JP2005230679A - Purification cylinder for waste gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a purification cylinder for waste gas capable of efficiently purifying waste gas containing harmful components discharged from a semiconductor manufacturing process, or the like, by using a purification agent and surely detecting the breakthrough of the purification agent immediately before that in the case of using a detection agent in a filling part on the downstream side of the purification agent. <P>SOLUTION: This purification cylinder for the waste gas is provided with an inlet for the waste gas, the filling part of the purification agent, and a discharge port for purified gas. The filling part of the purification agent is provided with an annular plate such that an outer peripheral edge is tightly adhered to the inner wall surface of the purification cylinder. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an exhaust gas purification cylinder. More specifically, exhaust gas containing harmful components discharged from semiconductor manufacturing processes, etc. is purified efficiently using a purifier, and the exhaust gas can be reliably detected immediately before the purifier breaks through. Related to the tube.

  Various gases are used in the semiconductor manufacturing industry. As hydride gases, arsine, phosphine, silane, diborane, hydrogen selenide, etc. are used. As acid gases, fluorine, chlorine, hydrogen fluoride, hydrogen chloride, Chlorine trifluoride, boron trifluoride, boron trichloride, silicon tetrafluoride, silicon tetrachloride, titanium tetrachloride, aluminum chloride, germanium tetrafluoride, tungsten hexafluoride, etc. include ammonia, Monomethylamine, dimethylamine, trimethylamine, hydrazine and the like are used in large quantities. Since these gases are toxic, exhaust gases containing these harmful components must be purified prior to being released into the atmosphere after being used in a semiconductor manufacturing process or the like.

  Conventionally, as the exhaust gas purification method, there are many dry purification methods for purifying by purifying the purification cylinder by filling the purification cylinder, introducing the exhaust gas into the purification cylinder, and capturing the harmful components in contact with the purification agent. It has been implemented. In the dry cleaning method, each of the various cleaning agents has a specific cleaning ability for harmful components (hazardous component processing amount per unit amount of cleaning agent), and can capture a certain amount of harmful components. If exceeded, it could not be captured and had to be replaced with a new cleaning agent. Therefore, purifiers having excellent purifying ability have been developed for each harmful component.

In addition, in order to prevent the harmful component from flowing out to the downstream side, a viewing window is provided at the relatively downstream position of the purifier filling portion so that the inside of the purification tube can be observed from the outside of the purification tube, It has been practiced to fill this with a detection agent that changes color upon contact with the harmful component, and to detect the harmful component immediately before the purifier layer breaks through. As such a detection agent, a detection agent that changes its color sharply in a short time upon contact with a harmful component and has a large color change is preferable, and various detection agents have been developed together with the purifying agent.
JP-A-8-129209 JP-A-10-235185

  In the dry cleaning method, when the harmful gas comes into contact with the cleaning agent, the harmful component and the cleaning agent cause a chemical reaction, or the harmful component is adsorbed by the cleaning agent, and the harmful component is captured by the cleaning agent. Such a reaction part or adsorbing part of harmful components gradually proceeds downstream from the upstream side of the purifier layer. However, due to the difference in the position between the central part and the peripheral part of the purifier layer, the accumulation state of the pulverized material contained in the harmful gas in the purifier layer, etc., the drift of the exhaust gas occurs. Normally, the purifier layer does not progress uniformly. This tendency is particularly noticeable when the diameter of the purification cylinder is large. Even if a purification agent with excellent purification ability is used, it cannot be used efficiently, and even if an excellent detection agent is used, this does not cause discoloration. May flow to the downstream side of the purification cylinder.

For this reason, a means capable of preventing or mitigating the drift of exhaust gas is desired, but even the generation mechanism has not been elucidated so far.
Therefore, the problem to be solved by the present invention is to elucidate the generation mechanism of the drift of the exhaust gas, and to efficiently purify the exhaust gas containing harmful components discharged from the semiconductor manufacturing process etc. Is used for the filling portion on the downstream side of the purifying agent, to provide an exhaust gas purifying cylinder capable of reliably detecting this just before the purifying agent breaks through.

  As a result of intensive studies to solve these problems, the present inventors have found that in the conventional purifying cylinder, the reaction part or the adsorbing part of the harmful component progresses more in the periphery of the inner wall surface of the purifying cylinder than in the central part. I found it to be faster. This is because, for example, when a spherical cleaner is used, the cleaner tends to be packed in the hexagonal close-packed state in the center, whereas the inner wall faces a large gap because the cleaner contacts the flat surface, and In the peripheral part of the wall surface, sufficient pressure is not applied when filling with the purifier compared to the central part, and the porosity increases, so when exhaust gas is flowed, the flow rate of exhaust gas in that part becomes faster and along the inner wall surface Presumably, this is because harmful components preferentially flow. In addition, the exhaust gas flow velocity also varies in the periphery of the inner wall surface, and when this is large, it has been speculated that harmful components may flow downstream of the purification cylinder without discoloration of the detection agent.

Further, the present inventors circulate the inner wall surface by providing an annular plate in the purifier filling portion so that the outer peripheral edge is in close contact with the inner wall surface of the purification cylinder against the drift generated as described above. It has been found that the exhaust gas path to be used is long, the purification agent usage rate is reduced due to the drift of exhaust gas, and the outflow of harmful components to the downstream side of the purification cylinder can be mitigated or prevented.
That is, the present invention is an exhaust gas purification cylinder having an exhaust gas inlet, a purifier filling portion, and a purified gas discharge port, wherein the outer peripheral edge is on the inner wall surface of the purification tube. An exhaust gas purifying cylinder characterized in that an annular plate is provided so as to be in close contact.

The present invention is applied to a purification cylinder filled with a purification agent that purifies exhaust gas containing harmful components such as hydride gas, acid gas, and basic gas discharged from a semiconductor manufacturing process or the like.
In the exhaust gas purification cylinder of the present invention, the harmful components to be purified are hydride gas such as arsine, phosphine, silane, diborane, hydrogen selenide, fluorine, chlorine, hydrogen fluoride, hydrogen chloride, trifluoride. Chlorine gas, boron trifluoride, boron trichloride, silicon tetrafluoride, silicon tetrachloride, titanium tetrachloride, aluminum chloride, germanium tetrafluoride, tungsten hexafluoride and other acidic gases, ammonia, monomethylamine, dimethylamine, Examples include basic gases such as trimethylamine and hydrazine, and organometallic compounds. These are usually discharged in a state in which they are contained in a base gas such as nitrogen, hydrogen, argon, or helium.

  The purification agent in the present invention is not particularly limited as long as it can purify the exhaust gas containing the harmful components by a dry purification method. Examples of these purifiers include hydride gas purifiers mainly composed of manganese dioxide and copper oxide, and halogen-based gas obtained by impregnating activated carbon with an alkali metal salt of formic acid and / or an alkaline earth metal salt of formic acid. And a purifying agent for basic gas in which a copper salt is impregnated with a composition mainly composed of manganese dioxide and copper oxide. Moreover, a powdered product may be generated in combination with the harmful component.

Hereinafter, although the exhaust gas purification cylinder of the present invention will be described with reference to FIGS. 1 to 6, the present invention is not limited thereto.
1, 3 and 5 are longitudinal sectional views showing examples of the exhaust gas purifying cylinder of the present invention. 2 and 4 are configuration diagrams showing examples of exhaust gas paths of the purification cylinders shown in FIGS. 1 and 3, respectively. FIG. 6 is a plan view showing an example of an annular plate used in the purification cylinder of the present invention.

As shown in FIGS. 1, 3, and 5, the exhaust gas purification cylinder of the present invention has an exhaust gas purification cylinder having an exhaust gas inlet 1, a purifier filling portion 2, and a purified gas discharge port 3. The purification cylinder is provided with an annular plate 4 in the purifier filling portion 2 so that the outer peripheral edge is in close contact with the inner wall surface of the purification cylinder.
The purification cylinder of the present invention is manufactured by filling the inside with a purification agent and installing an annular plate at a predetermined position.

  In the purifier filling portion of the purifying cylinder of the present invention, the porosity is increased at the inner wall surface of the purifying cylinder and the peripheral portion of the annular plate, and the porosity is decreased at the central portion. Accordingly, in the exhaust gas passage 5 that circulates between the surface of the inner wall of the purification cylinder and the surface of the annular plate as shown in FIGS. 2 and 4, the flow rate of the exhaust gas is relatively high, and it circulates through the central portion of the purifier filling portion. In the exhaust gas path 6 to be performed, the flow rate of the exhaust gas becomes relatively slow. However, since the exhaust gas path 5 is long and the exhaust gas path 6 is short, the flow rate of the exhaust gas in the downstream direction, that is, the traveling speed of the reaction part or adsorption part of the harmful component in the downstream direction can be set to be substantially the same.

  The above settings vary depending on the type of exhaust gas, the type of purification agent, the size and shape of the purification cylinder, processing conditions, etc., and cannot be specified unconditionally. The length of the shortest path of the exhaust gas that circulates only on the surface of the inner wall surface of the cylinder and the surface of the annular plate is 1.2 to 3.0 of the length of the shortest path of the exhaust gas that circulates in the central part of the purifier filling portion. It is set to be doubled. In the present invention, normally, a plurality of annular plates having the same shape and the same size are used so as to fall within the above-mentioned range. The diameter of the central opening 10 of the annular plate is set to about 15 to 75% of the inner diameter of the purification cylinder.

  In the above, when the length of the shortest path inside the purifier filling portion of the exhaust gas path 5 is less than 1.2 times the length of the shortest path inside the purifier filling portion of the exhaust gas path 6, The progress of the harmful component in the downstream direction of the reaction part or the adsorption part is faster in the peripheral part of the inner wall surface of the purification cylinder than in the part, and the effect of the present invention is reduced. Further, when the length of the shortest path inside the purifier filling portion of the exhaust gas path 5 exceeds 3.0 times the length of the shortest path inside the purifier filling portion of the exhaust gas path 6, the purification is performed instead. The central part of the tube is more disadvantageous in the central part than the peripheral part of the inner wall surface of the reaction part or the adsorption part.

  In the exhaust gas purification cylinder of the present invention, a viewing window 8 filled with a detection agent 7 for detecting harmful components in the exhaust gas can be provided in the filling portion downstream of the purification agent. In the case of providing a viewing window filled with the detection agent, as shown in FIG. 5, a guide plate 9 that guides the exhaust gas to the detection agent filling part can be provided in the purification agent filling part upstream of the viewing window. . The shape and size of the guide plate are not particularly limited, but usually a disc-shaped guide plate of about 30 to 70% of the inner diameter of the purification cylinder is used. By doing in this way, this can be reliably detected immediately before the purifier breaks through. Even when such a guide plate is provided, the length of the shortest path inside the purifier filling portion of the exhaust gas path 5 and the length of the shortest path inside the purifier filling portion of the exhaust gas path 6 are as follows. It is preferable to be within the above-mentioned relationship without considering the guide plate.

  Further, in the exhaust gas purifying cylinder of the present invention, it is preferable to provide the tip of the exhaust gas inlet and the tip of the purified gas outlet at the center in the horizontal direction of the purifier. By setting it as such a structure, waste gas can be flowed equally with respect to a horizontal direction.

  With the exhaust gas purification cylinder of the present invention, exhaust gas containing harmful components discharged from a semiconductor manufacturing process or the like can be efficiently purified using a purifier. In addition, when a viewing window filled with a detection agent is installed in the purifier filling portion, it is possible to reliably detect this just before the purification agent breaks through.

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited by these.

(Production of purification cylinder)
As the exhaust gas purification cylinder, a purification cylinder using three annular plates in FIG. 1 was manufactured. The purification cylinder has an inner diameter of 200 mm and a height of 1000 mm, and is filled with a purification agent in which congo red is supported on spherical alumina having a diameter of 2 to 5 mm so that the filling length is 500 mm. Three annular plates having a central opening with a diameter of 100 mm and a thickness of 5 mm were provided at equal intervals. Moreover, the viewing window was installed so that the position of 10 mm from the bottom of the purification agent filling part might become the center. In addition, the length of the shortest path of the exhaust gas that circulates only on the surface of the inner wall surface of the purification cylinder and the surface of the annular plate is 700 mm, and the length of the shortest path of the exhaust gas that circulates in the central part of the purifier filling portion is 500 mm. It is.

(Purification test)
Nitrogen gas containing 6000 ppm of hydrogen chloride was circulated through the exhaust gas purification cylinder at a flow rate of 200 ml / min. During this time, the time until hydrogen chloride began to be detected in the gas discharged from the discharge port of the purification cylinder was measured. The results are shown in Table 1. Further, Table 1 shows the results of calculating the usage rate of the cleaning agent from the ratio of the cleaning agent taken out from the exhaust gas purification cylinder and discolored from red to blue. In this purification test, discoloration of the cleaning agent was confirmed from the viewing window before the above time.

(Examples 2 and 3)
A purification test was conducted in the same manner as in Example 1 except that the concentration of hydrogen chloride in the purification test of Example 1 was changed to 3000 ppm and 12000 ppm, respectively. Table 1 shows the results of obtaining the time until hydrogen chloride begins to be detected from the discharge port and the usage rate of the purifier. In these purification tests, discoloration of the cleaning agent was confirmed from the viewing window before the above time.

(Examples 4 and 5)
A purification test was conducted in the same manner as in Example 1 except that the flow rate of nitrogen gas containing hydrogen chloride in the purification test of Example 1 was changed to 100 ml / min and 400 ml / min, respectively. Table 1 shows the results of obtaining the time until hydrogen chloride begins to be detected from the discharge port and the usage rate of the purifier. In these purification tests, discoloration of the cleaning agent was confirmed from the viewing window before the above time.

(Example 6)
In the production of the purification cylinder of Example 1, a purification cylinder was produced in the same manner as in Example 1 except that five annular plates were used. (The length of the shortest path of exhaust gas flowing through only the surface of the inner wall surface of the purification cylinder and the surface of the annular plate: 900 mm, the length of the shortest path of exhaust gas flowing through the central part of the purifier filling portion: 500 mm) A purification test was conducted in the same manner as in Example 1 except that a cylinder was used. Table 1 shows the results of obtaining the time until hydrogen chloride begins to be detected from the discharge port and the usage rate of the purifier. In this purification test, discoloration of the cleaning agent was confirmed from the viewing window before the above time.

(Example 7)
In the production of the purification cylinder of Example 1, a purification cylinder was produced in the same manner as in Example 1 except that nine annular plates were used. (The length of the shortest path of the exhaust gas flowing through only the surface of the inner wall surface of the purification cylinder and the surface of the annular plate: 1300 mm, the length of the shortest path of the exhaust gas flowing through the central portion of the purifier filling portion: 500 mm) A purification test was conducted in the same manner as in Example 1 except that a cylinder was used. Table 1 shows the results of obtaining the time until hydrogen chloride starts to be detected from the outlet and the usage rate of the purifier. In this purification test, discoloration of the cleaning agent was confirmed from the viewing window before the above time.

(Example 8)
In the production of the purification cylinder of Example 1, the purification cylinder was produced in the same manner as in Example 1 except that an annular plate having a central opening diameter of 150 mm and a thickness of 5 mm was used. (The length of the shortest path of the exhaust gas flowing through only the surface of the inner wall surface of the purification cylinder and the surface of the annular plate: 600 mm, the length of the shortest path of the exhaust gas flowing through the central portion of the purifier filling portion: 500 mm) A purification test was conducted in the same manner as in Example 1 except that a cylinder was used. Table 1 shows the results of obtaining the time until hydrogen chloride begins to be detected from the discharge port and the usage rate of the purifier. In this purification test, discoloration of the cleaning agent was confirmed from the viewing window before the above time.

(Comparative Example 1)
In the production of the purification cylinder of Example 1, a purification cylinder was produced in the same manner as in Example 1 except that the annular plate was not used. A purification test was conducted in the same manner as in Example 1 except that this purification cylinder was used. Table 1 shows the results of obtaining the time until hydrogen chloride begins to be detected from the discharge port and the usage rate of the purifier. In this purification test, discoloration of the cleaning agent could not be confirmed from the viewing window before the above time. Further, a large amount of unused purifier remained in the lower center of the purifier filling portion, and the breakage of the portion without the viewing window in the peripheral portion of the inner wall surface of the purifying cylinder was remarkably fast.

The longitudinal cross-sectional view which shows the example of the purification cylinder of the exhaust gas of this invention Configuration diagram showing an example of the exhaust gas path of the purification cylinder of FIG. 1 is a longitudinal sectional view showing an example of an exhaust gas purification cylinder other than FIG. 1 of the present invention. The block diagram which shows the example of the exhaust gas path | route of the purification | cleaning cylinder of FIG. 1 is a longitudinal sectional view showing an example of an exhaust gas purification cylinder other than those shown in FIGS. The top view which shows the example of the annular plate used for the purification cylinder of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exhaust gas introduction port 2 Purifier filling part 3 Purified gas discharge port 4 Annular plate 5 Exhaust gas passage which circulates the surface of the inner wall of the purification cylinder and the surface of the annular plate 6 The central part of the purifier filling unit Flowing exhaust gas path 7 Detecting agent 8 Viewing window 9 Guide plate 10 Central opening of the annular plate

Claims (8)

  An exhaust gas purifying cylinder having an exhaust gas inlet, a purifier filling portion, and a purified gas discharge port, and annular so that the outer peripheral edge is in close contact with the purifying agent filling portion An exhaust gas purification cylinder provided with a plate.   The length of the shortest path of the exhaust gas that circulates only on the inner wall surface of the purification cylinder and the surface of the annular plate inside the purifier filling portion is the length of the shortest path of the exhaust gas that circulates in the central portion of the purifier filling portion. The exhaust gas purifying cylinder according to claim 1, wherein the shape, size, and number of the annular plates are set so as to be 1.2 to 3.0 times the height.   The exhaust gas purification cylinder according to claim 1, wherein a plurality of annular plates are provided.   The exhaust gas purification cylinder according to claim 3, wherein the plurality of annular plates have the same shape and the same size.   The exhaust gas purification cylinder according to claim 1, wherein the diameter of the central opening of the annular plate is 15 to 75% of the inner diameter of the purification cylinder.   The exhaust gas purification cylinder according to claim 1, wherein a viewing window filled with a detection agent for detecting harmful components in the exhaust gas is provided in a filling portion on the downstream side of the purification agent.   The exhaust gas purifying cylinder according to claim 6, wherein a guide plate that guides the exhaust gas to the detecting agent filling portion is provided in the purifying agent filling portion on the upstream side of the viewing window. The exhaust gas purifying cylinder according to claim 1, wherein the tip of the exhaust gas introduction port and the tip of the purified gas discharge port are provided at a central portion in a horizontal direction of the purification tube.

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