JPH044014A - Gas purification device - Google Patents

Abstract

PURPOSE: To contrive to remove a trace of impurities in hydrogen gas or the like by filling up an active substance in an airtight chamber around a filter and an inside space section and by bringing the gas which is moving from an inlet-side filter to an outlet-side filter through the airtight chamber into contact with the active substance. CONSTITUTION: An airtight inside space section positioned between filters (20, 21) in an airtight chamber (C) is formed. In this airtight chamber (C), a baffle (24) is installed between the filters (20, 21) facing an annular side wall. And, a gas passing through inbetween the filters (20, 21) is deflected along the circumference of the baffle (24) from an inlet (18) to an outlet (19). Further, a heater (16) is mounted inside the said inside space section, and an outside vessel (27) surrounding a main vessel (11 to 13) to form a space around it is installed. In order to thermally insulate the main vessel (11 to 13) from the outside vessel (27), a ceramic insulating plate (26) is mounted in the said space and an active substance (25) (example: Zr) which is to nearly fill up the airtight chamber (C) is placed in the surroundings of the filter (20, 21) and of the said inside space section.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas purification device. More particularly, the present invention relates to an apparatus for removing low level impurities present in an inert carrier gas or hydrogen gas to produce a high purity process gas, the reactive impurities being I )I
) is reduced to level b.

[Conventional technology]

In certain types of production systems, such as VLSI production systems, it has become standard to perform work under an inert gas atmosphere. In view of the small size and the possibility of corrosion of parts, it is important that the processing gas be of extremely high purity. In fact, impurities such as oxygen gas and volatile hydrocarbons need to be reduced to the level I)I)b. This level is actually so low that it is almost unmeasurable. In many other processes as well, the gas used must be of extremely high purity, whether it is an inert gas such as argon or xenon, or an active gas such as hydrogen.

A variety of gas purification systems are commercially available. For example, LABELEA Inc.
R, INC,) and Semi-Gas Systems Inc. (SE former-GAS SYSTEMS, IE,
), etc., an in-line cartridge filled with gel filtration material or polymeric resin absorbent material is connected in series to the gas supply line. These systems have straight flow paths and are generally intended to operate at room temperature conditions. Such systems are unable to reduce nitrogen or hydrogen gas to ppb levels, require large amounts of absorbent material, and require excessively low flow rates to reduce carbon dioxide gas, methane, and other hydrocarbons to ppb levels. required.

In other types of gas purification devices, the process gas is passed over a metal capture material. For example, at Suberco (5UPELCO), Cu-
CuO is used. Also, RD Matisse (R, D, MAT
HIS) uses a titanium metal cavernous body.
SS, P, A,) uses a Zr-V-Fe alloy. Upon heating, the latter two materials become effective scavengers for all reactive gas species, including nitrogen, carbon dioxide, and methane. However, such conventional purification systems have bulky heaters and flanges and rely on poor gas-solid catalysis. Systems using titanium metal also have the disadvantage of requiring significantly higher operating temperatures for purification.

[Purpose of the invention]

It is therefore an object of the present invention to provide an improved gas purification device. Another object of the invention is to provide an apparatus that is substantially smaller, easier to maintain, and less expensive than conventional systems.

[Summary of the invention]

These objectives are achieved in a gas purification system comprising an apparatus having the following configuration. That is, the apparatus includes a main container substantially forming a sealed chamber, an intake member having an intake port projecting from the sealed chamber and a filter located inside the sealed chamber, and a filter disposed at a position remote from the intake port. an extraction member having an extraction port projecting from the sealed chamber and a filter disposed within the sealed chamber away from the filter of the intake member; and an airtight inner space between the filters in the sealed chamber. and means for forming the section. A baffle is installed in the sealed chamber between the two filters, and the gas passing between the two filters is deflected by this baffle.

A heater is attached to the inner cavity. An outer container surrounds the main container and forms a space around it.

This space is thermally insulated by filling it with a heat insulating material, using a heat shield, or evacuating it. The active substance substantially fills the sealed chamber around the filter and the internal cavity, and the gas flowing from the inlet filter through the sealed chamber to the outlet filter comes into contact with this active substance. Preferably, the device also includes means for forming a second gas-tight interior within the sealed chamber and a thermal lightning pair. 20 thermocouples are for monitoring the temperature of the active material layer.

Such a configuration is extremely compact and can remove minute amounts of impurities that are barely measurable on the low ppb level. This device is low cost to manufacture and extremely easy to use and install.

According to a feature of the invention, both containers are made of stainless steel and welded together. The active substances used are made from zircon, titanium, calcium, yttrium or lanthanides with atomic numbers 67 to 71. Alternatively, the active material is made from an alloy containing these elements as major constituents. Or it is composed of a compound, mixture or hydride of these elements. Gases to be purified include inert gases such as argon, helium, krypton or xenon.

By suitably setting the active substance and the operating temperature, the device according to the invention can also be used for air, nitrogen gas or hydrogen gas.

According to the invention, it is also possible to use renewable active substances, such as gel filtration compounds or copper oxide. Furthermore, this active substance may be a catalyst.

[Detailed description of the invention]

The above-mentioned objects and other objects, features, and various effects will be more easily understood with reference to the accompanying drawings, tables, and examples.

As is clear from FIGS. 2 and 3, the device according to the invention is essentially axially symmetrical with respect to axis A. This device includes a main cylinder member 11 having a lid member 12 at the tip and a base plate 13.
It consists of These members are all made of stainless steel and are welded together to form a cylindrical sealed chamber C. The board 13 has a predetermined thickness and is used to mount components. The base plate 13 has a central passage into which a cylindrical member 14 is fitted. Cylindrical member 14
The terminal end of the cylindrical member 14 engages the threaded inner periphery of the base plate 13, and the opposite end face of the cylindrical member 14 is closed by a stainless steel stopper 15 using welding. This cylindrical member 14 accommodates a heater 16 having a conducting wire 17.

In addition, an input tube 1B and an output tube 19 are inserted through the substrate 13 on both sides in the diametrical direction with respect to the heater cylinder member 14. Inside the sealed chamber C, heat-treated filters 2° and 21 are attached to the input pipe 18 and the output pipe I9, respectively. In addition, as shown in FIG. 3, the substrate accommodates another cylindrical member 22, and this cylindrical member 22 houses a thermocouple 23. The thermocouple 23 is for monitoring the temperature inside the device, and has a conducting wire 23A connected to a control unit (not shown) like the conducting wire 17.

A pair of baffle plates 24 are attached to the sides of the heater tube 14 having an inner cavity. A pair of baffle plates 24
project diametrically oppositely from each other along a plane perpendicular to the plane containing the two filters 20 and 21. The outer peripheral end of the baffle plate 24 is slightly shorter than the inner peripheral surface of the main cylinder member 11 and extends toward the bottom plate member 12.

The sealed chamber C formed inside the cylindrical member 11 is connected to the cylindrical member 14.
and the surrounding area of the filter 20.21 is filled with an alloy trapping material. The capture material is in the form of a pellet 25 and is shown only in the upper left corner of FIG. 2 for clarity of drawing.

A machined ceramic heat insulating plate 26 is attached to the substrate 13 on the side opposite to the sealed chamber C. In addition, a cup-shaped container can 27 is engaged along the outer peripheral surface of the substrate 13 to form a space along the entire peripheral surface of the sealed chamber C.

This space is evacuable and preferably fitted with a heat shield. In this case, stainless steel container can 2
7 and the substrate 13 are welded together. It is then filled with a heat insulating material such as ceramic. Additionally, a cover cap 28 is fitted to protect the substrate 13. If the space inside the outer container can 27 is not evacuated, the container can 27 can be omitted, and a larger diameter can may be used to accommodate a thicker heat insulating layer.

The reactor configuration disclosed above provides various advantages not available in conventional gas purification devices intended for high purity applications. The main components of the reactor are mounted on a single element, here the substrate 13, which facilitates the arrangement of components and facilitates ease of assembly to reduce overall manufacturing costs. . The active substance is tip member 1
The reactor can be filled through a large opening closed by 2. By using such an assembly method, the size of the material to be filled can be selected from a wide range.

Such an assembly structure also facilitates internal cleaning operations and replacement of active substances. By using the thick substrate member 13, the inner heater cavity 14 and the outer container 27 surrounded by strong side walls, it is possible to prevent dangerous gaseous species such as tritium from diffusing out.

In use, heater 16 is energized and the interior of the device is heated to approximately 450°C. The gas to be purified is then introduced into the intake pipe 18 under normal pressure.

The gas is coarsely filtered by the filter 20, and then passes around the baffle plate 24 along the angular or circumferential direction to the filter 21 on the opposite side. Here, the gas enters the extraction pipe 19 and is led to external processing equipment. While traversing the closed chamber C in this manner, the gas effectively contacts the captured particles 25. The above-mentioned impurities are then removed from the gas.

This system is manufactured in three basic sizes with the following dimensions:

It is quite possible to construct larger or smaller devices as long as the relative proportions shown in the table are maintained.

As a general rule, the aspect ratio of internal length to diameter (C:
A) should be set between 10 and 6.0, preferably around 15 as shown in the example above.

By setting the aspect ratio in this manner, the difficulty in selecting the cartridge heater 1B can be minimized, and by minimizing the area/volume ratio, the insulation structure of the system can be made relatively simple. I can do it. When the aspect ratio is set to 6 or more, heat loss increases and a heater with an extremely large shaft length is required. Further, even if the aspect ratio is set to less than 1, heat loss increases, and many short heaters must be installed in the inner space.

In addition, the ratio of the main vessel diameter to the porous filter diameter should be set between 2 and 8. By setting such a ratio, the filters 20 and 21 have a relatively large surface area relative to the volume of the alloy particles contained therein, which makes it possible to reduce the decrease in gas thickness within the gas purification device. can.

As a modification of such a device, the baffle plate 24 is connected to the cylindrical member 11.
extends toward the inner surface of the However, these plates are substantially shorter than the cylindrical member 11 and are shorter than the filter 20.
．． 21 is also substantially short. As a result, the gas flow is axial and flows over the edges of the baffle plate 24 rather than angularly around the baffle plate.

Example 1 A small reactor/canister as shown in the table above is filled with 300 g of pallets made from Zr-V based alloy powder. Such a pallet has the trade name HY-5TO, for example.
It is sold as R402. The baffle plate and filter are arranged so that the flow of the reactant gas is radial through the pallet layer. This device is hermetically sealed by welding, and a heater 16 is energized to activate the active substance.
At the same time as heating to 00°C, the intake pipe 18 and the output pipe 19 are evacuated. The assembly is then cooled to room temperature and filled with argon gas to preserve the active state.

To perform gas purification, the apparatus is connected to a source of argon gas mixed with impurities at known levels. After the purifier is equilibrated at the selected active material bed temperature, gas is introduced into the purifier at a controlled flow rate. The extracted gas is sampled by a residual gas analyzer and the impurity concentration is determined as 1lFI. The experiment was continued using different flow rates and different active material bed temperatures for the same process gas. Similar data were obtained for various impurities and the results are shown in FIG. The flow rates and impurity levels used were both substantially greater than normally encountered. This compact reactor is designed for use with flow rates less than 21/min. This selection of conditions is intended to quantify gas purification in conventional experimental test equipment. 2
At 50° C., the oxygen gas concentration decreases by three orders of magnitude in the region where the flow rate exceeds 10 g/min.

(Example 2) Same small size reactor/absorption as in Example 1.
00g of HY-5TOR402 Pere Soto was filled and sealed by welding. The baffle plate and filter were arranged to allow gas to flow axially through the active material layer. Activation pretreatment and testing were performed in the same manner as in Example 1. A wider variety of impurity gases were tested and the results are shown in FIG.

It can be seen that the device according to the invention is clearly efficient. It is particularly effective against more active oxygen gas and nitrogen gas species.

Example 3 After filling the same small size reactor/absorption as used in Examples 1 and 2 with 200 g of pellets consisting of refined powder sold under the trade name HY-5TOR402, the device was vented by welding. Sealed. The baffles and filters are arranged to provide axial gas flow through the active material layer. The heater 16 is energized and heats the filling to 600° C. At the same time, the intake pipe 18 and the output pipe 19 are evacuated to activate the alloy. The assembly is then cooled to room temperature and backfilled with argon gas to preserve the activated state.

As shown in FIG. 4, impure argon gas was flowed through the apparatus along a single flow path.

As a result, impurity gases such as methane, carbon oxide, nitrogen, and oxygen were removed. The flow rates and impurity levels used were both set substantially higher than normally encountered, quantitatively exaggerating gas purification relative to conventional test equipment (RGA). Clearly, the device according to the invention has shown remarkable effectiveness, especially for the more active oxygen and nitrogen gas species.

(Example 4) Using the same apparatus as used in Example 3, as shown in FIG. 5, argon gas was circulated and purified to mainly remove hydrogen. The graph shows the hydrogen concentration in a closed space changing over time. The volume of this sealed space is 3,900 cc and is initially contaminated with 11,000 pp of hydrogen. This gas has a temperature of 1000 at 25°C.
It is circulated at a flow rate of cc/min.

The theoretical value is represented by a straight line, and as shown in the figure, it can be seen that the measured data corresponds extremely well to the theoretical value.

(Example 5) 400 g was placed in the same small-sized reactor as in the previous example.
HY-5TOR402 particles were used. Baffles were placed to allow gas to flow axially through the active material layer. After heating to activate the active material alloy,
Cooled. The active material alloy was hydrogenated by introducing hydrogen gas into the closed chamber at a low rate to avoid overheating. Adequate space is reserved in advance in the reactor to accommodate the particles that expand due to hydrogenation. The hydrogen gas to be purified was then flowed into the reactor. The results were similar to those in Example 1, indicating that the hydride of the active substance HY-5TOR402 was also an effective trapping material. However, to achieve the same degree of purification, the flow rate must be reduced.

〔Effect of the invention〕

As shown in the various embodiments described above, the apparatus according to the invention is practical for the purification of process gases in both cyclic and non-circulatory systems.

In addition, the apparatus according to the invention can be effectively used in the recovery of hydrogen isotopes (deuterium or tritium) from inert gas streams. Hydrogen isotopes are adsorbed by the active material during operation of the device and subsequently recovered by heating and/or vacuum treatment of the active material.

[Brief explanation of drawings]

FIG. 1 is a graph showing the impurity concentration at various flow rates in the inert gas purifier according to the present invention, FIG. 2 is a longitudinal sectional view of the gas purifier according to the present invention, and FIG. An end view of the device viewed from the right hand direction, and FIGS. 4, 5 and 6 are graphs showing the operation of the device according to the present invention.

Claims (1)

[Scope of Claims] 1. A main container having an end wall, a rear wall, and an annular side wall that substantially form a sealed chamber; an intake port that passes through the end wall and projects from the sealed chamber; an intake member having a filter located in the sealed chamber; an intake member inserted into the end wall and projecting from the sealed chamber away from the intake port; and an intake member having a filter located in the sealed chamber separated from the filter of the intake member. a means for forming an airtight inner cavity disposed between the two filters in the sealed chamber; a baffle extending in the direction, the gas passing between the two filters is deflected from the intake port along the periphery of the baffle toward the outlet port, and a heater disposed in the inner space. an outer container surrounding the main container and forming a space therearound; means disposed in the space for thermally insulating the main container from the outer container; both filters and the inner cavity. and an active substance disposed around and substantially filling the sealed chamber. 2. The gas purification apparatus according to claim 1, wherein both vessels are made of stainless steel and welded together. 3. Claim 2 comprising means for forming a second airtight internal cavity in the sealed chamber, and a thermocouple disposed in the internal cavity.
The gas purification device described in .