Temperature sensing dryer profile control
AssigneeJames River Corporation of Virginia
InventorRalph C. Clark
Life of this patent
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Abstract
A drying control system and method for obtaining a substantially uniformly dried low moisture content web efficiently with reduced energy usage in a papermaking process is provided. The drying rate of the web in this process is precisely controlled by detecting and monitoring the web or felt low and high cross-direction temperature profiles and then actuating drying rate modulators as required to increase or decrease the drying rate to produce a substantially flat temperature profile in response to temperature profile information provided to an automatically or manually controlled central control system by web high temperature and low temperature sensors.
Claims36
A drying control system for a papermaking process adaptable for use with a conventional papermaking machine which forms and then dries a wet web of paper to about a 3% moisture content, wherein said control system includes:
- (a) a cross-direction drying means controllable to modify the temperature across the web;
- (b) temperature detection means for determining a cross-direction temperature profile of the web;
- (c) modulation means for controlling the cross-direction drying means in response to variations in the temperature profile to reduce variations in the cross-direction temperature profile;
- and
- (d) central control means for controlling said cross-direction drying means and said modulation means in response to said temperature profile received from said temperature detection means to produce a substantially uniformly dried web.
A method of controlling drying in a papermaking process to produce a substantially uniformly dried paper web with a moisture content of about 3% with efficient energy usage including the steps of:
- (a) detecting the cross-direction temperature of the web at high and low temperature locations to produce a cross-direction web temperature profile;
- (b) providing the temperature profile to a central control means;
- and
- (c) adjusting the drying rate of the web as required to produce a substantially flat cross-direction temperature profile.
A drying control system for a papermaking process wherein a wet web of paper is formed from a slurry of papermaking fibers, dried by at least one drying apparatus to a moisture content of about 3% or less, and the final paper product is wound on a take up reel, comprising
- (a) high temperature detection means for detecting a cross-direction temperature profile of the web at a location where at least a portion of the web will have a temperature above the boiling point of water;
- (b) low temperature detection means for detecting a cross-direction temperature profile of the web at a location where, during drying, an entire cross-direction strip of the web will have a temperature below the boiling point of water;
- (c) drying rate modulating means for varying the drying rate of the web as required in response to the web cross-direction temperature profiles detected by said high and low temperature detection means;
- (d) weight and moisture scanner means for detecting the weight and moisture of the final paper product;
- (e) final weight and moisture control system means for receiving information from said weight and moisture scanner means;
- and
- (f) central control system means for receiving information from said high and low temperature detection means and said final weight and moisture control system means and processing said information to control said drying rate modulating means to maintain the cross-direction temperature profile of said web within predetermined temperature parameters for the weight of the final paper product.
A method of controlling drying in a papermaking process to produce a substantially uniformly dried paper web with a moisture content of about 3% with efficient energy usage including the steps of:
- (a) detecting the cross-direction temperature of a felt supporting the web at high and low temperature locations to produce a cross-direction web temperature profile;
- (b) providing the temperature profile to a central control means;
- and
- (c) adjusting the drying rate of the web as required to produce a substantially flat cross-direction temperature profile.
Dependencies are inferred from the claim text.