Water treatment system in exhaust gas

Abstract

The present invention provides a system for treating moisture in exhaust gas, which can prevent the backflow of water or the like that becomes liquid during the removal process and prevent the exhaust gas from leaking to the outside even if there is no space for setting a pipe with a water seal function when removing the moisture or the like contained in the exhaust gas. The valve control unit (81) determines whether the water stored in the tank (60) exceeds the high water level (H). When the valve control unit (81) determines that the high water level (H) is exceeded, an opening signal is sent to the drain valve (80), and the drain valve (80) is opened. As a result, the water in the tank (60) is discharged. The water level decreases with the drainage, but the valve control unit (81) determines whether the water level is below the low water level (L) set by the valve control unit (81). When the valve control unit (81) determines that the low water level (L) is below, a closing signal is sent to the drain valve (80), and the drain valve (80) is closed. Due to the setting of the low water level (L), it is difficult for the exhaust gas to mix into the drain pipe (70).

Description

Technical Field

[0001] The present invention relates to a system for treating moisture in exhaust gas, and in particular, to a system for treating moisture in exhaust gas as follows: when removing moisture contained in the exhaust gas, even if there is no space for setting up piping with a water seal function, it is possible to prevent the backflow of water that has become liquid during the removal process and to prevent the exhaust gas from leaking to the outside. Background Art

[0002] In the manufacturing process of semiconductor elements, liquid crystal panels, and solar cells, chemical vapor deposition (CVD) processing for forming a film using a chemical vapor reaction, etching processing, and the like are performed, and various gases are used in a process chamber.

[0003] Examples of the gas include silane (SiH4), NH3, and H2, which are film-forming material gases for semiconductor elements, liquid crystal panels, and solar cells; gaseous fluorides such as NF3, CF4, C2F6, SF6, CHF3, and CF6, which are used as cleaning gases when cleaning a sealed chamber of a plasma chemical vapor deposition device, for example, with plasma; and inert gases such as nitrogen (N2). Here, the H2 gas reacts with oxygen to become water vapor, which is included in the exhaust gas.

[0004] In addition to the above-mentioned semiconductor-related manufacturing processes, water vapor is also contained in the exhaust gas from food manufacturing equipment such as ham and vacuum drying equipment.

[0005] And, if Fig.10 As shown in FIG. 1 , in order to perform vacuuming for removing the harmful exhaust gas and water vapor, the turbomolecular pump 3 and the dry pump 5 are connected in series with the process chamber 1. And the structure is such that after a certain degree of vacuuming is performed by the dry pump 5 at the start of operation, the turbomolecular pump 3 is further used to evacuate to a necessary low pressure. However, in the case of chemical vapor deposition processing, the turbomolecular pump 3 is generally omitted.

[0006] The harmful exhaust gas output from the dry pump 5 is burned and decomposed by the combustion type detoxification device 10. At this time, the exhaust gas is slightly decompressed by the central scrubber 11 and is guided into the combustion type detoxification device 10.

[0007] However, the combustion type decontamination device 10 is sometimes not arranged according to the gas used in the process chamber 1 .

[0008] The exhaust gas passing through the dry pump 5 is usually at a high temperature of 150 degrees or the like due to the compression heat during exhaustion. On the other hand, the outlet pipe connected to the dry pump 5 is in contact with the outside air. Therefore, when passing through the outlet pipe, the exhaust gas is rapidly cooled at room temperature, and the moisture (water vapor) in the exhaust gas condenses inside the outlet pipe to form water droplets.

[0009] The outlet pipe may be connected to an exhaust pipe of other processing equipment in the factory, and the product may be generated or attached to an unexpected place due to water droplets generated in the outlet pipe.

[0010] Here, in order to prevent the water droplets, a cooling trap as disclosed in Patent Document 1 is provided in the outlet pipe of the dry pump 5 .

[0011] Patent Document 1: Japanese Patent Application Publication No. 2010-16215.

[0012] However, in order to prevent the exhaust gas from leaking to the outside, it is necessary to pay attention to the moisture captured by the cooling trap and discharge it. Fig.11 The S-shaped bent pipe 51 shown is arranged below the cooling trap, and liquefied water (water droplets) falls naturally. In this case, if water is filled inside the bent pipe 51, the exhaust gas is stopped by the water and does not leak to the outside. Therefore, in this case, the function of water sealing can be achieved with the aid of the bent pipe 51.

[0013] However, there are cases where the inside of the pipe is decompressed, and when the bent pipe 51 is installed, a space is required, and the aforementioned installation space has a height greater than a predetermined value including the decompression amount and the height between the bent parts of the pipe. In addition, with the decompression, it may be difficult for water to fall naturally when the bent pipe 51 is installed. Summary of the invention

[0014] The present invention is made in view of such previous problems, and its purpose is to provide a system for treating moisture in exhaust gas, which can prevent the backflow of water that becomes liquid during the removal process and prevent the exhaust gas from leaking to the outside when removing the moisture contained in the exhaust gas, even if there is no space for setting up piping with a water seal function.

[0015] Therefore, the present invention (technical solution 1) is a system for treating moisture in exhaust gas, and the system for treating moisture in exhaust gas uses a cooling trap to remove moisture contained in the exhaust gas discharged from a process, and is characterized in that it includes a tank, a water level metering mechanism, a piping, a valve, and a valve control mechanism, the tank stores the moisture flowing out of the cooling trap as liquid water, the water level metering mechanism measures the water level in the tank, the piping is connected to a drain port for discharging the water stored in the tank to the outside, the valve is arranged on the piping, and the valve control mechanism opens the valve to start drainage when the water level in the tank measured by the water level metering mechanism exceeds a first water level, and closes the valve to stop drainage when the water level is set to a second water level lower than the first water level, and the second water level is set at a position higher than the drain port.

[0016] When the water level in the tank measured by the water level measuring mechanism exceeds the first water level, the valve is opened to start drainage. Thus, even if the pipe diameter is small, the water in the tank will not flow back. On the other hand, when the water level in the tank reaches the second water level, the valve is closed to stop drainage.

[0017] In this way, the second water level is set to prevent exhaust gas from mixing into the drain pipe and leaking to the outside. In other words, the second water level is a water level set for water sealing. Therefore, the second water level needs to be set at a position higher than the drain port so that the drain port is completely covered with water. The water level in the tank is in a state where water is stored at ordinary times, and it is not lower than the second water level during drainage.

[0018] In addition to the function of storing water, the tank can also serve as a water seal for the drainage pipeline.

[0019] Furthermore, the present invention (claim 2) is characterized in that the cooling trap and the tank are connected by a pipe without a bend.

[0020] Since the tank can be used for water sealing, even if a pipe without a bend is installed between the cooling trap and the tank, the exhaust gas will not leak to the outside. Even if there is not enough space for the pipe with a bend to be connected between the cooling trap and the tank, the pipe without a bend can be used. Therefore, it is not necessary to install an expensive pipe with a bend, which reduces the cost accordingly, and even if the pressure inside the pipe without a bend is reduced, the water will fall naturally and easily.

[0021] Furthermore, the present invention (technical solution 3) is characterized in that a water discharge amount adjustment mechanism is provided in the pipe, and the water discharge amount adjustment mechanism adjusts the amount of the water stored in the tank discharged to the outside.

[0022] By providing a drainage volume adjustment mechanism, even when negative pressure is applied to the drainage side, the water level in the tank is always maintained at a position higher than the drainage port by a certain value from the time when the valve control mechanism issues a valve closing command until the valve is completely closed. Therefore, the water seal of the drainage line is reliably maintained.

[0023] Furthermore, the present invention (technical solution 4) is characterized in that the first water level is a water level set to prevent backflow from the tank to the cooling well side, and the second water level is a water level set to perform water sealing during the drainage so that the exhaust gas is not discharged from the pipe to the outside.

[0024] Effects of the Invention

[0025] As described above, according to the present invention, when the water level in the tank measured by the water level measuring mechanism exceeds the first water level, the valve is opened to start drainage, and when it reaches the second water level, the valve is closed to stop drainage, thereby preventing backflow and preventing exhaust gas from mixing into the drain pipe and leaking to the outside.

[0026] Thereby, the tank can serve as a water seal for the drainage line in addition to the function of storing water. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a configuration diagram of a system for treating moisture in exhaust gas according to an embodiment of the present invention.

[0028] Figure 2 It is a straight pipe.

[0029] Figure 3 This is a side profile view of the cooling trap.

[0030] Figure 4 It is a front cross-sectional view of the cooling trap.

[0031] Figure 5 yes Figure 4 Observe the section view in the AA direction.

[0032] Figure 6 This is a diagram showing a situation where exhaust gas is mixed into the inside of a drain pipe and leaks to the outside.

[0033] Figure 7 This is an example in which a drainage volume adjustment mechanism is provided in the drainage pipe.

[0034] Figure 8 This is an example of a displacement adjustment mechanism composed of a throttling device (side cross-sectional view).

[0035] Fig. 9 It is a three-dimensional diagram of the orifice plate.

[0036] Fig.10 It is a flow chart of exhaust gas treatment.

[0037] Fig.11 It is a bent pipe. DETAILED DESCRIPTION

[0038] The following is a description of an embodiment of the present invention. Figure 1 Indicated in.

[0039] Figure 1 In the embodiment, a cooling trap 20 is provided at the outlet pipe 7 connected to the dry pump 5. The cooling trap 20 is a device that condenses water vapor in the exhaust gas into water. The water flowing out of the cooling trap 20 passes through Figure 2 The straight pipe 50 shown in the figure falls naturally and is stored in the tank 60. Conventionally, the straight pipe 50 is not arranged between the cooling well 20 and the tank 60, but a bent pipe 51 is arranged.

[0040] In addition, a water level sensor 61 is provided in the tank 60. The water accumulated in the tank 60 flows through a drain pipe 70 connected to a drain port 63 provided on the bottom surface of the tank 60, and naturally falls to a drain device (not shown) provided in the factory, thereby being discharged. A drain valve 80 is provided in the middle of the drain pipe 70.

[0041] The water level signal measured by the water level sensor 61 is input to the valve control unit 81 , and the drain valve 80 is controlled based on the result determined by the valve control unit 81 .

[0042] The side profile of the cooling trap 20 is shown in Figure 3 In FIG. 1 , the front cross-sectional view of the cooling trap 20 is shown. Figure 4 In addition, Figure 4 The AA direction of the cross-section view is Figure 5 Indicated in.

[0043] The cooling trap 20 includes a cylindrical peripheral wall 21 , and the outlet pipe 7 is connected to an inlet port 23 protruding from the peripheral wall 21 . On the other hand, the pipe 9 leading to the factory exhaust equipment is connected to an outlet port 25 protruding from the peripheral wall 21 .

[0044] The disc-shaped cover 27 is mounted on the upper surface of the peripheral wall 21. On the other hand, the bottom surface 29 of the peripheral wall 21 is formed into a spherical shape, and water drops falling to the bottom surface naturally fall and gather in the center. A capillary 33 having a water supply port 31 at one end passes through the disc-shaped cover 27. Cooling water is supplied to the water supply port 31 from a water pipe device not shown in the figure. The capillary 33 is as shown in FIG. Figure 4 and Figure 5 As shown in FIG. 1 , after descending in the vertical direction, the capillary 33 bends near the inlet port 23, changes direction by 180 degrees, and rises. After that, the capillary 33 changes direction by 180 degrees again near the outlet port 25 and descends. After repeating the descending and ascending several times, the capillary 33 penetrates the disc-shaped cover 27 again. The water outlet 35 is formed at the other end of the capillary 33.

[0045] On the inner side of the peripheral wall 21, the guide plates 37 and 39 are combined at a certain interval so as to alternately change the protruding direction and are installed obliquely with respect to the capillary tube 33. A water outlet 41 is provided at the center of the bottom surface 29 and connected to the straight tube 50.

[0046] Next, the operation of the embodiment of the present invention will be described.

[0047] The high-temperature exhaust gas that has passed through the dry pump 5 enters from the inlet port 23 of the cooling trap 20, is blocked by the guide plates 37 and 39, and changes the direction of the flow to the left and right as shown by the dotted line in the figure, and slowly rises. At this time, the exhaust gas passes through the capillary 33 and is cooled. As a result, water vapor condenses inside the cooling trap 20. And the water droplets condensed at the cooling trap 20 are accumulated on the bottom surface 29 of the cooling trap 20. After that, the water accumulated here (the water here means the total amount of water that has been removed, in the state of liquefied water) passes through the straight pipe 50 and naturally falls to the tank 60.

[0048] Since the drain valve 80 is closed, the water is stored in the tank 60 as liquid water. Then, the valve control unit 81 determines whether the water level of the water stored in the tank 60 exceeds the high water level H set by the valve control unit 81. The high water level H corresponds to the first water level. When the valve control unit 81 determines that the water level exceeds the high water level H, it sends an opening signal to the drain valve 80, and the drain valve 80 opens.

[0049] As a result, the water in the tank 60 is discharged. The high water level H is set so that the water stored in the tank 60 does not overflow and flow back to the dry pump 5. The pipe diameter of the straight pipe 50 and the pipe diameter of the outlet pipe 7 are small, so backflow is easy to occur. Therefore, the high water level H is set with a predetermined margin.

[0050] The water level drops with drainage, but the valve control unit 81 determines whether the water level is below the low water level L set by the valve control unit 81. The low water level L corresponds to the second water level. When the valve control unit 81 determines that the water level is below the low water level L, a closing signal is sent to the drain valve 80, and the drain valve 80 is closed.

[0051] Thereafter, the water is stored in the tank 60 again.

[0052] Thus, the low water level L is set to prevent the exhaust gas from Figure 6 As shown, the water is mixed into the drain pipe 70 and leaks out to the outside. That is, the low water level L is a water level set for water sealing. Therefore, the low water level L needs to be set at a position higher than the drain port 63 so that the water completely covers the drain port 63. The water level in the tank is in a state where water is stored at ordinary times, and it is not below the low water level L during drainage.

[0053] Since the tank 60 can be used for water sealing, a straight pipe 50 is provided between the cooling well 20 and the tank 60 instead of the bent pipe 51 as in the past, and the exhaust gas does not leak to the outside. If it is assumed that the distance between the cooling well 20 and the tank 60 is about 20 cm, for example, and the distance between the bottom surface of the cooling well 20 and the ground 83 is about 30 to 50 cm, the bent pipe 51 cannot usually be provided at this distance, but in this case, the straight pipe 50 can also be used between the cooling well 20 and the tank 60.

[0054] Therefore, even if there is no space for installing the bent pipe 51, there is no problem, and it can be configured at a low cost corresponding to the need to install the expensive bent pipe 51. In addition, since it is a straight pipe 50, even if the internal pressure is reduced, water will naturally fall easily. In this way, the tank 60 can also have the function of a water seal for the drainage line in addition to the function of storing water.

[0055] Furthermore, in the valve control unit 81, when the signal from the water level sensor 61 exceeds the water level high HH which is the limit value of the water level height, an abnormal alarm of a high water level is issued, and when the signal is below the water level low LL which is the limit value of the low water level, an abnormal alarm of a low water level is issued.

[0056] Next, adjustment of the discharge amount will be described.

[0057] As described above, when the valve control unit 81 determines that the water level in the tank 60 is equal to or lower than the low water level L, it transmits a closing signal to the drain valve 80 and the drain valve 80 is closed.

[0058] Thereafter, the water is stored in the tank 60 again.

[0059] However, even when the negative pressure on the drainage side is large, the speed of the drainage flowing in the drainage pipe 70 may be faster than that of the natural fall. In this case, there is a time lag between the valve control unit 81 sending a closing signal to the drainage valve 80 and the drainage valve 80 being completely closed, so there is a possibility that a certain amount of drainage flows through the drainage pipe 70 during this time lag. In addition, it is also considered that the water level of the tank 60 is below the water level low LL at this time.

[0060] In order to avoid this adverse effect, a drainage amount adjustment mechanism is provided in the drainage pipe 70 to limit the flow of water stored in the tank 60 .

[0061] Next, the displacement adjustment mechanism will be described.

[0062] Figure 7 In the embodiment, the drainage volume adjustment mechanism 90 is provided downstream of the drainage valve 80. However, the drainage volume adjustment mechanism 90 may also be provided upstream of the drainage valve 80. Figure 8 In FIG. 1 , an example of the displacement adjustment mechanism 90 being constituted by a throttling device is shown. Figure 8 As shown, in the throttling device, an orifice plate 93 made of, for example, polyvinyl chloride, which is the same material as the drain pipe 70, is sandwiched between the flange 91A and the flange 91B. Fig. 9 Indicated in.

[0063] A through hole 95 is formed in the center of the orifice plate 93. In addition, a sealing groove 97A is engraved circumferentially on the left surface side of the orifice plate 93 at the portion where the end surface of the flange 91A contacts the left surface of the orifice plate 93, and an O-ring 99A is embedded in the sealing groove 97A. In addition, a sealing groove (not shown in the figure) is engraved circumferentially on the end surface side of the flange 91B at the portion where the end surface of the flange 91B contacts the right surface of the orifice plate 93, and an O-ring 99B is embedded in the sealing groove. In addition, the through hole 95 of the orifice plate 93 has a diameter of, for example, 5 mm, while the inner diameter of the drain pipe 70 is 20 mm.

[0064] When the throttle device is configured in this way, even when the throttle device is installed after the equipment is completed, the installation work can be easily performed.

[0065] However, the drainage volume adjustment mechanism 90 may also be a structure in which the diameter of the drainage pipe 70 is made thinner in a manner that takes into account the degree of negative pressure. In this case, the diameter of the drainage pipe 70 may be made thinner so that the water level of the tank 60 does not reach the low water level LL from the time when the water level of the tank 60 is detected to be the low water level L to the time when the drainage valve 80 is completely closed. A certain margin may be left in the diameter of the pipe. In this way, when the diameter of the drainage pipe 70 is made thinner, it is also easy to perform the pipe replacement operation after the equipment is completed.

[0066] In addition, a valve may be separately provided as the drainage volume adjustment mechanism 90, and the drainage volume may be adjusted by the valve control unit 81. However, the drainage volume may be adjusted by narrowing the drainage valve 80 when the water level of the tank 60 is detected to be the low water level L without separately providing a valve.

[0067] According to the above content, even when the degree of negative pressure on the drainage side is large, after the water level in the tank 60 is below the low water level L and a closing signal is sent from the valve control unit 81 to the drain valve 80, there is no possibility that the water level will be below the low water level LL during the time lag until the drain valve 80 is completely closed corresponding to the closing signal.

[0068] Therefore, the water level in the tank is always maintained at a higher position than the drain outlet at a certain value or more, and the water seal of the drain line is reliably maintained.

[0069] In the present embodiment, it is described that water vapor turns into water droplets in the cooling trap 20 , but the present embodiment is not limited to water vapor, and is also applicable to exhaust gas containing ethanol, resist liquid, etc.

[0070] In addition, the present invention can be modified in various ways without departing from the spirit of the present invention, and it is obvious that the present invention also includes such modifications.

[0071] Description of Reference Numerals

[0072] 5 Dry Pump

[0073] 20 Cooling Trap

[0074] 23 Inflow port

[0075] 25 Discharge port

[0076] 31 Water supply port

[0077] 33 Capillaries

[0078] 35 Water outlet

[0079] 37, 39 deflector

[0080] 50 straight pipe

[0081] 60 cans

[0082] 61 Water level sensor

[0083] 63 Drain

[0084] 70 Drain pipe

[0085] 80 Drain valve

[0086] 81 Valve control unit

[0087] 90 Displacement adjustment mechanism

[0088] 93-well plate.

Claims

1. A system for treating water in waste gas, wherein the system uses a cooling trap to remove water contained in waste gas discharged from a process, and is characterized in that: Equipped with tank, water level measuring mechanism, piping, valve, valve control mechanism, The tank stores the water flowing out of the cooling well as liquid water. The aforementioned water level measuring mechanism measures the water level in the tank. The pipe is connected to a drain port for discharging the water stored in the tank to the outside. The valve is arranged on the pipe. The valve control mechanism opens the valve to start draining when the water level in the tank measured by the water level measuring mechanism exceeds a first water level, and closes the valve to stop draining when the water level reaches a second water level set lower than the first water level. The second water level is set at a position higher than the drain outlet. The second water level is a water level set to perform water sealing during the drainage so that the exhaust gas is not discharged from the pipe to the outside. A drainage volume adjustment mechanism is provided at the aforementioned piping, and the aforementioned drainage volume adjustment mechanism adjusts the amount of the aforementioned water stored in the aforementioned tank discharged to the outside. During the period from when the aforementioned valve control mechanism starts to close the aforementioned valve until the aforementioned valve is completely closed, the water in the aforementioned tank remains above the aforementioned drainage port.

2. The system for treating moisture in exhaust gas according to claim 1, characterized in that: The cooling trap and the tank are connected by a pipe without any bends.

3. The system for treating moisture in exhaust gas according to claim 1 or 2, characterized in that: The first water level is a water level set so as to prevent backflow from the tank to the cooling well side.

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