Gas separation: processes – With control responsive to sensed condition – Pressure sensed
Reexamination Certificate
1999-04-30
2001-03-13
Spitzer, Robert H. (Department: 1724)
Gas separation: processes
With control responsive to sensed condition
Pressure sensed
C095S023000, C095S117000, C095S112000, C096S109000, C096S113000, C096S117000, C096S130000, C096S144000
Reexamination Certificate
active
06200365
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a device for continuously fractionating a gas by adsorption, a method for continuous adsorption fractionation with processor-controlled testing of an operating capability of an adsorption drier system, and a device having an in-service testing device in a processor-controlled adsorption drier system in which regeneration is performed by a flow of regeneration gas.
Adsorption fractionation is used in particular when drying compressed air. Compressed air is the energy medium used in production processes. Modern production methods and processing operations are placing ever higher demands on the requirements for compressed air. These days, it is no longer sufficient to provide a specified quantity of compressed air since the compressed air must also conform to specified purity criteria. That being the case, the need to be able to produce dry, clean compressed air has assumed a certain amount of importance. In the case of adsorption fractionation, water molecules from the air tend to adhere to an adsorbent.
A device for adsorption fractionation is described, for example, in a document entitled “Trockene Druckluft. Mit Sicherheit ein reiner Gewinn”, published by Ultrafilter GmbH, Büssingstra&bgr;e, D-42781 Haan, Germany, and in an English language version entitled “Dry Compressed Air The Cleanest Solution—Guaranteed” published by Ultrafilter International. The German language document is known by reference T.997.004.03.D 10.95 and the English language document is known by reference T 997.005 03 GB/D 6/96. With that device, it is possible to dry compressed air on a continuous basis. To that end, the device has two containers filled with adsorbent. When the device is operating, moist air is circulated through one of the containers, where it is dried accordingly, while some of the dried air is simultaneously fed into the other container where the adsorbent is regenerated in a direction opposite that of the flow, i.e. it picks up water molecules from the adsorbent. The air which is moistened again in that way is expanded during regeneration and discharged to the ambient environment.
Another device used for adsorption fractionation with gases is described in European Patent Application 0 168 336 A2, corresponding to U.S. Pat. No. 4,631,073. That publication contains a wealth of information giving details of the adsorption technique and some relating to process control.
The set-up costs for building such devices represent a considerable proportion of the costs involved. Accordingly, they will depend on the cost of the number of individual components to be assembled and the cost of manufacturing them. Furthermore, additional costs are also incurred if in-service testing has to be conducted on the device through the use of a function monitoring system. The components needed for that purpose also have to be mounted on the system, which means that the number of components will essentially depend on the type of in-service testing being used. Various techniques used for that purpose are known from the prior art, some more complex than others, and are configured to meet certain safety specifications.
A sampling device is known from U.S. Pat. No. 4,127,395, through the use of which a moisture sensor can be tested for operating capability. If an indicator shows that the moisture sensor has failed, the adsorption drier system can be automatically switched to time-controlled operation. Operation of that sampling device requires several additional lines to be run to the adsorption drier system. Another device is disclosed in U.S. Pat. No. 4,504,286, along with a method for controlling the switching function between two containers of adsorbent, whereby switching still continues even if the actual moisture monitoring function fails. That is a processor-controlled system which compares the maximum storage capacity of a bed of adsorbent with the time integer of the water flowing through it. A moisture analyzer is used in conjunction with other components to measure the proportion of water being circulated.
In practice, it has often been found while maintenance work is being carried out on supposed disruptions in the adsorption drier system, that it is necessary to check if the regeneration air is being discharged from alternating sides, either acoustically or by observing two manometers mounted on the containers for the adsorbents. Possible sources of failure in that area are the shuttle valves, discharge valves and overflow passages for regeneration air. However, it is not possible to give a more accurate plant-related diagnosis of the fault or even the source of the fault, particularly in older adsorption drier systems. Consequently, because of the type of testing, suspected disruptions in the adsorption drier plant are not further investigated unless there has already been a perceptible degradation in the quality of the compressed air being delivered.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to overcome the hereinafore-mentioned disadvantages of the heretofore-known methods and devices of this general type and to provide a device for operating a continuous process of adsorption fractionation for a gas, which is low in terms of manufacturing and assembly requirements and in particular enables integration of a safe in-service testing system that does not impose any significant additional requirements. The intention is also to provide an in-service testing device requiring few components and therefore having a low requirement in terms of manufacturing and assembly so that it can be integrated in a continuous adsorption fractionation device at a low cost. Another objective of the invention is to provide a method for safely testing the operating capability of an adsorption drier plant which can also be retrofitted, without incurring costs that are too excessive, on a continuous adsorption fractionation device and in particular one which can be integrated in order to ensure that in-service testing is highly reliable. In particular, the device, the in-service testing device and the method are intended to be so adapted to one another that their respective advantages in terms of low component requirements and manufacturing input can be judiciously combined with one another.
With the foregoing and other objects in view there is provided, in accordance with the invention, a device for continuously fractionating a gas by adsorption, in particular for drying or cleaning air, comprising at least one pair of containers including a first and a second container; a first shuttle valve and a second shuttle valve; a common gas inlet branching off through the first shuttle valve to the two containers; a common gas outlet branching off through the second shuttle valve to the two containers; a bypass line connecting the two containers in the vicinity of the gas outlet; a bypass outlet connected to the two containers in the vicinity of the gas inlet for individually shutting off the two containers; in order to increase the number of containers, at least one extruded container body is provided having mutually spaced apart outer surfaces, each container body having at least one container cavity and each container body having at least one line cavity, the at least one container cavity having two cavity openings in the outer surfaces; and a common pre-fabricated functional block into which the gas inlet, the gas outlet and the bypass outlet feed, the gas inlet and the gas outlet to and from the containers, the first and second shuttle valves and other components forming a line switching circuit integrated in the functional block.
The functional block may be pre-fabricated in a factory and tested so that no assembly steps or final assembly of the device will be required at the operating site. Desired ranges for a measurement value to be applied to a method of in-service testing can also be stored in it beforehand.
One advantage of the present invention is that the same functional blocks with differing layouts of containers re
Behrendt Matthias
Eimer Klaus
Patzig Dieter
Schuster Hans-Michael
Greenberg Laurence A.
Lerner Herbert L.
Spitzer Robert H.
Stemer Werner H.
Ultrafilter International AG
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