstream side from the communication part of the return path 6 in the supply path 2, and communicates with the upstream side from the communication part of the return path 6 in the discharge path 4. A supply path opening / closing valve 9 is provided between the communication points of the return path 6 and the detour path 8, and a discharge path opening / closing valve 10 is provided upstream from the communication position of the detour path 8 in the discharge path 4. . The supply passage opening / closing valve 9 and the discharge passage opening / closing valve 10 are controlled by a control unit (not shown).

  The passage direction switching means 5 reverses the passage direction of the volatile organic gas discharged from the supply passage 2 through the adsorption layer 3 and discharged from the discharge passage 4 (hereinafter, the first direction (direction indicated by arrow A in FIG. 1)). (Hereinafter, the second direction (the direction indicated by the arrow B in FIG. 1)). The volatile organic gas whose passage direction has been switched flows from the adsorption layer 3 to the supply path 2 and then reaches the discharge path 4 via the return path 6. Further, the passage direction switching means 5 switches the passage direction of the volatile organic gas whose passage direction is switched to the second direction to the reverse direction (that is, the first direction) again, and the volatile organic gas is returned from the return path 6 to the return path. 6 is passed through a part of the supply path 2 from the communication point 6 to the adsorption layer 3, the adsorption layer 3 and the discharge path 4. When the switching of the passing direction of the volatile organic gas is started, the supply passage opening / closing valve 9 is closed. When the passage direction switching means 5 switches the passage direction of the volatile organic gas from the first direction to the second direction, the discharge passage opening / closing valve 10 is closed. When the passage direction switching means 5 switches the passage direction of the volatile organic gas from the second direction to the first direction, the discharge path opening / closing valve 10 is opened.

  When the concentration of the volatile organic compound in the volatile organic gas discharged from the discharge passage 4 becomes higher than a predetermined concentration (or the volatile organic in the volatile organic gas discharged from the discharge passage 4) The volatile organic gas passage direction is switched when the concentration of the compound matches the predetermined concentration. The concentration of the volatile organic compound in the volatile organic gas discharged from the discharge path 4 is detected by a concentration detection unit (not shown) provided on the downstream side of the discharge path 4. The concentration detection unit is, for example, a temperature sensor provided in the catalyst of the combustion processing apparatus that communicates with the discharge path 4, and this temperature sensor detects the temperature of the catalyst determined by the combustion processing of the volatile organic compound. Utilizing the fact that the temperature of the catalyst changes according to the concentration of the volatile organic compound in the volatile organic gas, the concentration of the volatile organic compound in the volatile organic gas is determined from the temperature of the catalyst detected by the temperature sensor. To detect. The predetermined concentration is determined based on the time required for switching the passing direction of the volatile organic gas, the amount of volatile organic gas discharged from the discharge passage 4 at that time, and the like. The concentration of the volatile organic compound is set so as not to exceed a predetermined target concentration. Here, the target concentration is at least equal to or lower than the upper limit of the concentration of the volatile organic compound in the volatile organic gas in which the combustion processing apparatus can process the volatile organic gas.

  The passage direction switching means 5 includes a first pump unit 11 (for example, a vacuum pump) disposed in the return path 6, a concentration adjustment path 12, an adjustment path opening / closing valve 13 that opens and closes the concentration adjustment path 12, a communication path 14, and the like. , A second pump portion 15 (for example, an air pump) disposed in the communication path 14, a communication path opening / closing valve 16, and a return path opening / closing valve 17. The first pump unit 11, the control path on / off valve 13, the second pump unit 15, and the communication path on / off valve 16 are controlled by the control unit in the same manner as the supply path on / off valve 9 and the discharge path on / off valve 10.

  The concentration adjusting path 12 communicates with the upstream side of the arrangement place of the first pump unit 11 in the return path 6 and is connected to a dilution air supply source (not shown) for supplying dilution air. An adjustment path opening / closing valve 13 is disposed in the concentration adjustment path 12, and the amount of dilution air supplied to the return path 6 is adjusted by adjusting the opening thereof. The communication path 14 communicates with the upstream side of the return path 6 where it communicates with the concentration adjustment path 12 and joins the concentration adjustment path 12 on the upstream side to connect to the dilution air supply source. In the communication passage 14, a communication passage opening / closing valve 16 is disposed on the downstream side of the second pump portion 15. The return path opening / closing valve 17 is disposed between the communication location of the concentration adjustment path 12 and the communication location of the communication path 14 in the return path 6.

  When switching the passage direction of the volatile organic gas from the first direction to the second direction, the return path opening / closing valve 17 is opened, the regulation path opening / closing valve 13 and the communication path opening / closing valve 16 are closed, and the first pump unit 11 is opened. Causes the volatile organic gas to pass through the adsorption layer 3, a part of the supply path 2 from the adsorption layer 3 to the communication point of the return path 6, the return path 6 and the discharge path 4 in this order.

  When switching the passage direction of the volatile organic gas from the second direction to the first direction, the return path on / off valve 17 and the control path on / off valve 13 are closed, the communication path on / off valve 16 is opened, and the second pump The unit 15 sends the dilution gas from the dilution gas supply source to the return path 6. This dilution gas presses the volatile organic gas passing through the return path 6 against the adsorption layer 3. By pressing the dilution gas, the volatile organic gas is passed through the return path 6, a part of the supply path 2 from the communicating part of the return path 6 to the adsorption layer 3, the adsorption layer 3, and the discharge path 4 in this order.

  In the present embodiment, the passage direction switching means 5 functions as the dilution gas supply means 7. That is, when the dilution gas is supplied to the supply path 2, the return path on-off valve 17 and the control path on-off valve 13 are closed as in the case of switching the passage direction of the volatile organic gas from the second direction to the first direction. Then, the second pump unit 15 sends the dilution gas from the dilution gas supply source to the return path 6 with the communication passage opening / closing valve 16 opened, so that the dilution gas from the dilution gas supply source passes through the return path 6. To the supply path 2. When supplying the dilution gas to the discharge path 4, the return path on / off valve 17 is closed, the adjustment path on / off valve 13 is opened, and the communication path on / off valve 16 is closed, and the first pump section is closed. As a result, the dilution gas from the dilution gas supply source is supplied to the discharge path 4 via the return path 6. The dilution gas supply means 7 may be configured independently of the passage direction switching means 5, and the supply path 2 for the dilution gas is newly connected to the supply path 2 and the discharge path 4, and the supply path 2 is connected via the supply path 2. A dilution gas may be supplied from a dilution gas supply source.

  The detour 8 is provided with a detour open / close valve 18 in a closed state. When the concentration of the volatile organic compound in the volatile organic gas from the volatile organic gas storage container becomes lower than a predetermined concentration, the detour open / close is opened. The valve 18 is opened and volatile organic gas is passed through the bypass 8. At this time, the supply passage opening / closing valve 9 is closed. By passing the volatile organic gas through the bypass 8, the adsorption layer 3 is bypassed from the middle of the supply path 2 and passed through the discharge path 4. The concentration of the volatile organic compound in the volatile organic gas from the volatile organic gas storage container is measured in advance by measuring the time from when the supply from the volatile organic gas storage container starts until the concentration reaches a predetermined concentration. The detour opening / closing valve 18 may be opened at time. Further, when a concentration sensor is disposed upstream of the communication path of the detour 8 in the supply path 2 and the concentration detector detects the concentration of the volatile organic compound in the volatile organic gas lower than the predetermined concentration, the detour opening / closing valve 18. May be opened. The bypass circuit opening / closing valve 18 is controlled by the control unit similarly to the supply path opening / closing valve 9 and the discharge path opening / closing valve 10.

Hereinafter, an example of the concentration dilution method of the present invention using the concentration dilution apparatus 1 will be described.
First, the volatile organic gas from the volatile organic gas storage container is supplied to the adsorption layer 3 in the first direction. That is, volatile organic gas is supplied to the adsorption layer 3 through the supply path 2. The volatile organic compound in the volatile organic gas is adsorbed by the adsorbent provided in the adsorption layer 3, and the concentration of the volatile organic compound in the volatile organic gas that has passed through the adsorption layer 3 is reduced. In this case, the supply passage opening / closing valve 9 and the discharge passage opening / closing valve 10 are opened, and the return passage opening / closing valve 17, the communication passage opening / closing valve 16, and the bypass opening / closing valve 18 are at least closed.

  FIG. 2 is a graph schematically showing a state in which the concentration of the volatile organic compound in the volatile organic gas changes with time, and the vertical axis indicates the concentration of the volatile organic compound in the volatile organic gas. The time t is shown on the horizontal axis. The solid line indicates the concentration D of the volatile organic compound in the volatile organic gas discharged from the discharge path 4.

In an initial state in which the volatile organic gas is passed through the adsorption layer 3, the volatile organic compound is adsorbed on the supply path 2 side of the adsorbent provided in the adsorption layer 3. Thereafter, when the volatile organic gas continues to pass through the adsorption layer 3, one of the volatile organic compounds adsorbed on the adsorbent on the supply path 2 side by the volatile organic gas newly passing through the adsorption layer 3. Part desorbs from the adsorbent. Next, the desorbed volatile organic compound moves toward the discharge path 4 in the adsorption layer 3 and is adsorbed again on the adsorbent. Thereafter, when the volatile organic gas continues to pass through the adsorption layer 3, a part of the volatile organic compound in the adsorbent in the adsorption layer 3 moves to the discharge path 4 side (that is, the first direction), and the time t ₁ starts to be discharged from the adsorption layer 3. Thus began to gradually increasing the concentration D at time t ₁ as shown in FIG. 2, the keep more volatile organic gases passed through the adsorption layer 3, the concentration D reaches the predetermined concentration Dt. Here, the predetermined concentration Dt is the volatile organic gas discharged from the discharge path based on the time required for switching the passing direction of the volatile organic gas, the amount of volatile organic gas discharged from the discharge path at that time, and the like. The concentration of the volatile organic compound is set so as not to exceed a predetermined target concentration. The target concentration is at least equal to or less than the upper limit of the concentration of the volatile organic compound in the volatile organic gas in which the combustion processing apparatus can process the volatile organic gas.

When the concentration D becomes higher than the predetermined concentration Dt, the passage direction switching means 5 switches the passage direction of the volatile organic gas passing through the adsorption layer 3 from the first direction to the second direction (time t _{2 in} FIG. ₂ ). At the time of this switching, the supply passage opening / closing valve 9 and the discharge passage opening / closing valve 10 are closed. Thereafter, the concentration D becomes lower than the predetermined concentration Dt.

  The volatile organic gas whose passage direction has been switched to the second direction passes through the adsorption path 3 from the discharge path 4, and then a part of the supply path 2 from the adsorption layer 3 to the communication point of the return path 6, the return path 6. To the discharge path 4 in order. In this case, in the passage direction switching means 5, the return path on / off valve 17 is opened, the communication path on / off valve 16 and the control path on / off valve 13 are closed, and the first pump unit 11 supplies the volatile organic gas to the second. Suction is moving in the direction. If the volatile organic gas is continuously sucked by the first pump unit 11, the section from the discharge path 4 to the return path 6 through the adsorption layer 3 becomes negative pressure, and the volatile organic gas passes in the second direction. It becomes difficult. In order to eliminate this negative pressure, the passage direction switching means 5 temporarily closes the return path on-off valve 17 and opens the communication path on-off valve 16 to supply dilution air by the second pump unit 15. It is made to supply to the area to the adsorption layer 3 and the discharge path 4 via the return path 6.

The supply path on / off valve 9 is closed after the passage direction switching means 5 first switches the passage direction of the volatile organic gas passing through the adsorption layer 3, so that it is newly supplied from the volatile organic gas storage container. Volatile organic gas does not pass through the adsorption layer 3. For this reason, when switching the passage direction of the volatile organic gas for the first time, a new volatile organic gas from the volatile organic gas storage container is discharged to the combustion processing device via the bypass 8 without passing through the adsorption layer 3. From the viewpoint of processing efficiency, it is desirable that combustion processing is possible. For this purpose, it is necessary to extend the time during which the concentration D is higher than the predetermined concentration Dt until the time when the concentration of the volatile organic compound in the newly supplied volatile organic gas is lower than the predetermined concentration Dt. In this concentration dilution method, dilution gas is supplied to at least one of the supply path 2 and the discharge path 4 by the dilution gas supply means 7, and the time during which the concentration D first becomes higher than the predetermined concentration Dt is extended (for example, in FIG. 2). the time _{t 2} to time _{t 2} ').

Thereafter, from time t ₂ to time t ₃ when the concentration D starts to increase again, the volatile organic gas that is going to pass through the adsorption layer 3 in the second direction is adsorbed by the adsorbent on the discharge path 4 side in the adsorption layer 3. A part of the volatile organic compound that has been removed is desorbed and moved further toward the supply path 2 to be adsorbed again. By repeating this desorption / adsorption, a part of the volatile organic compound moves from the discharge path 4 side to the supply path 2 side in the adsorbent in the adsorption layer 3. Then, a part of the volatile organic compound adsorbed at time t ₃ starts to be discharged from the adsorbent supply path 2 side in the adsorption layer 3. Thus began the concentration D increases at time t ₃ as shown in FIG. 2, further when the volatile organic gases continue to pass in the second direction to the adsorption layer 3, the concentration D at time t ₄ at a predetermined density Dt It reaches.

  When the concentration D becomes higher than the predetermined concentration Dt, the passage direction switching means 5 switches the passage direction of the volatile organic gas passing through the adsorption layer 3 from the second direction to the first direction. Along with this switching, the discharge passage opening / closing valve 10 opens. The volatile organic gas whose passage direction is switched to the first direction passes through the adsorption layer 3 from the supply path 2 and reaches the discharge path 4. In this case, in the passage direction switching means 5, the return path opening / closing valve 17 is closed, the communication path opening / closing valve 16 is opened, the adjustment path opening / closing valve 13 is closed, and the second pump unit 15 supplies dilution gas. The volatile organic gas is supplied to the return path 6 and passes through the adsorption layer 3 in the first direction by the dilution gas. Thereafter, every time the concentration D becomes higher than the predetermined concentration Dt, the passage direction switching means 5 switches the passage direction of the volatile organic gas passing through the adsorption layer 3.

Here, as shown in FIG. 2, the concentration D suddenly decreases immediately after switching the passing direction of the volatile organic gas (for example, at times t ₂ and t ₄ ). Since the treatment amount by this concentration dilution method is determined by the integrated value of the concentration of the volatile organic compound in the volatile organic gas and the flow rate of the volatile organic gas, the concentration D at the time of switching the passage direction of the volatile organic gas Reduction will reduce the amount of processing. For this, the dilution gas supply means 7 supplies the dilution gas to at least one of the supply path 2 and the discharge path 4 to promote the movement of the volatile organic gas and suppress the decrease in the concentration D. (Refer to the one-dot chain line after time t ₂ ′ in FIG. 2).

  In the present embodiment, the concentration dilution method has been described using a single adsorption layer 3 included in the concentration dilution apparatus 1. However, the present invention is not limited to this, and two adsorption layers 3 as shown in FIG. You may use simultaneously. There is no change in the concentration dilution method except that each adsorption layer 3 is used at the same time. However, the concentration dilution apparatus 1A is different from the concentration dilution apparatus 1 in FIG. Different. That is, the supply path 2 has branch supply paths 2 a branched from the middle, and the branch supply paths 2 a communicate with the adsorption layers 3. Each supply passage opening / closing valve 9 is arranged in each branch supply passage 2a. The discharge path 4 includes each branch discharge path 4a communicating with each adsorption layer 3, and a merged discharge path 4b formed by joining each branch discharge path 4a. Each discharge passage opening / closing valve 10 is arranged in each branch discharge passage 4a. The return path 6 includes each branch return path 6a that communicates with each branch supply path 2a, and a merge return path 6b that joins each branch return path 6a and communicates with the merge discharge path 4b. Each branch return path 6a is provided with a return path opening / closing valve 17, and the first pump unit 11 is disposed in the merge return path 6b. The communication path 14 includes a branch communication path 14a branched downstream from the second pump portion 15, and each branch communication path 14a communicates with each branch return path 6a. A communication passage opening / closing valve 16 is disposed in each branch communication passage 14a.

It is a schematic diagram which shows simply an example of the concentration dilution apparatus which the concentration dilution method of volatile organic gas of this invention uses. It is the graph which showed simply the condition where the density | concentration of the volatile organic compound in volatile organic gas changes temporally. It is a simple block diagram of the concentration dilution apparatus provided with two adsorption layers.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Concentration dilution apparatus 2 ... Supply path 3 ... Adsorption layer 4 ... Discharge path 5 ... Passing direction switching means 6 ... Return path 7 ... Dilution gas supply means 8 ... Detour

Claims (5)

In a volatile organic gas concentration dilution method, the volatile organic gas is passed through an adsorption layer having an adsorbent that adsorbs a volatile organic compound contained in the volatile organic gas, and the concentration of the volatile organic compound is diluted. There,
A first direction passing step for passing the volatile organic gas through the adsorption layer in a first direction;
A second direction passing step for allowing the volatile organic gas to pass through the adsorption layer in a second direction opposite to the first direction,
A method for diluting a concentration of a volatile organic gas, wherein the volatile organic gas is passed through the adsorption layer at least once in the first direction passage step and the second direction passage step. A first direction detecting step for detecting a concentration of the volatile organic compound in the volatile organic gas that has passed through the adsorption layer in the first direction;
A second direction detecting step for detecting a concentration of the volatile organic compound in the volatile organic gas that has passed through the adsorption layer in the second direction;
First switching for switching from the first direction passing step to the second direction passing step when the concentration of the volatile organic compound in the volatile organic gas detected by the first direction detecting step is higher than a predetermined concentration. Steps,
Second switching for switching from the second direction passage step to the first direction passage step when the concentration of the volatile organic compound in the volatile organic gas detected by the second direction detection step is higher than a predetermined concentration. And a step of diluting the volatile organic gas according to claim 1.   A detour step of bypassing the volatile organic gas before passing through the adsorption layer from the adsorption layer when the concentration of the volatile organic compound in the volatile organic gas before passing through the adsorption layer is lower than a predetermined concentration; The volatile organic gas concentration dilution method according to claim 1 or 2, further comprising:   Before the first direction passing step, after the first direction passing step, before the second direction passing step, after the second direction passing step, diluted to the volatile organic gas in at least one place The method for diluting a concentration of a volatile organic gas according to claim 1, wherein gas is supplied. The adsorption layer is composed of a plurality of adsorption layers,
In the first direction passing step, the volatile organic gas is passed through the adsorption layers in the first direction,
5. The volatile organic gas concentration dilution method according to claim 1, wherein in the second direction passing step, the volatile organic gas is passed through the adsorption layers in the second direction.

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