Method of drying a web
View Patent ↗A method of drying a paper web is provided. The method utilizes a dryer, such as a through-dryer, having a first dryer section and a second dryer section. Within the first dryer section, a relatively wet paper web is dried at an elevated temperature, such as between about 400° F. to about 500° F. After being dried by the first dryer section, the web is relatively dry and is further dried by the second dryer section at a reduced temperature, such as between about 300° F. to about 400° F. A variety of control techniques can also be utilized to control the temperature of each dryer section.
1. A method for drying a paper web comprising:
distributing a supply air stream to a first dryer section and a second dryer section of a through-dryer;
contacting a relatively wet paper web with the supply air stream within said first dryer section at an elevated temperature to form a relatively dry paper web; contacting the relatively dry paper web with the supply air stream within said second dryer section at a reduced temperature in comparison to said elevated temperature; and selecting from one or both of the following:
i) combining a first stream of air with said supply air stream to provide said elevated temperature within said first dryer section; and
ii) combining a second stream of air with said supply air stream to provide said reduced temperature within said second dryer section.
2. A method as defined in claim 1 , wherein said elevated temperature is provided by combining said first stream of air with said supply air stream.
3. A method as defined in claim 2 , wherein said elevated temperature decreases within said first dryer section.
4. A method as defined in claim 2 , wherein said elevated temperature increases within said first dryer section.
5. A method as defined in claim 1 , wherein said reduced temperature is provided by combining said second stream of air with said supply air stream.
6. A method as defined in claim 5 , wherein said reduced temperature decreases within said second dryer section.
7. A method as defined in claim 5 , wherein said reduced temperature increases within said second dryer section.
8. A method as defined in claim 1 , wherein said relatively wet paper web has a solids consistency between about 20% to about 40%.
9. A method as defined in claim 1 , wherein said relatively dry paper web has a solids consistency between about 45% to about 70%.
10. A method as defined in claim 1 , wherein said elevated temperature ranges from about 400° F. to about 500° F.
11. A method as defined in claim 10 , wherein said elevated temperature ranges from about 450° F. to about 500° F.
12. A method as defined in claim 1 , wherein said reduced temperature ranges from about 300° F. to about 400° F.
13. A method as defined in claim 12 , wherein said reduced temperature ranges from about 300° F. to about 400° F.
14. A method for drying a paper web comprising:
distributing a supply air stream to a first dryer section and a second dryer section of a through-dryer;
contacting a relatively wet paper web with the supply air stream within said first dryer section at an elevated temperature of from about 400° F. to about 500° F. to form a relatively dry paper web;
contacting the relatively dry paper web with the supply air stream within said second dryer section at a reduced temperature of from about 300° F. to about 400° F.; and
selecting from one or both of the following steps:
i) combining a first stream of air with said supply air stream to provide said elevated temperature within said first dryer section; and
ii) combining a second stream of air with said supply air stream to provide said reduced temperature within said second dryer section.
15. A method as defined in claim 14 , wherein said elevated temperature is provided by combining said first stream of air with said supply air stream.
16. A method as defined in claim 15 , wherein said elevated temperature decreases within said first dryer section.
17. A method as defined in claim 15 , wherein said elevated temperature increases within said first dryer section.
18. A method as defined in claim 14 , wherein said reduced temperature is provided by combining said second stream of air with said supply air stream.
19. A method as defined in claim 18 , wherein said reduced temperature decreases within said second dryer section.
20. A method as defined in claim 18 , wherein said reduced temperature increases within said second dryer section.
21. A method as defined in claim 14 , wherein said elevated temperature ranges from about 450° F. to about 500° F.
22. A method as defined in claim 14 , wherein said reduced temperature ranges from about 300° F. to about 350° F.
23. A method for drying a paper web comprising:
distributing a supply air stream to a first dryer section and a second dryer section of a through-dryer;
contacting a relatively wet paper web having a solids consistency of between about 20% to about 40% with the supply air stream within said first dryer section at an elevated temperature to form a relatively dry paper web;
contacting the relatively dry paper web with the supply air stream within said second dryer section at a reduced temperature in comparison to said elevated temperature; and
selecting from one or both of the following:
i) combining a first stream of air with said supply air stream to provide said elevated temperature within said first dryer section; and
ii) combining a second stream of air with said supply air stream to provide said reduced temperature within said second dryer section.
24. A method as defined in claim 23 , wherein said elevated temperature is provided by combining said first stream of air with said supply air stream.
25. A method as defined in claim 24 , wherein said elevated temperature decreases within said first dryer section.
26. A method as defined in claim 24 , wherein said elevated temperature increases within said first dryer section.
27. A method as defined in claim 23 , wherein said reduced temperature is provided by combining said second stream of air with said supply air stream.
28. A method as defined in claim 27 , wherein said reduced temperature decreases within said second dryer section.
29. A method as defined in claim 27 , wherein said reduced temperature increases within said second dryer section.
30. A method as defined in claim 23 , wherein said elevated temperature ranges from about 400° F. to about 500° F. and said reduced temperature ranges from about 300° F. to about 400° F.
31. A method as defined in claim 23 , wherein said elevated temperature ranges from about 450° F. to about 500° F.
32. A method as defined in claim 23 , wherein said reduced temperature ranges from about 300° F. to about 350° F.
33. A method as defined in claim 23 , wherein said relatively dry paper web has a solids consistency between about 45% to about 70%.