Note: Descriptions are shown in the official language in which they were submitted.
- P/14-333
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DEVICE AND MBTHOD FOH THE NON-CLOfiGINt3 THROTTLING
OF 71 FLiIID $TRg7Vt DZ' SUSPENDED MhTTER
B1~CRGROUND OF THE INVENTION
The present invention relates to a device and a
method far the ncn-clogging throttling of a fluid Stream,
particu?arlv a stream of suspended pulp in a paper
machine or a pulp preparation plant.
Valves of many different types are known in the
prior art for throttling fluid streams, including ball
valves, flap valves, needle valves, and the like. An
essential disadvantage of these valves is that they
provide relativ~a narrow cross sections for establishing a
desired rate of Ilow. It is Known that narrow cross
sections tend to clog in an undQxirable msnnex upon tho
passage or pulp suspensions and, upon theix use in paper
making machines, they procuce fiber uripi.ngs, local
accumulations of fibers and deposits. This either
results in clegging of the valvo or elc~ fiber wipingc or
deposits are not bro:~ten up again before the start of the
sheet forming process duo to the absence of the influence
of shearing forces. As a xesult, in the most favoxabhe
case, formation flown are formed in the paper web.
However, experience shows that these non-homogeneous
elements in the sheet are fregutntly the starting point
for tearing of the entire web of paper and they thus lead
to. significant disturbances in the operation of a paper
machine.
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S',TMI'2ARY. OIL' THE I:WENTION
The object of the invention is to provide a
z°alva or a throttle member, in which t'rrQ formation of
fiber wipings and/or the danger of clogging is avo~,ded by
a suitable design.
The invention concerns a valve or throttling
devioe for a fluid stream, particularly a solid
conducting stream, and more particularly a fluid stream
of pulp suspension in the headbox of the paper making
machine. The valve or throttling device includes a
t hollow body of s~,:bstantially rotational sy:nnetry having a
longitudinal axis along the direction of liquid flow
through the body. The hollow body also includes a
variable cross section passage area which is of
substar_tially rotational symmetry. A throttle piece may
be provided in the body to defin8 a narrow cross section
annular throttle region through which the solid
conducting stream passes and where the solid conducting
stream rnigrt be blocked. Means, e.g. in the form of
2o tangential inlet flow to the hollow body, era provided to
impart a rotary component of flaw to tl~e liquid being fed
into the hollow body and being fed peat the throttle area
of the body, so that the liquid has a rotary component
around th= direction cf the main stream as the r.~tain
stream moves through the hollow body to the outlet from
the throttle device. othor means may be pro'trided for
providing the rotary component ~.o the liquid flow. For
example, the inner surfaces of the respective devices are
to be grovided with e.g. helical grooves, guide vanes
etc. which cause xota,tion Or the liquid.
The invention also concerns the method of
reaucing clogs in a valve or throttling crevice through
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imparting the rotary component of motion to the liquid
stream passing through the hollow body.
The inventors have recognized that the tenderiCy
of a valve toward clogging can be considerably reduced.
particularly in a type of valve construction which
corresponds to a needle valve, if a rotary component is
added to the flaw in the region of the narrowest point of
the valve. The rotary component breaks up any
turtaulences which may be present and also the fiber
ip wipings and,/or fiber accumulations thereby produo~a,
w:~ich might otrerwise lead to clogging.
Other features and advantagl~C of the pros~nt
invention will become apparent from the following
description of the -ynvontion which refers to the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
fig. 1 is a diagrammatic cross section through a valve
in accordance with the invention;
Fig. 2 is a section A-A through the valve oZ the
' irwention shoran in Fig. I;
Fig. 3 shows the ,ass of the valve or the invention in
the pulp-suspension feed of a headbox.
DFTA_TT_,ED DESGRT_ TTON OF EMBODI;~,' ~E. TS OF TIdF INVkNTIDN
Fig. 1 is a cross-sectional view of a throttle
device 1 in accordance with tho inv~ntion. In the
diagrammatic showing, the throttle device includes a body
which definss a cylindrical nollow e~pace of substantially
rotational symmetry having a constriction 3. A fluid
stream i~c fod in perpQndioular to the axis of the
3o cylindrical hollow space via an eccentrically arranged,
radius parallel feed 4. The fluid stream S thus enters
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the hollow space t,angentinlly and is there deflected
towarw the axial direc~ion along the hollow space which
dire~t~on is along the axis of the space. Triis imparts a
spiral course to the stream S withir, the cylindrical
hallow space. wi~hir. iris hollow space there .is also an
axially arranged ray 2. IL is provided with a widening
ors its lower side, which is the side facing the throttle
ox constriction 3. The ram :~ is displaceable in the
axial airection so that a narrowed annular restriction in
cross Section similar to that provided by a needlQ valve
i5 effected by axial displacement of the ram. In
contrast to an ordinary naodlo va~.ve, however, the
tangentially introduced stream s~;ffieiently flushes the
narrowed constriction era that no clogging by solids
entrained in the flow should occur at this point. This
is partioularly advantageous in connection with streams
of suspender. pulp .n paper machines in which such
clogging, and therefore formations of fiber wipings, can
have vexy unfavorable e~fects on the quality of the paper
produced.
The liquid exits through an outlet at thQ
bottom of the body 1.
Fig. 2 is a cross suction A-A through the
throttle Qevice of dig. Z. In the top view' shown, the
tangential feed of the stream s into tho c~~lindxical
inner space at the throttle device is clearly shown.
The invEntion is not lzmitod tc a purely
tangential feed of the stream into the throttle space of
a throttling device. 2t is also possible, for instance,
o to use suitable ball elements to change the direction of
the stroam fed within the entire solid angle so that, on
the one hand, an angle other than 90° with respect to the
mai:a axis og the throttling device can be adopted and at
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_ s _
the same time the eccentricity of the stream of pulp with
respect to the axis of the cylindrical throttling device
car. be controlled. In this weLy, simple control of the
angle of the rotating flow spiral within the thrott.inq
device is possible. As a result, on the one hand, t2-.e
cleanwng effect can be controlled in a desired manner
and, an the other hand, an add~.tional iriCredse or
xedu4tion of the throttling is possible without the
reduced passage area F having to be ;:rianged by moving or
ZO changlnq the ram 2.
Furthermore, the fluid wetted surfaces may be
surfaces for causing ratatien of the liquid. To da this,
the inner surfaces of the respective devices are to be
pravidod with e.g. helical groav4e, guides vanes etc.
which cause rotation of the liquid.
Fig. 3 chawa the use of the valve of Fige. 1
and 2, for example or the controlled feeding of dilution
water into the main atr4am of tho pulp suspension in a
paper machine headbox. T-~o cross-flow distributors Q1
and Q2 are shown, the pulp susponsion being fed in
slightly increased concentration from the cross-flew
distributor Q1 via a main line H to the headbox STA.
There are two distributors, each comprising a
main pipe, extending in rne cross direction or the
nachine and from open side of the headbox to the other
one. Each main pipe is connected to a p~,u:ality or small
diameter pipes, each of which generally is located in a
vertical plane situated perpendicularly can the length
axis of the main pipQ. Tha small diarn~ter pipes are
3o arranged one behind the other one, a5 se~ri In d Sl.de
alevational view.
The two-distributor-versyon comprises two such
distributors, urith the main pipes being located side by
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tide and parallel to oaoh other, trh~raioy any one of the
small d=ameter pipes of the second distributor is
cor.neoted to one single one of the small diameter pipes
of t:~e first distrib~.~tor. Normally, tre maid pipe of the
3 seoond distributor has a smaller diameter than the main
pipe of the first distributor.
on the main line H, a feed of dilution water
into the rain stream H at an angle other than 90° is
shovrn. The feed consists essentially og the throt:.le
1o elemer_~t 2 itself, the throttle element having the same
development as the one shown in fig. z and being
connected via its feed Iine dire,otly to the second cross-
flo~w distributor ~z rahlch conducts the dilution water.
~y tre correct selection of the angle batwraan the main
1~ stream H and the secondary stream N fed by the throttling
dQVICA, tho rr~sult is obtain~d th-rt, xagaxdlacs pf the
amount of the secondary stream N fed, the sum of the
amount of suspension f~d to the headbox r~_n.ains constant.
By the development of the throttle d~2vice Z, any
2o formation of fiber wiping in the throttle devise ie
avQ,~'.ded, avoiding reduction in the q~:ality of the paper
produced. 1'he throttle device 7. is operated in such a
nanner t:~at, at the normal operating point, an average
amount of pulp suspension is fed by the throttle device
25 1, so that no settling processes o~ solids in the
throttle device are possible. The regulation of the
density of the pulp, and therefore of the concentration
of the total suspension Zxom streams N and H, then takes
placQ around this central operating point_ Ths sum of
3~ the total flow remains constant, and a verl~ sensitively
adjusted regulaticn of the concentration is obtained as a
result o: the canstracti~n of the throttle device 1.
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Although the prnsant inv~ntion hao~ boon
described in relati4ri to a particular embodiment thereof,
many other variations and mcdificatyone and other uses
will became appaxer.t to those skilled in the art. It is
pre~arrQd, t~xerefore, that the present invention be
limited not by the apeci.~~_c discla5ure herein, but only
by the. appended claims.
SPEC182132
