U.S. patent number 3,771,236 [Application Number 05/167,206] was granted by the patent office on 1973-11-13 for method and apparatus for treating sheet-like material with fluid.
Invention is credited to James T. Candor, Robert R. Candor.
United States Patent |
3,771,236 |
Candor , et al. |
November 13, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
METHOD AND APPARATUS FOR TREATING SHEET-LIKE MATERIAL WITH
FLUID
Abstract
In air-through dryers for wet sheet-like material, such as
paper, textiles, etc., the moist sheet-like material is passed
adjacent a high velocity air hood so as to be subjected to an air
pressure differential across the same. Thus, heated or unheated air
is caused to be engaged against one side of the sheet-like material
and pass therethrough to the other side thereof to remove moisture
from such sheet-like material as the air passes therethrough, such
moisture being removed by a pushing out of the moisture by the air,
by air entrainment and/or by adiabatic evaporation. A belt means of
this invention comprising a perforated flexible wall carrying felt,
fabric or other similar material on one side thereof is utilized in
a manner to engage against the moist sheet-like material to
compress the same during the passage of air through the perforated
flexible wall and through the moist sheet-like material to assist
in the water removal thereof by either tending to cause the
porosity of the drying sheet-like material to remain substantially
constant so that an optimum substantially constant air flow passes
therethrough or to cause a greater air flow rate through the wetter
portions of said sheet-like material than through the drier
portions thereof.
Inventors: |
Candor; Robert R. (Dayton,
OH), Candor; James T. (Dayton, OH) |
Family
ID: |
26803070 |
Appl.
No.: |
05/167,206 |
Filed: |
July 29, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
105894 |
Jan 12, 1971 |
3699663 |
|
|
|
Current U.S.
Class: |
34/452; 34/92;
34/115 |
Current CPC
Class: |
F26B
13/16 (20130101); D06B 15/04 (20130101); D21F
5/182 (20130101) |
Current International
Class: |
D21F
5/18 (20060101); D06B 15/04 (20060101); D06B
15/00 (20060101); F26B 13/10 (20060101); D21F
5/00 (20060101); F26B 13/16 (20060101); F26b
005/05 () |
Field of
Search: |
;34/115,16,23,92,116,118,123,162,117,151,155 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Dority, Jr.; Carroll B.
Assistant Examiner: Schwartz; Larry I.
Parent Case Text
This application is a continuation-in-Part application of its
copending parent patent application, Ser. No. 105,894, filed Jan.
12, 1971, now U.S. Pat. No. 3,699,663, which, in turn, is related
to applicants' copending application, Ser. No. 886,090, filed Dec.
18, 1969, now U.S. Pat. No. 3,657,069 and entitled "METHOD AND
APPARATUS FOR TREATING SHEET-LIKE MATERIAL WITH POROUS AND/OR
PERMEABLE SHEET MEANS," and is related to applicants' copending
application entitled "METHOD AND APPARATUS FOR TREATING SHEET-LIKE
MATERIAL AND THE LIKE," filed Oct. 20, 1969, Ser. No. 868,396, and
now U.S. Pat. No. 3,592,585, which is a continuation-in-part
application of its copending patent application, Ser. No. 690,636,
filed Dec. 14, 1967, now U.S. Pat. No. 3,491,386, which, in turn,
is a continuation-in-part application of its copending patent
application, Ser. No. 635,848, filed May 3, 1967, now U.S. Pat. No.
3,447,174.
Claims
What is claimed is:
1. In an air-through drying apparatus for wet sheet-like material
wherein moisture from the wet sheet-like material is removed
therefrom by air flowing substantially transversely through the
sheet-like material by a pressure differential being created across
the sheet-like material as the same passes through a pressure
differential creating zone of said apparatus, the improvement
comprising means for automatically causing a lesser air flow rate
through the drier areas of a particular section of said sheet-like
material than the normal air flow rate therethrough normally caused
by the drier areas being more porous than the wetter areas of said
section of said sheet-like material when said section of said
sheet-like material is in said zone and regardless of the relative
locations of said wetter and drier areas in said section.
2. In an air-through drying apparatus as set forth in claim 1, the
further improvement wherein said means for automatically causing a
lesser air flow rate through the drier areas of said particular
section of sheet-like material also automatically causes the air
flow rate through the wetter areas of said particular section of
material to be greater than the normal air flow rate therethrough
normally caused by the wetter areas being less porous than the
drier areas of said section of said sheet-like material when said
section of said sheet-like material is in said zone and regardless
of the relative locations of said wetter and drier areas in said
section.
3. In an air-through drying apparatus as set forth in claim 1, the
further improvement wherein said means for automatically causing a
lesser air flow rate through the drier areas of said particular
section of sheet-like material also automatically causes the air
flow rate through all areas of said section of said sheet-like
material that is in said zone to be substantially the same
regardless of the different moisture contents of said areas of said
sheet-like material that are in said zone at that time.
4. In an air-through drying apparatus as set forth in claim 1, the
further improvement wherein said means for automatically causing a
lesser air flow rate through the drier areas of a particular
section of said sheet-like material comprises a flexible wall means
for engaging against said sheet-like material as the same passes
through said zone of said apparatus and being disposed on the
higher pressure side of said sheet-like material, said flexible
wall means having means for causing the air flow to compress said
flexible wall means against said sheet-like material while flowing
through said flexible wall means into said sheet-like material to
remove moisture therefrom.
5. In an apparatus as set forth in claim 4, the further improvement
wherein said flexible wall means has a flexible wall having opening
means passing therethrough, said flexible wall means having an air
open covering on the side of said flexible wall that is to engage
said sheet-like material.
6. In an air-through drying method for wet sheet-like material
wherein moisture from the wet sheet-like material is removed
therefrom by air flowing substantially transversely through the
sheet-like material when the sheet-like material is passed through
a pressure differential creating zone, the improvement comprising
the step of automatically causing a lesser air flow rate through
the drier areas of a particular section of said sheet-like material
than the normal air flow rate therethrough normally caused by the
drier areas being more porous than the wetter areas of said section
of said sheet-like material when said section of said sheet-like
material is in said zone and regardless of the relative locations
of said wetter and drier areas in said section.
7. In an air-through drying method as set forth in claim 6, the
further improvement wherein the step of automatically causing a
lesser air flow rate through the drier areas of a particular
section of sheet-like material comprises the step of also
automatically causing the air flow rate through the wetter areas of
said particular section of material to be greater than the normal
air flow rate therethrough normally caused by the wetter areas
being less porous than the drier areas of said section of said
sheet-like material when said section of said sheet-like material
is in said zone and regardless of the relative locations of said
wetter and drier areas in said section.
8. In an air-through drying method as set forth in claim 6, the
further improvement wherein the step of automatically causing a
lesser air flow rate through the drier areas of a particular
section of said sheet-like material comprises the step of also
automatically causing the air flow rate through all areas of said
section of said sheet-like material that is in said zone to be
substantially the same regardless of the different moisture
contents of said areas of said sheet-like material that are in said
zone at that time.
9. In an air-through drying method as set forth in claim 6, the
further improvement wherein the step of automatically causing a
lesser air flow rate through the drier areas of a particular
section of sheet-like material comprises the step of providing a
flexible wall means for engaging against said sheet-like material
as the same passes through said zone and being disposed on the
higher pressure side of said sheet-like material, said flexible
wall means having means for causing the air flow to compress said
flexible wall means against said sheet-like material while flowing
through said flexible wall means into said sheet-like material to
remove moisture therefrom.
10. In an air-through drying method as set forth in claim 9, the
further improvement wherein said step of providing said flexible
wall means comprises the step of providing a flexible wall having
opening means passing therethrough, said flexible wall means having
an air open covering on the side of said flexible wall that is to
engage said sheet-like material.
11. In a fluid-through apparatus for treating porous material by
fluid flowing substantially transversely through the material by a
pressure differential being created across the material as the same
passes through said apparatus, the improvement comprising means for
automatically causing a lesser fluid flow rate through the more
porous areas of a particular section of said material than the
normal fluid flow rate therethrough normally caused by such areas
being more porous than the lesser porous areas of said section of
said material when said section of said material is in said zone
and regardless of the relative locations of said more porous and
lesser porous areas in said section.
12. In a fluid-through apparatus as set forth in claim 11, the
further improvement wherein said means for automatically causing a
lesser fluid flow rate through the more porous areas of said
particular section of material also automatically causes the fluid
flow rate through the lesser porous areas of said particular
section of material to be greater than the normal fluid flow rate
therethrough normally caused by such areas being less porous than
the more porous areas of said section of said material when said
section of said material is in said zone and regardless of the
relative locations of said more porous and lesser porous areas in
said section.
13. In a fluid-through apparatus as set forth in claim 11, the
further improvement wherein said means for automatically causing a
lesser fluid flow rate through the more porous areas of said
particular section of material also automatically causes the fluid
flow rate through all areas of said section of said material that
is in said zone to be substantially the same regardless of the
different porosities of said areas of said material that are in
said zone at that time.
14. In a fluid-through apparatus as set forth in claim 11, the
further improvement wherein said means for automatically causing a
lesser fluid flow rate through the more porous areas of a
particular section of material comprises a flexible wall means for
engaging against said material as the same passes through said zone
of said apparatus and being disposed on the higher pressure side of
said material, said flexible wall means having means for causing
the fluid flow to compress said flexible wall means against said
material while flowing through said flexible wall means into said
material to treat the same.
15. In a fluid-through apparatus as set forth in claim 14, the
further improvement wherein said flexible wall means has a flexible
wall having opening means passing therethrough, said flexible wall
means having a fluid open covering on the side of said flexible
wall that is to engage said material.
16. In a fluid-through method for treating porous material by fluid
flowing substantially transversely through the material when the
material is passed through a pressure differential creating zone,
the improvement comprising the step of automatically causing a
lesser fluid flow rate through the more porous areas of a
particular section of material than the normal fluid flow rate
therethrough normally caused by the more porous areas being more
porous than the lesser porous areas of said section of said
material when said section of said material is in said zone and
regardless of the relative locations of said more porous and lesser
porous areas in said section.
17. In a fluid-through method as set forth in claim 16, the further
improvement wherein the step of automatically causing a lesser
fluid flow rate through the more porous areas of a particular
section of material comprises the step of also automatically
causing the fluid flow rate through the lesser porous areas of said
particular section of material to be greater than the normal fluid
flow rate therethrough normally caused by such areas being less
porous than the more porous areas of said section of said material
when said section of said material is in said zone and regardless
of the relative locations of said more porous and lesser porous
areas in said section.
18. In a fluid-through method as set forth in claim 16, the further
improvement wherein the step of automatically causing a lesser
fluid flow rate through the more porous areas of a particular
section of material comprises the step of also automatically
causing the fluid flow rate through all areas of said section of
said material that is in said zone to be substantially the same
regardless of the different porosities of said areas of said
material that are in said zone at that time.
19. In a fluid-through method as set forth in claim 16, the further
improvement wherein the step of automatically causing a lesser
fluid flow rate through the more porous areas of a particular
section of said material comprises the step of providing a flexible
wall means for engaging against said material as the same passes
through said zone and being disposed on the higher pressure side of
said material, said flexible wall means having means for causing
the fluid flow to compress said flexible wall means against said
material while flowing through said flexible wall means into said
material to treat the same.
20. In a fluid-through method as set forth in claim 19, the further
improvement wherein said step of providing said flexible wall means
comprises the step of providing a flexible wall having opening
means passing therethrough, said flexible wall means having a fluid
open covering on the side of said flexible wall that is to engage
said material.
21. In a fluid-through apparatus for treating porous material by
fluid flowing substantially transversely through the material by a
pressure differential being created across the material as the same
passes through said apparatus, the improvement comprising a porous
wall means being disposed in a sandwich relation with said porous
material and through which sandwich said fluid flows by said
pressure differential, and means for changing the porosity of at
least one area of said porous wall means to change the amount of
fluid flow therethrough and thus change the amount of fluid flow
through a corresponding area of said porous material disposed
adjacent thereto from the amount that said pressure differential
would normally cause to flow therethrough.
22. In a fluid-through apparatus as set forth in claim 21, the
further improvement wherein said means changing the porosity of
said porous wall means changes the porosity of said porous wall
means in a manner to cause a lesser fluid flow rate through the
more porous areas of a particular section of said porous material
than the normal fluid flow rate therethrough normally caused by
such areas being more porous than the lesser porous areas of said
section of said material when said section of said porous material
is in the pressure differential zone and regardless of the relative
locations of said more porous and lesser porous areas in said
section of said porous material.
23. In a fluid-through apparatus as set forth in claim 22, the
further improvement wherein said means causing a lesser fluid flow
rate through the more porous areas of said particular section of
said porous material also causes the fluid flow rate through the
lesser porous areas of said particular section of said porous
material to be greater than the normal fluid flow rate therethrough
normally caused by such areas being less porous than the more
porous areas of said section of said material when said section of
said porous material is in said zone and regardless of the relative
locations of said more porous and lesser porous areas in said
section of said porous material.
24. In a fluid-through apparatus as set forth in claim 22, the
further improvement wherein said means causing a lesser fluid flow
rate through the more porous areas of said particular section of
said porous material also causes the fluid flow rate through all
areas of said porous material that is in said zone to be
substantially the same regardless of the different porosities of
said areas of said porous material that are in said zone at that
time.
25. In a fluid-through apparatus as set forth in claim 22, the
further improvement wherein said porous wall means comprises a
flexible porous wall means for engaging against said porous
material as the same passes through said zone of said apparatus and
being disposed on the higher pressure side of said porous material,
said flexible wall means having means for causing the fluid flow to
compress said flexible wall means against said porous material
while flowing through said flexible wall means into said material
to treat the same.
26. In a fluid-through apparatus as set forth in claim 25, the
further improvement wherein said flexible wall means has a flexible
wall having opening means passing therethrough, said flexible wall
means having a fluid open covering on the side of said flexible
wall that is to engage said porous material.
27. In a fluid-through method for treating porous material by fluid
flowing substantially transversely through the material when the
material is passed through a pressure differential creating zone,
the improvement comprising the steps of disposing a porous wall
means in sandwich relation with said porous material so that said
fluid flows through said sandwich when disposed in said pressure
differential creating zone, and changing the porosity of at least
one area of said porous wall means to change the amount of fluid
flow therethrough and thus change the amount of fluid flow through
a corresponding area of said porous material disposed adjacent
thereto from the amount that said pressure differential creating
zone would normally cause to flow therethrough.
28. In a fluid-through method as set forth in claim 27, the further
improvement wherein said step of changing the porosity of said
porous wall means changes the porosity of said porous wall means in
a manner to cause a lesser fluid flow rate through the more porous
areas of a particular section of said porous material than the
normal fluid flow rate therethrough normally caused by the more
porous areas being more porous than the lesser porous areas of said
section of said porous material when said section of porous
material is in said zone and regardless of the relative locations
of said more porous and lesser porous areas in said section of said
porous material.
29. In a fluid-through method as set forth in claim 28, the further
improvement wherein the step of causing a lesser fluid flow rate
through the more porous areas of a particular section of said
porous material comprises the step of also causing the fluid flow
rate through the lesser porous areas of said particular section of
said material to be greater than the normal fluid flow rate
therethrough normally caused by such areas being less porous than
the more porous areas of said section of said porous material when
said section of said porous material is in said zone and regardless
of the relative locations of said more porous and lesser porous
areas in said section of said porous material.
30. In a fluid-through method as set forth in claim 28, the further
improvement wherein the step of causing a lesser fluid flow rate
through the more porous areas of a particular section of said
porous material comprises the step of also causing the fluid flow
rate through all areas of said section of said porous material that
is in said zone to be substantially the same regardless of the
different porosities of said areas of said porous material that are
in said zone at that time.
31. In a fluid-through method as set forth in claim 28, the further
improvement wherein said porous wall means comprises a flexible
porous wall means engaging against said porous material as the same
passes through said zone and being disposed on the higher pressure
side of said porous material, said flexible wall means having means
for causing the fluid flow to compress said flexible wall means
against said porous material while flowing through said flexible
wall means into said porous material to treat the same.
32. In a fluid-through method as set forth in claim 31, the further
improvement wherein said flexible wall means comprises a flexible
wall having opening means passing therethrough, said flexible wall
means having a fluid open covering on the side of said flexible
wall that is to engage said porous material.
33. In an air-through apparatus as set forth in claim 5, the
further improvement wherein said air open covering is formed of
compressible material.
34. In an air-through apparatus as set forth in claim 5, the
further improvement wherein said air open covering is formed of
non-compressible material.
35. In an air-through drying method as set forth in claim 10, the
further improvement comprising the step of forming said air open
covering from compressible material.
36. In an air-through drying method as set forth in claim 10, the
further improvement comprising the step of forming said air open
covering from non-compressible material.
37. In a fluid-through apparatus as set forth in claim 15, the
further improvement wherein said fluid open covering is formed of
compressible material.
38. In a fluid-through apparatus as set forth in claim 15, the
further improvement wherein said fluid open covering is formed of
non-compressible material.
39. In a fluid-through method as set forth in claim 20, the further
improvement comprising the step of forming said fluid open covering
from compressible material.
40. In a fluid-through method as set forth in claim 20, the further
improvement comprising the step of forming said fluid open covering
from non-compressible material.
41. In a fluid-through apparatus as set forth in claim 26, the
further improvement wherein said fluid open covering is formed of
compressible material.
42. In a fluid-through apparatus as set forth in claim 26, the
further improvement wherein said fluid open covering is formed of
non-compressible material.
43. In a fluid-through method as set forth in claim 32, the further
improvement comprising the step of forming said fluid open covering
of compressible material.
44. In a fluid-through method as set forth in claim 32, the further
improvement comprising the step of forming said fluid open covering
of non-compressible material.
Description
This invention relates to means for improving the fluid treating of
sheet-like material wherein the fluid is caused to pass through the
sheet-like material to treat the same, such as to remove moisture
therefrom during a drying operation on the sheet-like material.
One of the features of the aforementioned patent applications is to
provide a squeezing action on the material to be treated at the
same time that gaseous fluid is being passed through the material
to remove retained moisture thereof, the compressing or squeezing
action being provided by means creating a pressure differential
across a flexible nozzle means that engages against the material
and has opening means through which the fluid flow takes place.
One feature of the present invention is to provide improvements in
known air-through dryers of paper making apparatus by utilizing the
aforementioned compressing features of applicants' prior
applications.
In particular, one embodiment of this invention provides a belt
means which has a perforated flexible wall on one side thereof and
a relatively open fabric covering on the other side thereof so that
the fabric side of the belt means can engage against one side of
the paper web that is to be dried whereby a pressure differential
created across such belt means will cause the belt means to
compress the paper web against a backing structure and will cause
an air flow to pass through the perforations of the belt means,
through the paper web and through the backing means to not only
remove moisture from the paper web in substantially sheet form, but
to also thereafter entrain water particles therefrom in a manner
well known in the art and/or cause evaporation of the remaining
moisture in a manner well known in the art. In this manner, the
belt means of this invention provides the same function as the
nozzle means of the aforementioned patent applications.
Further, it will be seen that another of the features of this
invention is to provide a means for maintaining the porosity of the
paper web substantially constant even though the web is being dried
so that the air flow through such drying web will be substantially
constant from the inlet side of the air through apparatus to the
outlet side thereof.
This feature is accomplished by continuously and/or progressively
compressing the paper web as it is being dried by the air flow
passing therethrough so that the porosity of the web remains
substantially the same in the air through apparatus regardless of
the amount of moisture being removed therefrom.
However, another feature of this invention is to tend to cause a
greater air flow rate through the wetter sections of paper web than
through the drier sections thereof to compensate for irregularities
in making paper webs or merely to more effectively dry the paper
web as the case may be.
Accordingly, it is an object of this invention to provide an
improved apparatus having one or more of the novel features set
forth above or hereinafter shown or described.
Another object of this invention is to provide an improved method
having one or more of the novel features set forth above or
hereinafter shown or described.
Other objects, uses and advantages of this invention will be
apparent from a reading of this description which proceeds with
reference to the accompanying drawings forming a part thereof and
wherein:
FIG. 1 is a fragmentary, cross-sectional view illustrating one
prior known air-through dryer utilizing the features of this
invention.
FIG. 2 is a view similar to FIG. 1 illustrating another type of
prior known air-through dryer utilizing the features of this
invention.
FIG. 3 is a view similar to FIG. 1 and illustrates another prior
known air-through dryer utilizing the features of this
invention.
FIG. 4 is an enlarged, fragmentary cross-sectional view taken on
line 4--4 of FIG. 1.
FIG. 5 is an enlarged, fragmentary cross-sectional view taken on
line 5--5 of FIG. 1.
FIG. 6 is an enlarged, fragmentary cross-sectional view taken on
line 6--6 of FIG. 1.
FIG. 7 is a fragmentary, bottom perspective view of the roll means
of the apparatus of FIG. 1 illustrating one means of this invention
for maintaining the side edges of the belt means of this invention
in contact with the peripheral edges of the roll of the apparatus
of FIG. 1 and/or FIG. 2.
FIG. 8 is a fragmentary, cross-sectional view illustrating another
prior known air-through dryer utilizing the features of this
invention.
FIG. 9 is a fragmentary, cross-sectional view taken on line 9--9 of
FIG. 8.
FIG. 10 is a schematic, cross-sectional view illustrating the
progressive compacting action of the belt means of this invention
on the web to be dried, FIG. 11 illustrating such action in
straight line form rather than in circular form as provided by the
apparatus of FIG. 8.
FIG. 11 is a view similar to FIG. 10 and illustrates how the
flexible belt of this invention tends to cause a greater flow rate
through the wetter sections of the web material than through the
drier sections thereof.
FIG. 12 is a view similar to FIG. 8 and illustrates another
embodiment of this invention.
While the various features of this invention are hereinafter
described and illustrated as being particularly adapted to remove
moisture from paper webs as the same are being formed in
conventional paper making apparatus, it is to be understood that
the various features of this invention can be utilized singly or in
any combination thereof to provide means for treating other
materials, such as textiles, food products, etc., as desired.
Further, while this invention is described in connection with only
one dryer drum for each type of paper making machine, it is to be
understood that the belt means of this invention could be utilized
with one or more air-through dryer drums for any one paper making
apparatus, as desired.
Therefore, this invention is not to be limited to only the
embodiments illustrated in the drawings, because the drawings are
merely utilized to illustrate some of the wide variety of uses of
this invention.
Further, while the embodiments of this invention are illustrated in
the drawings as providing arcuate paths of travel for the sheet
means being treated by the air flow, it is to be understood that
such sheet means can be passed in a substantially straight line
manner through the apparatus as set forth in certain of the
aforementioned patent applications.
Referring now to FIG. 4, an air-through drying apparatus is
generally indicated by the reference numeral 10 and comprises an
air-through drying apparatus as set forth in FIG. 1 of the U.S.
Pat. to Holden, No. 3,284,285, that is modified by a belt means 11
of this invention in a manner hereinafter described, the
air-through dryer 10 of FIG. 1 will be hereinafter referred to as
the Holden dryer and reference is hereby made to such Holden patent
for particular details of the structure, theory and operation of
the Holden dryer that are not here-inafter set forth.
In FIG. 2, another air-through dryer is generally indicated by the
reference numeral 12 and is of the type disclosed in FIG. 1 of the
U.S. Pat. to Sisson, No. 3,303,576, that is modified by the
improved belt means 11 of this invention in a manner hereinafter
described, the air-through dryer 12 of FIG. 2 being hereinafter
referred to as the Sisson dryer and reference is hereby made to
such Sisson patent for particular details of the structure, theory
and operation of the Sisson dryer that are not hereinafter set
forth.
Referring now to FIG. 3, another air-through dryer is generally
indicated by the reference numeral 14 and is of the type set forth
in FIG. 5 of the U.S. Pat. to Daane, No. 3,447,247, that is also
modified by the belt means 11 of this invention in a manner
hereinafter described, the air-through dryer 14 of FIG. 3 being
hereinafter referred to as the Daane dryer and reference is hereby
made to such Daane patent for particular details of the structure,
theory and operation of the Daane dryer that are not hereinafrer
set forth.
In FIG. 8, another air-through dryer is generally indicated by the
reference numeral 80 and is of the type set forth in FIGS. 1-6 of
the U.S. Pat. to Burgess et al., No. 3,418,723 that is also
modified by the belt means 11 of this invention in a manner
hereinafter described, the air-through dryer 80 of FIG. 8 being
hereinafter referred to as the Burgess dryer and reference is
hereby made to such Burgess et al patent for particular details of
the structure, theory, and operation of the Burgess dryer that are
not hereinafter set forth.
The improved belt means 11 of this invention that is utilized in
the Holden dryer 10, the Sisson dryer 12, the Daane dryer 14 and
the Burgess dryer is best illustrated in FIG. 4 and comprises a
flexible, perforated sheet 15 having a plurality of openings 16
passing therethrough in any suitable manner to produce a desired
compressing and air flow effect that will be apparent hereinafter,
the flexible sheet 15 having opposed sides 17 and 18 and carrying a
compressible or non-compressible, relatively open fabric or felt
band or covering 19 on the side 18 thereof with the band 19
providing an outer flat surface 20 for engaging against the desired
material to be dried by the particular apparatus 10, 12, 14 or 80
as will be apparent hereinafter. The openness and fiber structure
of the covering band 19 can be so selected that the same will not
have a tendency to mark or crush a paper web to be dried by the
belt means 11, at least not to an adverse degree.
The openings 16 through the flexible wall 15 of the belt means 11
of this invention are so selected that the same will permit air or
other fluids to pass therethrough in such a manner that the fluid
passing through the openings 16 and, through the covering 19 to the
outer surface 20 thereof will be somewhat diffused by the covering
19 so that while jet-like fluid flow is passing through the belt
means 11 as will be apparent hereinafter, such jet-like air means
is substantially uniform and completely covering and flowing out of
the outer surface 20 thereof in a manner somewhat produced by the
jet patterns 21 schematically illustrated in FIG. 6 and hereinafter
more fully described. Of course, the openings 16 can be formed in
any manner to enhance the jet action of the fluid passing
therethrough. For example; the openings 16 can be substantially
frusto-conically shaped in the manner illustrated in FIG. 6. Of
course, the openings 16 passing through the flexible wall 15 may be
in slot form, or other configurations, if desired.
In any event, one of the features of the openings 16 of the
flexible wall 15 of the belt means 11 is to permit a suitable fluid
pressure to build up on the side 17 thereof so as to cause the
flexible wall 15 to be moved in a direction away from the pressure
build up on the side 17 thereof while still permitting fluid flow
through the openings 16 thereof in high velocity jets as will be
apparent hereinafter.
The Holden air-through dryer 10 of FIG. 1 comprises a rotatable
cylinder or roll 22 rotatably mounted on a hollow shaft 23 and
having a hollow interior 24 fluidly interconnected to the exterior
peripheral surface 25 thereof by a plurality of openings 26 passing
therethrough, the openings 26 being substantially non-restrictive
to fluid flow therethrough. The interior 24 of the cylinder 22 is
divided into a pressure chamber 27 by stationary baffle means 28
carried by the shaft 23 that have sealing ends 29 for sealing
engagement with the interior peripheral surface 30 of the roll 22
in the manner fully set forth in the aforementioned patent to
Holden.
A fabric, felt or foraminous support means or belt 31 is adapted to
carry a moist paper web 32 thereon and convey the same through a
first nip defined by the cylinder 22 and a roller 33 with the paper
32 facing the exterior surface 25 of the cylinder 22, around part
of the cylinder 22 and through another nip created by a roller 34
cooperating with the cylinder 22, the paper sheet 32 and carrier 31
moving in unison from left to right in FIG. 1 whereby the paper
sheet 32 would be held directly against the exterior surface 25 of
the drum 22 adjacent the chamber 27 of the drum 22 if the belt
means 11 of this invention were not utilized. If desired, a
suitable chamber defining housing 35 can be disposed adjacent the
roll 22 so as to define a chamber 36 on the other side of the
chamber 27 of the roll 22, the chamber 36 being adapted to be
interconnected to a vent or suction pump (not shown) by a conduit
means 37.
The chamber 27 of the roll 22 is adapted to be pressurized by a
suitable air pressure source (not shown) leading to the chamber 27
through the axially disposed hollow shaft 23 that has an outlet 38
in the manner fully set forth in the patent to Holden et al.
The belt means 11 of this invention is adapted to be fed between
the paper sheet 32 and the outside surface 25 of the drum 22 at the
roller means 33 and be separated therefrom at the roller means 34
as illustrated in FIG. 1 while passing around suitable guide
rollers 39 and 40 leading respectively to and away from the drum 22
as illustrated with the band or covering 19 of the belt means 11
facing toward the paper sheet 32 so as to engage against the paper
sheet 32 and move in unison therewith about the roll 22 between the
rollers 33 and 34.
Without the belt means 11 of this invention, the aforementioned
patent to Holden teaches that pressurized air in the chamber 27 of
the roll 22 is forced out of the openings 26 of the roll 22
directly into the paper sheet 32 and through the paper sheet 32 and
foraminous carrier 31 into the chamber 36 of the housing means 35
to be exhausted out of the conduit means 37 thereof as the paper
sheet 32 and carrier 31 pass about the roll 22, such air flow
through the paper sheet 32 first stripping the moisture therefrom
in sheet form and thereafter removing additional moisture by the
air entrainment thereof in the air flowing through the paper sheet
32 in the manner previously described.
The patent to Holden teaches that the carrier 31 can be utilized to
compress the paper web against the surface 25 of the roll 22 by
placing the carrier 31 under tension between the rollers 33 and 34,
the squeezing purpose of the carrier 31 being to reduce the void
volume of the sheet 32 so that more water therefrom can be swept
directly away by the air flow therethrough rather than by
entrainment as would be the case when the sheet 32 is not
compressed against the roll 22. In particular, see column 1, lines
39-60 of the patent to Holden.
The patent to Sisson states that one of the problems in air-through
dryers is that the air flow through the paper web is not uniform
across the width of the moist paper web. For example, see column 1,
lines 54-71 of the patent to Sisson.
The patent to Daane also describes the non-uniform air flow through
the paper web as being a problem of air-through dryers. For
example, see column 1, lines 63-71 of the patent to Daane.
The patent to Burgess et al. while emphasizing the drying effect of
the air flow through the web material mainly emphasizes the
advantages of having the heated air impinging against the exposed
surface of the wet web material to break down the boundary layer at
such surface and thereby enhance heat transfer to the wet web.
However, it io believed that by utilizing the belt means 11 of this
invention in the Holden air-through dryer 10, as well as in other
types of air-through dryers, an improved moisture removable
operation will be provided by overcoming the problems mentioned by
Sisson and Daane, by having the advantages of Burgess et al., and
by further advantages as will be apparent hereinafter. In
particular as the air pressure in the chamber 27 presses against
the side 17 of the flexible sheet 15 of the belt means 11, the same
causes the sheet 15 and covering 19 thereof to move outwardly and
thereby compact and compress the paper sheet 32 against the carrier
31 while high velocity jets of air pass through the openings 16 in
the flexible wall 15 and through the covering 19 so as to pass
completely through the paper sheet 32 as provided by the arrow
pattern 21 illustrated in FIG. 6 to remove moisture from the sheet
32 and pass out through the carrier 31 in a manner believed to
remove a greater quantity of moisture from the paper sheet 32 since
the paper sheet 32 is being continuously compressed by the flexible
wall 15 to cause the remaining moisture therein to flow into the
voids and fill the same so as to be swept therefrom by the jet air
flow passing through the sheet 32 which would not be the case once
the larger pores of the sheet 32 had been swept clean by the air.
The flexible wall 15 also causes the belt means 11 to conform to
the contour of the paper web 32 so that any billowing thereof is
taken up by the flexible wall 15. Also, the jets of air passing out
of the openings 16 of the wall 15 produce their water sweeping
action independently of the action of the other jets in the manner
described in the patent to Daane.
Further, it is believed that as the moisture is continuously being
removed from the sheet 32 by the jets of air passing through the
openings 16 of the belt means 11 of this invention, so that the
paper 32 becomes more porous, a greater pressure differential is
caused to exist across the flexible wall 15 to cause the same to
compress the paper sheet 32 against the backing 31 with a greater
force to thereby tend to maintain the porosity of drier portions of
the sheet 32 the same as the wetter portions thereof so that a
constant air flow is provided through the sheet 32 from the inlet
side of the apparatus 10 to the exit side thereof.
This feature of maintaining a constant air flow through the wet web
regardless of where a particular section of the wet web is in the
air-through dryer is best illustrated in FIG. 10 and will be
hereinafter more fully described in connection with the Burgess
dryer 80 illustrated in FIGS. 8-11. However, it is to be understood
that the description of the constant air flow effect of the belt
means 11 in the Burgess dryer 80 will equally apply to the action
of the belt means 11 in the other air-through dryers of this
application as well as in other applicable air-through dryers.
Thus, it can be seen that the belt means 11 of this invention is
believed to enhance the air-through drying action of the Holden
air-through dryer 10 by causing a continuous and progressively
increasing compression or squeezing of the paper sheet means 32 as
the same passes from right to left through the apparatus 10 between
the rollers 33 and 34 so as to increase the amount of time that the
moisture in the sheet 32 is being swept therefrom as moisture
particles so that less time is required to pass air through the
sheet means to remove the remaining moisture strictly by an air
entrainment action and/or evaporative action. The belt means 11
also uniformily compresses the paper web 32 across the entire width
thereof since the flexible wall 15 of the belt means conforms to
the contours of the sheet 32 and, thus, any billowing thereof
relative to the drum 22. The belt means 11 also sweeps moisture
from the paper web 32 by a plurality of jets that are independent
of each other so that uniform moisture removal is created across
the entire width of the paper web 32. Of course, the amount or
force of squeezing is so controlled that such force will not
adversely affect the sheet 32.
In order to hold the side edges 40 and 41 of the belt means 11 of
this invention in substantially sealing relation with the
peripheral side edges 42 and 43 of the roll means 22 between the
seals 29 of the baffle means 28 at the chamber 27 so that the
pressurized air will not tend to flow out of the same at the sides
40 and 41 thereof, a plurality of rollers 44 can be disposed
adjacent the roll 22 at the side edges 42 and 43 thereof to hold
the side edges 40 and 41 of the belt means 11 in sealing relation
thereagainst as the belt means 11 passes around the roller 22, the
paper web 32 having its side edges disposed inboard of the rollers
44 as illustrated by dotted lines in FIG. 7.
Of course, it is to be understood that the belt means 11 can also
be directly fastened to and completely around the roll 22 at the
side edges 41 and 43 thereof so that the same will perform in the
same manner as previously described except that the same will be
carried by the drum 22 and not pass around the guide rollers 39 and
40 as illustrated.
The Sisson air-through dryer 12 of FIG. 2 will now be described and
such apparatus 12 comprises a roll 45 having a hollow center 46
interconnected to the exterior surface 47 thereof by a plurality of
openings 48 passing through the roll 45. A foraminous backing 31 is
adapted to pass around the outside surface 45 of the roll 45 by
being passed around suitable rollers 49, 50 and 51 as illustrated
with the paper sheet 32 passing between the backing 31 and the roll
45 as illustrated so that air inside the chamber 46 in the roll 45
will pass out of the same and through the paper 32 and the backing
31 in somewhat the same manner as the Holden device 10 previously
described except that the air under pressure for the interior 46 of
the roll 45 is directed into the same from the exterior of the roll
45 by a nozzle means 52 located between the rollers 50 and 51 and
receiving air from a suitable fan means 53 that passes the air
through suitable heating means 54 to the nozzle means 52 and, thus,
through the exterior of the roll 45 into the interior 46 thereof. A
removable chamber defining means 55 is provided by the apparatus 12
to be disposed about the outside of the roll 45 and define a
chamber 56 that is adapted to be evacuated by suitable fan or pump
means 57 so that a resulting pressure differential between the
chamber 56 and the interior 46 of the roll 45 will exist across the
surface 47 of the drum 45 and cause the heated air in the interior
46 thereof to pass through the openings 48 and, thus, through the
paper sheet 32 and backing 31 into the chamber 56 to be exhausted
therefrom with such air flow removing moisture from the sheet 42 in
somewhat the manner previously described in connection with the
Holden device 10.
However, the belt means 11 of this invention is utilized in the
Sisson device 12, the belt means 11 being fed by suitable roller
means 39 against the outside surface of the paper 32 at the roller
50 so that the covering 19 of the belt means 11 faces the sheet 32
while the flexible wall 15 engages against the roll 45 and is
carried about the same to the roller 51 where the belt means 11 is
directed away from the roll 45 and around the guide roller 40 in
the manner previously described.
Thus, it can be seen that as the paper sheet 32 is fed around the
roll 45, the same is being continuously compressed by the belt
means 11 of this invention against the backing means 31 for the
reasons previously set forth in connection with the Holden device
10 so as to progressively squeeze or compress the sheet 32 by the
pressure differential being created across the flexible wall 15 in
the manner previously described during the air flow through the
paper sheet 32 so as to remove a greater quantity of moisture
therefrom than when the belt means 11 of this invention is not
being utilized.
The Daane air dryer 14 of FIG. 3 is substantially an air
impingement device which directs jets of air out of opening means
58 of a stationary hood 59 toward a perforated roll or drum 60
having the interior 61 thereof evacuated by suitable pump means 62
so that as a paper sheet passes around the roller 60 adjacent the
openings 58 of the hood 59, the impinging air will pass directly
through the paper sheet and, thus, through the openings 63 of the
roll 60 to be exhausted from the interior 61 thereof. The hood 59
includes an interior chamber 64 adapted to receive air under
pressure from a pump or fan means 65 with such air being heated by
suitable heater means 66 before passing into the interior 64 of the
hood 59.
A fabric or foraminous carrier 31 carries the paper sheet 32 and is
guided against the exterior surface 67 of the roll 60 by a guide
roller 68 so that the fabric 31 engages against the exterior
surface 67 of the roll 50 while the nozzle means 58 of the hood 59
directs the jets or air directly against the paper sheet 32 to
strip moisture therefrom as the air passes through the paper sheet
32 and into the interior 61 of the drum 60, the paper sheet 32 and
fabric carrier 31 being directed away from the roll 60 by guide
roller means 69.
However, the belt means 11 of this invention is utilized in the
Daane dryer 14, the belt means 11 being also fed around the drum 60
at the roller means 68 and then away from the drum 60 by the roller
means 69 with the belt means 11 being fed toward the roller 68 by
the roller means 39 and away from the roller means 69 by the roller
means 40 in the manner previously described. In this manner, the
covering side 20 of the cover means 19 of the belt means 11 will
engage against the paper sheet 32 as the same passes around the
roll 60 and the jets of air from the opening 58 of the hood or cap
59 will engage against the flexible wall 15 and will cause the belt
means 11 to continuously compress toward the paper sheet 32 and
squeeze the same against the backing 31 on the roll 60 while
issuing jets of air out of the openings 16 of the belt means 11 for
moisture removal from the paper sheet 32 as the paper sheet 32
passes beneath the hood 59 in the manner previously described. If
desired, the hood 59 can be substantially sealed to the moving
flexible wall 15 of the belt means 11 as the same passes underneath
the same by annular seal means 70 carried by the hood 59 in much
the same manner as the seal means provided by the hood means of the
air-through dryer of the U.S. Pat. to Villalobos, No. 3,541,697.
Also, the air jet producing structure 58 can be removed as the belt
11 of this invention will provide its own individual air jet flow
as previously described.
The Burgess dryer 80 of FIGS. 8 and 9 comprises a high velocity air
flow hood 81 disposed about a rotatably mounted drum 82 having
openings 83 passing therethrough and being covered on the outer
side 84 thereof by a wire, fabric, or other porous covering 85 as
illustrated to prevent marking of the paper sheet 32 when the same
is pressed against the drum 82. The interior 86 of the drum 82 is
adapted to be interconnected to a vacuum source by a central
conduit means 87 having openings 88 therein leading to the chamber
86 and to the interior 89 of the conduit means 87 that is
interconnected to the vacuum source in any suitable manner.
The paper sheet 32 can be fed from a conventional steam dryer "can"
90 to a guide roller 91 that causes the paper sheet 32 to engage
against the covering 85 on the roll or drum 82 and be carried
therewith through the chamber 92 created between the hood 81 and
the drum 82 to an exit guide roller 93 and, thus, to another dryer
"can" 94.
The interior 92 of the dryer hood 81 is supplied with heated air
under pressure by an inlet conduit means 95 in any suitable manner
so that the heated air in the chamber 92 will impinge against the
sheet 32 to break down the boundary layer thereof to transfer heat
thereto and also be passed through the paper sheet 32, covering 85,
openings 83, and into the chamber 86 by the vacuum condition being
created between the interior 86 of the drum 82 and the high
pressure in the chamber 92 in the manner fully set forth in the
patent to Burgess et al.
In order to substantially seal the chamber 92 from the exterior of
the hood 81, flexible seals 96 and 97 are carried by the hood 81
and respectively engage against the guide rollers 91 and 93 as
illustrated. Also, as illustrated in FIG. 9, the peripheral edge 98
of the dryer hood 81 can carry a brush or flexible seal 99 that
engages against the surface 84 of the drum 82 outboard of the
covering 85 thereon as illustrated. In addition, a high pressure
air lock sealing means 100 can be provided adjacent the periphery
98 of the hood 81 to prevent the high pressure heated air in the
chamber 92 from escaping to the atmosphere by the use of high
pressure unheated air in the air lock 100 in substantially the
manner set forth in the U.S. Pat. to Cole et al., No. 3,432,936,
which also discloses an air-through dryer of the air pressure hood
type having such air lock sealing means.
The belt means 11 of this invention is confined entirely within the
hood chamber 92 whereby the belt means 11 passes around the inlet
guide roller 101 so that its fabric or porous covering side 20 will
engage against the paper sheet 32 at the inlet side 102 of the
air-through dryer 80 and move in unison therewith to the exit side
103 of the air-through dryer 80 where the belt 11 is looped around
a guide roller 104. The return run of the belt 11 is spaced from
the drum 82 by passing around other guide rollers 105, 106 and 107
and then back to the inlet guide roller 101.
An internal seal member 108 is carried by the conduit means 87 and
seals against the interior surface 109 of the drum 82 from just
beneath the exit guide roller 104 all the way across to just
beneath the inlet guide roller 101 as illustrated so that the only
air flow that can take place from the chamber 92 into the interior
86 of the drum 82 is through the belt 11 from the inlet guide
roller 101 around to the exit guide roller 104.
Because the belt means 11 of this invention is completely disposed
within the chamber 92 of the hood 81, the same retains its latent
heat that is treated by the heated air passing into the chamber 92.
However, in order to further heat the belt means 11 of this
invention, suitable heaters 110 can be utilized to heat the return
run of the belt means 11 before the same is pressed against the
moist sheet 32 at the inlet guide roller 101.
The operation of the air-through apparatus 80 is modified by the
belt means 11 will now be described.
As the moist paper sheet 32 enters the air-through apparatus 80 by
passing around part of the guide roller 91, the same passes between
the belt means 11 of this invention and the covering 85 of the drum
82 to be carried in unison therewith through the chamber 92 to the
exit guide roller 104 where the belt means 11 moves away from the
same. However, as the paper material 32 moves from the inlet guide
roller 101 to the exit guide roller 104, the pressure differential
created across the belt means 11 of this invention by the air
pressure in the chamber 92 and the vacuum condition in the chamber
86 causes the air to pass through the openings 16 of the flexible
wall 15 of the belt means 11 to produce the air impingement jet
effect previously described against the paper sheet 32 with such
air flow then passing through the paper 32, covering 85 and
openings 83 of the drum 82 into the drum chamber 86 to be exhausted
in the manner previously described out through the conduit 87 so
that as the paper sheet 32 moves from the inlet guide roller 101 to
the exit guide roller 104, the moisture content thereof is
progressively reduced whereby the normal tendency is for the
porosity of the paper sheet 32 to increase as the moisture content
thereof is reduced from the inlet guide roller 101 to the exit
guide roller 104.
However, it is one of the features of this invention to tend to
provide a substantially constant air flow through the paper sheet
32 as the same moves from the inlet guide roller 101 to the exit
guide roller 104, even though the moisture content thereof is being
progressively reduced and, thus, the porosity thereof is being
progressively increased so that the tendency would be for the air
to flow through the more porous portions of the sheet 32 with a
greater rate than through the less porous portions thereof adjacent
the inlet guide roller 101.
By way of example, assume that the combination of the force of the
air pressure in the chamber 92 and the vacuum condition in the
chamber 86 would normally cause an average air flow rate through
the paper sheet 32, if the belt means 11 of this invention were
removed, at a value 10K where K is equal to some measurement of air
flow and 10K is calculated to be the optimum air flow rate for the
particular paper web 32. This may mean that adjacent the inlet
roller 101 where the paper web 32 is more moist and, thus, less
porous, the air flow rate therethrough may be only 5K, whreas
adjacent the middle roller 106 the air flow through the partially
dried web 32 may be at the optimum 10K, whereas adjacent the exit
guide roller 104 the air flow through the paper web 32 may be at
15K. Thus, if it is found that the optimum air flow rate through
the particular web 32 should be 10K, from the inlet guide roller
101 to the exit guide roller 106, an insufficient amount of air
flow is being provided through the web 32 adjacent the inlet roller
101 whereas from the middle guide roller 106 to the exit guide
roller 104, a greater amount of air flow is being provided through
the paper web 32 over the optimum amount desired so that
considerable waste of drying air for adiabatic drying purpose is
being wasted at both the beginning and ending portions of the paper
web travel through the apparatus 80.
However, it is believed that by utilizing the belt means 11 of this
invention, the air flow rate created therey through the paper web
32 adjacent the inlet guide roller 101 will be substantially the
same as the air flow rate through the paper web 32 adjacent the
exit guide roller 104 because the belt means 11 of this invention
can be adapted to continuously and progressively compress the paper
web 32 from the inlet guide roller 101 to the exit guide roller 104
with an increasing amount of pressure so that the resultant
porosity of the paper web 32 will remain the same from the inlet
guide roller 101 to the exit guide roller 104 thereof.
For example, reference is now made to FIG. 10 wherein the
compressing action of the belt means 11 of this invention is
indicated in straight line form, with the left-hand part thereof
being adjacent the inlet guide roller 101 thereof and the
right-hand portion thereof being adjacent the exit guide roller
104. It can be seen that as the porosity of the paper web 32
increases because of its increasing water removal therefrom as the
web 32 passes from left to right in FIG. 10, the tendency would be
for more air to flow through such dryer portions of the web 32.
However, as the paper web 32 becomes more porous, the pressure
differential across the belt means 11 of this invention would
correspndingly increase so that the resultant pressure force acting
on the belt means 11 to move the belt 11 toward the backing means
82 increases and squeezes the paper web 32 with a greater force
than the force on the belt 11 where the paper web 32 is more moist,
and, thus, less porous, so that the resultant effect is to reduce
the porosity of the paper web 32 from its normal porosity at the
dryer portions thereof to thereby only permit the same air flow
rate therethrough as being provided in the moist portions
thereof.
Thus, it can be seen in FIG. 10 that the initial compressing of the
belt 11 against the paper web 32 at the inlet side of the apparatus
80 can cause the porosity of the paper web 32 adjacent the inlet
guide roller 101 to be 5X where X is a suitable measurement of
porosity so as to permit an optimum air flow rate therethrough of
10K whereas the normal removal of water from the paper web 32 by an
air flow therethrough would cause the paper web 32 adjacent the
exit roller 104 at the right hand end of FIG. 11 to normally be at
a porosity of 10X. However, because the belt means 11 is
compressing the paper web 32 adjacent the right hand side of FIG.
11 with a greater force than adjacent the left hand side thereof,
such compressing force has reduced the porosity of the dryer
portions of the paper web 32 to the same 5X porosity as at the
inlet side thereof so that the air flow rate therethrough is still
at the optimum air flow rate of 10K.
Such compressing action can be visualized by realizing that the air
pressure on the lower side 17 of the flexible wall 15 in FIG. 10 is
at one pressure value and tends to force the flexible wall 15
toward the paper web 32 while tending to pass through the openings
16 thereof into the area or fabric covering 19 between the flexible
wall 15 and the paper web 32 so that when the web 32 has a
particular porosity that resists the air flow therethrough, a back
pressure of air builds up in the covering 19 to tend to push the
flexible wall away from the paper web 32 whereby the resultant
pressure differential between the air pressure in the covering 19
and the air pressure on the side 17 of the wall 15 determines the
effective squeezing force of the belt means 11 acting on the paper
web 32 and tending to compress the paper web 32 against the backing
82.
Thus, the less porous the material 32 is adjacent the belt means
11, the smaller the resultant pressure differential acting across
the flexible wall 15 and, thus, the less the compressing force
being provided by the belt means 11 against the paper web 32.
However, as the porosity of the paper web 32 increases because of
the moisture being removed therefrom by the air flow passing
therethrough as the paper web travels from left to right in FIG.
10, the result of the increasing porosity of the paper 32 is to
cause a reduction in the back air pressure in the covering 19
because a greater flow rate of air can now pass through the less
porous paper 32 from the covering 19. However, because the pressure
in the covering 19 now goes down, the resulting pressure
differential acting across the flexible wall 15 correspondingly
increases in value so that the net result is a greater pushing
force of the belt means 11 against the paper web 32 to compress the
same and by thus compressing the paper web 32 with a greater force
the porosity thereof decreases so that the porosity of the paper
web from left to right in FIG. 10 remains substantially the same
and the air flow rate through the paper web 32 from left to right
in FIG. 10 remains substantially constant. Should a particular
section of the belt means 11 compress the paper web 32 with too
great a force so that the porosity of the paper web 32 being
squeezed thereby is reduced to too great of an extent, such as to
4X, the flow rate therethrough drops off to 9K whereby the back
pressure in the covering 19 builds up to reduce the resulting
pressure differential acting across the flexible wall 15 so that
the flexible wall 15 somewhat backs off from the paper web 32
whereby the paper web 32 will expand slightly until its porosity
will be at the value 5X and, thus, the air flow therethrough will
return to the constant 10K rate.
In this manner, not only is a constant air flow provided through
the paper web 32 from the inlet roll 101 to the exit roll 104 in
the manner previously described because of the compressing effect
of the belt means 11 thereon tending to maintain the porosity of
the paper web 32 substantially the same from the inlet guide roller
101 to the exit guide roller 104, but also such belt means 11 is
acting on the paper web 32 from one longitudinal side edge thereof
to the other longitudinal side edge thereof in the same manner so
that in the gross direction of the paper web 32, the porosity of
the paper web 32 will remain substantially constant and the air
flow therethrough will remain substantially constant because in the
dryer portions of the web 32, the belt means 11 will be compressing
the same with a greater force than in the wetter regions thereof in
the manner previously described.
Also, a greater sealing is effected at the longitudinal side edges
of the paper web 32 in the manner illustrated in FIG. 9 because the
flexible belt means 11 of this invention overlap such longitudinal
side edges and conforms to the contour thereof to effect positive
sealing against the drum 82 so that the entire air flow into the
drum 82 must pass through the belt means 11 of this invention, and,
thus, into the paper web 32 moving in unison therewith around the
supporting drum 82.
As previously stated, such compressing action on the belt means 11
of this invention to provide the constant air flow through the
paper web 32 from the inlet side to the exit side of the
air-through apparatus 80 also is accomplished by the belt means 11
applied to the other air-through apparatus previously described as
well as other applicable air-through apparatus.
Thus, a person can determine what is the optimum porosity for a
particular paper web 32 and what air flow rate should be provided
therethrough and once such figures have been calculated, a belt
means 11 can be developed having the proper size of openings 16
provided therethrough so as to maintain the optimum air flow rate
therethrough from the inlet side to the exit side of the
air-through dryer utilizing the same whereby it is believed that a
more economical use of the heated air in an air-through dryer will
be provided by utilizing the belt means 11 of this invention.
Further, because the belt means 11 of this invention is in direct
contact with the paper web 32 being dried thereby, heat is
transferred into the paper web 32 by conduction and assists the air
jets passing through the belt means 11 of this invention to break
down the boundary layer of the paper web 32 to have all of the
advantages of an air impingement device and the additional
advantages of heat transfer by direct conduction, uniform air flow
through the paper web and an initial compressing of the paper web
to the desired porosity thereof at the inlet side of the
air-through dryer which initial porosity will then remain
substantially constant from the inlet side to the exit side thereof
by the self-seeking compression action of the belt means 11 of this
invention.
For example, it may be found that it is desirable to initially
compress the paper web 32 at the inlet side of the air-through
dryer by a certain amount, such as 30 percent, to produce a
porosity thereof which will provide the optimum air flow rate
therethrough for a particular pressure differential and for a
particular air temperature so that when the initial porosity of the
paper web 32 has been changed to an optimum porosity thereof, such
optimum porosity of the paper web 32 will remain uniform throughout
the travel of the paper web 32 through the air-through dryer.
The aforementioned description and theory of the compressing action
of the belt 11 of this invention for tending to maintain a
substantially constant air flow rate through the wet web 32 as it
progresses from the inlet side to the outlet side of the
air-through apparatus is based on the assumption that the fiber
content and construction of the paper sheet 32 is substantially
uniform throughout the entire sheet 32 as would be provided in
textiles and if the covering 19 of the belt means 11 remains of the
same porosity even though being compressed with greater forces.
However, it is realized that in actual practice, a paper sheet is
not uniform through the cross direction thereof so that after the
paper sheet leaves the web forming section and the press section of
a paper making machine, certain areas thereof are thicker than
others, other areas have the fiber content and arrangement thereof
different than other areas thereof, etc. and such irregularities
also cause an irregularity in the moisture profile of the paper
sheet so that it is found that it is actually desired to have a
greater air flow rate through the wetter sections of the paper
sheet than in the drier sections thereof as the sheet passes
through an air through dryer to more uniformly dry the paper sheet
or web.
It is believed that the flexible belt 11 of this invention can be
so constructed and arranged that the same will cause a greater air
flow through the wetter sections of the paper sheet than through
the dryer sections thereof if the covering 19 of the flexible belt
11 is formed of a certain type of material that decreases its
porosity as it is compressed. Thus, because a dryer section of the
paper sheet 32 is more porous than a wetter section of the web 32,
the flexible belt 11 of this invention tends to compress the dryer
section in the manner previously described to change the porosity
of the dryer section to the same porosity as the wet sections at
the inlet side of the air-through dryer. Such compressing action of
the flexible belt 11 of this invention also causes the compressible
fabric covering 19 thereof to compress to reduce its porosity and
its volume content as well as cause a partial closing of the
openings 16 in the flexible wall 15 aligned therewith so that the
volume or rate of air passing through the flexible belt 11 in a
compacting portion thereof as caused by a corresponding dryer
portion of paper web 32 adjacent thereto is at a flow rate less
than the rate of flow of air being passed through the wetter
sections of the paper sheet 32.
Thus, it can be realized that the flexible belt 11 of this
invention while tending to maintain a constant air flow through the
paper sheet from the inlet side to the outlet side of the
air-through dryer as well as in a cross direction of the paper
sheet 32 also tends to force a greater air flow rate through the
wetter sections of the paper than through the dryer sections
thereof because of the aforementioned compressing action on the
compressible covering layer 19 thereof. In fact, it may be found
that the openings 16 in the flexible wall 15 of the belt means 11
may themselves tend to close up more in the areas thereof that are
doing the greatest compressing than in the areas thereof which are
doing the greatest compressing thereof which would be those areas
of the belt 11 adjacent the wetter sections of the paper 32.
Therefore, by selecting the proper material for the covering 19,
the covering 19 can provide a minimum desired air flow rate
therethrough when fully compressed by the effect of a dry section
of paper web adjacent the same and a maximum desired air flow rate
when least compressed by the effect of a wetter section of paper
adjacent the same.
Accordingly, the covering 19 will be less compressed and therefore
more porous adjacent the wet sections of paper and more compressed
and therefore less porous adjacent the dryer sections of paper so
that the belt means 11 of this invention actually seeks out the
wetter sections of paper to force a greater air flow rate
therethrough than at the drier section.
Thus, it is believed that the greater air flow rate through the
wetter sections of the paper web will produce a more economical
water removal operation whether the same is an air sweeping of the
moisture, an air entrainment of the moisture, or an air adiabatic
evaporation of the moisture.
in fact, by having the compressible covering 19 on the flexible
sheet 15 of the belt 11 of this invention, the air flow rate
through the belt 11 and through the paper sheet 32 may actually be
greater adjacent the inlet side of the particular air-through
apparatus utilizing such belt 11 than the flow rate thereof
adjacent the outlet side thereof because the wetter sections are
adjacent the inlet side whereby a greater drying effect is created
at the inlet side than at the outlet side of the apparatus.
Returning now to FIG. 8, it is to be understood that the belt means
11 of this invention need not be in contact with the paper web 32
throughout its entire movement through the hood 81. For example,
reference is now made to FIG. 12 wherein another air-through dryer
of the Burgess type is generally indicated by the reference numeral
80A and parts thereof similar to the apparatus 80 previously
described are indicated by like reference numerals followed by the
reference letter A.
As illustrated in FIG. 12, the belt means 11A is only in engagement
with the paper web 32A from the inlet guide roller 101A to a middle
guide roller 111 which is located only approximately half-way
around the drum 82A so that from the roller 111 to the exit roller
93, the paper web 32 is not covered by the belt means 11A of this
invention.
However, the seal structure 108A of the apparatus 80A is
soconstructed and arranged that the same defines two separate
chambers 112 and 113 in the drum 82 with such chambers 112 and 113
being independently acted on by vacuum creating means so that the
chamber 112 cooperates with the belt means 11A of this invention in
the manner previously described and the chamber 113 acts on the
paper web 32 in combination with the hood 81A in the conventional
air-through manner described in the Burgess et al. patent. Thus, it
may be found that the shorter length of time that the belt means
11A makes contact with the paper web 32A is sufficient and that it
is desirable to merely have a direct air flow through the paper web
32A after such compressing belt action in order to fluff such paper
thereby in order to add bulk thereto such as for tissue, toweling,
and like uses of the paper web 32.
Thus, it can be seen in that the various types of air through
dryers illustrated in FIGS. 1, 2, 3, 8 and 12, the belt means 11 of
this invention is believed to improve the operation thereof because
the belt means 11 causes the web or sheet to be continuously and
progressively compressed or squeezed so that as the same passes
through the air through dryer, the moisture therein not only tends
to continuously fill all voids thereof and be readily swept
therefrom by the air flow therethrough than would be the case if
the air flow through the paper sheets is merely trying to remove
moisture therein by air entrainment rather than by sweeping the
same ahead of the high velocity of the air flow passing
therethrough, but also such belt means 11 is maintaining the
porosity of the paper web in what is believed to be optimum
porosity thereof even though the moisture in the paper web is being
removed therefrom so as to normally tend to increase the porosity
of the paper web whereby a more effective and constant air flow
rate is provided through the paper web to further enhance the
drying thereof.
While the form of the invention now preferred has been disclosed
and described as required by the patent statutes, other forms may
be utilized, all coming within the scope of the claims which
follow.
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