Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a device for spraying a cooling
agent on steel blooms, comprising spray nozzles connected to a
mixing chamber having separate inlets for the impellant and the
cooling agent, the nozzle outlets being so adapted that the impel-
lant-coolant mlxture implnges on thc bloom surface ln a broad fan
and at an acute angle .in mutually opposed di.rections, the nozzle
ou-tlets projecting from a com~on nozzle housing into which the
mixing chamber opens, while the coolant union on the mixing chamber
is formed by a replaceable insertion pipe projecting into the
mixing chamber. The invention is particularly applicable to a
continuous casting installation from which blooms emerge in the
form of cast ribbons, the nozzles being directed into each gap
between successive pairs of guide.rolls for the cast ribbon and
being directed parallel to the guide roll axes, and the noz~le
housing being disposed between the mid-plane of the guide roll
axes and the bloom surface.
A device having the significant features specified above
forms the subject of prior German Patent Application P 28 16 441.2-2~.
~ The cited prior Application is concerned substantially with the
20 following problems:-
1. The mixture of water, air, steam or gas should be uniformlydistributed over the bloom and uniformly accelerated as it is
sprayed over the width of the`bloom.
2. It should be possible to spray into the roll shadows (i.e.,
the generally triangular gaps between the bloom surface and the
xolls), and simultaneously the clearing aCtiQn of the mixture stream
should remove stagnant water and scale part1cles from the gaps
between the rolls.
3. The water throughput should be adjustable, without of
course impairing the spray pattern and without replacing a given
npzzle.
The object of the present invention is to provide such a
* published October 18th 1979
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device with an improved performance so tha-t:
a) a more extensive heat exchange surface is
attained by a broader fan-shaped jet,
b) a more intensive cooling action is brought
about by smaller droplets and the individual droplets can
evaporate more rapidly, while
c) droplets which do not evaporàte are cleared
laterally across the bloom. In addition, it is intended to
simplify the nozzle design.
Accordingly, the invention as herein broadly claimed,
lies in the provision of a device for spraying a cooling agent
on a steel bloom having a bloom surface, comprising: spray
nozzles connected to a mixing chamber having separa-te inlets
for an impellant and a cooling agent to be mixed in said
chamber; nozzle outlets adapted so that the impellant-coolant
mixture impinges on the bloom surface in a broad fan and at an
acute angle in mutually opposed directions, the nozzle outlets
projecting Erom a common nozzle housing into which the mixing
chamber opens, said coolant inlet includiny a coolant union on
the mixing chamber formed by a replaceable insertion pipe pro-
jecting into the mixing chamber, the nozzle housing being
essentially cylindrical and having a cylindrical entry bore,
while the nozzle outlets are formed by two prismatic milled
apertures in the nozzle housing, diametrically opposite each
other and each opening radially into the entry bore.
The invention avoids the concept embodied in the
device of the prior patent application P 28 16 441.2-24 of
providing opposed nozzle outlet openings, i.e. openings
directed towards each other. This provides the advantageous
possibility of broadening the jet to the required extent
without mutual interference between the jets (which would
ensue with the device of the above prior patent application).
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The concept of the invention, whereby -the nozzle
construction is so modified that the jets are no longér directed
in opposition to each other, simultaneously leads to a simpler
nozzle construction.
Preferably, the cylindrical entry bore of the
nozzle housing is formed as a blind hole haviny a hemi-
spherically shaped inner end, while the milled lateral
apertures forming the nozzle outlets open into the hemi-
spherical end-zone of the entry bore in the nozzle housing.
A ~urther preferred feature of the invention consists
in that a disc-shaped spinner is provided inside the entry bore
in the nozzle housing, in advance of the nozzle outle-ts. The
spinner is
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preferably adapted so that the previously formed mix-ture of water
and air, which contains a higher proportion of water in the centre
of the mixing chamber (considered radially) than in the peripheral
zones, is mixed still more intensively. In this way the average
drolet diameter can be advantageously reduced.
An embodiment of the invention will now be described, by way
of example only, with reference to the accompanying drawings,
in which:-
Figure 1 is a plan view (taken from the line I-I in Figure 2)
of part of a cast ribbon passing between guide rolls;
Figure 2 is a part sectional view taken from the line II-I~
in Figure l;
Figure 3, on a larger scale than that of Figures 1 and 2
is an exploded view of a cooling device (with some parts partly
sectioned) in accordance with the invention and for use as indicated
in Figures 1 and 2;
Figure 4 is a view of the nozzle housing seen at the bottom
oE Figure 3, looking in the direc-tion oE -the arrow A;
Figure 5 is a section taken on the line V-V in Figure 3; and
Figure 6 is a plan view of -the spinner half of which can be
: seen in the sectioned half of the nozzle housing in Figure 3.
Figures 1 and 2 show pairs of opposed parallel guide rolls 10
` and 11 in a continuous casting machine for steel blooms. Each
steel bloom 12 passes between the guide rolls 10 and 11 of each pair,
and successive pairs of guide rolls are disposed with relatively
small intermediate spacings a. A cooling device 14 is directed
towards the upper face of the steel bloom 12 between each adjacent
pair of guide rolls 10.
As shown in more detail in Figure 3, the cooling device 14
comprises a nozzle housing 15 and a mixing chamber 16 having a
lateral union 17 to admit an impellant, for example ai.r, and a
coaxial union 13 for coolant, for example water.
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As Figure 3 further shows, the coolant union 18 is substan-
tially adapted as a tubular insert 19 projecting into -the tubular
mixing chamber 16. A fixing nut 20 having an internal thread 21
is welded to the upper end of the tubular insert 19. The nut 20
and the thread 21 are used to fix the tubular insert 19 on a
corresponding thread 22 on the mixing chamber 16. An external
thread 23 is provided on the upper end of the nut 20, for connection
to a coolant supply line, normaly for example with the aid of a
cap nut. The coolant, water, is admitted into the -tubular insert
10 19 at 23 and passes thence into the mixing chamber 16 at a flow
rate which is precisely determined by the internal diameter of
the tubular insert 19. Thus, by replacing a given tubular insert
19 by one of larger or smaller diameter, it is a simple matter to
adjust the flow rate of cooling water independen-tly of the flow
rate of air entering the mixing chamber 16 at 17 and independently
of the geometry of the nozzle housing 15. Since the tubular insert
19 can be replaced with ease, various flow rate .ratios of coolant
to impellant can be selected wi-th corresponding ease withou-t inter-
fering in any way with the nozzle housing 15 itself. Moreover, no
ad~ustments need be made for this purpose in the pressure settings
of the coolant supply line on the one hand or the impellant supply
line on the other.
By reason of the rela-tively large cross-section of the mixing
chamber 16 r friction losses in the mixture advancing tc the nozzle
are kept low, with the advantageous e.ffect of raising the exit
velocity.
~ further advantage in the same sense accrues from the fact
that the stream of mixed coolant and impellant in the nozzle
housing 15 is divided into two separate streams. As Figure 3 fur-
ther shows, the nozzle housing 15 has a cylindrical en-try bore 24,
in the form of a blind hole. The entry bore 24 has two shoulders,
and an internal thread 25 at its upper end meshes with a correspon-
~s~
ding e~ternal thread 26 o~ the mixing chamber 16. The blind hole24 contains a disc-shaped spinnex 27, which is supported axially
on a shoulder ~8 in the blind hole 24 of the nozzle housing 15.
Figure 6 shows the spinner 27 in plan view. Its circular periphèry
has four milled radial notches 29 spaced at angles of 90 to each
other. The spinner 27, in conjunction with the arrangement and
construction already described, brings about still more intensive
mixing in the mixture of water and air already present in the mixing
chamber 16, whereby the average droplet diameter in the je-ts
emerging from the nozzle housing 15 can be advantageously reduced
still further. It will be seen by reference also to Figures 4 and
5, that the nozzle has two outlets formed by two diametrically
opposed prismatic milled apertures 30 and 31 in the nozzle housing
15. The apertures 30 and 31 are milled so that they penetra-te
into the blind-hole entry bore 24 in the nozzle housing 15, in a
hemi-spherical end-zone 32 o -the entry bore 24 to form two nozzle
outlets 33, the shape of each of which is shown particularly clear-
ly in Figure 4. The prismatic milled apertures 30 and 31 are
inclined at an angle (Figure 3) of 5 relative to their respective
planes of symmetry about the horizontal plane of the bloom
surface. The nozzle outlets 33 produce two broad fan jets directed
in opposite directions (see Figures l and 2). The two fan jets
extend in plan view (Figure 1) over a larger angle ~ and at right
angles thereto tFigure 2) over a smaller angle ~. The advantage of
extending the jet over a wide angle~ is to be seen in that within
a short distance from the nozzle outlet the entire breadth of the
free bloom surface - seen in the casting direction 13 - is covered
with spray. The advantage of extending the je-t over the angle ~
consists in that the incidence zone of the spray jet on the bloom
surface - seen in the jet direction 34 - is increased. The planes
of the fan jets extending over the angle~lie parallel to the bloom
surface. In other words, a larger proportion of he exposed bloom
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surface between guide rolls 10 - denoted by the dimension c in
Figure 1 - is covered within a shorter distance from the nozzle
housing 15 than can be achieved with the device of the prior
Application P 28 16 441.2-24. These advantages, based on the angles
c-,~ and~ , significantly improve the uniformity of bloom cooling.
The above advantages appertain to each fan jet individually. The
distinction between the fan jets produced by a device in accordance
with the invention and by the prior device of P 28 16 441.2-24
is substantially charac-terised in that individual fan jets are
produced, having a broad extent (angle ~) and little widening at
right angles thereto (an~le ~), whereas the device of the prior
Application P.28 16 441.2-~4 produces somewhat flattened oval jets
from approximately circular initial jets.
Another significant distinction from the prior device of P
28 16 441.2-24 consists in that the nozzle housing 15 is located
no further than 150 mm from the nozzle-facing end of the tubular
insert 19 in the mixing chamber 16. This dimension b is shown in
Figure 3. It relates o course ot the assembled state of the
individual components and not as shown exploded in Figure 3.
Figures 1 and 2 also disclose a further significant feature
of the invention~ This consists in that the successive spray
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devices 14 ~}}i~Y~ in the casting direction 13 are alternately dis-
placed through a distance d from the cen-tral axis 35 of the cast
ribbon, first to the left and then to the right. The lateral displa-
cement d of each spray device 14 is adjusted according to the width
e of the sprayin~ gap. In fact, as Figure 2 shows, it amounts to
about half the breadth f of the unsprayed bloom surface. Since
the spray device in the next guide-roll gap is displaced over the
same distance d on the other side of the central axis 35, the
entire breadth of the bloom 12 is covered with liquid by a pair
of cooling devices 14.
To summarise, the following significant advantages accrue from
the device of the invention:
The prismatic apertùres 30,3,l ~orming the nozz~e outlets 33,
each spraying outwards from the central axis of the mixing chamber
16, produce fan jets the angular dimensions (~ and ~ ) of which
can be adjusted by varying the geometry of the entry bore 24 and
of the apertures 30,31. This facilitates a more uniform coverage
of the bloom surface re~uiring cooling. The mixing chamber 16 in
conjunction with the spinner 27 in the nozzle housing 15 produces
more effective mixing between the water and air, thereby reducing
the droplet size in the spray jets. The smaller droplets in the
spra~ jets ensure more intensive cooling of the bloom surface,
since the individual droplets evaporate more rapidly. Finally, the
device of the invention has the special advantage tha-t -the two
spray jets do not intersect, but are both directed outwardly. This
facilitates a very simple nozzle housing construction.
