Method and apparatus for drying a fiber web at elevated ambient pressures
AssigneeInstitute of Paper Science and Technology, Inc.
InventorsDavid I. Orloff, Timothy Patterson, Isaak Rudman
Life of this patent
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Abstract
A method and apparatus for drying a fiber web is provided by pressing the web, preferably by impulse drying and then introducing the web into a gas pressurized zone followed by reducing the pressure in the zone, the reduction preferably being effected with cooling of the fiber web.
Claims21
A method for drying a web comprising the steps of passing the web and a water receiving felt between a heated surface and another surface, applying pressure between said surfaces and releasing said pressure over a first time period, from an initial value at a first rate, further releasing said pressure over a transition time period, and releasing said pressure an additional amount more gradually than said first rate, over an ending time period which is substantially longer than the first time period.
A method for drying a web containing an internal fluid comprising the steps of passing the web between a heated surface having a temperature between the atmosphere boiling temperature of said fluid and a temperature in excess of the thermodynamic critical temperature of said fluid, applying pressure between said surfaces and releasing said pressure over a first time period, from an initial value at a first rate, further releasing said pressure over a transition time period, and releasing said pressure an additional amount at a generally linear rate which is more gradually than said first rate, over an ending time period which is substantially longer than the first time period.
A method for drying a web comprising the steps of passing the web between a heated surface and another surface, applying pressure between said surfaces and releasing said pressure according to an operating curve of pressure versus time, the operating curve having an initial part for a first time period during which pressure is reduced from an initial value at a first rate, a transition part and a subsequent shallow slope ending part having a shallower slope than the initial part, in which pressure is reduced from a second value more gradually than said first rate, over an ending time period substantially longer than the first time period.
Dependencies are inferred from the claim text.