An Improved Method of and Apparatus for Drying Paper and similar Materials.
Year: 1897

page_text: Date of Application, 16th Feb., 1897-Accepted, 3rd Apr., 1897
COMPLETE SPECIFICATION.
An Improved Method of and Apparatus for Drying Paper and
similar Materials.
We, ALFRED ARNOLD HUNTING, of 26 Mason Street, Salem, and EVAN ARTHUR
LEIGH, of 352 Hancock Street, Wollaston, both in Massachusetts, United States of
America, Mechanical Engineers, do hereby declare the nature of this invention and
in what manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
This invention relates to a novel method and apparatus for drying materials in the
form of a sheet or web, and is especially adapted for drying paper or like fibrous
stock. As now commonly practised, paper stock in the form of a sheet or web of
varying thickness is exposed to heat in a chainber, usually a room of considerable
size, into which air is admitted by natural draught, and which is commonly heated by
steam pipes arranged about the said room.
This method of drying the paper, which depends upon the heat alone, is defective,
owing to the fact that the air in the chamber or room soon becomes saturated with
moisture absorbed from the paper, which requires that the paper be left for a long time
in the chamber or until the saturated air has been changed by natural draught or by
a very high temperature in the room. This long exposure of the partially dried paper
web causes the latter to twist or curl, so that when the paper is thoroughly dried, it
is twisted out of shape, and is cracked, split or torn off, thereby occasioning a
considerable waste, which, in large mills, is a very important item. This defective
condition of the paper is due to the imperfect method of drying the paper, and it is
the object of this present invention to obviate these defects, so that the paper may be
thoroughly and evenly dried ou both surfaces in a substantially short space of time and
before it has a chance to twist or curl.
In accordance with this invention, the wet paper stock, which for the purpose of
this invention may be supposed to be in the form of a web, is subjected to the action
of air, preferably heated, and which is also partially freed from moisture, normally.
contained therein under atmospheric conditions, and in which freed condition, the
capacity of the air for absorbing moisture is greatly increased, the said air being
adinitted into the drying chamber or room at a substantially high velocity and
distributed in a continuous transverse stream over both surfaces of the paper web at
a plurality of points or stations, and then exhausted from the said room at substantially
the same rate, and preferably at a greater rate than the said air is being admitted,
whereby air at a substantially low temperature but at a substantially high velocity may
be used.
By this method, the paper web is exposed to a current of non-saturated air, which
is in the best condition to effect a thorough drying of the paper stock. The method
just referred to, may and preferably will be carried out with an apparatus substantially
such as will be hereinafter specifically described.
Fig. 1 represents in partial section and side elevation a drying chamber or room
containing a paper drying apparatus embodying this invention.
Fig. 2, a top or plan view of the apparatus shown in Fig. 1, the chamber or room
in which the apparatus is located being shown in section.
Fig. 3, a side elevation of the apparatus shown in Fig. 1, the building or structure
being shown in section.

page_text: Fig. 4, an edge view of one of the air delivery nozzles.
Fig. 5, a side or end elevation of the nozzle shown in Fig. 4.
Fig. 6, a front elevation of the nozzle shown in Fig. 4, and
Fig. 7, a modified form of nozzle to be referred to.
Referring to Fig. 1, A represents the drying room of a building or structure A1
of any suitable or desired construction, the said buildings as herein shown supporting
the walls A 2 of an auxiliary chamber A 3. The room or chamber A has located
within it the main portion of my improved drying apparatus, which consists
essentially of a main distributing pipe a, preferably extended in the direction of the
length of the room A, and having connected to it at suitable intervals apart branch
distributing pipes a 1 a 2, respectively, provided with discharge nozzles a 3 a 4, each
having preferably a continuous discharge slot or orifice (see Fig. 4).
The branch distributing pipe a 2 is extended downward below the nozzle a 3 of
the pipe a 1, so that its attached nozzle a 4 is located below the nozzle a 3 a suitable
distance to afford a passage for the web or sheet a 5 of paper or other fibrous
stock to be dried, and the said pipe a 2, is for the best results, of slightly larger area
than the pipe a 1. In the present instance, the branch pipe a 2 is shown in
Fig. 3 as curved at its lower end as at 2 and is located at one side of the branch
pipe a 1.
The main distributing pipe a has connected to it, a plurality of the branch
pipes a 1 a 2, and the said main distributing pipe is so proportioned as to deliver
substantially the same amount of air at substantially the same velocity from the
nozzles a 3 a 4 of all the branch pipes connected to it. The main distributing pipe a
has connected to it an air supply pipe b, which in the present instance is extended up
into the chamber A 3 and forms an outlet for a heater chamber 61, within which may
be located one or more coils of pipes connected to a suitable source of heat and not
herein shown. The heater chamber 61 may have secured to it or forming part of it,
but separated therefrom in suitable manner, herein represented by a dotted line 2, a
chamber 63, within which may be located a condenser of any usual or suitable form,
such for instance, as a coil of pipes through which water is circulated, the said pipes
being not herein shown.
The condenser chamber 63 communicates with the discharge outlet of a blower or
air forcing apparatus 64, which also may be of any usual or suitable construction
containing within it a rotary fan which may be driven in any suitable manner, it being
herein represented in the present instance as driven by a pulley 65 on a shaft extended
through the air inlet pipe 66, the latter communicating with the atmosphere, it being
herein represented as extended up through the roof of the auxiliary chamber A 3.
The main distributing pipe a is made of decreasing area in cross section from the point
of its connection with the air supply pipe b toward its opposite end or ends as clearly
shown in Fig. 1, the branch-pipes a being connected thereto at the junctions of
sections of smaller area with sections of larger area, so that substantially the saine
quantity of air will be discharged through the nozzles of the branch pipes connected
to the main distributing pipe near its center, as will be discharged from the nozzles of
the branch pipes connected to the main distributing pipe near its ends, and as a result,
the web a 5 is subjected on both its upper and lower surfaces, to the action of air
blasts uniformly and equally distributed against the surfaces of the paper throughout
its passage through the drying apparatus. The nozzles a3 a4 are preferably made
of substantially the form shown in Figs. 4, 5 and 6, and are of substantially the
width of the web or sheet to be acted upon, each nozzle having a continuous discharge
slot or orifice extended across the paper web, so that the entire width of the paper on
both surfaces may be subjected to a continuous stream of air, and as a result both
surfaces of the paper are evenly dried.
Instead of making the nozzle with one continuous slot as shown in Figs. 4, 5
and 6, it may be provided with diverging perforations or openings having their walls
converging to substantially a point (see Fig. 7) so that the air will issue from the said
openings in jets which intersect one another and meet in front of the nozzle and form
one continuous stream of air, which acts on the sheet or web. The diverging openings

page_text: in the nozzle shown in Fig. 7 is the equivalent of the nozzle shown in Figs. 1, 5
and 6, and produces a continuous stream of air acting transversely on the sheet
or web.
The paper web or sheet a 5, while the air blasts are in operation, will be practically
supported by the current of air on its underside, but I prefer to employ between each
set of branch pipes a support shown as a roller c, which may be rotated or driven by
any suitable mechanism, and upon which the paper may rest, in case of accidents or
stoppage to the apparatus, as for instance, in the case of the breaking of the paper
sheet or web. in operation, the heated air issuing from the nozzles 3 a 4, rapidly
absorbs the moisture in the paper sheet or web, and in order to successfully dry the
paper, it is necessary that this air should be taken away from the presence of
the paper before it is completely saturated. This fact is of vital importance to the
successful accomplishment of a perfect drying of the paper in a substantially short
space of time, and in order that the saturated air may be taken away from the sheet or
web as fast as formed, an air exhausting apparatus is employed having a capacity equal
to and preferably even greater than the air forcing apparatus.
The air exhausting apparatus may be an exhaust fan of any usual or suitable
construction, and is herein represented as a box or chamber c4 located in the
chamber A 3 and containing a suitable fan driven as herein represented by a pulley c 5,
the containing case or chamber c4 of the exhaust apparatus, having its inlet port or
opening connected by a pipe c6 to branch pipes c 7, c 8 communicating with the drying
room or chamber A preferably at both its top and bottom, the branch pipe e 8 being
herein represented as communicating with the chamber at its bottom, and the branch
pipe 7 communicating with the said chamber at its top.
As represented in Fig. 1, the branch pipes c 7 c 8 are located within the chamber A,
but it is evident that they may be located without the walls of the said chamber and
communicate therewith through suitable openings.
The air exhausting chamber c4 has its outlet opening or port communicating with
the atmosphere, it being herein represented as connected by a pipe c9 extended through
the roof of the auxiliary chamber A 3.
I prefer to employ a condensing apparatus in connection with the heater as in
certain seasons of the year, the atmospheric air is heavily charged with moisture,
which by means of a condenser can be reduced before being admitted into the drying
chamber, but I do not desire to limit my invention in this respect, as the use of
the condenser may be dispensed with on days in which the atmospheric air is
substantially dry.
I prefer to construct the apparatus as herein shown and to locate the heater 1 and
the condenser outside of the drying chamber A, but I do not desire to limit my
invention to any particular location of the said parts. Furthermore, I do not desire
to limit my invention to the drying of the paper stock in the form of a sheet or web,
as it is evident the said stock may be loose and supported upon a suitable screen
made to travel between the series of nozzles.
The discharge slots of the nozzles a3 a4 are made narrow, so that the air is
projected from the said nozzles in thin streams or sheets, which impinge on both
sides of the paper at substantially diametrically opposite points with a twofold
beneficial result namely, 1st. The thin streams of air strike the paper web on opposite
sides with substantially great force, thereby driving the sizing toward the center of
the paper web and penetrating the pores of the paper web to such extent as to ensure
a rapid and complete drying of the paper. 2nd. The thin sheet of air is projected
with such velocity that it is not broken up or disturbed by the current of air created
by the exhaust apparatus, and as a result, the thin sheet of air does its work efficiently
and is influenced or acted upon by the exhauster only after it has performed its work
on the
paper.
The drying apparatus herein shown is particularly well adapted for drying paper
stock, but it may also be used to dry other fibrous stock, as, for instance, sheets or
webs of cloth

page_text: Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is performed, we declare that what we
claim is:
1. That improvement in the method of drying fibrous material in the form of a
sheet or web, which consists in forcing air into a drying room or chamber and
discharging the said air against the opposite surfaces of the said sheet or web in
continuous streams extending transversely across both surfaces of the sheet or web at
a plurality of points, the continuous transverse streams of air being discharged at each
point to the same amount and at the same velocity to obtain an even drying of both
surfaces of the material, and exhausting the moistened air from the said room or
chamber at substantially the same rate as the said air is forced into the chamber,
substantially as described.
2. An apparatus for drying paper comprising a drying chamber provided with
means for feeding a sheet or web of paper or other fibrous material therethrough,
a series of substantially equi-distant nozzles having substantially equal and restricted
mouths extended across the entire path of the said sheet or web that is to be dried,
and located above and below the said sheet substantially in line with each other, an
air supplying apparatus of different areas in cross section for the said nozzles, an air-
forcing apparatus connected with the air supply pipe, and an air exhausting apparatus
for the said chamber, substantially as described.
3. An apparatus for drying fibrous stock in the form of a sheet or weh comprising an
air forcing apparatus, a main distributing pipe connected with the air forcing apparatus
and of varying areas in cross section decreasing from the connection of the distributing
pipe with the air forcing apparatus, a series of branch pipes connected to the main
distributing pipe at the junctions of sections of smaller area with sections of larger area,
a series of discharge nozzles connected to the said branch pipes in pairs located
above and below the plane in which the paper web is moved, and each nozzle
having a continuous slot or orifice extended transversely of the paper web and of
a length substantially equal to the width of the paper web, substantially as and for
the purpose specified.
4. An apparatus for drying fibrous stock in the form of a sheet or web comprising
an air-forcing apparatus, a main distributing pipe connected with the air forcing
apparatus and of varying areas in cross section decreasing from the connection of the
distributing pipe with the air forcing apparatus, a series of depending upper
and lower branch pipes connected to the main distributing pipe at the junctions of
sections of smaller area with sections of larger area, and of substantially the same
length, discharge nozzles for each branch pipe arranged in pairs with the discharge
nozzles of the upper branch pipes in substantially the same plane and the
discharge nozzles of the lower branch pipes in substantially the same plane, with
the discharge mouths of the upper and lower nozzles of each pair in substantially the
same vertical plane and of a length substantially equal to the width of the paper web,
whereby the said web may be simultaneously acted upon at a number of points by a
plurality of continuous streams of air striking the upper and lower surfaces in
substantially the same vertical plane, substantally as described.
Dated this 16th day of February 1807
D. YOUNG & Co.,
11 & 12 Southampton Buildings, London, W.C.,
Agents for the Applicants.