Gas separation: apparatus – Apparatus for selective diffusion of gases – Plural separate barriers
Reexamination Certificate
1999-05-18
2001-05-22
Spitzer, Robert H. (Department: 1724)
Gas separation: apparatus
Apparatus for selective diffusion of gases
Plural separate barriers
C096S004000
Reexamination Certificate
active
06235087
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a device for supplying a purified gas to a plant which is purged using this purified gas, comprising a feed line which is connected, on the one hand, to a source of the purified gas and, on the other hand, to an inlet of the plant.
2. Description of the Related Art
A wide variety of plants, for example in the fabrication of electronic components, require the use of filtered and inert atmospheres.
For example, silicon wafers intended to carry microelectronics circuits are stored in an enclosed space with a nitrogen atmosphere which has only a few ppm of impurities, consisting in particular of oxygen. One example for storing and transporting wafers is described in U.S. Pat. No. 5,644,855.
Given that the purified gas is progressively contaminated with impurities, it is necessary to replenish the nitrogen atmosphere in the enclosed space as time progresses. This replenishment is generally carried out by supplying the enclosed space constantly with a certain flow of purified nitrogen coming from a purified gas source, and by discharging the contaminated nitrogen.
However, the cost of purified nitrogen is very high, so that replenishing the inert atmosphere in the storage space represents a significant contribution to its running costs.
Furthermore, these known plants also have the drawback that, if there is a fault with the source of the purified gas, all parts of the plant which are purged will be affected by this, which in the aforementioned example may make it necessary to discard all the silicon wafers stored.
Systems for separating gases using a membrane, which are applicable to electronics or other fields, are known in particular from EP-A-754 487 as well as U.S. Pat. Nos. 5,308,382, 5,240,471, 5,290,341, 5,378,439 and 5,383,957.
The object of the invention is to overcome these various drawbacks by providing a device for supplying a purified gas, in particular nitrogen, to a plant such as, for example, a wafer storage space for microelectronics, which makes it possible on the one hand to reduce the running cost of such a plant and, on the other hand, to give the plant some degree of autonomy from the source.
SUMMARY OF THE INVENTION
To this end, the invention relates to a device for supplying a purified gas to a plant which is purged using this purified gas, comprising a feed line which is connected, on the one hand, to a source of the substantially pure gas and, on the other hand, to an inlet of the plant, the purified gas being contaminated with impurities on passing through the plant, characterized in that it furthermore comprises a line which is intended to recover the contaminated gas at the outlet of the plant and is connected to the feed line and, arranged one after the other downstream of where the recovery line is connected to the feed line, a compressor and means for separating the impurities from the contaminated gas by permeation in order to supply a purified gas to the plant.
The plant according to the invention may have one or more of the following characteristics:
the permeate obtained by the separation means principally consists of impurities,
the permeate obtained by the separation means principally consists of the purified gas,
the separation means comprise, arranged in series, a first and a second permeater, the permeate of one of the permeaters principally consisting of impurities whose permeation rate is higher than that of the purified gas to be supplied to the plant, and the permeate of the other principally consisting of the purified gas,
the separation means comprise, for each permeater, a line for discharging the impurities, and a valve which is arranged in this impurity discharge line and is controlled by means for detecting the residual level of impurities in the purified gas at the outlet of the permeater,
it furthermore comprises, arranged in the feed line upstream of where the recovery line is connected to the feed line, means for buffer storage of the substantially pure gas,
the buffer storage means comprise a reservoir for storing the pure gas under pressure, a non-return valve arranged in the feed line upstream of the storage reservoir, and a regulating valve which is arranged in the feed line downstream of the storage reservoir and is controlled by the pressure of the contaminated gas at the outlet of the plant.
REFERENCES:
patent: 4857082 (1989-08-01), DiMartino, Sr. et al.
patent: 5053058 (1991-10-01), Mitariten
patent: 5063753 (1991-11-01), Woodruff
patent: 5102432 (1992-04-01), Prasad
patent: 5152966 (1992-10-01), Roe et al.
patent: 5240471 (1993-08-01), Barbe et al.
patent: 5266101 (1993-11-01), Barbe et al.
patent: 5290341 (1994-03-01), Barbe
patent: 5308382 (1994-05-01), Prasad
patent: 5332547 (1994-07-01), Olson et al.
patent: 5378283 (1995-01-01), Ushikawa
patent: 5378439 (1995-01-01), Delobel et al.
patent: 5383957 (1995-01-01), Barbe et al.
patent: 5538536 (1996-07-01), Fuentes et al.
patent: 5644855 (1997-07-01), McDermott et al.
patent: 5649995 (1997-07-01), Gast, Jr.
patent: 5676736 (1997-10-01), Crozel
patent: 5785741 (1998-07-01), Li et al.
patent: 5858065 (1999-01-01), Li et al.
patent: 0 585 158 (1994-03-01), None
patent: 0 754 487 (1997-01-01), None
Chevalier Gilbert
DuPont Pascal
Burns Doane Swecker & Mathis L.L.P.
L'Air Liquide, Societe Anonyme pour l'Etude et l'
Spitzer Robert H.
LandOfFree
Device for supplying a purified gas to a plant purged using... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for supplying a purified gas to a plant purged using..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for supplying a purified gas to a plant purged using... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2496930