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US3940860A Expired / Lapsed US ⏱️ 0.0 years remaining

Method and apparatus for drying a hygroscopic material possessing fibrous structure

Assignee: Pretema AG
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Filing: 1974-12-13
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Granted: 1976-03-02
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Expires: 1994-12-13
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Abstract

Abstract A method of, and apparatus for, drying a hygroscopic material possessing a fibrous structure, such as wood and cardboard, which is impinged in a closed drying compartment by a flowing drying medium, which is heated and demoisturized, and wherein after the introduction of the material to be dried into the drying compartment the drying medium is heated to a predetermined temperature and maintained during the entire drying process at such temperature. The drying medium is moved past the material to be dried in order to remove from such material the expelled moisture. From the point in time of reaching the aforementioned predetermined temperature and a fixed value of the moisture content of the drying medium, calculated after the course of a certain time duration, the drying medium is demoisturized for such length of time until its moisture content has dropped to the aforementioned fixed value. And thereafter in alternate sequence there is interrupted the dehumidification or demoisturizing of the drying medium during the entire predetermined time duration from the point in time of the momentary attainment of the mentioned fixed value of the moisture content of the drying medium, and finally after expiration of the mentioned predetermined time duration the drying medium is demoisturized for such length of time until its moisture content has reached the aforementioned fixed value.

Inventors

  • 👤 Josef Unterreiner

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-30 06:36
CPC Classifications
F; F26; F26B; F26B21/00; F26B21/30; F26B21/33; F26B21/20; F26B2210/00; F26B2210/16

Claims Analysis

Total Claims: 4
Claim 1
Independent Claim 215 words
A method of drying hygroscopic material possessing fibrous structure, such as wood and cardboard, and which is impinged in a closed drying compartment by a flowing drying medium, which is heated and demoisturized, the improvement comprising the steps of: after the introduction of the material to be dried into the drying compartment heating the drying medium to a predetermined temperature, maintaining throughout the entire drying process the drying medium at this predetermined temperature, moving the drying medium past the material to be dried in order to take-up the moisture expelled by such material, and from the point in time when there is reached the aforementioned predetermined temperature and a fixed value of the moisture content of the drying medium, and after expiration of a predetermined time duration, demoisturizing the drying medium for such length of time until its moisture content has dropped to the aforementioned fixed value, thereafter in alternate sequence interrupting the demoisturizing of the drying medium during the entire predetermined time duration from a point in time when there is momentarily attained the aforementioned fixed value of the moisture content of the drying medium, and then after expiration of the aforementioned predetermined time duration demoisturizing the drying medium for such length of time until its moisture content has reached the aforementioned fixed value.
Claim 2
Independent Claim 215 words
A method of drying hygroscopic material possessing fibrous structure, such as wood and cardboard, and which is impinged in a closed drying compartment by a flowing drying medium, which is heated and demoisturized, the improvement comprising the steps of: after the introduction of the material to be dried into the drying compartment heating the drying medium to a predetermined temperature, maintaining throughout the entire drying process the drying medium at this predetermined temperature, moving the drying medium past the material to be dried in order to take-up the moisture expelled by such material, and from the point in time when there is reached the aforementioned predetermined temperature and a fixed value of the moisture content of the drying medium, and after expiration of a predetermined time duration, demoisturizing the drying medium for such length of time until its moisture content has dropped to the aforementioned fixed value, thereafter in alternate sequence interrupting the demoisturizing of the drying medium during the entire predetermined time duration from a point in time when there is momentarily attained the aforementioned fixed value of the moisture content of the drying medium, and then after expiration of the aforementioned predetermined time duration demoisturizing the drying medium for such length of time until its moisture content has reached the aforementioned fixed value.
Claim 3
Independent Claim 133 words
An apparatus for drying a hygroscopic material having a fibrous structure, such as wood and cardboard, comprising a closed drying compartment equipped with a heating element for heating a drying medium which impinges the material, a dehumidifier element for the periodic demoisturizing of the drying medium, a circulation device for moving the drying medium past the material to be dried, a control device for controlling the heating element and the dehumidifier, said control device including a measuring feeler arranged in the flow path of the drying medium which is moved past the material to be dried, a hygrostat for switching-off the dehumidifier, a thermostat for switching-in and switching-out the heating element, and a timer switch which can be switched-on by the hygrostat and after expiration of its running time duration switches-on the dehumidifier.
Claim 4
Independent Claim 133 words
An apparatus for drying a hygroscopic material having a fibrous structure, such as wood and cardboard, comprising a closed drying compartment equipped with a heating element for heating a drying medium which impinges the material, a dehumidifier element for the periodic demoisturizing of the drying medium, a circulation device for moving the drying medium past the material to be dried, a control device for controlling the heating element and the dehumidifier, said control device including a measuring feeler arranged in the flow path of the drying medium which is moved past the material to be dried, a hygrostat for switching-off the dehumidifier, a thermostat for switching-in and switching-out the heating element, and a timer switch which can be switched-on by the hygrostat and after expiration of its running time duration switches-on the dehumidifier.

References Cited (Backward Citations)

US1603103A Cited
US1997826A Cited
US2370422A Cited
US3337967A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1979-03-02 1979-09-01 1980-03-02 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1983-03-02 1983-09-01 1984-03-02 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1987-03-02 1987-09-01 1988-03-02 $7700.00 Window Closed / Lapsed

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