CA1300344C - Superpurifier for argon gas and process for purifying argon gas - Google Patents
Superpurifier for argon gas and process for purifying argon gasInfo
- Publication number
- CA1300344C CA1300344C CA000512228A CA512228A CA1300344C CA 1300344 C CA1300344 C CA 1300344C CA 000512228 A CA000512228 A CA 000512228A CA 512228 A CA512228 A CA 512228A CA 1300344 C CA1300344 C CA 1300344C
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- Prior art keywords
- getter
- argon gas
- gas
- superpurifier
- alloy
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B23/00—Noble gases; Compounds thereof
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Gas Separation By Absorption (AREA)
- Separation Of Gases By Adsorption (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
Abstract The present invention relates to a superpurifier for argon gas and to a process for superpurifying an argon gas.
According to the invention, the superpurifier comprises means for contacting an impurity-containing argon gas with a getter material which is an alloy of zirconium, vanadium and iron. The getter material of the superpurifier selectively sorbs impurities from an impurity-containing argon gas thereby producing a purified argon gas. The present invention also relates to a method of purifying an impurity-containing argon gas using this superpurifier.
The present invention provides means for obtaining an argon gas of higher purity than can be obtained by prior purifying processes and apparatus.
According to the invention, the superpurifier comprises means for contacting an impurity-containing argon gas with a getter material which is an alloy of zirconium, vanadium and iron. The getter material of the superpurifier selectively sorbs impurities from an impurity-containing argon gas thereby producing a purified argon gas. The present invention also relates to a method of purifying an impurity-containing argon gas using this superpurifier.
The present invention provides means for obtaining an argon gas of higher purity than can be obtained by prior purifying processes and apparatus.
Description
SUPERPURIFIER FOR ARGON GAS
AND PROCESS FOR PURIFYING ARGON GAS
, . . . _ tPrior Art]
Argon, present in air and constituting about one percent o- its ~olume, is separat_d from nitrogen and okygen by low=
temperature fractional distillation. It is filled either in -liquid or gaseous form in~o cylinders and put on the market. -A hlgh grade inert gas, argon is in wide use. ~o provideatmospheres for heat treatments of metals, for the manufacture of semiconductor substrates and the like. When it is to be employed in super.ine microprocessing, it must be further purifled by removing impurities to a greater purity immediately before use. For large.-volume consumptlon in industrial pro-cesses lt is customary to vaporize liquid argon and supply the resulting gas through pipings. Here the problem is how to meet the requirement of rapid and positlve removal of the impurities, such as nitrogen, oxygen, hydrogen, carbon dloxide, carbon monoxide, water, methane, and other nydroearbons, from the gasified argon.
Wlth the view to removing these impurities it has been proposed to comblne two steps, that is, passing argon gas .
.
~` 1300344 through a bed of active charcoal or active alumina or through a molecular sieve of zeolite or the like to eliminate water, carbon dioxide, and hydrocarbons and then contacting the gas with a metallic getter of copper or nickel preheated to a temperature range of 150 to 300C. Alternatively, the two-step process is followed by an additional step of bringing the gas into pressure contact with a molecular sieve type 5-A under a pressure of 5 to 25 atm. for further purification through removal of residual nitrogen, oxygenj hydrogen" and carbon monoxide. The specification of Japanese Patent Application Public Disclosure No. 107910/1984, which describes the proposed procoss, also mæ~es clear that argon gas containing the i,~puri-ties listed in the following table -Constituent 2 C0 H2 N2 H2 P
-(ppm) 1 100 200 200 60C
was purified in the foregoing way to a composition as tabled below:
Constituent 2 C0 H2 N2 H20 P
(ppm) 1 _ 1 20 -72C
' .
tProblem the Invention is to Solve~ .
The argon gas purification process disclosed in the afore- -- . ' ' ''' ' ' -"--` ' - .
~ .
~300344 .
mentioned specification of Pat. App. Pub. Discl. No. 107910/1984 is an excellent process ~or obtaining high-purity argon gas.
However, the recent progress of the semiconductor industry suggests that more and more precise microprocessing and hence argon of even higher purity will be required for future produc-tion of highly integrated circuits. In fact, there is already strong demand for high-purity ar~on gas for t~sting purposes.
The technical problem the present invention is intended to solve is lowe.ing the current levels of impurities according to the prior art technology to much lower levels, by two figures in parts per million.
ri~ieans for Solving the Problem]
We have intensively studied on the means for purifying argon gas to decrease its impurity concentrations by two o~s of magni~ude ppm frcm the usual levels as stated above. As a result,-we have discovered a getter that performs even better than the above-mentioned metallic getter of copper or nickel and have arr~ved at an apparatus and a process capable of most effec-tlvely purifying argon gas by the use of the particular getter.
The present invention has now been perfected on this basis.
The apparatus according to this invention is a superpurifier for argon gas characterized in that an outer shell is provided with an inYet for argon gas to be purified, an outlet for purified argon gas, at least one getter chamber packed with a getter alloy of zirconium-vanadium-lron system and disposed ~ - 3 ~
' ' .
midway between the two openings, a flow passage so formed that the argon gas that enters the inlet flows through the getter chamber and leaves the outlet, and the heater means incorporated into the outer shell to maintain the getter alloy at the temperature at which it functions, the weight composition of the zirconium-vanadium-iron alloy of getter being such that the percentages by weight of the three elements, when plotted in a ternary composition diagram, come within a polygon (Fig. 1) having as its corners the points defined by a. 75%Zr-20%V-5%Fe, b. 45%Zr-20%V-35%Fe, and c. 45~Zr-50%V-5%Fe.
The process according to the invention is a process for superpurifying argon gas characterized by the steps of properly dehydrating argon gas to be purified to a moisture content of 1 ppm or less, and then removing impurities by adsorption from the gaæ of the low moisture content by passing the latter through a getter bed packed with a getter alloy of zirconium=vanadium-iron system maintained at a temperature of 20 to 400C, said getter alloy having a weight composition such that the percentages by weight of the three elements, when plotted in a ternary composition diagram, come within a polygon (Fig. 1) having as its corners the points defined by a. 75%Zr-20%V-5%Fe, b. 45%Zr-20%V-35%Fe, and :' ~
c. 45%Zr-50%V-5%Fe.
The ternary getter alloy of zirconium, vanadium, and iron to be used in the present invention may be the one described in U.S. Patent Specification No. 4,312,669.
The weight composition that gives a getter of particularly good performance is such that the percentages by weight of the three elements, when plotted in a ternary composition diagram (Fig. 1), come within a polygon having as its corners the points defined by a. 75%Zr-20%V-5%Fe, b. 45%Zr-20%V-35%Fe, and c. 45%Zr-50%V-596Fe.
Such a ternary alloy getter characteristically adsorbs moisture and water vapour quantitatively at temperatures in the range of 20 to 400C, preferably in the range of 200 to 350C, without evolving hydrogen, and over a wider temperature range, it adsorbs hydrogen, C0, CO2, and other gases. These properties have been found advantageously utilizable in the argon gas superpurifier of the invention.
The weight ratio of the elements constituting the ternary alloy getter for use in the superpurifier of the invention may be varied as de8ired within the range specified above. In any case it is advisable to choose the best possible compositional ratio in view of the getter properties.
The zirconium content in the ternary alloy should not be r ~, ' too hi8h nor too low for otherwise the alloy would tend to evolve hydrogen while adsorbing moisture and also would become plastic creating difficulty.to transform into;`powder.
The vanadium content should not be too low, either, because it would maXe the alloy unable to exhibit fully satisfactory gas adsorp~ion performance.
On the basis of the iron weight the ~/eight percentage of vanadium is desired to rang~ from 75 to 85%.
The optimum ternary alloy composition of the getter for the superpurifier of the invention may be such that the per-centages by weight of the three elements, when plot~ed in a ternary composition diagr~m, come witnin a polygon (~ig. 1) having as its corners the points defined by d. 70%Zr-25~0V-5hFe, e. 70~Zr-24,'OV-6%Fe, f. 66~Zr-24Y~v-loo~re~
g. 47%Zr-43%V-10%Fe, h. 47%Zr-45~0V-8%re, and 1. 50,'OZr-45%V-5,OF_.
The p.ocess for preparing these zlloys is described in the above-mentioned U.S. Patent Specification No. 4,312,66g. The products manufactured and marketed by SAES Getters S.p.A. of Milan, Italy, may desirably be used.
It is desirable- that the getter alloy be used in the form of an lntermetallic compound, which is readily pulverized and 1~00344 can be handled with eaæe. Moreover, the increased surface area renders the powdered material more active.
The ternary alloy getter is packed in at least one getter chamber provided midway in a gas flow passage between the inlet for argon gas to be purified and the outlet for purified gas.
The packed getter chamber or chambers combine with heater means, installed as an accessory to an outer shell to maintain the getter at its working temperature, to make up an argon gas superpurifier of the invention.
Argon gas to be purified is passed through this superpurifier where it contacts the getter so as to be freed from its impurities by adsorption.
The getter to be packed in the chamber takes the form of pellets in preference to fine particles since the former are easier to provide sufficient interstices therebetween for the gas flow. Also, the getter as pellets of uniform size rather than ~mall lumps irregular in size renders it easy to maintain a con~tant void ratio in the getter bed, to design the apparatus, and to reproduce the good performance. Thus, while the getter in the form of ~ine particles or small lumps is not ob~ectionable, the use of pelletized getter, compression molded of the alloy powder, is preferred as it better meets the requirements for industrial designing and manufacture of the argon gas superpurifier.
The heater means to be incorporated in the apparatus of ~r the lnvention to keep the ~ct~c~ hot cnou~h ror the adsorption reaction may take varied forms as will be explained later in.
connection with preferred embodiments of the invention. The heating method may be electric heating or indirect heating by the use of a heating medium circulated through a double-wall structur~ or the like. Also, the heating zone may be suitably chosen, for example, in the gas preheatlng region upstream of the get~er bed or chamber, or around or inside ~he getter mass.
Since it is desirable that sufficient heating be done to effect a smooth adsorption reaction of the getter with the gas and procuce as uniform a tempe-ature distribution as feasible, the combination of the heating method and zone may be varied, according to the necessity, to best a~tain the end.
While it is possible that the gette~ chamber in the appara-tus of the invention be provided inside the outer she~l, as d~rectly packed in the la.~er, a preferred ar.angement is such that the getter bed consists of at least one cartridge packed with the getter material and which is adapted to be fitted in the outer shell detachably for ease of replacement. The getter components according to this invention adsorb and remove impurities from impure argon gas by chemical adsorption that involves chemical changes. They therefore are consumed stoichi-ometrically and have a limited life. After service for a pre-determined period the getter must be replaced by fresh one;
otherwise the purpose of superpurifying argon gas will no longer be achieved. To this end the superpurifier including the outer shell packed with the getter may be handled as a single unit and replaced as such from time to time. It is also possible to fill up the getter in a cartridge instead and dismount the cartridge from the outer shell for replacement at proper inter-vals of time. The cartridge type is more practical with large=
size equipment.
The cartridge desirably employs a metal case so perforated as to facilitate the gas flow.
Because the superpurifier of the invention is intended to purify argon gas until the concentrations of i~s ingredien~s as impurities are reduced to 0.01 ppm or less each, it is advisable that tne inne. wall por~ion of the ap~aratus with which the purified gas emer~ing from tne getter chamber comes in contact be made of a metal polished on the surface to be close-grained and smooth enou~h to minimize gas adsorption and which does not form powder due to corrosion. Such metals include, for example, but are not limited to, stainless steels 7P '~
and proprietary alloys such as Hastelloy, Incoloy, and Monel metal. Any other metal material which satisfies ~he above requirements may be suitably chosen and used. The chosen metal may be "baked", or heat treated, before use to reduce the volume of subsequent gas release from the metal material itself.
As stated above, the inner wall material of the apparatus that contacts the purified argon gas is desired to have a ~ l rac~ r k s 9_ ! ~
!i 13~3~
densely and smoothly polished surface to minimize gas adsorption.
The desirable degree of smoothness of the polished surface is numerically defined to be such that the roughness of the inner wall surface to contact argon gas is 0.5 ~m or less, preferably 0.25 ~m or less in terms of the centerline average height (R~) ~Japanese Industrial Standard (JIS) B 0601-1970]. This numerical range is not always critical but is recommended as a dependable, safe range.
Although the polished inner wall material is advantageously used in the zone where the gas flowing out of the cartridge chamber comes in contact, it is, of course, possible to use it also in the zone where the gas passing through the cartridge contacts. In many cases it is rather inconvenient to use the polished material only in the zone where the gas that has flowed past the cartridge contacts. The surface polishing and baking will markedly shorten the time period required before highly purified ga~ begins to be obtainsd at a constant rate, even from a new apparatus.
In the apparatus of the present invention the means for ~olving the technical problem can be variously embodied as suggested above. Thus it i6 to be understood that the invention i8 not limited to the specific embodiments thereof so far described but various modifications may be made without departing from the spirit and scope of the invention.
Dehydration in the process of the invention is done on the ~ ' . ` 1~00~44 following grounds. Tho moisture content in impure argon gas usually is by far the higher than the levels of other impuri-ties. When special weight is placed on moisturè removal, the getter li~e and therefore the service li~e o~ thé argon gas superourifier will be remarkably extended or, stated different-ly, a s~-iking increase in the volume of purified argon gas will be realized. Any known denydration technique may be adopted provided it does not obstruct the practice of the present invention. For example, the dehydration may be by adsorption with a molecular sieve of synthetic zeolite or the like, wi~h alumina g_l, or with phospnorus pentoxide, or by freezing at a cryogenic temperature below -1~0C, or by adso-p-tion witn silica gel, active charcoal, or other adsorbent at low temperature below -~0C. Fig. 11 shows the relation between the moisture content in the gas to De purified and the getter life. When the gas has a la^ge moisture conte.~', it is dehyd-rated before superpuriLication, preferably to a moisture content of 1 ppm or less.
In order to control tne moisture content within the range of l ppm or less, the system is designed for operation as follows. Using a moisture meter capable of continuously making trace moisture content measurement, the moisture level in the dehydrated argon gas is automatically monitored. When the moisture content in the argon following the dehydration has gradu3~ly risen near 1 ppm, the dehydrator is switched on before the 1 ppm level is reached, so that the moisture content in the argon gas before entering the getter bed i8 kept within the range of 1 ppm or less. Analyzers suited for such continuous, automatic measurement of trace moisture contents are, for example, moisture meters manufactured by Endress und Hauser GmbH
of West Germany and marketed under the trade-marks "ENDRESS-HAUSER HYGROLOG, WMY 170" AND "- WMY 370", products trade-marked "PANAMETRICS Hygrometer, Model 2100", "- Model 700", and "-System I" by Panametrics Inc. of the U.S., and another American trade-mark product "Du Pont 510 Moisture Analyzer" by E.I. Du Pont de Nemours & Co. Other analyzers of performance comparable to or better than the above may, of course, be employed instead.
Such a moisture meter may also be used for the measurement and monitoring of the moisture content in the argon gas after purification. The results of analysis are utilized as data indicativs of decreasing adsorbability of the getter and for the decision on timing of any switchover of the superpurifier operation or of replacement of the getter-filled cartridge.
For the detection and determination of trace impurities other than moisture in argon gas, an analyzer for ultramicro amounts of gases (mass-filter type mass spectometer for high-sensitivity continuous analysis) manufactured by Nichiden-ANELVA Corporation (in Japan) under the trade-mark "TE-360B~ may be used. The analytical values are utilized as a measure of declining performance of the getter and for the decision , .. .
on timing for the switchover of the superpurifier operation or replacement of the getter cartridge.
As regards those analytical values, it is advisable to set up a purification system so that, whenever any of prefixed upper limits or levels of individual impurities is reached, a switch-over in operation is automatically accomplished as scheduled.
Such a system will ensure high quality ol the final argon gas.
In order that the impurities be removed from the dehydrated argon gas by passage through and adsorption by the getter bed of zirconium-vanadium-iron alloy, the reaction temperature is ~ept in the range of 20 to 400C. At a temperature below 20C, the impurit-ies are adsorbed by the getter surface but cannot be expected to diffuse into the get~er mass. Thus the adsorp-tion practically comes to an end in the state of saturation on the surface, without fully ma~ing use of the getter capacity.
In the speci~ied range of 20 to 400C the getter performs adsorption to the full, allo~ing the impurities to diffuse thoroughly therein. The apparent life of the getter is accord-ingly extended.
On the other hand, in the temperature region above 400C, the hydrogen once adsorbed by the getter can be desorbed because it has an equilibrium adsor~tion pressure higher than those of other impurities. Setting a reaction temperature in excess of 400C ls therefore undesirable.
Among the specified temperature range of 20 to 400C, a narrower ran8e of 220 to 380C is most preferred. A tempera-ture in the latter range is the most recommended reaction temperature in that it assures a high adsorption rate and thorough diffusion of the impurities into the bed of getter with no possibility of hydrogen desorption.
tEunctional Effects]
The argon gas suDerpurifier of the presen~ invention is suited for superpurifying the conventionally purified argon gas to an even higher purity. It can purify a~gon gas by passa$e therethrough to lower the concentrations of impurities in the feed, such as oxygen (2)~ carbon monoxide (C0), carbon dioxide (C02), nitrogan (~12), hydrogan (Y.2), methane (C~4), and water (H20), down to 0.01 ppm or less each. Thus it real-izes superpurification of argon gas to such a high purity that none of existing purifiers have ever achieved.
Moreover, the life of getter used in the argon g2S super-purifie. of the invention can be markedly extended and the volume of argon gas purification greatly increased by first decreasing the moisture content in the impure argon gas to 1 ppm or less by proper dehydration in accordanca with the process of the invention and then passing the dehydrated gas through the superpurifier of the invention.
~Embodiments]
The present invention will now be described in more detail below in connection with embodiments thereof.
~. :
1~00344 In the accompanylng drawings:
Figure 1 i9 a zlrconium-vanadium-iron ternary diagram of the getter alloy;
Figures 2-10 are vertical sectional views of different argon gas superpurifier apparatus; and Figure 11 is a graph illustrating the relatlonship between the moisture content in argon gas and the getter life.
- 14a -.
, ~ .
Argon gas superpurifiers embodying the invention are illustrated in Figs. 2 through 10. Fig. 2 shows an argon gas superpurifier comprising: an outer shell 3 made of a stainless steel tube (grade SUS 304 TP conforming to Japanese Industrial Standard JIS G 3448) which has an argon gas inlet 1 formed near the top and an argon gas outlet 2 near the bottom, the shell being covered with a heat insulator 12 all over the surface: a top cover 14 fitted to the top of the outer shell 3; a heater 6 inserted through the top cover 14 into the space 25 inside the shell: a bed of getter 4 packed in the space defined below the heater 6 between upper and lower buffers 16, 15; and a perforated plate 7 held by a support 13 which in turn is secured to the inner wall of the outer shell and is supporting the bed as well as the perforated plate. The getter used was ternary alloy getter of zirconium (68-72 wt%), vanadium (24-25 wt%~, and iron (5-6 wt%) manufactured and marketed by SAES Getters S.p.A., Type No. "St. 707" in the form of columnar pellets having a diameter o~ 3 mm and height of 4 mm.
The buffers, indicated at 15, 16, consist of a layer each of small alumina spheres 4 mm in diameter packed up to a height of about 5 cm. They aorrect any ununiform flow of the gas through the getter bed, keep the fine particles of the getter from scattering, and uniformalize the temperature distribution.
While the embodiment being described u~ed small alumina spheres in forming the buffers, small stainless steel balls or a stack of fine-mesh stainless steel screens may be employed instead. Also, the buffers are not always used, and a buffer=less embodiment will be described later.
In the upper portions of the buffers 15, 16 are embedded sheathes 20, 19 accommodating thermometers 18, 17, respectively.
Chromel-Alumel thermocouples are used as the thermometers.
Argon gas g to be purified is introduced into the vessel at the inlet 1, heated by the heater 6, passes through the upper buffer 16 and thence, as a uniform flow, through the bed of getter 4 where it is freed from impure gas contents by adsorption. The purified gas is led through the perforated plate 7 and taken out of the vessel at the outlet 2.
Fig. 3 and following figures show other embodiments of the invention. Throughout these figures like parts are designated by like numerals and the description is omitted or minimized each.
Fig. 3 shows a superpurifier of the same construction as the embodiment in Fig. 2 excepting that an electric heater ~ ~ is coiled round the outer shell 3 and a thermocouple 22 is installed to measure the heatsr temperature. This modification facilitates the temperature control of the getter bed.
Although Figs. 2 and 3 illustrate the embodiments in which the bed of getter 4 is directly packed in the outer shell 3, the getter bed may be separately provided as well. Fig. 4 shows an arrangement of cartridge 5 where the getter 4 and buffers ~300344 15, 16 are accommodated in a cylinder equipped with perforated plates 7 at both ends. After service for a given period, the cartridge 5 may be taken out by removing the top cover 14 and replaced by a new one. This permits more efficient operation than with the arrangements of Figs. 2 and 3.
Fig. 5 shows another embodiment 11, in which the outer shell 3 is of a double-wall construction, consisting of an inner wall 24 and an outer wall 23. The space between the walls provides a passage through which a heating medium such as steam flows from a heating medium inlet 30 to an outlet 31. A coolant may be passed instead of heating medium depending on the case. In the space defined by the inner wall is accommodated a cartridge 5 containing a getter 4, with a coil of electric heater 6 embedded in the getter. The heater 6 is connected to an external power source not shown through leads 8 (only one of them being shown) and a terminal assembly 10. The cartridge 5 has inner and outer porous walls 26 concentrically held in spaced relation by a support 13. The inner wall 24 of the outer shell is abutted at its lower end against a bottom plate with a flange 27, through which a gas inlet pipe 1 and an outlet pipe 2 extend. The pipe 2 serves also to support the cartridge 5. brgon gas 9 to be purified is fed through the inlet 1 into the outer space 25, heated thereto a proper temperature, and thence forced through the porous wall 26 into the getter layer 4 for puriflcation. the purified gas flows out into the inner space 25 and taken out via the outlet 2.
.~ , 1;~00344 Flg. 6 shows s~ill another embodiment of superpurifier 11.
The outer shell 3 ls a8ain of double-wall constructlon, with a space formed therein to circulate a heating medium introduced at an inlet 30 and discharged at an outlet 31 to perform tem-perature control. Inside the inner wall is disposed a cartridge 5 packed with a getter 4 between per,orated plates. On both sides of the cartridge are arranged heaters 6 which are connect-ed to external power sources through leads 8. Impure argon gas 9 is fed at an inlet 1, preheated by the heating medium, purified by passage through the getter mass 4'kept at a given tem?e.ature by the heate~s 6, and then take'n out at an outlet 2.
Yet another embodiment of superpurifier 11 is shown in Fig.
7. A cylind-ical outer shell 3 supports a cartrldge 5 by means of upper and lower pl2tes (not shown). The cartridge S com-prises a built-in electric heater 6,with leads 8 and a mass of getter 4 filled ln the s?ace between upper and lower pe--forated plates or buffer layers, with the heater embedded there-in, Fig. 8 shows another apparatus ll embodying the invention.
An inner cylinder is provided inside an outer shell 3 which consists of inner and outer walls and a heat insulator 12 filling up the space between the walls. A getter 4 is packed in the space between the inner cylinder and the outer shell, and an electric heater 6 coiled round a ceramic rod 36 is inserted into the central space in the inne- cylinder. Argon -` 1300344 gas 9 to be purified enters the vessel at an inlet 1, passes through the getter 4, and the purified gas leaves the vessel at an outlet 2.
Fig. 9 shows another embodiment, wh~ch is a modification of the superpurifier illustrated in Fi8. 4 and is characterized by means for recovering the heat of purified argon. Argon gas 9 to be purified enters a heat exchanger 28 installed under the purifier body, undergoes heat exchange with the outgoing gas, and the gas so preheated moves th~ough a pipe 29 surrounded by a heat insulator 12 and through an upper inlet 1 into a bed of getter 4. The purified gas is cooled in the heat exchanger and leaves the purifier at an outlet 2.
Fig. 10 shows a further embodiment. The outer shell 3 is a double-wall cylinder, and a heating medium is introduced into the spac_ between the walls at an inlet 33 and is discharged at an outlet 34. Inside the outer shell 3 is disposed a gas-tight cartrldge 35. The space in the cartridge case is parti-tioned horizontally with a plurality of perforated plates 7, and a plurality of getter beds 4 are formed, each filling-up the space formed by every other pair of the perforated plates.
The getter beds have electric heaters 6 embedded therein, one for each; and supplied with electricity through leads 37, 38.
Argon gas 9 to be purified flows in at an inlet 1 and the puri-fied gas flows out at an outlet 2.
Examples of the invention which used a specific getter composition will now be explained.
The instruments used for gas analyses in the examples were as follows:
Gas analysis instrument:
Gas chromatograph-mass spectrometer, Model TE-360B
(mfd. by Anelva Corp.) Moisture meter:
Hygrometer, Model 700 (mfd. by Panametric Co.) Surface roughness meter:
Surfcorder, Model SE-3H
(mfd. by Kosaka Laboratory Co., Ltd.) lç 1 A powdered non-evaporable getter alloy naving a weight composition of 70%Zr-24.6%V-5.4%Fe and a particle si~e of between 50 and 250 ~m is placed in the superpurifier for argon gas shown in Fig. 2. The stainle6s steel (SUS 304) cylinder has an outside diameter of 21.7 mm and an inside diameter of 17.5 mm, its length being 350 mm. The length of cylinder occupied by the getter material, including the heights, 5 mm each, of the upper and lower buffers of alumina spheres, (bed height) is 200 mm. Impure argon is introduced into the superpurifier at a temperature of 25C and a pressure of 6 kg/cm2 (gauge) at a flow rate of 0.6 ~/min. The argon flows through the non-evaporable getter bed held at 350 and issues at a pressure , , .
1~00344 ,of 4 kg/cm2 (gauge) from the outlet where its impurity level i~ measured for various gases. This impurity level ig: measur- !
ed 40 min after the start of the flow of argon.;
Table - Inlet impurity Outlet impurity Gaslevel (ppm)level (pDm?
2 0~4 0.006 N2 0 5 0.011 CH40.06 0.007 CO 0.07 0.002 C2 . 4 0.002 H20 5 0 no trace The level of impurities in the outlet gas remains .constant for 930 hours.
Example 2 Pellets were produced having a diameter of 3 mm and height of 4 mm by compression of a non-evaporable getter alloy haYing a composition and particle size identical to those of the getter alloy of Example l. The pellets were loaded into the super-purifier shown in Fig. 3. The stainless steel (SUS 304) cylind-er had an outer diameter of 89.l mm and an inner diameter of 83.l mm. Its length was 660 mm. The length of the cylinder occupied by the pellets of getter material, including the thicknesses of the upper and lower buffers (of alumina spheres~
~,~, ,, i'.
,~ ' .
- 21 - ~
' '' each having a bed height of 5 mm, was 185 mm. Impure argon was introduced into the superpurifier at a temperature of 25C
and a pressure of 4 kg/cm2 (gauge) at a flow rate of 12 ~/min.
The impure argon flowed through the non-evaporable getter bed held at a temperature of 350C by means of a spiral resist-ance heater and issued at a pressure of 3.95 kg/cm2 (gauge) from the outlet while its impurity level was measured for .
various gases. The impurity level was measured 40 min after the start of the flow of argon. The results obtained were as shown in Table II.
: . Table I~
. _ _ Inlet impurity Outlet impurity Gas level (ppm)level (ppm) 2 6.0 0.01 N2 7.5 0.02 CH4 2.0~ 0.009 CO 9.5 0.003 C2 6.3 0.003 H20 5.0 no trace The methane impurity level wa~ obtained by delibe.ately adding CH4 to the inlet gas.
The level of the impurities in the outlet gas remain.ed constant for 930 hours.
Example 3 .... . ,, ' ,: .
.
In this example the procedure of Example 2 was repeated in all respects except that the H20 impurity level waq 1 ppm and not 5 pp~.
- Table III shows the results.
, - Table III
.. i Inlet impurityOutlet impurity Gas level (P~m? level (ppm) 2 6.0 0.01 N2 7 5 0.02 CH4 2 0~ 0 009 CO 9.5 0.003 C2 6.3 0.003 H20 1.0 no trace The methane impurity level was obtained by deliberately adding CH4 to the inlet gas.
The level of the impurities in the outlet gas.remained constant for2~70 hours.
Example 4 Pellets were p~oduced exactly as in Example 2 and placed ln the cartridge shown in Fig. 4. The cartridge had an outside diameter of 80 mm, an inside diameter of 78 mm, and length of 244 mm. The same mass of pellets ~as used as in Example 2.
The cartridge was then placed in a cylinder identical to that of Example 2 (except that its length was 719 mm). Impure .
~- 23 -.~ " " ' .
.
~` `
argon was caused to flow through the superpurifier at the same inlet pressure, temperature, and flow rate as described in Example 2. The cartridge was maintained at 350C. The outlet gas pressure and composition were found to be identical to those found in Example 2 at the point 40 min after the start of the flow of argon. The level of the impurities in the outlet gas again remained constant for 930 hours.
Exam~le 5 In this example the procedure of Example 2 wa3 followed in all respects except that the inner surface roughness of the cylinder..was Ra = 0 5 ym (no.mally Ra = 2.5 ym) and the stain-less steel outlet piping (outside diameter 9.5 mm and inside diameter 7.5 mm) had an inner surface roughness of Ra = 0.2 ym.
The results shown in Table IV were ob;ained 40 min after the start of the flow of ar~on.
Table IV
Inlet impurity Ou-let impurity Gas level (pDm) level (pp~) 2 6.0 0.003 N2 7-5 0.002 CH4 2.0 0.009 CO 9.5 . 0.003 C2 6.3 Ø003 H20 5.0 no trace - - . ; - ~
- . - 24 -:
.
The leyel of the impuritles in the outlet gas remained constant for 930 hours. ~ - ¦
Example 6 ,- - ¦
. In this example the procedure of Example 5 was followed in.all respects except that the water vapor content of the argon gas to be purified was reduced to below 0.6 ppm by first passing it through a dryer bed consisting of a stainless steel (SUS
304) cylinder having an outside diameter of 89.1 mm, inside diameter of 83.1 mm, and length of 830 mm filled to a bed height of 500 mm with a molecula. sieve type 5-A. The outlet pressure from the dryer bed and therefore the inlet pressuro to the superpurifier was found to be 3.7 kg/cm2 (gaugo) and the super- -purifier outlet pressure was 3.7 kg/cm2 (gauge). This impurity level was measured 40 min after the start of the flow of argon.
The results were as shown in Table V.
Table V
Inlet impurity Outlet impurity Gas level (ppm) level (ppm) 2 6.0 0.003 .
N2 7.5 0.002 .. CH4 2.0 0.009 CO 9.5 0.003 C2 6.3 0.003 H20 0.6 no trace .~ . -- . . . .. .
.
. - - 2~ - ; .
.
The level of the impurities in the outlet gas remained constant for 2670 hours.
- - The procedure of Example 6 was repeated except that the temperature wa~ varied to see the effects of different getter temperatures. The results are given in Table VI.
.Table VI
.. .. . _ ........... .
Outlet impurity level (ppm) Inlet impurity at temperature level (ppm) 20C 200~C . 350C 400C
.. _ ....
2 6.0 0.003 0.003 0.003 0.003 N2 7.5 0.002 0.002 0.002 ! ~O . 002 CH4 2.0 2.0 0.2 0.009 0.006 C0 9.5 0.003 0.003 0.003 0.003 C2 6.3 0.003 0.003 0.003 0.003 H20 0.6 no trace no trace no trace no trace Outlet gas remained 30 hr 390 hr 2670 hr 2900 hr constant for .
Power 0 0.56 kW/h 1.04 kW/h 1.2 kW/h .. ... ....
The table indicates that excellent effects were achieved in the temperature range of 20 to 400C, especially in the .
range of 200 to 400C.
-: .
' . , :.,',` ;' I
; ' ' ' , ' -- ~300344 Examples 7, 8, 9 and 10 . Pellets were produced having a diameter of 3 mm and a length of 4 mm by compression of non-evaporable getter powder~
ha~ing weight composition indicated ln the following Table and having particle sizes of 50 - 250 ~m (150 ~m in average).
These pellets were loaded into a superpuri~ier having the same construction in the same manner as Example 2. Argon gas containing impurities was introduced into the superpurifier at a temperature of 25 C, inlet pressure of 4 kgicm2 (gauge) and a flow rate of 12 l/min.
The impurity-containing argon gas was passed through the bed of the non-evaporable getter kept at a temperature of 350 C by means of a spiral resistance heater and emerged from the outlet at a pressure of 3.95 kg/cm2 (gauge). The impurity level was measured 40 min after the start of the flow of argon and the results in Table VII were obtained.
. , ~ . .
.~ ~ . , . I
,~ .
, ~ : , . . . .
.; .
.
TABLE VII
Ex. 7 Ex, 8 Ex. 9 Ex. 10 Getter Zr(%) 65 48 46 46 alloy comp. V (%) 25 44 21 37 Fe(%) 10 8 33 17 Gas Inlet Outlet impurities imp. (ppm) (ppm) 2 6.0 0.01 0.01 0.02 0.03 N2 7.5 0.02 0.02 0.02 0.02 CH4 2.0 0.006 0.01 0.01 0.01 CO 9.5 0.003 0.003 0.008 0.005 CO2 6.3 0.003 0.003 0.006 0.006 H2O 5.0 no trace no trace no trace no trace Period of time for which outlet impurity was 780 530 900 810 constant (hrs) -The outlet impurity levels were constant for the length of time indicated in the table.
AND PROCESS FOR PURIFYING ARGON GAS
, . . . _ tPrior Art]
Argon, present in air and constituting about one percent o- its ~olume, is separat_d from nitrogen and okygen by low=
temperature fractional distillation. It is filled either in -liquid or gaseous form in~o cylinders and put on the market. -A hlgh grade inert gas, argon is in wide use. ~o provideatmospheres for heat treatments of metals, for the manufacture of semiconductor substrates and the like. When it is to be employed in super.ine microprocessing, it must be further purifled by removing impurities to a greater purity immediately before use. For large.-volume consumptlon in industrial pro-cesses lt is customary to vaporize liquid argon and supply the resulting gas through pipings. Here the problem is how to meet the requirement of rapid and positlve removal of the impurities, such as nitrogen, oxygen, hydrogen, carbon dloxide, carbon monoxide, water, methane, and other nydroearbons, from the gasified argon.
Wlth the view to removing these impurities it has been proposed to comblne two steps, that is, passing argon gas .
.
~` 1300344 through a bed of active charcoal or active alumina or through a molecular sieve of zeolite or the like to eliminate water, carbon dioxide, and hydrocarbons and then contacting the gas with a metallic getter of copper or nickel preheated to a temperature range of 150 to 300C. Alternatively, the two-step process is followed by an additional step of bringing the gas into pressure contact with a molecular sieve type 5-A under a pressure of 5 to 25 atm. for further purification through removal of residual nitrogen, oxygenj hydrogen" and carbon monoxide. The specification of Japanese Patent Application Public Disclosure No. 107910/1984, which describes the proposed procoss, also mæ~es clear that argon gas containing the i,~puri-ties listed in the following table -Constituent 2 C0 H2 N2 H2 P
-(ppm) 1 100 200 200 60C
was purified in the foregoing way to a composition as tabled below:
Constituent 2 C0 H2 N2 H20 P
(ppm) 1 _ 1 20 -72C
' .
tProblem the Invention is to Solve~ .
The argon gas purification process disclosed in the afore- -- . ' ' ''' ' ' -"--` ' - .
~ .
~300344 .
mentioned specification of Pat. App. Pub. Discl. No. 107910/1984 is an excellent process ~or obtaining high-purity argon gas.
However, the recent progress of the semiconductor industry suggests that more and more precise microprocessing and hence argon of even higher purity will be required for future produc-tion of highly integrated circuits. In fact, there is already strong demand for high-purity ar~on gas for t~sting purposes.
The technical problem the present invention is intended to solve is lowe.ing the current levels of impurities according to the prior art technology to much lower levels, by two figures in parts per million.
ri~ieans for Solving the Problem]
We have intensively studied on the means for purifying argon gas to decrease its impurity concentrations by two o~s of magni~ude ppm frcm the usual levels as stated above. As a result,-we have discovered a getter that performs even better than the above-mentioned metallic getter of copper or nickel and have arr~ved at an apparatus and a process capable of most effec-tlvely purifying argon gas by the use of the particular getter.
The present invention has now been perfected on this basis.
The apparatus according to this invention is a superpurifier for argon gas characterized in that an outer shell is provided with an inYet for argon gas to be purified, an outlet for purified argon gas, at least one getter chamber packed with a getter alloy of zirconium-vanadium-lron system and disposed ~ - 3 ~
' ' .
midway between the two openings, a flow passage so formed that the argon gas that enters the inlet flows through the getter chamber and leaves the outlet, and the heater means incorporated into the outer shell to maintain the getter alloy at the temperature at which it functions, the weight composition of the zirconium-vanadium-iron alloy of getter being such that the percentages by weight of the three elements, when plotted in a ternary composition diagram, come within a polygon (Fig. 1) having as its corners the points defined by a. 75%Zr-20%V-5%Fe, b. 45%Zr-20%V-35%Fe, and c. 45~Zr-50%V-5%Fe.
The process according to the invention is a process for superpurifying argon gas characterized by the steps of properly dehydrating argon gas to be purified to a moisture content of 1 ppm or less, and then removing impurities by adsorption from the gaæ of the low moisture content by passing the latter through a getter bed packed with a getter alloy of zirconium=vanadium-iron system maintained at a temperature of 20 to 400C, said getter alloy having a weight composition such that the percentages by weight of the three elements, when plotted in a ternary composition diagram, come within a polygon (Fig. 1) having as its corners the points defined by a. 75%Zr-20%V-5%Fe, b. 45%Zr-20%V-35%Fe, and :' ~
c. 45%Zr-50%V-5%Fe.
The ternary getter alloy of zirconium, vanadium, and iron to be used in the present invention may be the one described in U.S. Patent Specification No. 4,312,669.
The weight composition that gives a getter of particularly good performance is such that the percentages by weight of the three elements, when plotted in a ternary composition diagram (Fig. 1), come within a polygon having as its corners the points defined by a. 75%Zr-20%V-5%Fe, b. 45%Zr-20%V-35%Fe, and c. 45%Zr-50%V-596Fe.
Such a ternary alloy getter characteristically adsorbs moisture and water vapour quantitatively at temperatures in the range of 20 to 400C, preferably in the range of 200 to 350C, without evolving hydrogen, and over a wider temperature range, it adsorbs hydrogen, C0, CO2, and other gases. These properties have been found advantageously utilizable in the argon gas superpurifier of the invention.
The weight ratio of the elements constituting the ternary alloy getter for use in the superpurifier of the invention may be varied as de8ired within the range specified above. In any case it is advisable to choose the best possible compositional ratio in view of the getter properties.
The zirconium content in the ternary alloy should not be r ~, ' too hi8h nor too low for otherwise the alloy would tend to evolve hydrogen while adsorbing moisture and also would become plastic creating difficulty.to transform into;`powder.
The vanadium content should not be too low, either, because it would maXe the alloy unable to exhibit fully satisfactory gas adsorp~ion performance.
On the basis of the iron weight the ~/eight percentage of vanadium is desired to rang~ from 75 to 85%.
The optimum ternary alloy composition of the getter for the superpurifier of the invention may be such that the per-centages by weight of the three elements, when plot~ed in a ternary composition diagr~m, come witnin a polygon (~ig. 1) having as its corners the points defined by d. 70%Zr-25~0V-5hFe, e. 70~Zr-24,'OV-6%Fe, f. 66~Zr-24Y~v-loo~re~
g. 47%Zr-43%V-10%Fe, h. 47%Zr-45~0V-8%re, and 1. 50,'OZr-45%V-5,OF_.
The p.ocess for preparing these zlloys is described in the above-mentioned U.S. Patent Specification No. 4,312,66g. The products manufactured and marketed by SAES Getters S.p.A. of Milan, Italy, may desirably be used.
It is desirable- that the getter alloy be used in the form of an lntermetallic compound, which is readily pulverized and 1~00344 can be handled with eaæe. Moreover, the increased surface area renders the powdered material more active.
The ternary alloy getter is packed in at least one getter chamber provided midway in a gas flow passage between the inlet for argon gas to be purified and the outlet for purified gas.
The packed getter chamber or chambers combine with heater means, installed as an accessory to an outer shell to maintain the getter at its working temperature, to make up an argon gas superpurifier of the invention.
Argon gas to be purified is passed through this superpurifier where it contacts the getter so as to be freed from its impurities by adsorption.
The getter to be packed in the chamber takes the form of pellets in preference to fine particles since the former are easier to provide sufficient interstices therebetween for the gas flow. Also, the getter as pellets of uniform size rather than ~mall lumps irregular in size renders it easy to maintain a con~tant void ratio in the getter bed, to design the apparatus, and to reproduce the good performance. Thus, while the getter in the form of ~ine particles or small lumps is not ob~ectionable, the use of pelletized getter, compression molded of the alloy powder, is preferred as it better meets the requirements for industrial designing and manufacture of the argon gas superpurifier.
The heater means to be incorporated in the apparatus of ~r the lnvention to keep the ~ct~c~ hot cnou~h ror the adsorption reaction may take varied forms as will be explained later in.
connection with preferred embodiments of the invention. The heating method may be electric heating or indirect heating by the use of a heating medium circulated through a double-wall structur~ or the like. Also, the heating zone may be suitably chosen, for example, in the gas preheatlng region upstream of the get~er bed or chamber, or around or inside ~he getter mass.
Since it is desirable that sufficient heating be done to effect a smooth adsorption reaction of the getter with the gas and procuce as uniform a tempe-ature distribution as feasible, the combination of the heating method and zone may be varied, according to the necessity, to best a~tain the end.
While it is possible that the gette~ chamber in the appara-tus of the invention be provided inside the outer she~l, as d~rectly packed in the la.~er, a preferred ar.angement is such that the getter bed consists of at least one cartridge packed with the getter material and which is adapted to be fitted in the outer shell detachably for ease of replacement. The getter components according to this invention adsorb and remove impurities from impure argon gas by chemical adsorption that involves chemical changes. They therefore are consumed stoichi-ometrically and have a limited life. After service for a pre-determined period the getter must be replaced by fresh one;
otherwise the purpose of superpurifying argon gas will no longer be achieved. To this end the superpurifier including the outer shell packed with the getter may be handled as a single unit and replaced as such from time to time. It is also possible to fill up the getter in a cartridge instead and dismount the cartridge from the outer shell for replacement at proper inter-vals of time. The cartridge type is more practical with large=
size equipment.
The cartridge desirably employs a metal case so perforated as to facilitate the gas flow.
Because the superpurifier of the invention is intended to purify argon gas until the concentrations of i~s ingredien~s as impurities are reduced to 0.01 ppm or less each, it is advisable that tne inne. wall por~ion of the ap~aratus with which the purified gas emer~ing from tne getter chamber comes in contact be made of a metal polished on the surface to be close-grained and smooth enou~h to minimize gas adsorption and which does not form powder due to corrosion. Such metals include, for example, but are not limited to, stainless steels 7P '~
and proprietary alloys such as Hastelloy, Incoloy, and Monel metal. Any other metal material which satisfies ~he above requirements may be suitably chosen and used. The chosen metal may be "baked", or heat treated, before use to reduce the volume of subsequent gas release from the metal material itself.
As stated above, the inner wall material of the apparatus that contacts the purified argon gas is desired to have a ~ l rac~ r k s 9_ ! ~
!i 13~3~
densely and smoothly polished surface to minimize gas adsorption.
The desirable degree of smoothness of the polished surface is numerically defined to be such that the roughness of the inner wall surface to contact argon gas is 0.5 ~m or less, preferably 0.25 ~m or less in terms of the centerline average height (R~) ~Japanese Industrial Standard (JIS) B 0601-1970]. This numerical range is not always critical but is recommended as a dependable, safe range.
Although the polished inner wall material is advantageously used in the zone where the gas flowing out of the cartridge chamber comes in contact, it is, of course, possible to use it also in the zone where the gas passing through the cartridge contacts. In many cases it is rather inconvenient to use the polished material only in the zone where the gas that has flowed past the cartridge contacts. The surface polishing and baking will markedly shorten the time period required before highly purified ga~ begins to be obtainsd at a constant rate, even from a new apparatus.
In the apparatus of the present invention the means for ~olving the technical problem can be variously embodied as suggested above. Thus it i6 to be understood that the invention i8 not limited to the specific embodiments thereof so far described but various modifications may be made without departing from the spirit and scope of the invention.
Dehydration in the process of the invention is done on the ~ ' . ` 1~00~44 following grounds. Tho moisture content in impure argon gas usually is by far the higher than the levels of other impuri-ties. When special weight is placed on moisturè removal, the getter li~e and therefore the service li~e o~ thé argon gas superourifier will be remarkably extended or, stated different-ly, a s~-iking increase in the volume of purified argon gas will be realized. Any known denydration technique may be adopted provided it does not obstruct the practice of the present invention. For example, the dehydration may be by adsorption with a molecular sieve of synthetic zeolite or the like, wi~h alumina g_l, or with phospnorus pentoxide, or by freezing at a cryogenic temperature below -1~0C, or by adso-p-tion witn silica gel, active charcoal, or other adsorbent at low temperature below -~0C. Fig. 11 shows the relation between the moisture content in the gas to De purified and the getter life. When the gas has a la^ge moisture conte.~', it is dehyd-rated before superpuriLication, preferably to a moisture content of 1 ppm or less.
In order to control tne moisture content within the range of l ppm or less, the system is designed for operation as follows. Using a moisture meter capable of continuously making trace moisture content measurement, the moisture level in the dehydrated argon gas is automatically monitored. When the moisture content in the argon following the dehydration has gradu3~ly risen near 1 ppm, the dehydrator is switched on before the 1 ppm level is reached, so that the moisture content in the argon gas before entering the getter bed i8 kept within the range of 1 ppm or less. Analyzers suited for such continuous, automatic measurement of trace moisture contents are, for example, moisture meters manufactured by Endress und Hauser GmbH
of West Germany and marketed under the trade-marks "ENDRESS-HAUSER HYGROLOG, WMY 170" AND "- WMY 370", products trade-marked "PANAMETRICS Hygrometer, Model 2100", "- Model 700", and "-System I" by Panametrics Inc. of the U.S., and another American trade-mark product "Du Pont 510 Moisture Analyzer" by E.I. Du Pont de Nemours & Co. Other analyzers of performance comparable to or better than the above may, of course, be employed instead.
Such a moisture meter may also be used for the measurement and monitoring of the moisture content in the argon gas after purification. The results of analysis are utilized as data indicativs of decreasing adsorbability of the getter and for the decision on timing of any switchover of the superpurifier operation or of replacement of the getter-filled cartridge.
For the detection and determination of trace impurities other than moisture in argon gas, an analyzer for ultramicro amounts of gases (mass-filter type mass spectometer for high-sensitivity continuous analysis) manufactured by Nichiden-ANELVA Corporation (in Japan) under the trade-mark "TE-360B~ may be used. The analytical values are utilized as a measure of declining performance of the getter and for the decision , .. .
on timing for the switchover of the superpurifier operation or replacement of the getter cartridge.
As regards those analytical values, it is advisable to set up a purification system so that, whenever any of prefixed upper limits or levels of individual impurities is reached, a switch-over in operation is automatically accomplished as scheduled.
Such a system will ensure high quality ol the final argon gas.
In order that the impurities be removed from the dehydrated argon gas by passage through and adsorption by the getter bed of zirconium-vanadium-iron alloy, the reaction temperature is ~ept in the range of 20 to 400C. At a temperature below 20C, the impurit-ies are adsorbed by the getter surface but cannot be expected to diffuse into the get~er mass. Thus the adsorp-tion practically comes to an end in the state of saturation on the surface, without fully ma~ing use of the getter capacity.
In the speci~ied range of 20 to 400C the getter performs adsorption to the full, allo~ing the impurities to diffuse thoroughly therein. The apparent life of the getter is accord-ingly extended.
On the other hand, in the temperature region above 400C, the hydrogen once adsorbed by the getter can be desorbed because it has an equilibrium adsor~tion pressure higher than those of other impurities. Setting a reaction temperature in excess of 400C ls therefore undesirable.
Among the specified temperature range of 20 to 400C, a narrower ran8e of 220 to 380C is most preferred. A tempera-ture in the latter range is the most recommended reaction temperature in that it assures a high adsorption rate and thorough diffusion of the impurities into the bed of getter with no possibility of hydrogen desorption.
tEunctional Effects]
The argon gas suDerpurifier of the presen~ invention is suited for superpurifying the conventionally purified argon gas to an even higher purity. It can purify a~gon gas by passa$e therethrough to lower the concentrations of impurities in the feed, such as oxygen (2)~ carbon monoxide (C0), carbon dioxide (C02), nitrogan (~12), hydrogan (Y.2), methane (C~4), and water (H20), down to 0.01 ppm or less each. Thus it real-izes superpurification of argon gas to such a high purity that none of existing purifiers have ever achieved.
Moreover, the life of getter used in the argon g2S super-purifie. of the invention can be markedly extended and the volume of argon gas purification greatly increased by first decreasing the moisture content in the impure argon gas to 1 ppm or less by proper dehydration in accordanca with the process of the invention and then passing the dehydrated gas through the superpurifier of the invention.
~Embodiments]
The present invention will now be described in more detail below in connection with embodiments thereof.
~. :
1~00344 In the accompanylng drawings:
Figure 1 i9 a zlrconium-vanadium-iron ternary diagram of the getter alloy;
Figures 2-10 are vertical sectional views of different argon gas superpurifier apparatus; and Figure 11 is a graph illustrating the relatlonship between the moisture content in argon gas and the getter life.
- 14a -.
, ~ .
Argon gas superpurifiers embodying the invention are illustrated in Figs. 2 through 10. Fig. 2 shows an argon gas superpurifier comprising: an outer shell 3 made of a stainless steel tube (grade SUS 304 TP conforming to Japanese Industrial Standard JIS G 3448) which has an argon gas inlet 1 formed near the top and an argon gas outlet 2 near the bottom, the shell being covered with a heat insulator 12 all over the surface: a top cover 14 fitted to the top of the outer shell 3; a heater 6 inserted through the top cover 14 into the space 25 inside the shell: a bed of getter 4 packed in the space defined below the heater 6 between upper and lower buffers 16, 15; and a perforated plate 7 held by a support 13 which in turn is secured to the inner wall of the outer shell and is supporting the bed as well as the perforated plate. The getter used was ternary alloy getter of zirconium (68-72 wt%), vanadium (24-25 wt%~, and iron (5-6 wt%) manufactured and marketed by SAES Getters S.p.A., Type No. "St. 707" in the form of columnar pellets having a diameter o~ 3 mm and height of 4 mm.
The buffers, indicated at 15, 16, consist of a layer each of small alumina spheres 4 mm in diameter packed up to a height of about 5 cm. They aorrect any ununiform flow of the gas through the getter bed, keep the fine particles of the getter from scattering, and uniformalize the temperature distribution.
While the embodiment being described u~ed small alumina spheres in forming the buffers, small stainless steel balls or a stack of fine-mesh stainless steel screens may be employed instead. Also, the buffers are not always used, and a buffer=less embodiment will be described later.
In the upper portions of the buffers 15, 16 are embedded sheathes 20, 19 accommodating thermometers 18, 17, respectively.
Chromel-Alumel thermocouples are used as the thermometers.
Argon gas g to be purified is introduced into the vessel at the inlet 1, heated by the heater 6, passes through the upper buffer 16 and thence, as a uniform flow, through the bed of getter 4 where it is freed from impure gas contents by adsorption. The purified gas is led through the perforated plate 7 and taken out of the vessel at the outlet 2.
Fig. 3 and following figures show other embodiments of the invention. Throughout these figures like parts are designated by like numerals and the description is omitted or minimized each.
Fig. 3 shows a superpurifier of the same construction as the embodiment in Fig. 2 excepting that an electric heater ~ ~ is coiled round the outer shell 3 and a thermocouple 22 is installed to measure the heatsr temperature. This modification facilitates the temperature control of the getter bed.
Although Figs. 2 and 3 illustrate the embodiments in which the bed of getter 4 is directly packed in the outer shell 3, the getter bed may be separately provided as well. Fig. 4 shows an arrangement of cartridge 5 where the getter 4 and buffers ~300344 15, 16 are accommodated in a cylinder equipped with perforated plates 7 at both ends. After service for a given period, the cartridge 5 may be taken out by removing the top cover 14 and replaced by a new one. This permits more efficient operation than with the arrangements of Figs. 2 and 3.
Fig. 5 shows another embodiment 11, in which the outer shell 3 is of a double-wall construction, consisting of an inner wall 24 and an outer wall 23. The space between the walls provides a passage through which a heating medium such as steam flows from a heating medium inlet 30 to an outlet 31. A coolant may be passed instead of heating medium depending on the case. In the space defined by the inner wall is accommodated a cartridge 5 containing a getter 4, with a coil of electric heater 6 embedded in the getter. The heater 6 is connected to an external power source not shown through leads 8 (only one of them being shown) and a terminal assembly 10. The cartridge 5 has inner and outer porous walls 26 concentrically held in spaced relation by a support 13. The inner wall 24 of the outer shell is abutted at its lower end against a bottom plate with a flange 27, through which a gas inlet pipe 1 and an outlet pipe 2 extend. The pipe 2 serves also to support the cartridge 5. brgon gas 9 to be purified is fed through the inlet 1 into the outer space 25, heated thereto a proper temperature, and thence forced through the porous wall 26 into the getter layer 4 for puriflcation. the purified gas flows out into the inner space 25 and taken out via the outlet 2.
.~ , 1;~00344 Flg. 6 shows s~ill another embodiment of superpurifier 11.
The outer shell 3 ls a8ain of double-wall constructlon, with a space formed therein to circulate a heating medium introduced at an inlet 30 and discharged at an outlet 31 to perform tem-perature control. Inside the inner wall is disposed a cartridge 5 packed with a getter 4 between per,orated plates. On both sides of the cartridge are arranged heaters 6 which are connect-ed to external power sources through leads 8. Impure argon gas 9 is fed at an inlet 1, preheated by the heating medium, purified by passage through the getter mass 4'kept at a given tem?e.ature by the heate~s 6, and then take'n out at an outlet 2.
Yet another embodiment of superpurifier 11 is shown in Fig.
7. A cylind-ical outer shell 3 supports a cartrldge 5 by means of upper and lower pl2tes (not shown). The cartridge S com-prises a built-in electric heater 6,with leads 8 and a mass of getter 4 filled ln the s?ace between upper and lower pe--forated plates or buffer layers, with the heater embedded there-in, Fig. 8 shows another apparatus ll embodying the invention.
An inner cylinder is provided inside an outer shell 3 which consists of inner and outer walls and a heat insulator 12 filling up the space between the walls. A getter 4 is packed in the space between the inner cylinder and the outer shell, and an electric heater 6 coiled round a ceramic rod 36 is inserted into the central space in the inne- cylinder. Argon -` 1300344 gas 9 to be purified enters the vessel at an inlet 1, passes through the getter 4, and the purified gas leaves the vessel at an outlet 2.
Fig. 9 shows another embodiment, wh~ch is a modification of the superpurifier illustrated in Fi8. 4 and is characterized by means for recovering the heat of purified argon. Argon gas 9 to be purified enters a heat exchanger 28 installed under the purifier body, undergoes heat exchange with the outgoing gas, and the gas so preheated moves th~ough a pipe 29 surrounded by a heat insulator 12 and through an upper inlet 1 into a bed of getter 4. The purified gas is cooled in the heat exchanger and leaves the purifier at an outlet 2.
Fig. 10 shows a further embodiment. The outer shell 3 is a double-wall cylinder, and a heating medium is introduced into the spac_ between the walls at an inlet 33 and is discharged at an outlet 34. Inside the outer shell 3 is disposed a gas-tight cartrldge 35. The space in the cartridge case is parti-tioned horizontally with a plurality of perforated plates 7, and a plurality of getter beds 4 are formed, each filling-up the space formed by every other pair of the perforated plates.
The getter beds have electric heaters 6 embedded therein, one for each; and supplied with electricity through leads 37, 38.
Argon gas 9 to be purified flows in at an inlet 1 and the puri-fied gas flows out at an outlet 2.
Examples of the invention which used a specific getter composition will now be explained.
The instruments used for gas analyses in the examples were as follows:
Gas analysis instrument:
Gas chromatograph-mass spectrometer, Model TE-360B
(mfd. by Anelva Corp.) Moisture meter:
Hygrometer, Model 700 (mfd. by Panametric Co.) Surface roughness meter:
Surfcorder, Model SE-3H
(mfd. by Kosaka Laboratory Co., Ltd.) lç 1 A powdered non-evaporable getter alloy naving a weight composition of 70%Zr-24.6%V-5.4%Fe and a particle si~e of between 50 and 250 ~m is placed in the superpurifier for argon gas shown in Fig. 2. The stainle6s steel (SUS 304) cylinder has an outside diameter of 21.7 mm and an inside diameter of 17.5 mm, its length being 350 mm. The length of cylinder occupied by the getter material, including the heights, 5 mm each, of the upper and lower buffers of alumina spheres, (bed height) is 200 mm. Impure argon is introduced into the superpurifier at a temperature of 25C and a pressure of 6 kg/cm2 (gauge) at a flow rate of 0.6 ~/min. The argon flows through the non-evaporable getter bed held at 350 and issues at a pressure , , .
1~00344 ,of 4 kg/cm2 (gauge) from the outlet where its impurity level i~ measured for various gases. This impurity level ig: measur- !
ed 40 min after the start of the flow of argon.;
Table - Inlet impurity Outlet impurity Gaslevel (ppm)level (pDm?
2 0~4 0.006 N2 0 5 0.011 CH40.06 0.007 CO 0.07 0.002 C2 . 4 0.002 H20 5 0 no trace The level of impurities in the outlet gas remains .constant for 930 hours.
Example 2 Pellets were produced having a diameter of 3 mm and height of 4 mm by compression of a non-evaporable getter alloy haYing a composition and particle size identical to those of the getter alloy of Example l. The pellets were loaded into the super-purifier shown in Fig. 3. The stainless steel (SUS 304) cylind-er had an outer diameter of 89.l mm and an inner diameter of 83.l mm. Its length was 660 mm. The length of the cylinder occupied by the pellets of getter material, including the thicknesses of the upper and lower buffers (of alumina spheres~
~,~, ,, i'.
,~ ' .
- 21 - ~
' '' each having a bed height of 5 mm, was 185 mm. Impure argon was introduced into the superpurifier at a temperature of 25C
and a pressure of 4 kg/cm2 (gauge) at a flow rate of 12 ~/min.
The impure argon flowed through the non-evaporable getter bed held at a temperature of 350C by means of a spiral resist-ance heater and issued at a pressure of 3.95 kg/cm2 (gauge) from the outlet while its impurity level was measured for .
various gases. The impurity level was measured 40 min after the start of the flow of argon. The results obtained were as shown in Table II.
: . Table I~
. _ _ Inlet impurity Outlet impurity Gas level (ppm)level (ppm) 2 6.0 0.01 N2 7.5 0.02 CH4 2.0~ 0.009 CO 9.5 0.003 C2 6.3 0.003 H20 5.0 no trace The methane impurity level wa~ obtained by delibe.ately adding CH4 to the inlet gas.
The level of the impurities in the outlet gas remain.ed constant for 930 hours.
Example 3 .... . ,, ' ,: .
.
In this example the procedure of Example 2 was repeated in all respects except that the H20 impurity level waq 1 ppm and not 5 pp~.
- Table III shows the results.
, - Table III
.. i Inlet impurityOutlet impurity Gas level (P~m? level (ppm) 2 6.0 0.01 N2 7 5 0.02 CH4 2 0~ 0 009 CO 9.5 0.003 C2 6.3 0.003 H20 1.0 no trace The methane impurity level was obtained by deliberately adding CH4 to the inlet gas.
The level of the impurities in the outlet gas.remained constant for2~70 hours.
Example 4 Pellets were p~oduced exactly as in Example 2 and placed ln the cartridge shown in Fig. 4. The cartridge had an outside diameter of 80 mm, an inside diameter of 78 mm, and length of 244 mm. The same mass of pellets ~as used as in Example 2.
The cartridge was then placed in a cylinder identical to that of Example 2 (except that its length was 719 mm). Impure .
~- 23 -.~ " " ' .
.
~` `
argon was caused to flow through the superpurifier at the same inlet pressure, temperature, and flow rate as described in Example 2. The cartridge was maintained at 350C. The outlet gas pressure and composition were found to be identical to those found in Example 2 at the point 40 min after the start of the flow of argon. The level of the impurities in the outlet gas again remained constant for 930 hours.
Exam~le 5 In this example the procedure of Example 2 wa3 followed in all respects except that the inner surface roughness of the cylinder..was Ra = 0 5 ym (no.mally Ra = 2.5 ym) and the stain-less steel outlet piping (outside diameter 9.5 mm and inside diameter 7.5 mm) had an inner surface roughness of Ra = 0.2 ym.
The results shown in Table IV were ob;ained 40 min after the start of the flow of ar~on.
Table IV
Inlet impurity Ou-let impurity Gas level (pDm) level (pp~) 2 6.0 0.003 N2 7-5 0.002 CH4 2.0 0.009 CO 9.5 . 0.003 C2 6.3 Ø003 H20 5.0 no trace - - . ; - ~
- . - 24 -:
.
The leyel of the impuritles in the outlet gas remained constant for 930 hours. ~ - ¦
Example 6 ,- - ¦
. In this example the procedure of Example 5 was followed in.all respects except that the water vapor content of the argon gas to be purified was reduced to below 0.6 ppm by first passing it through a dryer bed consisting of a stainless steel (SUS
304) cylinder having an outside diameter of 89.1 mm, inside diameter of 83.1 mm, and length of 830 mm filled to a bed height of 500 mm with a molecula. sieve type 5-A. The outlet pressure from the dryer bed and therefore the inlet pressuro to the superpurifier was found to be 3.7 kg/cm2 (gaugo) and the super- -purifier outlet pressure was 3.7 kg/cm2 (gauge). This impurity level was measured 40 min after the start of the flow of argon.
The results were as shown in Table V.
Table V
Inlet impurity Outlet impurity Gas level (ppm) level (ppm) 2 6.0 0.003 .
N2 7.5 0.002 .. CH4 2.0 0.009 CO 9.5 0.003 C2 6.3 0.003 H20 0.6 no trace .~ . -- . . . .. .
.
. - - 2~ - ; .
.
The level of the impurities in the outlet gas remained constant for 2670 hours.
- - The procedure of Example 6 was repeated except that the temperature wa~ varied to see the effects of different getter temperatures. The results are given in Table VI.
.Table VI
.. .. . _ ........... .
Outlet impurity level (ppm) Inlet impurity at temperature level (ppm) 20C 200~C . 350C 400C
.. _ ....
2 6.0 0.003 0.003 0.003 0.003 N2 7.5 0.002 0.002 0.002 ! ~O . 002 CH4 2.0 2.0 0.2 0.009 0.006 C0 9.5 0.003 0.003 0.003 0.003 C2 6.3 0.003 0.003 0.003 0.003 H20 0.6 no trace no trace no trace no trace Outlet gas remained 30 hr 390 hr 2670 hr 2900 hr constant for .
Power 0 0.56 kW/h 1.04 kW/h 1.2 kW/h .. ... ....
The table indicates that excellent effects were achieved in the temperature range of 20 to 400C, especially in the .
range of 200 to 400C.
-: .
' . , :.,',` ;' I
; ' ' ' , ' -- ~300344 Examples 7, 8, 9 and 10 . Pellets were produced having a diameter of 3 mm and a length of 4 mm by compression of non-evaporable getter powder~
ha~ing weight composition indicated ln the following Table and having particle sizes of 50 - 250 ~m (150 ~m in average).
These pellets were loaded into a superpuri~ier having the same construction in the same manner as Example 2. Argon gas containing impurities was introduced into the superpurifier at a temperature of 25 C, inlet pressure of 4 kgicm2 (gauge) and a flow rate of 12 l/min.
The impurity-containing argon gas was passed through the bed of the non-evaporable getter kept at a temperature of 350 C by means of a spiral resistance heater and emerged from the outlet at a pressure of 3.95 kg/cm2 (gauge). The impurity level was measured 40 min after the start of the flow of argon and the results in Table VII were obtained.
. , ~ . .
.~ ~ . , . I
,~ .
, ~ : , . . . .
.; .
.
TABLE VII
Ex. 7 Ex, 8 Ex. 9 Ex. 10 Getter Zr(%) 65 48 46 46 alloy comp. V (%) 25 44 21 37 Fe(%) 10 8 33 17 Gas Inlet Outlet impurities imp. (ppm) (ppm) 2 6.0 0.01 0.01 0.02 0.03 N2 7.5 0.02 0.02 0.02 0.02 CH4 2.0 0.006 0.01 0.01 0.01 CO 9.5 0.003 0.003 0.008 0.005 CO2 6.3 0.003 0.003 0.006 0.006 H2O 5.0 no trace no trace no trace no trace Period of time for which outlet impurity was 780 530 900 810 constant (hrs) -The outlet impurity levels were constant for the length of time indicated in the table.
Claims (3)
1. A superpurifier for argon gas having a moisture content of 1 ppm or less, comprising an outer shell with an inlet opening for argon gas to be purified, an outlet opening for purified argon gas, and at least one getter chamber containing a getter alloy of zirconium-vanadium-iron system being disposed between the two openings, with a flow passage so formed that the argon gas that enters the inlet flows through the getter chamber and leaves the outlet, there being provided heater means for maintaining the getter alloy at its operating temperature, the getter chamber comprising at least one cartridge comprising a perforated metal container packed with the getter alloy and detachably installed in the outer shell so that it can be easily replaced by a new one, and the apparatus material with which the argon gas purified by the flow through the getter chamber comes in contact being such that the inner wall surface to contact the gas has been polished to a surface roughness (R') of 0.5 µm or less in terms of the centerline average height, the weight composition of the zirconium-vanadium-iron alloy of getter being such that the percentages by weight of the three elements, when plotted in a ternary composition diagram, come within a polygon having as its corners the points defined by:
a. 75%Zr-20%V-5%Fe;
b. 45%Zr-20%V-35%Fe; and c. 45%Zr-50%V-5%Fe.
a. 75%Zr-20%V-5%Fe;
b. 45%Zr-20%V-35%Fe; and c. 45%Zr-50%V-5%Fe.
2. A superpurifier as claimed in claim 1, wherein the getter alloy to be used in the getter chamber is in the form of pellets made by compressing and palletizing a powdered Zr-V-Fe alloy.
3. A superpurifier as claimed in claim 1 or claim 2, wherein the weight composition of the getter alloy is such that the percentages by weight of the three elements, when plotted in a ternary composition diagram, come within a polygon having as its corners the points defined by:
a. 70%Zr-25%V-5%Fe;
b. 70%Zr-24%V-6%Fe;
c. 66%Zr-24%V-10%Fe;
d. 47%Zr-43%V-10%Fe;
e. 47%Zr-45%V-8%Fe; and f. 50%Zr-45%V-5%Fe.
a. 70%Zr-25%V-5%Fe;
b. 70%Zr-24%V-6%Fe;
c. 66%Zr-24%V-10%Fe;
d. 47%Zr-43%V-10%Fe;
e. 47%Zr-45%V-8%Fe; and f. 50%Zr-45%V-5%Fe.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60-140629 | 1985-06-28 | ||
| JP60140629A JPS623008A (en) | 1985-06-28 | 1985-06-28 | Argon super purification facilities and purification process |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1300344C true CA1300344C (en) | 1992-05-12 |
Family
ID=15273137
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000512228A Expired - Fee Related CA1300344C (en) | 1985-06-28 | 1986-06-23 | Superpurifier for argon gas and process for purifying argon gas |
Country Status (10)
| Country | Link |
|---|---|
| JP (1) | JPS623008A (en) |
| KR (1) | KR930006691B1 (en) |
| BE (1) | BE904997A (en) |
| CA (1) | CA1300344C (en) |
| DE (1) | DE3621014C2 (en) |
| FR (1) | FR2584063B1 (en) |
| GB (1) | GB2177079A (en) |
| IT (1) | IT1190142B (en) |
| NL (1) | NL192260C (en) |
| SE (1) | SE463511B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104291284A (en) * | 2014-10-09 | 2015-01-21 | 昆明物理研究所 | Ultrapure argon online purification system and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1227219B (en) * | 1988-09-26 | 1991-03-27 | Getters Spa | APPARATUS AND RELATED METHOD TO REMOVE GASEOUS IMPURITIES FROM INERT GASES AND ENSURE EXTREMELY LOW HYDROGEN LEVELS |
| DE3835825C1 (en) * | 1988-10-21 | 1990-03-08 | Kernforschungsanlage Juelich Gmbh, 5170 Juelich, De | |
| DE3926015A1 (en) * | 1989-08-05 | 1991-02-07 | Messer Griesheim Gmbh | METHOD FOR THE FINE PURIFICATION OF GASES |
| IT1237944B (en) * | 1990-01-05 | 1993-06-19 | Getters Spa | METHOD FOR DETERMINING THE END OF THE USEFUL LIFE OF AN INERT GAS PURIFIER AND RELATED EQUIPMENT |
| IT1246358B (en) * | 1990-07-12 | 1994-11-17 | Getters Spa | PROCESS TO ELIMINATE IMPURITIES FROM A WATER GAS |
| IT1247110B (en) * | 1991-02-28 | 1994-12-12 | Getters Spa | PROCESS FOR THE PURIFICATION OF FLUORINATED GASES |
| IT1270875B (en) * | 1993-04-29 | 1997-05-13 | Getters Spa | HYDROGEN PURIFICATION PROCEDURE AND RELATIVE PURIFIER |
| US5238469A (en) * | 1992-04-02 | 1993-08-24 | Saes Pure Gas, Inc. | Method and apparatus for removing residual hydrogen from a purified gas |
| RU2123971C1 (en) * | 1993-04-29 | 1998-12-27 | Саес Геттерс С.П.А. | Method and apparatus for removing gas impurities from hydrogen flow |
| US6436352B1 (en) | 1993-04-29 | 2002-08-20 | Saes Getter, S.P.A. | Hydrogen purification |
| CA2117319A1 (en) * | 1993-07-12 | 1995-01-13 | John D. Baker | Method for the purification of noble gases, nitrogen and hydrogen |
| JP3462560B2 (en) * | 1994-03-04 | 2003-11-05 | 日本パイオニクス株式会社 | Hydrogen gas purification method |
| KR970008347B1 (en) * | 1994-04-12 | 1997-05-23 | 한국에너지기술연구소 | Method and apparatus for separating argon and hydrogen from purge gas of nh3 synthesis |
| AU6595096A (en) * | 1995-07-21 | 1997-02-18 | Ultrapure Systems, Inc. | Single gas purifier vessel and heat exchanger |
| DE19528784C1 (en) * | 1995-08-04 | 1996-08-29 | Inst Neuwertwirtschaft Gmbh | Inert gas purificn. to purity suitable for laser and cryo-technology |
| WO1997035805A1 (en) * | 1996-03-28 | 1997-10-02 | Saes Pure Gas, Inc. | Method and apparatus for purifying hydrogen gas |
| US6059859A (en) * | 1997-09-19 | 2000-05-09 | Aeronex, Inc. | Method, composition and apparatus for water removal from non-corrosive gas streams |
| KR100492943B1 (en) | 1997-10-15 | 2005-06-02 | 사이스 푸어 가스 인코포레이티드 | Gas Purification System with Safety Device and Method for Purifying Gases |
| WO1999019049A2 (en) * | 1997-10-15 | 1999-04-22 | Saes Pure Gas, Inc. | Semiconductor manufacturing system with getter safety device |
| US6068685A (en) * | 1997-10-15 | 2000-05-30 | Saes Pure Gas, Inc. | Semiconductor manufacturing system with getter safety device |
| US6733571B1 (en) | 1999-07-12 | 2004-05-11 | Saes Pure Gas, Inc. | Gas purification system with an integrated hydrogen sorption and filter assembly |
| IT1319667B1 (en) * | 2000-11-17 | 2003-10-23 | Getters Spa | METHOD FOR MEASURING THE CONCENTRATION OF NITROGEN IN ARGON BY MEANS OF IONIC MOBILITY SPECTROSCOPY. |
| ITMI20011193A1 (en) | 2001-06-06 | 2002-12-06 | Getters Spa | METHOD FOR MEASUREMENT USING IONIC MOBILITY SPECTROSCOPY OF THE CONCENTRATION OF WATER IN ARGON, HYDROGEN, NITROGEN AND HELIUM |
| JP4520372B2 (en) * | 2005-06-21 | 2010-08-04 | シーケーディ株式会社 | Refining cylinder and air or inert gas circulation purification device |
| DE102009024055A1 (en) * | 2009-06-05 | 2010-12-09 | Netzsch-Gerätebau GmbH | Thermal analysis device and thermal analysis method |
| US10071336B1 (en) | 2017-01-24 | 2018-09-11 | Northrop Grumman Systems Corporation | Gas purification getter construction for airborne and space applications |
| JP2018150246A (en) * | 2017-03-10 | 2018-09-27 | 国立大学法人東北大学 | Organic compound deposition method |
| CN114193028A (en) * | 2021-11-26 | 2022-03-18 | 中国核工业第五建设有限公司 | Protective gas purity improving device, protective gas purifying method and welding protection method |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB961925A (en) * | 1959-04-10 | 1964-06-24 | Western Detail Manufacturers L | Improvements relating to the purification of argon and helium gas |
| FR1539693A (en) * | 1966-06-07 | 1968-09-20 | Japan Pure Hydrogen Company Lt | Process for removing impurities from noble gases |
| BE792561A (en) * | 1972-12-11 | 1973-03-30 | Getters Spa | Gas purifier - esp for rare gases and hydrogen with regeneration system for absorber cartridges |
| IT1110271B (en) * | 1979-02-05 | 1985-12-23 | Getters Spa | NON-EVAPORABLE TERNARY GETTERING ALLOY AND METHOD OF ITS USE FOR THE ABSORPTION OF WATER, WATER VAPOR, OTHER GASES |
| IT1115156B (en) * | 1979-04-06 | 1986-02-03 | Getters Spa | ZR-FE ALLOYS FOR HYDROGEN ABSORPTION AT LOW TEMPERATURES |
| IT1198325B (en) * | 1980-06-04 | 1988-12-21 | Getters Spa | STRUCTURE AND COMPOSITION GETTERANTS, PARTICULARLY SUITABLE FOR LOW TEMPERATURES |
| JPS59107910A (en) * | 1982-12-10 | 1984-06-22 | Toshiba Corp | Method for purifying gaseous argon |
| FR2557810A1 (en) * | 1984-01-05 | 1985-07-12 | Analyseurs Epurateur Sarl Ste | Noncontaminating process for removing the traces of impurities present in rare gases heated to a high temperature |
-
1985
- 1985-06-28 JP JP60140629A patent/JPS623008A/en active Granted
-
1986
- 1986-06-23 DE DE3621014A patent/DE3621014C2/en not_active Expired - Lifetime
- 1986-06-23 CA CA000512228A patent/CA1300344C/en not_active Expired - Fee Related
- 1986-06-23 FR FR8609025A patent/FR2584063B1/en not_active Expired - Lifetime
- 1986-06-26 BE BE2/61003A patent/BE904997A/en not_active IP Right Cessation
- 1986-06-26 KR KR1019860005145A patent/KR930006691B1/en not_active IP Right Cessation
- 1986-06-26 GB GB08615618A patent/GB2177079A/en active Granted
- 1986-06-27 NL NL8601691A patent/NL192260C/en not_active IP Right Cessation
- 1986-06-27 SE SE8602869A patent/SE463511B/en not_active IP Right Cessation
- 1986-06-27 IT IT20962/86A patent/IT1190142B/en active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104291284A (en) * | 2014-10-09 | 2015-01-21 | 昆明物理研究所 | Ultrapure argon online purification system and method |
| CN104291284B (en) * | 2014-10-09 | 2016-06-22 | 昆明物理研究所 | A kind of ultrapure argon in-line purification system and method |
Also Published As
| Publication number | Publication date |
|---|---|
| KR930006691B1 (en) | 1993-07-22 |
| SE463511B (en) | 1990-12-03 |
| IT8620962A1 (en) | 1987-12-27 |
| GB2177079A (en) | 1987-01-14 |
| SE8602869D0 (en) | 1986-06-27 |
| DE3621014C2 (en) | 1995-05-11 |
| DE3621014A1 (en) | 1987-01-08 |
| NL192260B (en) | 1996-12-02 |
| BE904997A (en) | 1986-10-16 |
| IT1190142B (en) | 1988-02-10 |
| GB8615618D0 (en) | 1986-07-30 |
| GB2177079B (en) | 1989-12-20 |
| SE8602869L (en) | 1986-12-29 |
| FR2584063A1 (en) | 1987-01-02 |
| KR870000239A (en) | 1987-02-17 |
| NL8601691A (en) | 1987-01-16 |
| JPS623008A (en) | 1987-01-09 |
| JPH0456771B2 (en) | 1992-09-09 |
| IT8620962A0 (en) | 1986-06-27 |
| NL192260C (en) | 1997-04-03 |
| FR2584063B1 (en) | 1990-12-21 |
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