Apparatus and process for throughair drying of a paper web
AssigneeKimberly-Clark Worldwide, Inc.
InventorsPhilip S. Lin, Ronald F. Gropp, Kevin B. Sartain
Life of this patent
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Abstract
A paper web drying apparatus and process is provided in which the heated air drying medium is replaced with between 10 percent to 100 percent of live steam. The addition of a steam component to the drying medium provides for a higher drying temperature to be supplied to the wet moving web. The introduction of live pressurized steam contributes to the load of force of the drying medium, thereby decreasing the energy requirements of blower motors. The introduction of pressurized live steam also lowers the free atmospheric oxygen content of the drying medium which reduces the burning or scorch hazard associated with high temperature drying of a cellulose web.
Claims25
A process of throughair drying a tissue web comprising:
- supplying a moving fibrous web of cellulose fibers;
- passing through the fibrous web a drying medium having a supply side temperature greater than about 450° F. and a steam content of at least about 10 percent by volume;
- wherein, as the drying medium passes through the fibrous web, the drying medium converts the water within the fibrous web to water vapor which is released into the moving drying medium and thereby dries the fibrous web.
A process of throughair drying a tissue web comprising:
- supplying a moving fibrous web of wet cellulose fibers;
- passing through the wet fibrous web a drying medium having a supply side temperature greater than a scorch temperature of the cellulose web and having a live steam content at a sufficient percent volume which avoids scorching of the web;
- converting the water content of the fibrous web to an evolved steam;
- and
- removing the evolved steam by the continued passage of a drying medium through the fibrous web and thereby providing a dry fibrous web.
A process of drying a wet cellulosic web comprising:
- supplying a moving fibrous web of wet cellulose fibers;
- supplying a first drying medium having a first free oxygen concentration;
- reducing the free oxygen concentration within the first medium by the introduction of a heated substantially oxygen-free fluid into the first drying medium, thereby providing a second drying medium having a second free oxygen concentration less than the first free oxygen concentration;
- and
- passing the second drying medium through the wet cellulosic web and thereby drying the web.
A process of throughair drying a tissue web comprising:
- supplying a moving fibrous web of cellulose fibers and water;
- supplying a first drying medium comprising heated air;
- releasing into the first drying medium pressurized steam, thereby providing a second drying medium, the pressurized steam raising the temperature of the second drying medium to a temperature greater than the temperature of the first drying medium;
- and
- passing the second drying medium through the moving fibrous web, thereby changing the water within the fibrous web to a water vapor, the water vapor removed from the fibrous web and released into the second drying medium and thereby providing a dry web.
A process of throughair drying a fibrous wet web using a throughair dryer in which a heated air drying medium is forced through the fibrous web, the improvement comprising:
- releasing pressurized steam into the drying medium, the released steam raising the temperature of the drying medium to a temperature greater than the atmospheric scorch temperature of the fibrous web;
- passing the drying medium having the pressurized steam through the fibrous wet web;
- converting moisture within the fibrous wet web to water vapor;
- and
- removing the water vapor from the web.
A paper web drying apparatus having a throughdrying drum wherein heated air is supplied to a hood which extends around a portion of the periphery of a drum and through which the heated air may pass, the hollow interior of the drum being connected to an exhaust means, the hood distributing heated air to the surface of the web, the improvement comprising:
- a drying medium conduit in fluid communication with the hood, the conduit in further communication with a source of a pressurized heated fluid substantially free of oxygen gas.
Dependencies are inferred from the claim text.