Note: Descriptions are shown in the official language in which they were submitted.
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EXCHANGE DEVICE FOR A BLOW LANCE
The invention relates to an exchange device for a
blow lance comprising a blow pipe and a cooling jacket
surrounding the blow pipe, with cooling water able to flow
through said cooling jacket whose inlet and outlet are
arranged at an end of the blow lance associated with a
coupling head.
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Blow lances are used for example to blow oxygen into a
converter during steel production. The problem with blow
lances used in this way is that after a certain time in
use, these blow lances become worn and need to be
exchanged.
To prevent premature damage to the blow lance by the high
ambient temperatures present in the region of the
converter, the blow pipe through which the gas blown into
the converter is conducted, is cooled by a coolant,
usually water. For this purpose, the blow lances usually
comprise a double jacket surrounding two connected
chambers, arranged coaxially in respect of each other and
in respect of the blowpipe. The coolant is conducted into
the first chamber which is directly adjacent to the blow
pipe; it then flows along the blow pipe until nearly to
the tip of said blow pipe and from there through the
second chamber, back to the outlet of the coolant jacket.
Conventional blow lances comprise flanges for connecting
the connecting pipes for the blow fluid and the coolant-
supply and coolant-removal, with the respective pipes
being connectable to said flanges. This type of
connection between the supply pipes and the removal pipes
poses the problem, when exchanging such a blow lance, in
that considerable time is required for disconnecting and
connecting the pipes. Furthermore, in the case of such
connections between the supply pipes or removal pipes and
the blow lance it is not possible to automate the change
procedure. Instead it has to be accepted that operation
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of the blow lance is interrupted for a considerable time
so as to avoid endangering the installation personnel
engaged in exchanging the blow lance.
The time required for exchanging the blow lance can be
shortened by a device which is described in the European
patent application EP 0 464 427 A2. With this known
exchange device, the section which in the blow lances
described above is provided for connecting the supply
pipes and removal pipes is allocated to a separate
coupling head. The coupling head is fixed to a frame
which in addition comprises a hydraulically activatable
lifting system. The remaining part of the blow lance can
be hooked into the lifting system in such a way that the
respective end of the blow lance can be inserted into the
seat of the coupling head. Both the terminal opening of
the blow pipe and the inlet and outlet of the cooling
jacket are arranged on the end face of the blow lance.
Correspondingly, the connections for coolant supply and
coolant removal as well as blow fluid supply are arranged
at the bottom of the seat of the coupling head,
associated with the face of the blow lance.
During the use of the known blow lance, the hydraulic
lifting device permanently holds the end face of the blow
lance in contact with the bottom face of the seat, so as
to ensure a constant seal of blow pipe, coolant inlet and
coolant outlet. Due to the considerable pressure with
which the coolant and the blow fluid are injected into
the blow lance, considerable contact forces are required
for maintaining a tight connection.
Another device is known from the European patent
application EP 0 441 767 A2. In this device, the
connections for coolant supply and coolant removal of the
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blow lance are arranged on a laterally attached plate,
together with the connection for the blow fluid. The
coupling head of the known device to which the blow lance
is disengageably coupled, also comprises a plate on which
the connections for the blow fluid and the coolant are
arranged accordingly. With this known device, too, a
hydraulically operated device is used to firmly press the
connections of the coupling head against the connections
of the blow lance.
While the above mentioned known exchange devices make it
possible to exchange a blow lance in a short time, they
have however the disadvantage that they require hydraulic
lifting devices and contact devices which are expensive
both from the point of view of initial cost and of
maintenance cost, to ensuxe permanently tight, safe
contact of the blow lance with the connections for
coolant supply and blow fluid.
An exchange device for a blow lance having the features
of the preamble of claim 1 is known from the US patent
specification US 3 170 977, wherein the inlet and outlet
apertures of the cooling jacket are arranged axially at a
distance. The apertures for the inlet and outlet are
constructed as ring slots which are open in the direction
of the end of the blow lance associated with the exchange
device.
When the blow lance is inserted into the seat of the
coupling head in the device known from the US patent
specification, two axially spaced chambers are formed
inside the seat, of which one is connected to the coolant
inlet and the other is connected to the coolant outlet of
the blow lance. The supply pipe of the coolant supply
discharges into the chamber connected with the coolant
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inlet while the chamber connected with the coolant outlet
is connected to the coolant removal pipe of the coolant
supply. In this way the cooling jacket of the blow lance
is connected to the coolant supply via the chambers.
A sealing ring is provided in the known device for
sealing the lowermost arranged chamber in the direction
of the blow lance tip against the environment. The
likewise annular face of the outer wall of the cooling
jacket is pressed against this sealing ring by means of a
mechanical locking device which exerts an axial force
directed into the seat of the device onto the blow lance.
An advantage of such a connection of the cooling jacket
of the blow lance to the coolant supply via chambers
formed in the area of the seat is that when the blow
lance is exchanged, the technical expenditure for the
coupling and uncoupling is low and the handling is easy.
Thus in the known exchange device, the blow lance can be
pulled from the seat in a simple movement as soon as the
locking device has been released. A disadvantage with the
known device is however that, similar to the known
devices described previously, considerable axial forces
must be applied to lock the blow lance into the seat of
the device in order to ensure secure sealing of the
chambers especially towards the environment. In addition,
the locking device must be suitable to compensate for
positional changes of the annular surface of the outer
cooling jacket wall which arise as a result of changes in
the length of the blow lance caused by temperature
changes and wear.
It is the object of the invention, starting from the
state of the art described previously, to provide an
exchange device for blow lances using simple means,
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wherein the expenditure for holding the blow lance in the
seat is reduced and wherein at the same time the sealing of
the chambers with the blow lance inserted is ensured with a
high degree of safety even under unfavorable operating
conditions.
In a broad aspect, the present invention
contemplates an exchange device for a blow lance (1)
comprising a blow pipe (20) and a cooling jacket (30)
surrounding the blow pipe (20), with cooling water able to
flow through said cooling jacket (30) whose inlet and outlet
(34, 35) are arranged at an end of the blow lance (1)
associated with a coupling head (2), the coupling head (2)
comprising a seat (7) into which the end of the blow lance
(1) is insertable, said seat comprising connections (13,
12, 4) for coolant supply, coolant removal and blow fluid
supply, the blow lance (1) being disengageably couplable to
the coupling head, with at least one of the inlet (34) and
the outlet (35) of the cooling jacket (30) leading to a
circumferential face of the blow lance (1), a connection
(13, 12) associated with said at least one of the inlet (34)
and outlet (35) of the cooling jacket leading to a lateral
face of the seat (7), said lateral face being associated
with the circumferential face, wherein with the blow lance
(1) inserted into the seat (7) of the coupling head (2), the
blow pipe (20) is connected in an interlocking and tightly
fitting manner with a pipe lug (6) of the seat (7), said
pipe lug (6) being connected to the blow fluid supply,
wherein with the blow lance (1) inserted into the seat (7)
of the coupling head (2), near each of the connection (13)
for the coolant supply and the connection (12) for the
coolant removal, a ring chamber (40, 41) is formed, and
wherein the chambers (40, 41) are arranged over one another
in an upwardly inserting direction of the blow lance (1),
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characterized in that a lower chamber of the two chambers
(40, 41) is formed by means of an annular groove (9a) formed
in the coupling head (2), and that above and below the
annular groove (9a), annular seals (10, 11) are positioned
in grooves provided therefor, which with the blow lance (1)
being inserted in the seat (7), lie radially against
respectively one circumferential surface of the blow
lance (1) .
The embodiment of the blow lance and of the
coupling head according to the invention makes it possible
to effect sealing of the individual inlets and outlets of
the blow lance by simple insertion of the blow lance into
the seat. There is no longer any need for an expensive
holding device after inserting the blow lance into the seat.
Nor is there any need for electrical, hydraulic or pneumatic
devices for the coupling action. Instead, a simple coupling
mechanism can be used, with the sealing means used in the
region of the respective sealing faces always being
sufficient to ensure reliable sealing of the individual
connections of the blow lance during its operation. In this
way, the invention provides an exchange device which is
economical to produce and which allows simple exchange of
the lance while providing a high degree of operational
safety.
In that with the blow lance inserted in the seat
of the coupling head, in the region of the connection flange
for coolant supply and/or the connection flange for coolant
removal, in each instance a chamber, in particular an
annular chamber, is formed. With an exchange device
configured in such a way the time required for aligning the
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blow lance of the coupling head is reduced to a minimum
because in this case it is no longer necessary to position
the inlet or outlet of the cooling jacket
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exactly opposite the respective connection of the
coupling head.
An economical embodiment of the invention, both
concerning the space required for the coupling head and
concerning the production of the blow lance, is
characterised in that both the inlet and the outlet of
the cooling jacket discharge into a circumferential face
of the blow lance.
To prevent unintended falling out of the blow lance from
the coupling head, the blow lance should be disengageably
lockable to the coupling head. This can be achieved in a
simple way in that the coupling head is lockable to the
blow lance by means of at least one hook swivellably
attached to said coupling head, and that the hook during
insertion of the blow lance into the seat of the coupling
head automatically moves into its locked position. If at
the same time the chamber associated with the connection
flange for the coolant supply, at least in some sections,
surrounds the free end face of that end of the blow lance
associated with the seat, the force exerted through the
coolant onto the lance in the direction of the tip of the
lance, causes the lance to be held in the hook without
any play.
It is also advantageous if the pipe lug and the blow pipe
are tightly interconnected via at least one annular seal,
which is arranged between the pipe lug and the blow pipe.
Below, the invention is illustrated in more detail by
means of a drawing showing one embodiment, as follows:
Fig. 1 shows a sectional front view, partly opened up,
of an exchange device for a blow lance; and
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Fig. 2 shows a sectional lateral view of the
exchange device according to Fig. 1.
The exchange device for a blow lance 1 shown in
the figures comprises a coupling head 2 which by way of a
guide 3 is attached to a frame (not shown) so as to be
adjustable in respect to its vertical, lateral and angular
position. The coupling head 2 comprises a first connection
flange 4 for a blow fluid, in particular oxygen, arranged at
the top 5 of the coupling head 2. A pipe insert 6 is fitted
into the connecting flange 4, with its end 6a associated
with the interior of the coupling head 2, reaching into a
seat 7.
The seat 7 of the coupling head is open towards
the bottom 8 of the coupling head 2. From the bottom 8, an
annular insert 9 is inserted into the seat 7 whose lower
section is enlarged towards the bottom 8 in the shape of an
inverted funnel. In the middle section of the annular
insert 9 there is a groove 9a which comprises a window-like
aperture 9b. Annular seals 10, 11 are inserted into grooves
provided for them above and below the annular groove 9a.
The aperture 9b of the annular insert 9 is
associated with a second connection flange 12 to which a
coolant removal pipe (not shown) can be connected. A third
connection flange 13 is arranged above the second connection
flange 12; it also discharges into the seat 7. A coolant
supply pipe (not shown) can be connected to the connection
flange 13.
The blow lance 1 comprises a blow pipe 20 situated
on the inside, with the end section 21 of said blow pipe 20
facing the coupling head 2 being enlarged and comprising
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an increased wall thickness compared to the remaining
length of the blow pipe. The end section 21 of the blow
pipe 20 is pushed onto the end section 6a of the pipe
insert 6, with three annular seals 23 arranged in
sequence in axial direction of the pipe section 6
providing a safe seal of the interlocking sections of the
pipe insert 6 and the blow pipe 20 against the
environment.
The blow pipe 20 is inserted in a cooling jacket 30 of
the blow lance 1 and is disengageably connected with said
cooling jacket. Said cooling jacket 30 comprises a
dividing wall 31 extending coaxially to the blow pipe 20
being arranged at a distance to said blow pipe 20, thus
forming a first chamber 32 and a second chamber 33 within
the cooling jacket 30. Inlet apertures 34 shaped on the
upper end of the blow lance 1, facing the seat 7, are
connected to the first chamber 32 of the cooling jacket.
By contrast, the second chamber 33 discharges into outlet
apertures 35 which are shaped in the cooling jacket 30,
offset in respect of the tip of the blow lance 1 (not
shown) below a first sealing face 36 provided between the
inlet apertures 34 and the outlet apertures 35. The first
and the second chamber 32, 33 of the cooling jacket are
connected in the area of the tip of the blow lance (not
shown) so that the coolant which flows through the inlet
apertures 34 into the first chamber 32 is conducted along
the blow pipe 20 to the tip of the blow lance 1 from
where it flows through the chamber 33 back to the outlet
apertures 35.
With the blow lance 1 inserted into the seat 7, the seal
of the annular insert 9 contacts the first sealing
face 36 of the blow lance 1, thus sealing the annular
chamber 40 formed by the annular groove 9a against a
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second chamber 41 formed in the upper region of the seat
7 which is connected with the connection flange 13 for
the coolant supply. The second chamber 41 of the_seat 7
surrounds the end face 42 of the blow lance 1, with the
effect that the pressure of the coolant present in the
chamber 41 exerts a force in the direction of the tip of
the blow lance 1 (not shown) on said blow lance 1.
Unintended falling out of the blow lance 1 from the
coupling head 2 is prevented by hooks 51 laterally
attached to the coupling head 2 by bolts 50 so as to be
swivellable. The hook-shaped ends of the hooks 51 engage
the ends of bolt-like projections 52 shaped to a
retention ring 53 which is firmly connected to the blow
lance 1. At their lower ends, the hooks comprise a
bevelled face 54. During insertion of the blow lance 1
into the seat 7, the projections 52 slide along the
bevelled faces 54 such that the hook 51 is swivelled away
from the feed path until the projections 52 have passed
the tip 55. Subsequently, the hook 51 resumes its resting
position. As a result of the pressure being exerted onto
chamber 41 by the coolant, subsequently the blow lance 1
is pushed into the seat of the hooks 51 where it is
retained without any play.
For exchanging the blow lance 1, after switching off the
coolant supply in the chamber 41, the blow lance 1 is
pushed into the seat 7 until the hooks 51 can be freely
swivelled. After swivelling away the hooks 51, the blow
lance can be withdrawn from the seat 7 and can be
replaced by a new blow lance 1.
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