Gas separation: apparatus – Apparatus for selective diffusion of gases – Plural separate barriers
Reexamination Certificate
2001-03-01
2003-04-01
Spitzer, Robert H. (Department: 1724)
Gas separation: apparatus
Apparatus for selective diffusion of gases
Plural separate barriers
C095S052000, C096S010000
Reexamination Certificate
active
06540818
ABSTRACT:
TECHNICAL FIELD TO WHICH THE INVENTION PERTAINS
The present invention relates to a hollow fiber membrane dehumidification device that dehumidifies compressed air by means of hollow fiber membranes.
PRIOR ART
Since the compressed air that is employed for a drive source for all kinds of devices becomes the cause of early corrosion of the devices when it contains a large amount of moisture, ordinarily it is employed as the drive source after it has been dehumidified by a dehumidifier. A freezing type and an adsorption type are generally adopted for this kind of dehumidification device, but in recent years hollow fiber membrane type dehumidification devices have attracted attention based on the facts that they have been miniaturized, made lighter, and had their maintenance operations simplified.
Previously, the above-mentioned hollow fiber membrane dehumidification devices involved as shown in
FIG. 4
the positioning of multiple hollow fiber membranes (
52
) in a housing chamber (
53
) inside a housing (
51
), and the sending in of compressed air from one end of these hollow fiber membranes (
52
), and while this compressed air was caused to flow through the inside the moisture in the compressed air was selectively discharged to the housing chamber (
53
) owing to the pressure difference between the partial pressure of the water vapor of the compressed air and the partial pressure of the water vapor of the outside housing chamber. Then, after the compressed air has been made into dehumidified air by dehumidifying it in this manner, it is discharged from the other end of the hollow fiber membranes, and made into a drive source by emitting it to the air tank at the rear stage, etc.
In addition, a portion of the dehumidified air that has been discharged is extracted as purged air by an orifice (
55
), and in addition to its being caused to flow back to the housing chamber (
53
) through a reflux route (
54
) the purged air and the water vapor inside the housing chamber (
53
) is emitted to the atmosphere through a through hole. Then, by maintaining the partial pressure of the water vapor inside the housing chamber (
53
) in a low state by the reflux of purged air and the emission of water vapor, it has been composed such that it is usually possible to dehumidify compressed air with an excellent dehumidification function.
PROBLEMS THAT THE INVENTION ATTEMPTS TO SOLVE
However, in the above-mentioned prior composition, just as in cases where the inner partitions of the hollow fiber membranes (
52
) and the housing (
51
) have been completely rent asunder by changes with the passage of time, when there arises abnormal operations in which a large volume of dehumidified air and high pressure air leak out to the housing chamber (
53
) by a route other than the reflux route (
54
), this air is emitted to the atmosphere together with the purged air through the through hole, so the pressure of the dehumidified air declines to a large extent. Therefore, it becomes impossible to emit the dehumidified air to the air tank at the rear stage, etc., at a pressure above that prescribed, so there is the problem that its reliability as a dehumidification device built into an air source system is low.
Therefore, the purpose of the present invention is the provision of a hollow fiber membrane type dehumidification device that can emit dehumidified air towards an air tank at the rear stage, etc. at a pressure above that prescribed even in the event that there arises abnormal operation wherein a large volume of dehumidified air leaks out to the housing chamber (
53
).
MEANS FOR SOLVING THE PROBLEMS
In order to solve the above-mentioned problems, the invention in claim 1 is a hollow fiber membrane dehumidification device characterized by the fact that it is equipped with (a) a housing chamber that has been opened to the atmosphere through a through hole; (b) a hollow fiber membrane that has been provided in said housing chamber, and that causes the compressed air that is supplied from one end to the inside to flow through, and at the same time discharges said compressed air from the other end as dehumidified air by discharging the moisture in said compressed air to the outside housing chamber; (c) a reflux route that causes a portion of the dehumidified air that has been dehumidified by said hollow fiber membrane to flow back to said housing chamber as purged air; (d) a first orifice provided on said reflux route; and (e) a second orifice that is provided on said reflux route and that possesses an opening diameter that is larger than that of the first orifice.
According to the above-mentioned composition, the majority of the dehumidified air that has been dehumidified by the hollow fiber membranes is sent into the air tank, while a portion of it is caused to flow back to the housing chamber through the medium of the first orifice of the reflux route as purged air, and after it is used for the dehumidification of the compressed air that flows through the hollow fiber membranes in this housing chamber it is emitted to the atmosphere through the medium of the second orifice of the through route.
At this time, since at the time of ordinary operation the second orifice provided on the through route that serves as the emission side from the housing chamber to the atmosphere possesses an opening diameter that is greater than that of the first orifice provided on the reflux route that serves as the supply side to the housing chamber, the volume of purged air emitted towards the housing chamber ends up being greater than the amount that flows in due to reflux. Owing to this, the pressure of the purged air in the housing chamber ends up being a lower pressure than the pressure of the compressed air that flows through the hollow fiber membranes, so the partial pressure of the water vapor inside the hollow fiber membranes becomes higher than the partial pressure of the water vapor of the outside housing chamber, and as a consequence it becomes possible to accumulate pressure with an excellent dehumidification function by sending compressed air into the air tank.
On the other hand, in those cases where there arises abnormal operation in which a large volume of high pressure air and dehumidified air leaks to the housing chamber owing to such reasons as the hollow fiber membranes being completely rent asunder by the changes with the passage of time, etc., the housing chamber is maintained at a pressure above that prescribed. The result of this is that even if high pressure air and dehumidified air has leaked to the housing chamber it is possible to send the dehumidified air reliably to the air tank with the pressure above that prescribed in this housing chamber.
In addition, the invention in claim
2
, being the hollow fiber membrane dehumidification device recorded in claim
1
, is characterized by the fact that said second orifice ensures that the pressure of the compressed air that is emitted to the rear stage of said dehumidification device is within the specified range when the compressed air supplied to one end of said hollow fiber membrane has flowed directly into said housing chamber without flowing back through said reflux route.
According to the above-mentioned composition, at the times of both normal operation and abnormal operation, it is possible to emit dehumidified air whose pressure is above that prescribed to an air tank reliably within the range of the practical pressure fluctuations of compressed air.
PREFERRED EMBODIMENT OF THE INVENTION
There follows below an explanation of the preferred embodiment of the present invention based on
FIG. 1
to FIG.
3
.
The hollow fiber membrane type dehumidification device for the embodiment of the present invention is employed by incorporating it into the air source system of such things as railway cars, large automobiles, ships, and other machine equipment. This air source system possesses, in order from the upper stage to the rear stage, as shown in
FIG. 1
, (a) an air compressor (
1
) that is a compressor employing the atmosphere as compressed air; (b) an after
James Ray & Associates
Nabco, LTD
Spitzer Robert H.
LandOfFree
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