Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to an apparatus to permit a
gas to be fed from a header to a chamber. The invention
finds particular application in paper making for the appli-
cation of steam to a paper sheet.
The steam heating of a paper sheet is widely
practised in paper making. The increase in sheet tempera-
ture that results provides increased drainage rates for the ~ -~
water thus reducing the amount of water to be evaporated in
the drier section. Water drainage is improved by the
application of steam principally because the heating of the
sheet reduces the viscosity of the water, thus increasing
the ability of the water to flow. Most of the heat transfer
takes place when the steam condenses in the sheet. The
condensation of the steam transforms the latent heat of the
steam to sensible heat in the water contained by the sheet.
A particular advantage of the steam heating of the
paper sheet is that the amount of steam applied may be
varied across the width of the sheet, in the cross machine
direction, so that the cross machine moisture profile of the
sheet may be modified. This is usually carried out to
ensùre that the moisture profile at the reel is uniform.
Apparatus are well known in the paper making art that can
sense the moisture profile of a sheet of paper. If such an
apparatus is positioned over the paper sheet, downstream of
a steam distributor able to control the moisture profile,
then after measuring the water profile in the sheet, steam
can be applied in varying amounts on a selective basis
across the sheet, thus achieving the required uniform mois-
ture profile at the reel.
.
It is known to divide a steam distributor into
compartments and to control the supply of steam to each
compartment, thus controlling the moisture profile of the
sheet.
The present invention provides a simple apparatus
having an efficient transfer of steam from a source of steam
to a chamber. The steam is passed from the chamber to the
paper sheet. In a preferred aspect, the invention provides
an apparatus in which effecting control of the moisture
profile of the sheet can be achieved.
Accordingly, the present invention provides an
apparatus to permit gas to be fed from a header to a chamber
adjacent the header, the apparatus comprising: a pipe
extending through the header; an inlet for the pipe in the
header; an outlet for the pipe in the chamber; a piston
within the pipe and reciprocable between a first position
where it closes the inlet and a second position where the
inlet is unobstructed; and means to move the piston between
the first and second positions.
In a preferred embodiment the chamber is divided
into a plurality of compartments with a pipe extending
through the header to each compartment of the chamber.
Aspects of the invention are illustrated, merely
by way of example, in the accompanying drawings in which:
Figure 1 is a section to an apparatus according to
the present invention;
Figure 2 illustrates the principal components of
the present invention;
~ ~3~ Y
Figure 3 illustrates a further apparatus according
to the present invention; and
Figure 4 is a section along the line 4-4 in Figure
3.
Referring to the drawings, Figure 1 illustrates a
sophisticated apparatus particularly useful in the press
section of a paper making machine. The apparatus is an
embodiment of the apparatus described and claimed in my
Canadian Patent Application Serial No. 371,823, filed
10 February 26th, 1981. The apparatus comprises a header into
which steam is introduced. On the exterior of the header is
formed a first chamber 4 and a second chamber 6. Steam
passes from the header 2 to the first chamber 4 through
outlets 8. From the first chamber 4 steam passes through
further outlets 10 to act as a steam curtain to prevent the
drawing in of air by the fast moving paper sheet 12. This ;
feature of the illustrated apparatus does not form part of
the preser.t invention and will not be discussed further.
The resistance to the drawing in of the air is facilitated
by a doctor edge 14, also not a feature of the present
invention. ;
Steam passes from the header 2 to the second
chamber 6 and the second chamber 6 is divided into a plurality
of compartments by partitions 16. Steam passes from the
second chamber 6 outwardly through openings 18 where the
main heating of the sheet takes place. The provision of
compartments permits profiling of the moisture content in
the paper sheet in a manner that will be described later.
The supply of steam between the header 2 and the
--3--
~l~3~
second chamber 6 is through a pipe 20 extending from outside
the apparatus through the header 2 to the second chamber 6.
The pipe 20 has an inlet 22 for steam in the header 2 and an
outlet 24 for steam in the second chamber 6. The inlet is
regulated by a piston 26 provided with sealing rings 28. A
connecting rod 30 extends from the piston 26 to a regulator
32. The regulator 32 is mounted by the provision of a
flange 34 on the end of pipe 20 and a corresponding flange
36 on the regulator 32. The two flanges may be bolted
together. The regulator is pneumatically operated by a
supply of compressed air available in any paper mill. As -
shown more particularly in Figure 2 the structure connecting
rod 30 extends through a gland structure comprising an
externally threaded member 38 engaged by internally threaded
member 40. There are packing rings 42 and sealing members
44 located by an externally threaded member 46 engaging
within internally threaded member 40. The actuator is
located by the base of its bracket 48 (see Figure 1) being
located between flange 36 and the internally threaded member
40-
In operation a predetermined amount of steam,controlled by the position of the piston 26, enters inlet 22
and passes through pipe 20 to the second chamber 16. The
second chamber being divided into compartments the amount of
steam fed across the apparatus can be controlled. The
amount of steam fed to each compartment is, of course,
controlled by the position of the piston 26 in each pipe 20.
In a typical arrangement the actuators 32 will be attached
to a supply of compressed air. Control of the air supply
--4--
,. , ' ., ',.... ,, . "'~ ' . ' '
~3~87
will be at a control station. Information from a moisture
profile sensor positioned downstream of the distributor of
the invention is fed to the same control station. Profile
sensors are well known in the art. An operator at the
station will vary the supply of air to individual actuators
depending on the moisture profile. By this means a desired
moisture profile can be achieved.
Heat loss is reduced by insulation 50.
Figures 3 and 4 illustrate a simpler adaptation of
the device for use particularly on a flat paper sheet 52
moving in machine direction A. Steam is supplied to a
header 54 through a steam supply pipe 56. A surrounding
chamber 58 is defined by housing 60 and there are end plates ~-~
62 provided with holes 64 whereby the apparatus may be
located in position. Partition 66 divide chamber 58 into a
plurality of compartments 67.
A pipe 68 passes through header 54 into chamber
58. Pipe 68 has an inlet 70 in header 54 and an outlet 72
in chamber 58. A piston 74 is movable within pipe 68 to ~ ;
open or close inlet 70. Piston 74 is mounted on a rod 76
extending through a gland structure 78 to hand wheel 80.
Gland structure 78 resembles the gland structure shown in
Figure 2 but there is a threaded collar 82 to engage a
threaded portion 84 on rod 76. Thus rotation of wheel 80
moves the rod 76 and then the piston 74 up and down. That
is control of the piston 74 is by hand. Thus the informa-
tion fed by the sensing device is read by the skilled man
who then varies the valve settings as required to obtain the
necessary moisture profile. The steam leaves the chamber 58
--5--
~3~
through openings 79 in a bottom plate 81 of the chamber 58.
The present invention thus provides a simple yet
effective means of controlling the supply of steam from a
header to a chamber.
--6--
. ~
,
