# Patent

## Title
Apparatus for use in pressure and temperature swing adsorption processes

## Abstract

A method for delivering at least two working gases from a common air supply comprising the steps of depleting the air in O.sub.2 in order to obtain a first gas mixture having an O.sub.2 content less than or equal to t1; delivering at least a portion of this first gas mixture as a first working gas; depleting another portion of this first gas mixture in O.sub.2 in order to obtain the second gas mixture having an O.sub.2 content less than or equal to t2, wherein t1 is greater than t2; and delivering the second gas mixture as a second working gas.

## Background
Field of the Invention

The present invention relates to a method for delivering at least two working gases, having different limiting O.sub.2 contents, from a common air supply.

Many industrial processes require the use of N.sub.2 /O.sub.2 working atmospheres having different limiting O.sub.2 contents. Such processes are sometimes employed on the same industrial site.

This is the case, for example, in the electronics industry in which the reflow-soldering and wave-soldering processes for assembling electronic components make use of N.sub.2 /O.sub.2 atmospheres typically having limiting O.sub.2 contents of respectively a few % in one case and a few thousand ppm in the second case.

Depending on the limiting O.sub.2 content to be obtained, several means for depleting the air from the supply in O.sub.2 may be used: cryogenic distillation, adsorption of oxygen on a catalytic bed, combination of oxygen with another gas, or selected permeation through a membrane.

In general, in order to deliver N.sub.2 /O.sub.2 working atmospheres of different limiting O.sub.2 contents for the implementation of industrial processes on the same site, either separate delivery means are used, thus multiplying the working-gas delivery devices, or a single atmosphere feed is used for all the processes, thus resulting in superfluous depletion in O.sub.2 for some of the processes. Such solutions are not optimal.

The object of the invention is to remedy the abovementioned problem and, in particular, to provide an economic method for delivering working gases having different limiting O.sub.2 contents from a common air supply.

For this purpose, the subject of the invention is a method for delivering at least two working gases from a common air supply, the limiting O.sub.2 contents, respectively t1 and t2, of which gases are such that t1 is greater than t2, characterized in that: having an O.sub.2 content less than or equal to t1; gas; to obtain a second gas mixture having an O.sub.2 content less than or equal to t2; and

Depending on the particular embodiments, the method may include one or more of the following characteristics: depletions in O.sub.2 is recovered for the purpose of using this oxygen-containing product; depletion in O.sub.2 ; 10%) and t.sub.2 is less than or equal to 1% (and preferably between 100 ppm and 5000 ppm).

The subject of the invention is also a device for delivering at least two working gases, having different limiting O.sub.2 contents, from a common air supply, characterized in that it comprises: air supply; outlet of the first means of depletion; outlet of the first means of depletion; and outlet of the second means of depletion.

Depending on particular embodiments, the device may include one or more of the following characteristics: mixtures directly to the outlet of the means of depletion; and the device comprises means connecting this outlet to a unit for consuming this oxygen-containing product; means of depletion; depletion in O.sub.2 by combination of the O.sub.2 with another gas or by adsorption of the O.sub.2 on a catalytic bed or else by selective permeation through a membrane.

Finally, the subject of the invention is a plant for the assembly of electronic components, comprising a chamber for storing electronic components in a controlled atmosphere, the limiting O.sub.2 content of the atmosphere in this chamber being t.sub.1, and at least one machine for assembling the components in a controlled atmosphere, the limiting O.sub.2 content of the atmosphere in this machine being t.sub.2 <t.sub.1, the plant being characterized in that it comprises a device for delivering working gases, which feeds said chamber with said first gas mixture and said assembly machine with said second gas mixture.

The invention will be better understood on reading the description which follows, given solely by way of example, and with reference to the appended figures.

FIG. 1 shows diagrammatically a device for delivering working gases according to the invention, which feeds two user stations (9, 11) whose requirements in working gas differ;

FIG. 2 shows schematically another device for delivering working gases according to the invention, which feeds three user stations (7, 9, 11) whose requirements in working gas differ.

The device in FIG. 1 comprises first means 1 of depletion in O.sub.2 by selective permeation through a polymer membrane and second means 3 of depletion in O.sub.2 by catalytic combination of the latter with hydrogen.

This device is intended to deliver the working atmospheres for a reflow-soldering oven 9 and for a wave-soldering machine, forming part of a plant for the assembly of electronic components.

Before their assembly in the reflow oven 9 or in the wave-soldering machine 11, the electronic components are stored in the electronic-component storage chamber 7 located upstream of the means 1.

The chosen working atmospheres at the various points in the plant shown are as follows: chamber 7, this air having beforehand been filtered, removed of any dust and dried, using the apparatus 15; depleting the air coming from the source 13 in O.sub.2 by selective permeation through a polymer membrane, and delivering, at their residual outlet 2, an N.sub.2 /O.sub.2 mixture having in this case an O.sub.2 content close to 1%. This mixture feeds, on the one hand, an electronic-component reflow-soldering oven 9 directly and, on the other hand, an inlet 4 of the second means 3 of depletion in O.sub.2 ; catalytically combining oxygen with hydrogen in order to form water. These means 3 comprise a dryer making it possible to condense the water produced, and removed at 6, and to obtain a gas depleted in O.sub.2 at their outlet 10.

The N.sub.2 /O.sub.2 mixture produced at the outlet 10 of the means 3 has an O.sub.2 content close to 50 ppm, feeding an electronic-component wave-soldering machine 11 directly.

The permeate mixture obtained at the second outlet 14 of the first means 1 of depletion in O.sub.2 is superoxygenated air having an O.sub.2 content close to 25%, used for feeding a superoxygenated-air-consuming unit 17.

This unit 17 may, for example, be an oven and may be located on the same industrial site as the plant for assembling the electronic components. The superoxygenated air obtained may thus be used to feed the flames of burners intended to melt the glass involved in the manufacture of television tubes.

The device according to the invention therefore makes it possible, by successive depletions of the air from the source 13 in O.sub.2, to feed with working gases processes whose limiting O.sub.2 contents are very different.

The method for delivering working gases employed is particularly economical since, on the one hand, it uses common means of depletion of O.sub.2 to deliver working gases of different limiting O.sub.2 content and, on the other hand, it eliminates the superfluous depletions of O.sub.2.

More briefly, FIG. 2 illustrates a case in which first (1A), second (1B) and third (5) means of depletion in oxygen are used, these being, respectively: outlet 2, an N.sub.2 /O.sub.2 gas mixture having a residual oxygen content close to 10%, so as to feed a component-storage chamber 7 with this mixture; outlet 10, an N.sub.2 /O.sub.2 gas mixture having a residual oxygen content typically ranging from 1 to 3%, so as to feed a component reflow-soldering oven 9 with this mixture; in order to form water. These means 5 comprise a dryer making it possible to condense the water produced, and removed at 8, and to obtain at their outlet 12 an N.sub.2 /O.sub.2 mixture whose O.sub.2 content is close to 50 ppm, feeding an electronic-component wave-soldering machine 11 directly.

## Claims

1. A method for delivering at least two working gases from a common air supply, in an electronic component plant comprising the steps of: an O.sub.2 content less than or equal to t1; gas to a chamber for storing electronic components in a controlled first atmosphere; obtain a second gas mixture having an O.sub.2 content less than or equal to t2, wherein t1 is greater than t2; and machine for assembling the components in a controlled second atmosphere.

2. The method according to claim 1, comprising employing said first and second gas mixtures themselves as the working gases.

3. The method according to claim 1, further comprising recovering at least one oxygen-enriched product resulting from one of said steps of depleting O.sub.2 for further use.

4. The method according to claim 3, wherein said oxygen-enriched product is superoxygenated air coming from the first step of depleting O.sub.2.

5. The method according to claim 1, wherein t1 is greater than or equal to 0.5%.

6. The method according to claim 5, wherein t1 is between 0.5% and 10%, and t2 is between 100 ppm and 5000 ppm.

7. The method according to claim 5, wherein t1 is between 0.5% and 10%.

8. The method according to claim 1, wherein t2 is less than or equal to 1%.

9. The method according to claim 8, wherein t2 is between 100 ppm and 5000 ppm.

10. A method for delivering at least two working gases from a common air supply, the method comprising the steps of: order to obtain a first gas mixture having an O.sub.2 content less than or equal to t1; gas; second O.sub.2 depletion process in order to obtain a second gas mixture having an O.sub.2 content less than or equal to t2, wherein t1 is greater than t2; and wherein said first O.sub.2 depletion process and said second O.sub.2 depletion process cannot both be a process wherein O.sub.2 is depleted by selectively permeating O.sub.2 through a membrane.

11. The method of claim 10, wherein said first and said second O.sub.2 depletion processes are selected from the group consisting of a process wherein O.sub.2 is depleted by combining O.sub.2 with another gas, a process wherein O.sub.2 is depleted by absorbing O.sub.2 on a catalytic bed, and a process wherein O.sub.2 is depleted by being selectively permeated through a membrane.

12. A device for delivering at least first and second working gases, comprising different limiting O.sub.2 contents, from a common air supply, comprising: wherein said at least first and second means for depleting the air in O.sub.2 do not both constitute a means wherein O.sub.2 is depleted by being selectively permeated through a membrane; air supply; outlet of the first means of depletion; first means of depleting; and second means of depletion.

13. The device according to claim 12, wherein the means for producing the working gases are means for tapping off the gas mixtures directly to the outlet of the means of depletion.

14. The device according to claim 12, wherein the means of depleting in O.sub.2 have an outlet for an oxygen-enriched product, and the device further comprises means connecting this outlet to a unit for consuming this oxygen-enriched product.

15. Device according to claim 14, wherein the oxygen-enriched product is superoxygenated air coming from the first means of depleting.

16. Device according to claim 12, wherein the first and/or second means of depleting in O.sub.2 are means of depleting in O.sub.2 by combination of the O.sub.2 with another gas or by absorption of the O.sub.2 on a catalytic bed or by selective permeation through a membrane.

17. The device according to claim 12, wherein said first and said second means for depleting the air in O.sub.2 are selected from the group consisting of a means wherein O.sub.2 is depleted by combining O.sub.2 with another gas, a means wherein O.sub.2 is depleted by absorbing O.sub.2 on a catalytic bed, and a means wherein O.sub.2 is depleted by being selectively permeated through a membrane.

18. A plant for the assembly of electronic components, comprising: atmosphere, wherein said atmosphere has a limiting O.sub.2 content in this chamber of t1, and atmosphere, wherein said second atmosphere has a limiting O.sub.2 content of t.sub.2 <t.sub.1, and first gas mixture, as a first working gas, and said assembly machine with a second gas mixture, as a second working gas; wherein said device for delivering working gases comprises: air supply; outlet of the first means of depletion; first means of depleting; and second means of depletion.

19. A device for delivering at least first and second working gases, comprising different limiting O.sub.2 contents, from a common air supply, comprising: wherein said first and second O.sub.2 depleting devices do not both operate using a process wherein O.sub.2 is depleted by selectively permeating O.sub.2 through a membrane; depleting device; outlet of the first O.sub.2 depleting device; communication with a conduit which delivers said first working gas to a first desired application; and with a conduit which delivers said second working gas to a second desired application.

20. The device according to claim 19, wherein said first and/or second O.sub.2 depleting device comprises a membrane separation device, a catalytic adsorption device, or a reactor for reacting O.sub.2 with another gas.

21. The device according to claim 19, wherein said first application is a chamber for storing electronic components in a controlled atmosphere.

22. The device according to claim 19, wherein said second application is a machine for assembling electronic components in a controlled atmosphere.

23. A plant for the assembly of electronic components, the plant comprising: atmosphere, wherein said atmosphere has a limiting O.sub.2 content in this chamber of t1; atmosphere, wherein said second atmosphere has a limiting O.sub.2 content of t2<t1; gas mixture, as a first working gas, and said assembly machine with a second gas mixture, as a second working gas; wherein said device for delivering working gases comprises: wherein said at least first and second means for depleting the air in O.sub.2 do not both constitute a means wherein O.sub.2 is depleted by being selectively permeated through a membrane; air supply; outlet of the first means of depletion; first means of depleting; and second means of depletion.

24. The plant according to claim 23, wherein said first and said second means for depleting the air in O.sub.2 are selected from the group consisting of a means wherein O.sub.2 is depleted by combining O.sub.2 with another gas, a means wherein O.sub.2 is depleted by absorbing O.sub.2 on a catalytic bed, and a means wherein O.sub.2 is depleted by being selectively permeated through a membrane.