U.S. patent application number 13/141738 was filed with the patent office on 2012-01-05 for method and device for controlling vibrations of a metallurgical vessel.
Invention is credited to Alexander Fleischanderl, Martin Hiebler, Guenther Staudinger, Peter Wimmer.
Application Number | 20120000315 13/141738 |
Document ID | / |
Family ID | 41591663 |
Filed Date | 2012-01-05 |
United States Patent
Application |
20120000315 |
Kind Code |
A1 |
Fleischanderl; Alexander ;
et al. |
January 5, 2012 |
Method and Device for Controlling Vibrations of a Metallurgical
Vessel
Abstract
In a method and a device for controlling vibrations of a
metallurgical vessel that occur while gas is being injected into
liquid molten metal located in the metallurgical vessel, a certain
total amount of gas per unit of time is injected into the liquid
molten metal, and the total amount of gas being is injected into
the liquid molten metal through a number of individual nozzles in
the metallurgical vessel, measured values correlating with the
vibrations of the metallurgical vessel occurring are being measured
during the injection, wherein while keeping the total amount of gas
injected per unit of time largely constant, the amount of gas
injected from individual nozzles per unit of time is changed in
dependence on the measured values that are measured and correlate
with the vibrations of the metallurgical vessel occurring.
Inventors: |
Fleischanderl; Alexander;
(Grunau, AT) ; Hiebler; Martin; (Linz, AT)
; Staudinger; Guenther; (Gmunden, AT) ; Wimmer;
Peter; (Linz, AT) |
Family ID: |
41591663 |
Appl. No.: |
13/141738 |
Filed: |
November 6, 2009 |
PCT Filed: |
November 6, 2009 |
PCT NO: |
PCT/EP2009/064720 |
371 Date: |
September 12, 2011 |
Current U.S.
Class: |
75/375 ;
266/80 |
Current CPC
Class: |
Y02P 10/20 20151101;
F27D 21/00 20130101; F27D 19/00 20130101; Y02P 10/216 20151101;
C21C 5/34 20130101; C21C 5/4673 20130101; C21C 2005/5288 20130101;
F27D 2019/0078 20130101 |
Class at
Publication: |
75/375 ;
266/80 |
International
Class: |
C21C 5/56 20060101
C21C005/56; C21D 11/00 20060101 C21D011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 23, 2008 |
AT |
A2013/2008 |
Claims
1. A method for controlling vibrations of a metallurgical vessel
occurring during the injection of gas into the metallurgical vessel
filled with liquid molten metal, the method comprising: injecting a
certain total amount of gas per unit of time into the liquid molten
metal, wherein the total amount of gas is injected into the liquid
molten metal through a number of individual nozzles in the
metallurgical vessel, and measuring measured values correlating
with the vibrations of the metallurgical vessel occurring during
the injection, wherein while keeping the total amount of gas
injected per unit of time largely constant, the amount of gas
injected from individual nozzles per unit of time is changed in
dependence on the measured values that are measured and correlate
with the vibrations of the metallurgical vessel occurring.
2. The method according to claim 1, wherein, at least for one of
the individual nozzles, the amount of gas injected from them per
unit of time is changed, at least for a time, in dependence on
measured values correlating with the vibrations of the
metallurgical vessel occurring.
3. The method according to claim 2, wherein the changing of the
intensity of at least one measured value correlating with the
vibrations of the metallurgical vessel occurring that is brought
about by changing the amount of gas injected from an individual
nozzle per unit of time is traced, and the changing of the amount
of gas injected from an individual nozzle per unit of time is
carried out until the at least one measured value correlating with
the vibrations of the metallurgical vessel occurring reaches a
prescribed value or until the gas flow from the nozzle reaches a
prescribed maximum or minimum.
4. The method according to claim 1, wherein the measured values
correlating with the vibrations of the metallurgical vessel
occurring are filtered and digitally processed before they are used
for changing the amount of gas injected from the individual nozzles
per unit of time.
5. The method according to claim 1, wherein, when measuring the
measured values correlating with the vibrations of the
metallurgical vessel occurring, at least one of frequencies and
intensities of vibrations are determined.
6. The method according to claim 1, wherein the measured values
correlating with the vibrations of the metallurgical vessel
occurring correlate with vibrations of the metallurgical vessel
that have frequencies between 0.1 Hertz and 100 Hertz or between
0.2 Hertz and 20 Hertz.
7. The method according to claim 1, wherein the measured values,
correlating with the vibrations of the metallurgical vessel
occurring, in dependence on which the amount of gas introduced from
individual nozzles per unit of time is changed correlate with
vibrations of the metallurgical vessel of frequencies that lie
between 0.2 Hertz and 20 Hertz.
8. A device for controlling vibrations of a metallurgical vessel
occurring during the injection of gas into the metallurgical vessel
filled with liquid molten metal and provided with a number of
individual nozzles for the injection of gas, the individual nozzles
being respectively connected to a gas feed line of their own,
comprising: at least one sensor for measured values correlating
with the vibrations of the metallurgical vessel occurring, a
processing unit for processing the measured values measured by the
sensor, and in at least two gas feed lines there is at least one
device for changing the gas flow through the gas feed line, and
each device for changing the gas flow is connected to the
processing unit.
9. The device according to claim 8, wherein the device for changing
the gas flow through the gas feed line allows a continuous changing
of the gas flow.
10. The device according to claim 8, wherein the device for
changing the gas flow through the gas feed line is a device for
changing the gas flow in stages.
11. The device according to claim 8, wherein the sensor for
measured values correlating with the vibrations of the
metallurgical vessel occurring is a vibration sensor.
12. The device according to claim 11, wherein the vibration sensor
is a torque measurement, a strain gage, a position pickup, a
velocity pickup or an acceleration pickup.
13. The method according to claim 1, wherein, for two or more of
the individual nozzles, the amount of gas injected from them per
unit of time is changed, at least for a time, in dependence on
measured values correlating with the vibrations of the
metallurgical vessel occurring.
14. A system for controlling vibrations of a metallurgical vessel
occurring during the injection of gas into the metallurgical vessel
filled with liquid molten metal, comprising: a metallurgical
vessel, a plurality of individual nozzles for injecting a certain
total amount of gas per unit of time into the liquid molten metal,
wherein the system is configured to measure values correlating with
the vibrations of the metallurgical vessel occurring during the
injection, and a control unit which, while keeping the total amount
of gas injected per unit of time largely constant, is operable to
change the amount of gas injected from individual nozzles per unit
of time in dependence on the measured values that are measured and
correlate with the vibrations of the metallurgical vessel
occurring.
15. The system according to claim 14, wherein, at least for one of
the individual nozzles, the amount of gas injected from them per
unit of time is changed, at least for a time, in dependence on
measured values correlating with the vibrations of the
metallurgical vessel occurring.
16. The system according to claim 15, wherein the changing of the
intensity of at least one measured value correlating with the
vibrations of the metallurgical vessel occurring that is brought
about by changing the amount of gas injected from an individual
nozzle per unit of time is traced, and the changing of the amount
of gas injected from an individual nozzle per unit of time is
carried out until the at least one measured value correlating with
the vibrations of the metallurgical vessel occurring reaches a
prescribed value or until the gas flow from the nozzle reaches a
prescribed maximum or minimum.
17. The system according to claim 14, wherein the measured values
correlating with the vibrations of the metallurgical vessel
occurring are filtered and digitally processed before they are used
for changing the amount of gas injected from the individual nozzles
per unit of time.
18. The system according to claim 14, wherein, when measuring the
measured values correlating with the vibrations of the
metallurgical vessel occurring, at least one of frequencies and
intensities of vibrations are determined.
19. The system according to claim 14, wherein the measured values
correlating with the vibrations of the metallurgical vessel
occurring correlate with vibrations of the metallurgical vessel
that have frequencies between 0.1 Hertz and 100 Hertz.
20. The system according to claim 14, wherein the measured values,
correlating with the vibrations of the metallurgical vessel
occurring, in dependence on which the amount of gas introduced from
individual nozzles per unit of time is changed correlate with
vibrations of the metallurgical vessel of frequencies that lie
between 0.2 Hertz and 20 Hertz.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a U.S. National Stage Application of
International Application No. PCT/EP2009/064720 filed Nov. 6, 2009,
which designates the United States of America, and claims priority
to Austrian Application No. A2013/2008 filed Dec. 23, 2008, the
contents of which are hereby incorporated by reference in their
entirety.
TECHNICAL FIELD
[0002] The invention relates to a method and a device for
controlling vibrations of a metallurgical vessel that occur while
gas is being injected from nozzles into liquid molten metal located
in the metallurgical vessel.
BACKGROUND
[0003] In particular in the case of AOD (argon oxygen
decarburization) converters used for producing stainless steel,
large amounts of gas are introduced into the liquid molten material
of the crude steel via nozzles. As a result, on the one hand the
partial pressure of gases in the molten material can be influenced,
on the other hand a bath flow is produced in the molten material by
the injected gas bubbles rising up. This flow leads to a desired
intermixing of the molten material. However, the rising gas bubbles
lead to a randomly fluctuating displacement of the centre of
gravity of the converter filled with liquid molten material,
causing the converter to vibrate. Parts of the plant that are
connected directly or indirectly to the converter--particularly
those that are rigidly connected to the converter--may also be made
to vibrate by the vibrations of the converter. Vibrations put a
severe load on the converter and the parts of the plant connected
to it, such as for example the gear mechanism provided for tilting
the converter and the suspension thereof, and may lead to premature
wear or rupture. The foundation on which the converter and
associated parts of the plant are located, such as the gear
mechanism for example, also undergo oscillations. These may have a
damaging effect on the foundation itself and the surroundings
thereof.
[0004] It is known from US20080047396 to monitor and control the
intermixing of a liquid molten metal by means of gas injection from
under-bath nozzles in such a way that the vibrations of the
metallurgical vessel are measured. The measurement result is an
indication of the quality of the intermixing. On the basis of the
measurement result, the total amount of gas injected per unit of
time, the blowing rate, is changed to achieve optimum intermixing.
However, reducing the blowing rate with respect to values fixed in
a blowing plan is synonymous with extending the tap-to-tap time,
and consequently with reducing the productivity of the
metallurgical vessel. Moreover, a change of the blowing rate may
also influence the metallurgical properties of the product.
SUMMARY
[0005] According to various embodiments, a method and a device for
controlling vibrations of a metallurgical vessel occurring during
the injection of gas into the metallurgical vessel filled with a
liquid molten metal can be provided that allow the vibrations of
the metallurgical vessel to be controlled while largely retaining
the blowing rate.
[0006] According to an embodiment, in a method for controlling
vibrations of a metallurgical vessel occurring during the injection
of gas into the metallurgical vessel filled with liquid molten
metal, a certain total amount of gas per unit of time being
injected into the liquid molten metal, and the total amount of gas
being injected into the liquid molten metal through a number of
individual nozzles in the metallurgical vessel, and measured values
correlating with the vibrations of the metallurgical vessel
occurring being measured during the injection, wherein, while
keeping the total amount of gas injected per unit of time largely
constant, the amount of gas injected from individual nozzles per
unit of time is changed in dependence on the measured values that
are measured and correlate with the vibrations of the metallurgical
vessel occurring.
[0007] According to a further embodiment, at least for one of the
individual nozzles, preferably two or more of them, the amount of
gas injected from them per unit of time can be changed, at least
for a time, in dependence on measured values correlating with the
vibrations of the metallurgical vessel occurring. According to a
further embodiment, the changing of the intensity of at least one
measured value correlating with the vibrations of the metallurgical
vessel occurring that can be brought about by changing the amount
of gas injected from an individual nozzle per unit of time is
traced, and the changing of the amount of gas injected from an
individual nozzle per unit of time is carried out until the at
least one measured value correlating with the vibrations of the
metallurgical vessel occurring reaches a prescribed value or until
the gas flow from the nozzle reaches a prescribed maximum or
minimum. According to a further embodiment, the measured values
correlating with the vibrations of the metallurgical vessel
occurring can be filtered and digitally processed before they are
used for changing the amount of gas injected from the individual
nozzles per unit of time. According to a further embodiment, when
measuring the measured values correlating with the vibrations of
the metallurgical vessel occurring, frequencies and/or intensities
of vibrations can be determined. According to a further embodiment,
the measured values correlating with the vibrations of the
metallurgical vessel occurring may correlate with vibrations of the
metallurgical vessel that have frequencies between 0.1 Hertz and
100 Hertz, preferably between 0.2 Hertz and 20 Hertz. According to
a further embodiment, the measured values, correlating with the
vibrations of the metallurgical vessel occurring, in dependence on
which the amount of gas introduced from individual nozzles per unit
of time is changed may correlate with vibrations of the
metallurgical vessel of frequencies that lie between 0.2 Hertz and
20 Hertz.
[0008] According to another embodiment, a device for controlling
vibrations of a metallurgical vessel occurring during the injection
of gas into the metallurgical vessel filled with liquid molten
metal and provided with a number of individual nozzles for the
injection of gas, the individual nozzles being respectively
connected to a gas feed line of their own, may have at least one
sensor for measured values correlating with the vibrations of the
metallurgical vessel occurring, and a processing unit for
processing the measured values measured by the sensor, wherein in
at least two gas feed lines there is at least one device for
changing the gas flow through the gas feed line, and each device
for changing the gas flow is connected to the processing unit.
[0009] According to a further embodiment of the device, the device
for changing the gas flow through the gas feed line may allow a
continuous changing of the gas flow. According to a further
embodiment of the device, the device for changing the gas flow
through the gas feed line can be a device for changing the gas flow
in stages. According to a further embodiment of the device, the
sensor for measured values correlating with the vibrations of the
metallurgical vessel occurring can be a vibration sensor. According
to a further embodiment of the device, the vibration sensor can be
a torque measurement, a strain gage, a position pickup, a velocity
pickup or an acceleration pickup.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The invention is described below on the basis of schematic
figures, which represent embodiments.
[0011] FIG. 1 and FIG. 2 show a device according to various
embodiments with a converter having under-bath nozzles.
[0012] FIG. 3 shows a device according to various embodiments with
a converter having under-bath nozzles and nozzles on the side wall
of the converter, a number of sensors being respectively arranged
at various locations.
DETAILED DESCRIPTION
[0013] According to various embodiments, in a method for
controlling vibrations of a metallurgical vessel occurring during
the injection of gas into the metallurgical vessel filled with
liquid molten metal,
[0014] a certain total amount of gas per unit of time is injected
into the liquid molten metal,
[0015] and the total amount of gas is injected into the liquid
molten metal through a number of individual nozzles in the
metallurgical vessel,
[0016] and measured values correlating with the vibrations of the
metallurgical vessel occurring are measured during the
injection,
[0017] wherein,
[0018] while keeping the total amount of gas injected per unit of
time largely constant, the amount of gas injected from individual
nozzles per unit of time is changed in dependence on the measured
values that are measured and correlate with the vibrations of the
metallurgical vessel occurring.
[0019] The amount of gas injected from individual nozzles per unit
of time is changed in dependence on the measured values that are
measured and correlate with the vibrations of the metallurgical
vessel occurring. As a result, the intermixing of the liquid molten
metal, and correspondingly the centre of gravity of the
metallurgical vessel filled with liquid molten metal, changes. It
is correspondingly possible to achieve the effect that vibrations
are increased or reduced. As a result, it is possible to keep parts
of the plant that are connected directly or indirectly to the
metallurgical vessel--in the case of a converter, for example,
essentially the suspension, support, baling ring, tilting drive,
gear mechanism and foundation--free from harmful vibration
frequencies or to reduce the intensity of vibrations with harmful
frequencies. As a result, the mechanical stressing of these parts
of the plant is reduced. Lower mechanical stressing, and
accompanying longer lifetimes, of the parts of the plant increase
the productivity of the metallurgical vessel.
[0020] Measured values correlating with the vibrations of the
metallurgical vessel occurring should be understood as meaning
measured values that allow a quantifiable conclusion to be reached
as to the vibrations of the metallurgical vessel occurring.
Measured values for the vibrations of the metallurgical vessel are
also included by the term "measured values correlating with the
vibrations of the metallurgical vessel occurring". The measured
values correlating with the vibrations of the metallurgical vessel
occurring are, for example, [0021] frequencies and/or intensities
of vibrations of the metallurgical vessel, and/or [0022]
frequencies and/or intensities of vibrations of parts of the plant
connected directly or indirectly to the metallurgical vessel.
[0023] If directly or indirectly connected parts of the plant are
made to vibrate by vibrations of the metallurgical vessel
occurring, these vibrations correlate with the vibrations of the
metallurgical vessel in a way that allows the vibrations of the
metallurgical vessel to be concluded from the measurement of these
vibrations of the parts of the plant. Such conclusions may be made
possible, for example, by measuring at the same time [0024]
vibrations of the metallurgical vessel occurring, and [0025]
measured values correlating with the vibrations of the
metallurgical vessel occurring, and by determining the correlation,
that is to say the interrelationship, between them. Knowledge of
the correlation determined in this way then allows the vibrations
of the metallurgical vessel to be concluded from the measured
values.
[0026] Parts of the plant connected directly to the metallurgical
vessel should be understood as meaning parts of the plant that are
connected straight to the metallurgical vessel. Parts of the plant
connected indirectly to the metallurgical vessel should be
understood as meaning parts of the plant that are connected to the
metallurgical vessel via a part of the plant or a number of parts
of the plant--that is to say indirectly.
[0027] Keeping the total amount of gas injected per unit of time,
that is the blowing rate, largely constant, makes it possible for
the productivity and the metallurgical properties of the product to
be kept largely constant.
[0028] It is known to a person skilled in the art that, in
industrial application, the blowing rate cannot be kept constant
entirely exactly, but that the actual value fluctuates about a
prescribed value over time. For the purposes of the present
invention, keeping largely constant should be understood as meaning
that the actual value fluctuates about a prescribed value over time
by +/-5%.
[0029] The metallurgical vessel may be any type of process vessel
for liquid molten metals, preferably for molten crude steel or
molten pig iron, that is to say for example converters, ladles,
crucibles or electric arc furnaces. A tiltable converter is
preferred.
[0030] The metallurgical vessel has nozzles for injecting gas into
the space enclosed by the vessel. The arrangement of the nozzles is
in this case chosen such that, during the operation of the
metallurgical vessel, they lie below the level of the liquid molten
metal in the metallurgical vessel; such nozzles are also known as
under-bath nozzles. Correspondingly, during operation, gas is
injected into the liquid molten metal through these nozzles. The
nozzles may be arranged in the bottom or the side walls of the
metallurgical vessel. The nozzles are preferably under-bath nozzles
arranged in the side walls of the metallurgical vessel.
[0031] The measurement during injection of the measured values
correlating with the vibrations of the metallurgical vessel
occurring is performed either continuously or at certain time
intervals. A continuous measurement has the advantage of providing
information at all times as to the current status of the
vibrations, but involves a considerable data processing effort. A
measurement at certain time intervals has the advantage over
continuous measurement that the data processing effort is reduced
on account of the lower amount of measurement data generated.
However, it only provides information about the status of the
vibrations at selected points in time.
[0032] According to one embodiment of the method, at least for one
of the individual nozzles, preferably two or more of them, the
amount of gas injected from them per unit of time is changed, at
least for a time, in dependence on measured values correlating with
the vibrations of the metallurgical vessel occurring.
[0033] The aim here should be to maintain for such a nozzle a gas
flow through the nozzle at all times, in order not to risk any
infiltrations of liquid molten metal into the nozzle and
consequently caused damage to the nozzle. Therefore, complete
switching-off of the gas flow through the nozzle should be avoided.
The greater the number of individual nozzles for which the amount
of gas injected from them per unit of time is changed, the more
finely balanced the control of the vibrations of the metallurgical
vessel can be.
[0034] The changing of the amount of gas injected per unit of time
may be performed in stages or continuously. In the case of changing
in stages, changes are made between setting stages predetermined on
the basis of the process engineering conditions. Continuous
changing offers the advantage over changing in stages that a more
finely balanced control of the vibrations of the metallurgical
vessel is possible, and is therefore preferred.
[0035] It is at the same time preferred that the changing of at
least one measured value correlating with the vibrations of the
metallurgical vessel occurring that is brought about by changing
the amount of gas injected from an individual nozzle per unit of
time is traced, and the changing of the amount of gas injected from
an individual nozzle per unit of time is carried out until the at
least one measured value correlating with the vibrations of the
metallurgical vessel occurring reaches a prescribed value or until
the gas flow from the nozzle reaches a prescribed maximum or
minimum. The maximum or minimum is prescribed on the basis of
process engineering specifications for the liquid molten metal that
is actually to be treated. The prescribed value for the at least
one measured value correlating with the vibrations of the
metallurgical vessel occurring is dependent on the extent to which
the vibrations of the metallurgical vessel are to be
controlled.
[0036] Since the two variants, changing by stages and continuous
changing, should be used at least for a time, mixed forms of them
are also possible. For example, the amount of gas injected per unit
of time may first be changed in stages and then, to make better
fine setting possible, changed continuously. Or it is first changed
continuously and then in stages.
[0037] According to a preferred embodiment of the method, the
measured values correlating with the vibrations of the
metallurgical vessel occurring are filtered and digitally processed
before they are used for changing the amount of gas injected from
the individual nozzles per unit of time. This makes it possible to
trace more accurately the variation of certain vibrations of the
metallurgical vessel, for example those known to be particularly
disruptive.
[0038] According to a preferred embodiment, when measuring the
measured values correlating with the vibrations of the
metallurgical vessel occurring, frequencies and/or intensities of
vibrations are determined.
[0039] According to one embodiment, the measured values correlating
with the vibrations of the metallurgical vessel occurring correlate
with vibrations of the metallurgical vessel that have frequencies
between 0.1 and 100 Hertz, preferably between 0.2 Hertz and 20
Hertz. The values 0.1 Hertz and 100 Hertz are included here.
Frequencies above 100 Hertz scarcely have any potential to be
disruptive.
[0040] According to a further embodiment, the measured values,
correlating with the vibrations of the metallurgical vessel
occurring, in dependence on which the amount of gas introduced from
individual nozzles per unit of time is changed correlate with
vibrations of the metallurgical vessel of frequencies that lie
between 0.2 Hertz and 20 Hertz. These frequencies should be
monitored particularly closely, since they have the greatest
potential for causing damage.
[0041] The frequencies and intensities of the vibrations of the
metallurgical vessel are measured by means of a vibration sensor or
a number of vibration sensors, it being possible for the measuring
principle to be based, for example, on torque measurement,
acceleration measurement, strain gages, position pickups or
velocity pickups.
[0042] Acceleration pickups, strain gages or position pickups are
preferably used, since they are inexpensive and can be fitted with
little effort.
[0043] According to further embodiments, a device for carrying out
the method according to various embodiments can be provided.
[0044] It is a device for controlling vibrations of a metallurgical
vessel occurring during the injection of gas into the metallurgical
vessel filled with liquid molten metal and provided with a number
of individual nozzles for the injection of gas, the individual
nozzles being respectively connected to a gas feed line of their
own,
[0045] with at least one sensor for measured values correlating
with the vibrations of the metallurgical vessel occurring,
[0046] with a processing unit for processing the measured values
measured by the sensor,
[0047] characterized in that
[0048] in at least two gas feed lines there is at least one device
for changing the gas flow through the gas feed line, and each
device for changing the gas flow is connected to the processing
unit.
[0049] The sensor measures measured values correlating with the
vibrations of the metallurgical vessel occurring, which are
processed in the processing unit. In this case, quantitative
information as to the vibrations of the metallurgical vessel
occurring, that is to say for example as to the frequency and
intensity of the vibrations, is obtained from the measured values.
The sensor may be fitted on the metallurgical vessel, for example a
converter. According to another embodiment, the sensor is fitted on
a part of the plant connected directly or indirectly to the
metallurgical vessel; for example, in the case of a converter, on
the gear mechanism provided for tilting the converter, on the
suspension, or on the foundation on which the converter and
associated parts of the plant, such as the gear mechanism for
example, are located. There is at least one sensor, but there may
also be a number of sensors. If a number of sensors are present,
they may be fitted at one or more of the aforementioned
locations.
[0050] Via the connection to the devices for changing the gas flow,
the processing unit gives these devices specifications for changing
the gas flow. On the basis of the information obtained in the
processing unit as to the vibrations of the metallurgical vessel
occurring, these specifications are devised such that vibrations of
the metallurgical vessel with certain frequencies should be
reduced. The specifications are devised on the basis of expert
knowledge stored in the processing unit. This expert knowledge may,
for example, be determined and stored during the commissioning of
the metallurgical vessel and consists, for example, of the natural
frequencies of the metallurgical vessel, the natural frequencies of
the parts of the plant connected directly or indirectly to said
vessel, or the natural frequency of the overall system comprising
the metallurgical vessel and parts of the plant connected directly
or indirectly to it. In the case of a converter as the
metallurgical vessel, the overall system essentially comprises the
foundation, gear mechanism, tilting drive, baling ring, suspension
and support.
[0051] The connection of the processing unit to the devices for
changing the gas flow may be direct. It may also be indirect; in
the case of valves as devices for changing the gas flow, for
example, via a valve unit for controlling the valves. The terms
connect and connection should be understood in this context as
meaning that the transmission of specifications to the devices for
changing the gas flow is possible. In the case of an indirect
connection, that is to say a connection via a further device, such
as for example a valve unit, this means that the transmission of
specifications from the processing unit takes place via the further
device.
[0052] The fact that there is at least one device for changing the
gas flow in at least two gas feed lines means that the total amount
of gas introduced per unit of time, the blowing rate, can be kept
largely constant, since a change at one nozzle can be compensated
by an opposite change at another nozzle.
[0053] More preferably, the device for changing the gas flow
through the gas feed line allows changing of the gas flow in
stages. It is therefore, for example, a control valve which
controls the current through-flow to the setpoint value.
[0054] According to one embodiment, the device for changing the gas
flow through the gas feed line is a device for continuously
changing the gas flow. It is therefore, for example, a control
valve which controls the current through-flow to the setpoint
value.
[0055] The sensor for measured values correlating with the
vibrations of the metallurgical vessel occurring is preferably a
vibration sensor. A vibration sensor is a device which converts the
mechanical vibrations into signals that can be used further, which
are preferably electrical signals.
[0056] More preferably, the vibration sensor is a torque sensor, an
acceleration pickup, a position pickup, a strain gage or a velocity
pickup. On account of price and simplicity, acceleration pickups,
position pickups and velocity pickups should be preferred.
[0057] In FIG. 1, gas, represented by bubbles in the crude steel,
is injected through under-bath nozzles 3a, 3b, 3c into a converter
2 filled with liquid crude steel 1. The under-bath nozzles 3a, 3b,
3c are respectively supplied with gas separately through the gas
feed lines 4a, 4b, 4c from a gas source line 6 connected to a gas
reservoir 5. The supply takes place in this case via a valve unit
7. In the valve unit 7, the total amount of gas injected per unit
of time can be controlled via valve 8. In the valve unit 7 in the
gas feed lines 4a and 4c, there are also valves 9, 10 for changing
the gas flow through the gas feed line. A vibration sensor 11 at
the converter 2 sends the vibration signals measured by it to a
processing unit 12. In this unit, specifications for changing the
gas flow for the valves 9, 10 are prepared on the basis of stored
expert knowledge and are passed on via a connecting line to the
valve unit 7, and consequently to the valves 9, 10. Each of the
valves 9, 10 is connected to the processing unit 12 via the valve
unit.
[0058] In FIG. 1, an amount of gas represented by 10 bubbles leaves
the under-bath nozzle 3a per unit of time, an amount of gas
represented by 10 bubbles leaves the under-bath nozzle 3b per unit
of time, and an amount of gas represented by 10 bubbles leaves the
under-bath nozzle 3c per unit of time. If the processing unit 8
establishes the presence of an unfavorable frequency A of the
vibrations of the converter, it gives the valves 9, 10
specifications on the basis of which said valves change the amount
of gas injected from the individual underbath nozzles 3a and 3c per
unit of time. The result of the change is represented in FIG. 2, in
which an amount of gas represented by 5 bubbles leaves the
under-bath nozzle 3a per unit of time, an amount of gas represented
by 10 bubbles leaves the under-bath nozzle 3b per unit of time and
an amount of gas represented by 15 bubbles leaves the under-bath
nozzle 3c per unit of time. The intensity of the frequency A of the
vibrations of the converter, represented in arbitrary units (au),
has become lower as a result of the change.
[0059] FIG. 3 shows a schematic drawing of a converter 2, which is
fastened in a baling ring 13 via a suspension element 14. A
supporting journal of the baling ring is connected to a gear
mechanism 15, which stands on a foundation 17 via a frame 16. For
better overall clarity, further suspension elements, parts of the
frame as well as further parts necessary for mounting the baling
ring have not been represented. In the converter itself there are a
number of nozzles in the side walls and in the bottom. The gas feed
lines leading to these nozzles are connected via a valve unit 7 to
the gas source line 6 extending from the gas reservoir 5. Vibration
sensors 11 at the converter, baling ring, gear mechanism, frame,
suspension element and foundation are connected by lines to the
processing unit 12. On the basis of the vibration signals measured
by these vibration sensors, the processing unit 12 prepares
specifications for changing the gas flow in gas feed lines leading
to the nozzles. These specifications are passed on to the valve
unit 7 via a connecting line for implementation by valves (not
represented) in the gas feed lines. [0060] 1 crude steel [0061] 2
converter [0062] 3a, 3b, 3c under-bath nozzles [0063] 4a, 4b, 4c
gas feed lines [0064] 5 gas reservoir [0065] 6 gas source line
[0066] 7 valve unit [0067] 8 valve [0068] 9 valve [0069] 10 valve
[0070] 11 vibration sensor [0071] 12 processing unit [0072] 13
baling ring [0073] 14 suspension element [0074] 15 gear mechanism
[0075] 16 frame [0076] 17 foundation
* * * * *