Note: Descriptions are shown in the official language in which they were submitted.
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WO 97/48851 PCT/FI97/00386
Equipment for combining a dilution flow with the stock flow
passed out of the inlet header in a paperboard machine
The invention concerns an equipment for combining a dilution flow with the
stock
flow passed out of the inlet header in a paperboard machine.
From the applicant's earlier patent applications FI 901593, FI 933027 and FI
942780, a what is called dilution headbox is known, which is understood as a
headbox construction in which the basis weight of the web can be regulated
across
the web width by through valves passing a dilution flow to different locations
of
width of the headboX and by regulating the quantity of said flow. The dilution
flow
is mixed with the stock flow passed out of the inlet header of the headbox.
The
dilution flow can consist of pure or fibrous liquid. Thus, the dilution water
can be,
for example, wire water taken as retention from the web.
In the present patent application, an equipment is described for combining a
dilution
flow with the stock flow derived from the inlet header of a paperboard
machine, in
which solution of equipment the dilution liquid, preferably dilution water, is
passed
into connection with the stock flow passed from the inlet header preferably in
connection with the tube manifold placed after the inlet header. In the
headbox
construction in accordance with the invention, the basis weight of the web can
be
regulated across the wire width by through regulation valves V1,V2... passing
the
desired dilution flow to different locations across the width of the headbox.
In the
solution in accordance with the invention the dilution flow is passed into
each row
of pipes in the tube manifold and in each row of pipes into all the pipes
placed one
above the other in the row of pipes. In this way the mixing of the dilution
flow with
the stock flow passed out of the inlet header can be made as efficient as
possible. In
accordance with the invention, the dilution flow duct consists of a resilient
pipe
passed from the valve, which pipe is preferably connected with the tube
manifold
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2
and out of which pipe the flow is distributed through a duct portion with
inclined
walls uniformly into each pipe in the rows of pipes in the tube manifold. When
a
narrowing duct end is employed, the flow can be distributed evenly into all
the pipes
in the row of pipes in the tube manifold, also into the first pipe in the
direction of
flow Ll of the dilution liquid. A poorly distributed dilution flow increases
the
instability/residual scattering of the basis weight of the paperboard.
In accordance with the invention, the narrowing duct portion for the dilution
flow
has been formed into a middle plate component so that one wall of the
narrowing
duct portion consists of a plate which is placed as the first plate in the
flow direction
Lz of the stock flow and which contains the flow ducts for the stock flow.
Further,
in the construction, at the outlet side of the plate that contains the duct
portion
narrowing in the flow direction, a separate throttle plate is employed, which
comprises throttle openings, in which connection the combined flow L1 + L2 is
mixed efficiently after the point of introduction of the dilution flow at said
throttle
point. In the present patent application, when a throttle plate is spoken of,
said plate
can also refer to a plate construction that comprises a resistance to flow in
general
for the combined flow L1 + L2. Thus, the throttle can also be substituted for
by a
flow widening. The effect of said widening on the conduct of the combined flow
L1
+ L2 is similar to the effect of a throttle construction.
The duct in accordance with the invention, which becomes narrower at its end,
has
been made most advantageously by machining, preferably milling, the duct into
a
metal plate. The set of flow pipes which produces turbulence in the flow and
which
comprises a step-like widening or narrowing, preferably the tube manifold
placed
right after the stock inlet header or the turbulence generator placed after an
inter-
mediate chamber, has been formed into one blank plate by drilling said flow
pipes
into said plate. Similarly, in a construction in accordance with the
invention, the
ends of the dilution liquid duct have been formed into said single plate by
machining
a narrowing duct end into the construction, out of which narrowing duct end
the
branch ducts are branched to the flow pipes intended for the stock flow.
CA 02258232 2005-04-29
In accordance with one aspect of the present invention, there is provided in
an
arrangement for combining a flow of dilution liquid with a flow of stock from
an inlet
header of a headbox of a paperboard machine, the arrangement including conduit
means
for passing the stock flow from the inlet header and dilution flow ducts
through which the
dilution liquid is passed, the conduit means comprising a plurality of
conduits extending
across a width of the headbox, the improvement comprising at least one of the
dilution
flow ducts being defined by walls and including a narrowing duct portion
having an
upstream end and a downstream end, a cross-sectional area defined by the walls
at the
upstream end being greater than a cross-sectional area defined by the walls at
the
downstream end, each of the dilution flow ducts being in flow communication
with at
least two of the conduits at one of a plurality of discrete locations across
the width of the
headbox such that the basis weight of a paperboard web formed upon discharge
from the
headbox is regulatable, and at least two branch ducts in flow communication
with the
narrowing duct portion of each of the at least one dilution flow duct, each of
the branch
ducts leading to a respective one of the at least two conduits.
In an embodiment of the invention, the ducts in the set of flow pipes, which
comprises a
stepwise widening/widenings producing turbulence in the flow, preferably in
the tube
manifold or in the turbulence generator, are composed of module-like units, in
which
connection the pipes in the tube manifold have been made into each module by
turning
and, moreover, into each module, the end of the dilution flow duct has been
made by
milling the end onto the front face of the module. When the modules are formed
in the
way mentioned above by drilling and milling and when the modules are assembled
side
by side, a unit of construction is obtained which can be constructed easily.
The throttle
placed in th.e tube manifold directly after the point of introduction of the
dilution fluid has
been made by turning a conical hole into the metal plate construction.
The arrangement of supply of dilution liquid in accordance with the invention
and its
modular nature are suitable in particular for the supply of the dilution
liquid into
connection with the tube manifold. The invention is, however, not supposed to
be
confined to the point of supply of dilution liquid mentioned above alone, but
the dilution
liquid can be introduced into a similar construction also at the rear side of
the
intermediate chamber in connection with the turbulence generator.
CA 02258232 2005-04-29
3a
In accordance with another aspect of the present invention, there is provided
claim a
method for combining a flow of dilution liquid with a flow of stock from an
inlet header
of a headbox of a paperboard machine at a location between the inlet header
and a slice
chamber of the headbox, comprising the steps of passing the stock flow from
the inlet
header through conduit means comprising a plurality of conduits extending
across a width
of the headbox, passing dilution liquid through a plurality of dilution flow
ducts each in
flow communication with at least two of the conduits situated at a discrete
position along
the width of the headbox, each of the dilution flow ducts being defined by
walls and
including a narrowing duct portion having an upstream end and a downstream
end, a
cross-sectic>nal area defined by the walls at the upstream end being greater
than a cross-
sectional area defined by the walls at the downstream end, and passing the
dilution liquid
from each of the dilution flow ducts through at least two branch ducts in flow
communication with the narrowing duct portion of the dilution flow duct and
into a
respective one of the at least two conduits.
In accordance with a further aspect of the present invention, there is
provided a method
for regulating the basis weight of a web upon its discharge from a headbox of
a
paperboard machine, comprising the steps of passing a stock flow from an inlet
header of
the headbox through conduit means comprising a plurality of conduits extending
across a
width of the headbox, introducing dilution liquid into the stock flow in at
least one of the
conduits by passing the dilution liquid through at least one of a plurality of
dilution flow
ducts each leading to at least two of the conduits situated at a discrete
position along the
width of the headbox, the at least one dilution flow duct being defined by
walls and
including a narrowing duct portion having an upstream end and a downstream
end, a
cross-sectional area defined by the walls at the upstream end being greater
than a cross-
sectional area defined by the walls at the downstream end, and passing the
dilution liquid
from the at least one dilution flow duct through at least two branch ducts in
flow
communication with the narrowing duct portion of the at least one dilution
flow duct and
into one of the conduits, regulating the flow of the dilution liquid through
the dilution
flow ducts 1;o thereby regulate the basis weight of the web, and discharging
the stock flow
including the dilution liquid from the headbox to form the web.
CA 02258232 2005-04-29
3b
The invention will be described in the following with reference to some
preferred
embodiments of the invention illustrated in the figures in the accompanying
drawings, the
invention being, however, not supposed to be confined to said embodiments
alone.
Figure 1A is a sectional view of the headbox of a paperboard machine, and what
is
shown is th.e arrangement of supply of dilution liquid in connection with the
tube
manifold placed after the inlet header.
Figure 1B is an illustration in part of the construction of Fig. 1A from
above.
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4
Figure 1C shows the set of valves V1,V2... for the regulation of the dilution
liquid
viewed in the direction of the arrow K1 in Fig. 1A.
Figure 2 is a sectional view taken along the line I-I in Fig. 1B. What is
shown is
the supply of dilution liquid into connection with the tube manifold on a
larger scale.
Figure 3 is an axonometric view of modular construction components M1 and M2.
Figure 4A is an illustration in part of the module M1 shown in Fig. 3 viewed
in the
area of the tube manifold in the direction of the arrow K2 in Fig. 3.
Figure 4B is a sectional view taken along the line II-II in Fig. 4A.
Figure 4C is a sectional view taken along the line III-III in Fig. 4A.
Figure 4D shows a throttle plate placed at the outlet side of the tube
manifold (in the
flow direction of the stock). The illustration is substantially similar to the
sectional
view shown in Fig. 4B.
Figure 5 shows an embodiment of the invention which is in the other respects
similar
to the sectional view of Fig. 4C, except that in this embodiment the branch
ducts
E1.1~E1.2~E1.3 have been milled into the construction so that the flow is
directed
against the stock flow L1. In this way the mixing of the flows can be made
efficient.
Figure 6A shows a second embodiment of the arrangement of supply of dilution
liquid.
Figure 6B is a sectional view taken along the line IV-IV in Fig. 6A.
Figure 7A shows an embodiment of the invention in which one structural wall of
the
conically narrowing duct D1 is formed by a side wall of an adjacent module.
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Figure 7B is a sectional view taken along the line V-V in Fig. 7A.
Figure 8A shows an embodiment of the invention in which the supply of the
dilution
liquid into the stock flow takes place in the turbulence generator after an
intermedi-
5 ate chamber,
Figure 8B shows the construction of Fig. 8A viewed from above.
Figure 9 shows an embodiment of the construction in accordance with the
invention
in which the stock ducts and the dilution liquid ducts have been made into one
single
plate by machining. The plate extends across the entire width of the headbox.
As is shown in Fig. 1A, the headbox 10 of the paperboard machine comprises an
inlet header J, after the inlet header J a system of pipes, i.e. a set of
pipes 11 of the
tube manifold, which produces turbulence in the stock flow, and after the set
of
pipes an intermediate chamber 12, which is opened into the stilling chamber
13.
After the intermediate chamber 12, there is a second set of pipes which
produces
turbulence in the stock flow, i. e. the turbulence generator G . The pipes G
1,1, G 1 .2
in the turbulence generator G are further opened into the slice cone 16, which
comprises lamellae 17a1,17a2,17a3 in the way shown in the figure. The stock is
passed further out of the slice cone 16 through an outflow gap onto the
forming wire
H. As is shown in the figure, the outflow opening after the slice cone 16
comprises
a top slice bar n and a mechanism 18 for its regulation. The position of the
top slice
bar n can be regulated by means of the adjustment spindles 19 and adjustment
motors 20 included in the regulation mechanism 18. The flow Ll of the dilution
liquid is regulated by means of the valves V 1, V2. . . The equipment
comprises a
. number of distribution ducts D~,D2... for dilution flow across the width of
the
headbox, in which connection the desired dilution flows can be introduced into
different locations of width across the headbox, and said flows can be
regulated at
each location of width by regulating the valve V 1, V2. . . of the dilution
flow. As is
shown in Fig. 1A, the dilution liquid, preferably dilution water, is passed
into
different locations of width across the headbox of the paper machine so that
the
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6
dilution water is passed into the pipes
llal,i,llal.2,11a1..~;Ila2.l,11a2.2,11a2,3;
lla3.l,lla3.~,11a3.3 ... in each vertical row in the tube manifold 11.
Fig. 1B illustrates the construction as shown in Fig. 1A viewed from above.
Fig. 1 C illustrates the system of valves V 1, V2, V3 . . . used in the
regulation of the
dilution liquid. The dilution liquid is passed from the dilution liquid inlet
header J2
into the dilution liquid supply ducts D 1,D2. . . through the valves V ~ , V2.
. . By means
of the valves, the flow of the dilution liquid L1 is regulated in each duct
D1,D2...
independently from the other ducts.
Fig. 2 is a sectional view taken along the line I-I in Fig. 1B. As is shown in
the
figure, from the inlet header J 1 a stock flow L 1 is passed into each pipe 11
a 1.1,
llal.2,l1a1.3;11a2.l,l1a2.2,11a2_3; lla3.i,l1a3,2,11a3.3 ... in the tube
manifold 11.
The dilution liquid is passed as a dilution flow I2 into each pipe
llat.l,llal.2,
11a1.3 in a vertical row in the tube manifold. The flow is passed through the
distribution duct D1 or equivalent of the distribution pipe into the vertical
row in the
tube manifold 11 and further into each pipe 11 a 1.1,11 a 1,2,11 a 1.3 in each
vertical
row. Similarly, in the other different locations of width and vertical
sections in the
tube manifold, the dilution flow is passed out of the distribution ducts
D2,D3... into
the pipes lla2.i,l1a2.2,11a2,3;11a3.l,l1a3.2,11a3,3 ... in the vertical rows
at
corresponding locations in the tube manifold 11.
As is shown in Fig. 2, the distribution duct D1,D2 for dilution flow becomes
narrower at its end so that the narrowing of the duct D 1 takes place towards
the
lowest pipe llal_3 in the tube manifold 11. As is illustrated in Fig. 2 by
means of
dashed lines, the duct portion Dla of the duct Di, which has been formed
between
the rows of pipes in the system of pipes, has additionally been formed so that
its
wall portion S 1 is placed as inclined in relation to the vertical plane. The
branch
ducts are opened from the wall S2 of the duct portion Dla into the pipes
llal.i,
11a1.2... in the vertical rows in the set of pipes 11.
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7
By means of said narrowing arrangement of ducts, the pressure can be kept
invari-
able in all the outlets E1.~,E1,2,E1.3 of fhe duct D1. As is shown in the
figure, the
cross-sectional shape of the distribution ducts E1.1,E1.2,Et.3 branched from
the
dilution flow duct D~ is rectangular.
Similarly, the cross-sectional shape of the end Dla of the duct D1 is
rectangular, and
said narrowing duct shape is produced by milling the end wall S1, which is
placed
inclined in relation to the vertical plane, in the end area of the duct D 1.
The duct D 1
portion Dla is connected with a resilient flexible duct portion Dlb, which
comprises
a regulation valve V 1 at its end. The dilution liquid is passed into the duct
D 1 out of
the dilution liquid inlet header J2.
The outlets of the branch ducts E1.1,E1.2~E1.3 into the pipes
llal.l,llal.2,l1a1.3 in
the tube manifold 11 are placed at the forward side of the throttle
21a1,~,21a1.2,
21a1,3 in relation to the flow direction L1. The throttle 21a1.1,21a1.2,21a1,3
is a
conical contraction of the duct, which terminates in a straight duct portion
22a1.1,
22a1.2,22a~.3 (FIG. 4D). The most usual embodiment is a construction in which
there is one single plate into which the pipes llal,l,llal,2,l1a1,3...;
lla2.l,11a2.2,
l 1a2.3... formed into said plate of the tube manifold 11 have been made by
drilling,
the branch ducts E1.1,E1.2~E1.3 having been made into the front face T' of
said
plate by machining.
The pipes llal.l,llal.2,l1a1.3...; 11a2.1,11a2,2, 11a2,3... in the tube
manifold 11
consist of two portions of sets of pipes, i.e. of pipes that have been
machined,
preferably drilled, into a separate plate and of separate pipe components
connected
with said pipes.
Fig. 3 illustrates the modular structural components M1 and M2 in the mixing
part
of the tube manifold 11. ' The structural components or modules M ~ , M2. . .
are
preferably metallic plates T, into which the pipes llal.l,llal_2,1ia1.3 in the
initial
part of the tube manifold 11 have been made by drilling into the plate T. As
each
module M t ,M2 has been made as a separate structural component, the ducts D
1,
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8
D2. . . can be made into it, onto the front faces T' of the modules M 1, M2. .
. , easily
by milling. Similarly, the duct D1,D2 shape narrowing towards the end in the
end
portions Dla,D2a... of the ducts can be accomplished by making the end wall S1
of
the duct D1,D2..., whose cross-sectional shape is otherwise rectangular,
inclined in
the area of the end portion Dla,D2a... Similarly, the branch ducts
E1_1,E1.2~E1.3~~~e
E2.1 ~E2.2~E2.3~ ~ ~ ~ E3.1 ~E3.2~E3.3 ~ ~ ~ can be made easily by milling
into the front wall
T' of the plate T of each module M 1,M2. . .
In the embodiment shown in the figure, the ducts E1.1,E1.2~E1.3 are placed
perpen-
dicularly to the central axes X1_1,X1.2~X1.3 of the pipes llal.l,llal_2,11a1,3
in the
tube manifold. In such a case the flows Ll and L2 meet each other at a right
angle.
Fig. 4A shows the module M1 viewed in the direction of the arrow K2 in Fig. 3.
Fig. 4B is a sectional view taken along the line II-II in Fig. 4A.
Fig. 4C is a sectional view taken along the line III-III in Fig. 4A.
The illustrations in Figs. 4B and 4C do not show the throttle plate 20, but
the fitting
of said plate in connection with the construction is illustrated in Fig. 4D.
Fig. 4D shows the throttle plate 20 in connection with the front part, i.e.
the plate
T, in the tube manifold 11. At the outlet side of the throttle plate 20, the
separate
pipes in the final part of the tube manifold 11 are placed, as is shown in
Fig. 2.
Fig. 5 shows a second embodiment of the invention, which is in the other
respects
similar to the sectional view in Fig. 4C, except that in said embodiment the
branch
ducts E1.1,E1.Z~E1.3 have been milled into the construction so that the flow
direction
of the flow L1 out of the duct D1 can be directed so that it is oblique
against the
flow L2 coming from the inlet header J1. In such a case the mixing of the
dilution
flow L~ and the stock flow L2 can be made efficient.
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9
The embodiment of Fig. 5 is mainly similar to the sectional view in Fig. 4C.
Fig. 6A shows an embodiment of the invention in which the duct portions Dla,
D2a... of the ducts D1,D2... have been formed into a construction plate 50,
which
is placed alongside the throttle plate 20 and so that the narrowing duct
portion Dla,
D2a... is fitted to be opened so from the front face T" of the plate 50 that
the
cleaning of the duct system Dla,D2a... can be carried out by detaching a
separate
plate 60, which contains the initial part of the system of flow ducts
(llal.l,l 1a1.2...;
11 a2.1,11 a2.2 . . . ; G 1.1 ~ G 1.2 ~ ~ ~ ~ G2.1 ~ G2.2 ~ ~ ~ ) intended for
the flow L2 coming from
the inlet header J1. Thus, when the plate 60 is detached, the narrowing ducts
Dla~D2a~ ~ ~ and the connected branch ducts El.1,E1.2~ ~ ~ are opened for
cleaning, and
the extension portion Dlb,D2b... connected with the narrowing duct Dla,D2a...
does
not interfere with the washing of the system of ducts, but said washing can be
carried out by detaching the plate 60.
Fig. 6B is a sectional view taken along the line IV-IV in Fig. 6A.
Fig. 7A illustrates a plate-like module M1,M2 in accordance with the
invention. The
illustration in Fig. 7A is taken mainly in the direction of the arrow K2 in
Fig. 3. The
embodiment of Fig. 7A differs from that of Fig. 3 mainly in the respect that
one
side wall of the adjacent modular structural components, i.e. of the modules
M1,M2,
is defined by the duct D1,D2... What is shown is an embodiment in which one
wall
S4 of the conical portion DIa,D2a... of the duct D1,D2... is formed by one
side wall
F1 of the module M2 adjacent to said module M1. The initial part of the tube
manifold 11 has been formed out of plate-like modules Ml,M2,M3... by intercon-
necting said modules M1,M2,M3... in the direction of width of the headbox of
the
paperboard machine.
Fig. 7B is a sectional view taken along the line V-V in Fig. 7A.
Fig. 8A shows an embodiment of the invention in which the mixing of the
dilution
liquid and the stock flow takes place after the intermediate chamber 12 in the
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turbulence generator G at the forward end of its pipes G1.1,G1.2'G1.3~ ~ ~ ~
G2.1'G2.2'
G2.3... in a way similar to the solution described above.
Fig. 8B shows the construction of Fig. 8A viewed from above in the area of the
5 forward end of the turbulence generator G.
Fig. 9 is an illustration in part of an embodiment of the invention which
comprises
narrowing ducts D 1,D2. . . for dilution liquid in connection with a tube
manifold 11
composed of a single plate-like structural component T. The pipes in the tube
10 manifold 11 can have been made into a metallic plate construction
conventionally by
machining, preferably drilling. The ducts D1,D2... that supply dilution liquid
have
been made into the front face of the plate construction T, as was the case in
the
embodiments described above, by milling or by means of some other method of
machining. The plate T extends across the entire width of the headbox. The con-
struction can also be used in connection with the turbulence generator, after
the
intermediate chamber, or it can be used in a headbox construction which
comprises,
after the inlet header J1, just one system of pipes that produces turbulence
and, after
that, the slice cone.
