U.S. patent application number 14/261058 was filed with the patent office on 2014-11-06 for method for operating an oxygen blowing lance in a metallurgical vessel and a measurement system for determining a measurement signal used in the method.
This patent application is currently assigned to SMS Siemag Aktiengesellschaft. The applicant listed for this patent is SMS Siemag Aktiengesellschaft. Invention is credited to Pavlo GRYGOROV, Hans-Jurgen ODENTHAL, Jochen SCHLUTER, Norbert UEBBER.
Application Number | 20140327192 14/261058 |
Document ID | / |
Family ID | 58098768 |
Filed Date | 2014-11-06 |
United States Patent
Application |
20140327192 |
Kind Code |
A1 |
GRYGOROV; Pavlo ; et
al. |
November 6, 2014 |
METHOD FOR OPERATING AN OXYGEN BLOWING LANCE IN A METALLURGICAL
VESSEL AND A MEASUREMENT SYSTEM FOR DETERMINING A MEASUREMENT
SIGNAL USED IN THE METHOD
Abstract
A method for operating a blowing lance for blowing a gas in a
metallurgical vessel, wherein the head of the blowing lance
includes at least one supersonic nozzle, operating parameter
measurement signals used for the purpose of process control are
continuously acquired. The inlet pressure and/or the inlet
temperature of the gas at the supersonic nozzle and/or the
vibration amplitude and/or the vibration frequency of the blowing
lance and/or the time at which ignition occurs during the oxygen
blowing process and/or the location at which ignition occurs during
the oxygen blowing process is detected and/or measured in the head
of the lance by a detector or sensor arranged in the head of the
lance near the supersonic nozzle during operation of the blowing
lance. The measurement signal(s) are transmitted to a control unit
connected to the detector or sensor and made available for
controlling the operation of the blowing lance.
Inventors: |
GRYGOROV; Pavlo; (Munchen,
DE) ; ODENTHAL; Hans-Jurgen; (Mettmann, DE) ;
SCHLUTER; Jochen; (Dortmund, DE) ; UEBBER;
Norbert; (Langenfeld, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SMS Siemag Aktiengesellschaft |
Dusseldorf |
|
DE |
|
|
Assignee: |
SMS Siemag
Aktiengesellschaft
Dusseldorf
DE
|
Family ID: |
58098768 |
Appl. No.: |
14/261058 |
Filed: |
April 24, 2014 |
Current U.S.
Class: |
266/44 ;
266/87 |
Current CPC
Class: |
C21C 5/4606 20130101;
C21C 5/4613 20130101; F27D 21/0014 20130101; C21C 5/4673 20130101;
F27B 3/085 20130101; F27D 19/00 20130101; F27D 2021/0007 20130101;
F27D 3/16 20130101; F27D 2019/0043 20130101; F27D 2003/164
20130101; C21C 5/32 20130101; F27D 2003/169 20130101 |
Class at
Publication: |
266/44 ;
266/87 |
International
Class: |
C21C 5/32 20060101
C21C005/32; C21C 5/46 20060101 C21C005/46 |
Foreign Application Data
Date |
Code |
Application Number |
May 2, 2013 |
DE |
10 2013 208 079.4 |
Claims
1. A method for operating a blowing lance for blowing a gas in a
metallurgical vessel, wherein a replaceable head of the blowing
lance comprises at least one supersonic nozzle, the method
comprising the steps of: detecting and/or measuring inlet pressure
and/or inlet temperature of the gas at the at least one supersonic
nozzle and/or vibration amplitude and/or vibration frequency of the
blowing lance and/or a time at which ignition occurs during an
oxygen blowing process and/or a location at which ignition occurs
during the oxygen blowing process, in the head of the lance with a
detector or sensor arranged in the head of the lance in an area of
the supersonic nozzle during operation of the blowing lance; and
transmitting measurement signal(s) thus acquired during the
operation of the blowing lance, to an evaluation and/or process
control unit connected to the detector or sensor and making the
signals available for controlling the operation of the blowing
lance.
2. The method according to claim 1, wherein the inlet pressure of
the gas at an entrance to the at least one supersonic nozzle is
detected and/or measured in the head of the lance by at least one
pressure sensor arranged in the head of the lance in the area of
the at least one supersonic nozzle during operation of the blowing
lance.
3. The method according to claim 1, wherein the inlet temperature
of the gas at an entrance to the at least one supersonic nozzle is
detected and/or measured in the head of the lance by at least one
temperature sensor arranged in the head of the lance in the area of
the at least one supersonic nozzle during the operation of the
blowing lance, especially during a blowing process, preferably an
oxygen blowing process.
4. The method according to claim 1, further comprising
simultaneously detecting and/or measuring feed pressure of the gas
at a gas feed station located a distance away from the at least one
supersonic nozzle.
5. The method according to claim 1, wherein the vibration amplitude
and/or the vibration frequency of the blowing lance is detected
and/or measured in the head of the lance by at least one vibration
sensor arranged in the head of the lance in the area of the at
least one supersonic nozzle during the operation of the blowing
lance.
6. The method according to claim 1, further comprising detecting
optical emission(s) occurring upon ignition of oxygen jets in the
head of the lance by at least one light sensor arranged in the head
of the lance in the area of the at least one supersonic nozzle
during the operation of the blowing lance.
7. The method according to claim 1, further comprising detecting
optical emissions occurring outside the blowing lance in the head
of the lance by at least one light sensor or at least one camera
equipped with a light sensor, which is arranged in the head of the
lance in the area of the at least one supersonic nozzle and is
optically aimed directly through an orifice open of the blowing
lance.
8. The method according to claim 1, wherein the lance is a
multi-hole lance comprising several supersonic nozzles, at least
one detector or sensor being assigned to each supersonic
nozzle.
9. The method according to claim 1, wherein at least one detector
or sensor selected from the group consisting of pressure sensors,
temperature sensors, vibration sensors, and/or light sensors, is
assigned to the blowing lance.
10. The method according to claim 1, including transmitting the
acquired measurement signal(s) from the detector or sensor to the
evaluation and/or process control unit in hardwired fashion by a
cable arranged in or on the blowing lance or in wireless fashion by
a radio module connected to the detector and/or sensor and arranged
in the blowing lance.
11. The method according to claim 1, including supplying the
detector(s) or sensor(s) with electric power by an
energy-harvesting module arranged in the blowing lance.
12. A measurement system for determining measurement signals used
for process control during operation of a blowing lance for blowing
gas in a metallurgical vessel, wherein the measurement system
comprises: a blowing lance with a replaceable head having at least
one supersonic nozzle; an evaluation and/or process control unit
for receiving and processing measurement signals; and a detector or
sensor arranged in the head of the lance in an area of the at least
one supersonic nozzle, which detector or sensor is connected to the
evaluation and/or process control unit, detects and/or measures in
the head of the lance during the operation of the blowing lance
inlet pressure and/or inlet temperature of gas at the at least one
supersonic nozzle and/or vibration amplitude and/or vibration
frequency of the blowing lance and/or a time when ignition occurs
during an oxygen blowing process and/or a location where ignition
occurs during the oxygen blowing process, and transmits the
measurement signal(s) acquired during operation of the blowing
lance to the evaluation and/or process control unit connected to
the at least one detector or sensor so that the signals are
available for controlling operation of the blowing lance.
13. The measurement system according to claim 12, wherein the
detector or sensor is at least one pressure sensor arranged in the
head of the lance in the area of the at least one supersonic
nozzle, which sensor detects and/or measures, in the head of the
lance, the inlet pressure of the gas at an entrance to the at least
one supersonic nozzle during operation of the blowing lance, and
transmits the measurement signal(s) to the evaluation and/or
process control unit for controlling the operation of the blowing
lance.
14. The measurement system according to claim 12, wherein the
detector or sensor is at least one temperature sensor arranged in
the head of the lance in the area of the at least one supersonic
nozzle, which sensor detects and/or measures, in the head of the
lance the inlet temperature of the gas at an entrance to the at
least one supersonic nozzle during the operation of the blowing
lance, and transmits the measurement signal(s) to the evaluation
and/or process control unit for controlling the operation of the
blowing lance.
15. The measurement system according to claim 12, wherein the
detector and sensor is a vibration sensor arranged in the head of
the lance in the area of the at least one supersonic nozzle, which
sensor detects and/or measures, in the head of the lance, the
vibration amplitude and/or the vibration frequency of the blowing
lance during operation of the blowing lance, and transmits the
measurement signal to the evaluation and process control unit for
controlling the operation of the blowing lance.
16. The measurement system according to claim 12, wherein the
detector or sensor is at least one light sensor or at least one
camera equipped with a light sensor arranged in the head of the
lance in the area of the at least one supersonic nozzle, which
sensor or sensor-equipped camera detects and/or measures, in the
head of the lance, optical emission(s) occurring when oxygen jets
ignite during the operation of the blowing lance, and transmits the
measurement signal(s) to the evaluation and/or process control unit
for controlling the operation of the blowing lance.
17. The measurement system according to claim 12, wherein the
detector or sensor is at least one light sensor or at least one
camera equipped with a light sensor arranged in the head of the
lance in the area of the at least one supersonic nozzle, which
sensor or sensor-equipped camera is optically aimed directly
through an orifice of the blowing lance, detects and/or measures,
in the head lance, optical emissions occurring outside the lance
during the operation of the blowing lance, and transmits the
measurement signal(s) to the evaluation and/or process control unit
for controlling the operation of the blowing lance.
18. The measurement system according to claim 12, wherein the
blowing lance is a multi-hole lance with multiple supersonic
nozzles, wherein at least one detector or sensor is assigned to
each of the supersonic nozzles.
19. The measurement system according to claim 12, wherein the
blowing lance comprises at least one detector or sensor selected
from the group consisting of pressure sensors, temperature sensors,
vibration sensors, and/or light sensors.
20. The measurement system according to claim 12, wherein the
detector or sensor is connected to the evaluation and/or process
control unit in a hardwired manner by a cable arranged in or on the
blowing lance or in a wireless manner by a radio module arranged in
the blowing lance, wherein when the detector or sensor is
wirelessly connected to the evaluation and/or process control unit
the detector or sensor is connected to an energy-harvesting module
installed in the blowing lance.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority of DE 10 2013 208
079.4, filed May 2, 2013, the priority of this application is
hereby claimed and this application is incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] The invention pertains to a method for operating a
gas-blowing lance, especially an oxygen blowing lance, in a
metallurgical vessel, wherein the preferably replaceable head of
the blowing lance comprises at least one supersonic nozzle. The
invention is also directed at a measurement system for determining
measurement signals used during the operation of a gas-blowing
lance, especially an oxygen blowing lance, in a metallurgical
vessel for the purpose of process control, wherein the measurement
system includes a blowing lance, preferably an oxygen blowing
lance, with a preferably replaceable head comprising at least one
supersonic nozzle, and an evaluation and/or process control unit to
receive and process the measurement signals.
[0003] In certain methods of steel production such as the basic
oxygen furnace (BOF) method or the argon-oxygen decarburization
(AOD) method, it is conventional practice to subject the molten
metal in the metallurgical vessel to a flow of a gas, especially a
flow of oxygen (O.sub.2) or nitrogen (N.sub.2). For this purpose, a
blowing lance is typically lowered into the metallurgical vessel
from above, and the gas is blown from it onto the molten metal.
[0004] Gas can also be blown onto the melt in processes involving
the melting of scrap in an electric-arc furnace (EAF). Gas is
usually blown onto the melt at least in the following metallurgical
units: BOF converters, AOD converters, the burner and injector
nozzles for an electric-arc furnace (EAF) or a CONCARC furnace
(CON=converter, ARC=arcing), the burner and injector nozzles for a
reducing furnace (SAF=submerged arc furnace), and the nozzles for
vacuum treatment systems such as VOD (Vacuum Oxygen
Decarburization) or RH (Ruhrstahl-Heraeus) units. During the
production of steel in a BOF converter, the oxygen is blown onto
the metal bath by means of the blowing lance. The head of the lance
is typically 1.4-3 m away from the surface of the bath. In the head
of a blowing lance of this type there are usually several
convergent-divergent nozzles arranged at previously determined
angles, which accelerate the gas to supersonic speed. The
convergent-divergent nozzles are called "supersonic" or "Laval"
nozzles. The gas typically leaves these supersonic nozzles at
approximately twice the speed of sound and with a great deal of
momentum, whereupon it strikes the metal bath. In the molten metal
bath, an oscillating blowing trough is formed, and the blown-on gas
ensures an intensive decarburization reaction. A foamy slag forms
on the molten metal bath as a result of the gaseous reaction
products which rise up.
[0005] According to isentropic stream filament theory, the geometry
of a Laval or supersonic nozzle can be designed for only a single
value--namely its ideal operating point or "design point"--with
respect to any one case of the inlet pressure p.sub.0 of the
supersonic nozzle, the inlet temperature T.sub.0 of the nozzle, and
the static backpressure p.sub.A in the metallurgical vessel. The
inlet pressure p.sub.0 at this ideal operating point is therefore
also called the design pressure, and the inlet temperature T.sub.0
at this ideal operating point is also called the design
temperature. Only when the supersonic nozzle is operated at its
ideal operating point does the expanded stream of gas lie solidly
against the nozzle wall until leaving the nozzle and is the gas
accelerated to supersonic speed. As soon as the real flow through
the nozzle deviates from the ideal design state or ideal operating
point, however, complex flow patterns (diamond wave patterns) in
the form of expansion waves or density surges develop both inside
and outside the nozzle, which can cause wear of the nozzle edge and
lead to premature separation of the jet from the nozzle wall. When
the cold gas jet separates from the nozzle wall, a recirculation
region develops, which allows hot converter gas to reach the nozzle
wall, as a result of which the nozzle suffers wear. To reduce or
prevent such wear of the nozzle, the supersonic nozzle must
therefore be operated at its operating point as consistently as
possible.
[0006] At the tip of a blowing lance there is a replaceable head,
which, depending on the application, includes several
convergent-divergent supersonic or Laval nozzles to accelerate the
gas to supersonic speed. A lance head of this type can be used in
the following types of metallurgical vessels or units, among
others: in BOF and AOD converters, in SIS (Siemag Injection System)
injectors for electric-arc furnaces (EAF), in reducing furnaces
(SAF), and in vacuum systems (RH, VOD).
[0007] With respect to both the immediate inlet pressure p.sub.0,
i.e., the design pressure of the supersonic nozzle in question, and
the inlet temperature T.sub.0, i.e., the associated design
temperature of the supersonic nozzle, the geometry of a supersonic
or Laval nozzle can be designed for only one optimal operating
point of the associated supersonic nozzle at a static backpressure
p.sub.A in the associated metallurgical vessel or unit. Only when
both of the process variables, i.e., the design pressure/inlet
pressure and the inlet temperature/design temperature, are
maintained during converter operation will the supersonic or Laval
nozzle work at its optimal operating point and will the nozzle
suffer only minimal wear. Normally, during operation in practice,
the upstream pressure p.sub.vs and the volume flow rate of the gas
are measured at a valve station where the gas is made available to
the blowing lance. These are variables which are usually used in
the design of the ultrasonic nozzle. Thus the pressure loss
.DELTA.p.sub.verl occurring downstream from the valve station,
i.e., in the pipelines and pressure hoses, including the entire
blowing lance, is estimated in order to determine the inlet
pressure p.sub.0 on the basis of the equation
p.sub.0=p.sub.vs-.DELTA.p.sub.verl. The exact pressure loss
.DELTA.p.sub.verl is difficult to determine theoretically, because
to do this it is necessary to perform a compressible pressure loss
calculation for all the components, for which purpose the exact
layout of the gas lines must be known. For this reason, the process
variables p.sub.0, T.sub.0, and p.sub.A required for nozzle design
are always known in the form of approximations. Whether the
supersonic or Laval nozzle in question will then in fact work at
its design point or ideal operating point during practical use in
the steel mill is uncertain. If it does not, the service life of
the lance and the stability of the process will become worse.
[0008] During the blowing process, furthermore, the oxygen jet
emerging from the blowing lance ignites when it makes contact with
the liquid pig iron. Because the converter or the metallurgical
vessel in question is often filled not only with pig iron but also
with coolants such as steel scrap, the oxygen jet emerging from the
blowing lance can also be thrown back by the scrap, if its
temperature is not high enough for ignition. Thus very often the
combustion of the oxygen does not start immediately, i.e., as soon
as the blowing process begins. It is extremely important, however,
to know the exact time at which ignition occurs, because knowing
when the associated decarburization reaction of the molten metal
bath begins is vital to the management of the process. Depending on
the position of the scrap and the position of the liquid pig iron
in the vessel, furthermore, the ignition time can also be different
for each nozzle of a multi-hole blowing lance. Differentiated
knowledge of the time and place of ignition would make it possible
to achieve a correspondingly exact differentiation according to the
oxygen that is used and that which is not.
[0009] Finally, a melt-slag emulsion forms in the converter or
metallurgical vessel during conventional blowing processes. As a
result of the decarburization reaction, the volume of slag
increases enormously, so that slag can actually be ejected, which
results in an increase in production costs and the risk of a
shutdown. During the blowing process, furthermore, slag and molten
metal, especially liquid steel, adhere to the blowing lance, which
is usually water-cooled. This skull which forms on a blowing lance
is undesirable and must be removed, because the overall mass of the
blowing lance increases undesirably and the orifices of the
supersonic nozzles can become partially clogged.
[0010] A method for operating an oxygen blowing lance in a
metallurgical vessel is known from WO 2012/136698 A1, in which the
pressure and the temperature are measured at the entrance to a
supersonic nozzle of a blowing lance by means of an independent
measurement device, which, without external supply lines or feed
lines, performs time-resolved pressure and/or temperature
measurements and stores the corresponding measurement values. An
independent measuring device of this type, also called a "data
logger", is installed in the head of the blowing lance and then
measures the pressure and/or the temperature over the course of its
(battery-operated) service life and stores these data. The
independent measurement device is then removed from the head of the
lance and, after the measurement data have been read out, a
calibration curve is set up. The operation of the oxygen blowing
lance, which no longer carries the independent measuring device, is
then controlled on the basis of this calibration curve. The
disadvantage of using data loggers is that the pressure loss
.DELTA.p.sub.verl, the inlet pressure p.sub.0t present during the
course of operation, and the inlet temperature T.sub.0t present
during the course of operation can be determined only after the
fact, i.e., after the lance has been taken out. The inlet pressure
p.sub.0t and the inlet temperature T.sub.0t are not recorded
continuously in real time during the blowing process, which means
that it is not guaranteed that the supersonic nozzle of the blowing
lance will operate at its ideal operating point during the course
of operation.
[0011] It is known from practical experience, furthermore, that
conventional vibration sensors mounted on the carriage of the lance
can be used to detect vibrations of the blowing lance during
operation in a metallurgical vessel. The measurement signals thus
acquired can be used to draw conclusions concerning the extent to
which slag has formed in the metallurgical vessel and the tendency
to eject slag. The vibration measurements are made on the carriage,
because the vibration sensors are protected from heat there and
because the lance can be replaced without having to worry about the
sensors. The disadvantage of this solution is that the vibrations
measured on the carriage are much weaker than those which occur at
the tip of the lance, which is the area most affected by slag
formation, and they can also be influenced by variables which are
independent of the process. Thus the acquired measurement signals
provide only an imprecise picture of the conditions in the area of
the tip of the lance. In addition, in the case of measurements
which are conducted above the lance dome, the deflections of the
blowing lance are not detected in optimal fashion. Finally, in the
case of measurement sensors mounted near the blowing lance dome,
there is the danger that they can suffer wear and be damaged as a
result of the heat to which they are subjected and the effect of
the dust acting on them.
[0012] It is known from WO 2011/151143 A2 that a camera comprising
CCD sensors or photodiodes placed in the gap between the converter
mouth and the exhaust hood can be used to measure the course of the
radiation intensity over time and to determine the time at which a
previously determined radiation intensity is reached or at which a
previously determined increase in radiation intensity occurs, which
is the point in time at which the oxygen jet emerging from the
blowing lance ignites. This method for determining the time of
ignition during the blowing process on the basis of observation,
from the outside, of the light emissions from the arcing zone which
forms at the time of ignition suffers from the disadvantage that,
as a result of the large amount of smoke generated after ignition,
information on the ignition process can be obtained only indirectly
via the radiation of this smoke. As a result, the reliability of
the measurement result is limited. In addition, it is impossible to
determine in a differentiated manner the ignition of the individual
oxygen jets, usually five to six, emerging from a multi-hole
nozzle.
SUMMARY OF THE INVENTION
[0013] The invention is based on the goal of creating a solution
which makes possible the continuous detection of operating
parameter measurement signals for the purpose of process control
during the operation of a gas-blowing lance, especially an oxygen
blowing lance, in a metallurgical vessel.
[0014] In a method of the type described in detail above, this goal
is achieved according to the invention in that the inlet pressure
p.sub.0t and/or the inlet temperature T.sub.0t of the gas at the at
least one supersonic nozzle and/or the vibration amplitude A and/or
the vibration frequency .omega. of the blowing lance and/or the
time at which ignition occurs during the oxygen blowing process
and/or the location at which ignition occurs during the oxygen
blowing process is/are detected and/or measured, preferably
continuously, during the operation of the blowing lance, especially
during a blowing process, preferably an oxygen blowing process, by
means of at least one detector or sensor mounted in the head of the
lance in the area of the supersonic nozzle, and in that the
measurement signal(s) thus obtained during operation of the blowing
lance is/are transmitted, preferably on-line, to an evaluation
and/or process control unit connected to the at least one detector
or sensor and made available for the purpose of controlling the
operation of the blowing lance.
[0015] In the case of a measurement system of the type described in
detail above, the previously mentioned goal is again achieved in
that a detector or sensor is mounted in the head of the lance in
the area of the at least one supersonic nozzle, which detector or
sensor, is connected by appropriate transmission means to the
evaluation and/or process control unit; detects and/or measures,
preferably continuously, in the head of the lance, during the
operation of the blowing lance, especially during a blowing
process, preferably an oxygen blowing process: the inlet pressure
p.sub.0t and/or the inlet temperature T.sub.0t of the gas at the at
least one supersonic nozzle and/or the vibration amplitude A and/or
the vibration frequency .omega. of the blowing lance and/or the
time at which ignition occurs during the oxygen blowing process
and/or the location at which ignition occurs during the oxygen
blowing process; and transmits, preferably on-line, the measurement
signal(s) thus acquired during the operation of the blowing lance
are transmitted to the evaluation and/or process control unit
connected to the at least one detector or sensor and makes them
available for the purpose of controlling the operation of the
blowing lance.
[0016] The invention thus proceeds from the central idea of
mounting, in the head of the blowing lance, one or more detectors
and/or sensors, which detect operating parameters by suitable
measurement technology during operation, that is especially during
the time that the blowing lance is in its working or operating
position in the metallurgical vessel and is delivering the gas, and
transmit the acquired measurement signals continuously and on-line
during operation to an evaluation and/or process control unit and
thus make them available for the purpose of controlling the
operation of the blowing lance. The measurement signals obtained in
this way, which represent the current operating state in relation
to the operating parameters in question, can then be used directly
for the purpose of process control during ongoing operation of the
blowing lance.
[0017] According to one aspect of the invention, the current inlet
pressure p.sub.0t of the gas at the entrance to the at least one
supersonic nozzle of the blowing lance is detected and/or measured
by means of at least one detector and/or sensor. According to a
second aspect of the invention, the inlet temperature T.sub.0t of
the gas at the entrance to the at least one supersonic nozzle of
the blowing lance is detected and/or measured during the blowing
process in the head of the lance, especially continuously, by means
of at least one detector or sensor.
[0018] The operating parameter measurement signals acquired in the
first aspect and/or in the second aspect of the invention are then
transmitted to an evaluation and/or process control unit directly,
preferably on-line, and made available for the purpose of
controlling the operation of the blowing lance. Thus it is
possible, for example, to adjust the valve pressure p.sub.vs and
thus regulate the inlet pressure p.sub.0t currently being reached
at the entrance to the supersonic nozzle in the head of the lance,
this inlet pressure being set to a value which corresponds at least
essentially and/or approximately, i.e., with perhaps only a small
deviation, to the design pressure p.sub.0. It is therefore possible
in this way, by means of the invention, to operate a supersonic
nozzle--and in the case that a detector or sensor is provided at
the entrance to each supersonic nozzle or Laval nozzle of a blowing
lance--to operate all of the supersonic nozzles at all times at a
point which is at least close to their design point, that is, in or
at their ideal operating point. As a result, stable process
conditions for the gas-blowing process are obtained, especially for
oxygen blowing, which leads to a significant increase in durability
and to a longer service life of the preferably replaceable head of
the lance. Continuous detection of the inlet pressure p.sub.0t and
of the inlet temperature T.sub.0t during a blowing process
therefore makes it possible to adjust the pressure p.sub.vs
dynamically at the valve station during the blowing process, so
that the head of the lance can be operated at its design point and
nozzle wear can be minimized.
[0019] According to the invention, therefore, the current inlet
pressure p.sub.0t and the current inlet temperature T.sub.0t
present at the moment in question in the interior of the blowing
lance, that is, in the head of the lance, are measured during the
blowing process. This time-dependent pressure and temperature
measurements are carried out by means of detectors and/or sensors.
The measurement data are transmitted over a cable or possibly
wirelessly to a connected evaluation and/or process control unit
such as a PC. The power required to operate the detectors and/or
sensors can be supplied over the cable or by a battery or by means
of an energy-harvesting module.
[0020] According to these first two aspects of the invention,
therefore, pressure and possibly temperature sensors for
determining the current inlet pressure p.sub.0t and the current
inlet temperature T.sub.0t of the oxygen or of the blowing gas in
the blowing lance are installed in the blowing lance or directly in
the head of the lance. At the same time that the pressure
measurement(s) is/are being carried out in the blowing lance or in
the head of the lance, the pressure or upstream pressure p.sub.vs
at the valve station supplying the blowing gas or the oxygen should
also be measured. This makes it possible to perform an on-line
calculation of the pressure loss
.DELTA.p.sub.verl=p.sub.vs-p.sub.0t and to monitor the deviation of
the current inlet pressure p.sub.0t and the current inlet
temperature T.sub.0t of the blowing gas or of the oxygen from the
corresponding design variables of the supersonic nozzle in
question, namely, from the design pressure p.sub.0 and the design
temperature T.sub.0, during the blowing process. The upstream
pressure p.sub.vs at the valve station can thus be adjusted in such
a way that an inlet pressure p.sub.0t which corresponds to the
design pressure p.sub.0 is present at the entrance to one or all of
the supersonic or Laval nozzles of the blowing lance. This has the
effect of minimizing the wear of the head of the lance. The
variable T.sub.0t is not necessary for actual operation, but the
design temperature T.sub.0 is required as a theoretical design
variable for the nozzle design. It is not possible to determine the
static pressure p.sub.A in the metallurgical vessel in this way.
For the design of the nozzle, however, this parameter plays only a
subordinate role, because the pressure p.sub.A deviates only
slightly from the ambient pressure of 1.01 bars. The measurement
data, i.e., the acquired operating parameter measurement signals,
can be transmitted by cable or wirelessly, in the latter case by
means of a radio module, for example, installed in the blowing
lance, to an evaluation and/or process control unit such as a
computer, especially a PC, which is available to the operating
personnel. The process variables inlet pressure p.sub.0 and inlet
temperature T.sub.0 directly at the Laval nozzle necessary for the
correct theoretical design of a supersonic nozzle according to the
isentropic flow filament theory and the static (back)pressure
p.sub.A in the metallurgical vessel can now be detected
continuously by means of the inventive method and the inventive
measurement system as the actual time-dependent values at the
moment in question. These variables p.sub.0t and T.sub.0t can be
measured continuously during the blowing process by means of the
detectors and/or sensors mounted in the head of the lance. The
static pressure p.sub.A in the metallurgical vessel plays only a
subordinate role in the design process and thus in the automatic
regulation of the operation of the supersonic nozzle(s) in or at
their ideal operating point, because it usually fluctuates only
moderately around the ambient pressure (1.01 bars.+-.0.2 bar). When
the pressure p.sub.vs at the valve station is also measured
continuously, the pressure loss .DELTA.p.sub.verl between the valve
station and entrance of the gas into the head of the blowing lance
can also be determined continuously during the blowing process.
[0021] Especially for the realization of the first two aspects of
the invention described above, an advantageous embodiment of the
inventive method is characterized in that, the inlet pressure
p.sub.0t of the gas at the entrance to the at least one supersonic
nozzle is detected and/or measured, especially continuously, by
means of at least one pressure sensor mounted in the head of the
lance in the area of the at least one supersonic nozzle during the
operation of the blowing lance, especially during a blowing
process, preferably an oxygen blowing process; and in particular in
that the inlet temperature T.sub.0t of the gas at the entrance to
the at least one supersonic nozzle is detected and/or measured,
especially continuously, by means of at least one temperature
sensor mounted in the head of the lance in the area of the at least
one supersonic nozzle during the operation of the blowing lance,
especially during a blowing process, preferably an oxygen blowing
process.
[0022] It is especially advisable in this case for the feed
pressure p.sub.vs of the gas at a gas feed station installed a
certain distance away from the at least one supersonic nozzle to be
detected and/or measured simultaneously, especially
continuously.
[0023] In a similar manner, an embodiment of the inventive
measurement system is characterized in that a pressure sensor is
mounted in the head of the lance in the area of the at least one
supersonic nozzle, which sensor is connected by appropriate
transmission means to the evaluation and/or process control unit;
detects and/or measures, especially continuously, the inlet
pressure p.sub.0t of the gas at the entrance to the at least one
supersonic nozzle during the operation of the blowing lance,
especially during a blowing process, preferably an oxygen blowing
process; and transmits, preferably on-line, the measurement
signal(s) thus acquired during the operation of the blowing lance
to the evaluation and/or process control unit connected to the at
least one pressure sensor and thus makes them available for the
purpose of controlling the operation of the blowing lance; and/or
in that at least one temperature sensor is mounted in the head of
the lance in the area of the at least one supersonic nozzle, which
sensor is connected by appropriate transmission means to the
evaluation and/or process control unit; detects and/or measures,
especially continuously, the inlet temperature T.sub.0t of the gas
at the entrance to the at least one supersonic nozzle during the
operation of the blowing lance, especially during a blowing
process, preferably an oxygen blowing process; and transmits,
preferably on-line, the measurement signal(s) thus acquired during
the operation of the blowing lance to the evaluation and/or process
control unit connected to the at least one temperature sensor and
thus makes them available for the purpose of controlling the
operation of the blowing lance.
[0024] According to a third aspect of the invention, it is provided
that, by means of at least one vibration sensor installed directly
in the head of the lance, the vibration amplitude A and/or the
vibration frequency .omega. of the blowing lance, especially an
oxygen blowing lance, is detected and measured during the operation
of the blowing lance. As a result of the measurement by means of
detectors and/or sensors mounted in the head of the lance, it is
possible to achieve a reliable, maintenance-free and efficient
vibration measurement at the blowing lance in the metallurgical
vessel, especially a converter, so that the increase in the level
of the slag and the possible ejection of slag from the vessel can
be recognized as well as the presence of skull on the blowing
lance. It is therefore possible to measure the vibrations of the
blowing lance, especially an oxygen blowing lance or BOF lance, by
means of a sensor system mounted inside the blowing lance. The
measurement is made in the head of the lance at a point as close as
possible to the orifice, that is, at the "low point" of the blowing
lance, and as a result the measurement signals are highly
significant, in fact more significant than those according to the
prior art. The measurement is preferably carried out by means of a
wireless sensor system (detectors and/or sensors), wherein,
however, a hardwired system or system with transmission lines is
also possible. The latter possibility, however, is associated with
certain problems, namely, that, if the lower part of the lance,
that is, the head of the lance located above the sensor system
formed by the detectors and/or sensors, is damaged, the feed lines
and possibly the sensor system itself may have to be replaced,
which is expensive. In the case of vibration sensors as well, power
can be supplied to the wireless sensor system by batteries,
accumulators, or an energy-harvesting module.
[0025] For the realization of this third aspect of the present
invention, the third aspect is characterized in that the vibration
amplitude A and/or the vibration frequency .omega. of the blowing
lance is detected and/or measured in the head of the lance,
especially continuously, by means of at least one vibration sensor
mounted in the head of the lance in the area of the at least one
supersonic nozzle during the operation of the blowing lance,
especially during a blowing process, preferably an oxygen blowing
process.
[0026] In a similar manner, it is provided in accordance with an
embodiment of the measurement system, that at least one vibration
sensor is mounted in the head of the lance in the area of the at
least one supersonic nozzle, which sensor is connected by
appropriate transmission lines to the evaluation and/or process
control unit; detects and/or measures in the head of the lance,
preferably continuously, the vibration amplitude A and/or the
vibration frequency .omega. of the blowing lance during the
operation of the blowing lance, especially during a blowing
process, preferably an oxygen blowing process; and transmits,
preferably on-line, the measurement signal(s) thus acquired during
the operation of the blowing lance to the evaluation and/or process
control unit connected to the at least one vibration sensor and
thus makes them available for the purpose of controlling the
operation of the blowing lance.
[0027] By means of the vibration sensors mounted in the head of the
lance to determine the vibration amplitude A and/or the vibration
frequency .omega. of a gas blowing lance, especially an oxygen
blowing lance, it is possible to measure the amplitude and/or
frequency of the vibrations continuously and, in association with
that, to monitor the height of the slag in the converter or
metallurgical vessel. When the level of the slag is low, the
frequency spectrum is dominated by the natural harmonic vibrations
of the blowing lance. When the level of the slag is high, the lance
is enclosed by the slag. A stochastic component of the vibrations,
caused by the slag, now develops and increases. The formation of
skull on the tip of the lance also changes the mass of the lance.
The amount of adhering slag or steel can be estimated by measuring
the natural frequencies, and an early decision can be made about
replacing the lance. The measured vibration amplitudes A and/or
vibration frequencies w are also transmitted, especially in a
wireless manner and in particular by radio, to the evaluation
and/or process control unit, especially a computer, preferably a
PC, which is available to the operator for use. At least one radio
module is assigned to the associated vibration sensor or sensors
and is connected to it or to them.
[0028] According to a fourth aspect, photodiodes, photodetectors,
or light sensors, especially CCD (Charge-Coupled Device) sensors or
CMOS (Complementary Metal Oxide Semiconductors; metal-oxide
semiconductors) are arranged inside the head of the lance to
detect, in the head of the lance, the optical emissions which occur
during a blowing process upon ignition of the oxygen jets. This
makes it possible to detect in real time when an oxygen blowing
lance ignites, wherein the photodiode or the at least one optical
sensor or detector is arranged inside the blowing lance in such a
way that the optical emissions of the arcing zone caused by the
ignition of the oxygen jets can be detected by the sensor inside
the blowing lance. The measurement signals thus obtained can then
be subjected to further processing in the assigned evaluation
and/or process control unit. In this case as well, the measurement
signals and data are transmitted over a cable or wirelessly by
radio. Again, power can be supplied to the wireless optical sensor
system by means of batteries, accumulators, or an energy-harvesting
module.
[0029] The light sensors (CCD sensors, CMOS sensors) or a camera
comprising such sensors, diodes, or detectors for determining the
time when ignition occurs during the oxygen blowing process are
installed directly in the head of the lance. It is provided in this
case that one or more light sensors are arranged in the interior of
the blowing lance, preferably in the head of the lance, in order
that the exact time of ignition can be determined. The optical
emission associated with the ignition of the oxygen jets is
detected by the sensor or sensors inside the head of the blowing
lance, and the measurement signals and the associated information
thus acquired are transmitted to the evaluation and/or process
control unit, especially to a computer or PC, either in hardwired
fashion over a cable or wirelessly by radio.
[0030] To implement the above-described fourth aspect of the
invention, one embodiment of the method is characterized in that
the optical emission(s) which occur when the oxygen jets are
ignited is/are detected in the head of the lance by means of at
least one light sensor, especially a CCD or CMOS sensor, or by at
least one camera equipped with such a sensor arranged in the head
of the lance in the area of the at least one supersonic nozzle
during the operation of the blowing lance, especially during a
blowing process, preferably an oxygen blowing process. In an
embodiment of the measurement system, it is similarly provided that
at least one light sensor, especially a CCS or CMOS sensor, or at
least one camera equipped with such a sensor is arranged in the
head of the lance in the area of at least one supersonic nozzle,
which sensor or sensor-equipped camera is connected by appropriate
transmission means to the evaluation and/or process control unit;
detects and/or measures in the head of the lance the optical
emission(s) which occur when the oxygen jets ignite during the
operation of the blowing lance, especially during a blowing
process, preferably an oxygen blowing process; and transmits,
preferably, on-line, the measurement signal(s) thus obtained during
the operation of the blowing lance to the evaluation and/or process
control unit connected to the at least one light sensor, especially
a CCS or CMOS sensor, or to the at least one camera and thus makes
them available for the purpose of controlling the operation of the
blowing lance.
[0031] With the inventive embodiment according to the fourth
aspect, an accurate determination of the time of ignition can be
made; and if a sensor/detector is assigned to each supersonic
nozzle of a multi-hole blowing lance, the ignition time can also be
differentiated with respect to the individual oxygen jets.
[0032] A fifth aspect of the invention has the goal of detecting
and/or measuring the place where ignition occurs during the oxygen
blowing process. In this regard, light sensors, especially CCD or
CMOS sensors or detectors, photodiodes, or photodetectors or a
camera equipped with such components should be arranged directly in
the head of the lance, and the sensor surfaces receiving the
incident light should be aimed optically through an orifice of the
blowing lance and especially the orifice of an assigned supersonic
nozzle. The light sensors installed in this way in the head of the
lance serve to determine the place where ignition occurs during the
oxygen blowing process. When several properly aimed optical sensors
are used or when a camera is used, it is possible to determine not
only the time of ignition but therefore also, in the case of the
multi-hole blowing lances conventionally used, the places where
ignition occurs. Because, in the normal case, the head of a blowing
lance contains several supersonic nozzles, a light sensor can be
assigned to each nozzle. In this way, it becomes possible to
recognize the ignitions of the oxygen jets in a differentiated
manner, because, when an oxygen jet strikes the liquid pig iron, an
arcing zone is formed, whereas, when the arcing zone strikes scrap,
no arcing zone is formed, so that the areas detected in the case in
question will differ with respect to their optical emission(s). The
advantage of the installation in the interior of the blowing lance
is that the sighting opening of the camera or of the sensors is
continuously flushed clean by the flow of oxygen. The measurement
signals obtained can then be transmitted over a cable or by radio
to the evaluation and/or process control unit, especially a
computer or PC, and used there for the purpose of process control.
This fifth aspect of the invention therefore consists in detecting
the place where the oxygen jet ignites by installing an optical
sensor or detector inside the blowing lance in such a way that it
can detect, from inside the blowing lance, the optical emissions of
the arcing zone caused by the ignition of the oxygen jets, and thus
so that the measurement signals or data thus obtained can then be
subjected to further processing in the assigned evaluation and/or
process control unit. The data are transmitted either in hardwired
fashion over a cable or in wireless fashion by radio. In this case
as well, the power can be supplied to the wireless optical sensor
system by means of batteries, accumulators, or an energy-harvesting
module, wherein the detector(s) or sensor(s) is/are supplied with
electric power by means of a energy-harvesting module installed in
the blowing lance.
[0033] To realize this fifth aspect of the invention, the inventive
method is characterized in that the optical emissions occurring
outside the lance are detected in the head of the lance by means of
at least one light sensor, especially a CCD or CMOS sensor, or at
least one camera equipped such a sensor arranged in the head of the
lance in the area of the at least one supersonic nozzle and aimed
optically through an orifice of the blowing lance during the
operation of the blowing lance, especially during a blowing
process, preferably an oxygen blowing process.
[0034] The measurement system for realizing this fifth aspect of
the invention is characterized similarly in that at least one light
sensor, especially a CCD or CMOS sensor, or at least one
sensor-equipped camera is arranged in the head of the lance, in the
area of the at least one supersonic nozzle, which sensor or
sensor-equipped camera is optically aimed directly through an
orifice of the blowing lance; is connected in hardwired fashion to
the evaluation and/or process control unit; detects and/or
measures, in the head of the lance, the optical emissions occurring
outside the blowing lance during the operation of the blowing
lance, especially during a blowing process, preferably an oxygen
blowing process; and transmits, preferably on-line, the measurement
signal(s) thus obtained during the operation of the blowing lance
to the evaluation and/or process control unit connected to the at
least one light sensor or the at least one camera and makes them
available for the purpose of controlling the operation of the
blowing lance.
[0035] In the case of a multi-hole lance comprising several
supersonic nozzles, it is especially advisable for at least one
detector or sensor to be assigned to each supersonic nozzle or
assigned in the case of a corresponding blowing lance of the
measurement system.
[0036] According to a further elaboration of the method and of the
measurement system, one or more detectors or sensors from the group
consisting of pressure sensors, temperature sensors, vibration
sensors, and/or light sensors are assigned to the blowing lance, or
the blowing lance comprises one or more detectors or sensors from
the group consisting of pressure sensors, temperature sensors,
vibration sensors, and/or light sensors.
[0037] The transmission of the measurement data to the evaluation
unit such as a PC and the power supply to the measuring sensors or
detectors can be provided over a cable, for example. When the
blowing lance is replaced, however, the head of the lance or the
lower part of the lance is usually cut off because of wear, the
presence of skull, or damage. In the case of a hardwired power
supply, there is the danger that the cable will also be cut. A
wireless method of measurement signal and measurement data
transmission is therefore especially advantageous. This can be
done, for example, by means of radio transmission. In this case,
the sensor or detector in question can be equipped with a battery
or an energy-harvesting module to guarantee the power supply. In a
further elaboration, therefore, the inventive method is
characterized in that the measurement signal(s) originating from
the detector and/or sensor is/are transmitted to the evaluation
and/or process control unit in hardwired fashion by means of a
cable arranged in or on the blowing lance or in wireless fashion by
means of a radio module connected to the detector and/or sensor and
arranged in the blowing lance.
[0038] It is also advantageous in this case for the detector(s) or
sensor(s) to be supplied with electric power by an
energy-harvesting module arranged in the blowing lance.
[0039] In an advantageous elaboration of the invention, the
measurement system is characterized, finally, in that the
detector(s) or sensor(s) is/are connected in hardwired fashion to
the evaluation and/or process control unit by means of a cable
arranged in the blowing lance or in wireless fashion by means of a
radio module arranged in the blowing lance, wherein in particular
the detector(s) or sensor(s) connected in wireless fashion to the
evaluation and/or process control unit is/are preferably connected
to an energy-harvesting module arranged in the blowing lance.
[0040] The above-mentioned detectors and/or sensors can thus be
equipped with a wireless data and/or power transmission system
inside the blowing lance. As a result, the effort required to
install new sensors and/or detectors is less than it would be in
the case of hardwired or cabled sensors or detectors. This reduced
effort for reinstallation is especially advantageous when the
blowing lance must be cut off above the sensors because of, for
example, the presence of skull on the blowing lance, so that a new
lance part can be welded on. The sensors, designed as wireless
components in this sense, can be equipped with an energy-harvesting
source or energy-harvesting module to avoid the need to replace the
power source. A generator, for example, can serve as an energy
source in the lance, which extracts its energy from the flow of gas
or from the vibration of the lance. In cases where vibrations are
being measured and an energy-harvesting module is used, the energy
can be can be derived from the vibrations of the blowing lance.
[0041] When several properly oriented optical sensors or detectors
or a camera equipped with such sensors is used, it is possible to
determine not only the time when ignition occurs but also, in the
case of the conventional multi-hole blowing lances, the locations
where the ignitions occur. Because the head of a blowing lance
usually contains several supersonic nozzles, a corresponding light
sensor or detector can be assigned to each supersonic nozzle. In
this way, there is the possibility of detecting the ignitions of
the oxygen jets in a differentiated manner.
[0042] With the help of the evaluation and/or process control unit,
the measurement signals detected or measured or determined by the
sensors and/or detectors or the data derived from those signals can
be evaluated and used for the purpose of controlling the process
and the operation of the model on which the process is based.
[0043] The various features of novelty which characterize the
invention are pointed out with particularity in the claims annexed
to and forming a part of the disclosure. For a better understanding
of the invention, its operating advantages, specific objects
attained by its use, reference should be had to the drawings and
descriptive matter in which there are illustrated and described
preferred embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWING
[0044] In the drawing:
[0045] FIG. 1 shows a schematic cross section of a blowing lance
with an associated metallurgical vessel and gas supply;
[0046] FIG. 2 shows a schematic diagram of the area of the head of
a lance with a hardwired sensor arranged therein;
[0047] FIG. 3 shows a schematic diagram of the area of the head of
a lance with a wireless sensor installed therein; and
[0048] FIG. 4 shows a schematic diagram of a sensor system for
detecting the locations where the ignitions occur.
DETAILED DESCRIPTION OF THE INVENTION
[0049] FIG. 1 shows a blowing lance 2, especially an oxygen blowing
lance, which has been introduced from above into a metallurgical
vessel 1 designed as a converter; when in operation in the working
position shown in FIG. 1, the lance blows gas onto a metal bath 3
in the metallurgical vessel 1. At the end of the blowing lance 2
located at the bottom in the diagram of FIG. 1, a replaceable head
4 is mounted, which forms the tip of the blowing lance. Inside the
head 4 of the lance are several supersonic nozzles, which are
indicated by the dashes proceeding from the head 4 of the
lance.
[0050] Through a feed line 5 consisting of pipes or hoses, the
blowing lance 2 is connected to a gas feed station 6, which
comprises a valve station 7, by means of which the gas 8 to be
blown out from the head 4 of the lance can be supplied in regulated
fashion to the feed line 5. In the exemplary embodiment, the gas 8
is a gas used in oxygen blowing processes, that is, oxygen or an
oxygen-containing gas mixture such as an argon-oxygen gas. It is
also possible, however, to supply nitrogen or a nitrogen-containing
gas mixture to the feed line 5. When gas 8 is flowing into the feed
line 5, a pressure p.sub.vs, called the upstream pressure, can be
adjusted and automatically regulated at the valve station 7. The
pressure p.sub.vs is measured continuously during the operation of
the blowing lance 2 for process control purposes.
[0051] In the metallurgical vessel 1 or converter, a static
(back)pressure p.sub.A is present during the operation of the
blowing lance 2. The individual supersonic or Laval nozzles in the
head 4 of the lance are designed for an ideal operating point
(design point), at which the design pressure p.sub.0 and the design
temperature T.sub.0 are present at the entrance to each of the
supersonic nozzles. During the operation of the blowing lance 2,
the inlet pressures p.sub.0t and the individual inlet temperatures
T.sub.0t currently prevailing at the entrance to each of the
supersonic or Laval nozzles are continuously detected and/or
measured. Because the pressure loss .DELTA.p.sub.verl from the
valve station to the entrance area of each supersonic nozzle is
determined by the relationship .DELTA.p.sub.verl=p.sub.vs-p.sub.0t,
it is possible to perform an on-line calculation of the pressure
loss .DELTA.p.sub.verl and thus to monitor the deviation between
the inlet pressure p.sub.0t and of the inlet temperature T.sub.0t
of the oxygen supplied to the individual supersonic nozzles from
the design variables p.sub.0 and T.sub.0 during the blowing
process. In this way, the upstream pressure p.sub.vs at the valve
station 7 can be adjusted in such a way that the correct design
pressure p.sub.0 is present as the inlet pressure p.sub.0t at the
entrance to each supersonic or Laval nozzle.
[0052] The inlet pressure p.sub.0t and the inlet temperature
T.sub.0t are acquired by means of a detector or sensor 9a, 9b,
which is arranged in head 4 of the lance in such a way that it
detects and/or measures, at the entrance to all or at least one of
the supersonic nozzles assigned to it, the inlet pressure p.sub.0t
and/or the inlet temperature T.sub.0t of the gas 8 to be blown. If
a detector or sensor 9a, 9b is assigned to the entrance of each
supersonic nozzle, then the number of detectors and/or sensors 9a,
9b arranged in the head 4 of the lance will be the same as the
number of Laval or supersonic nozzles.
[0053] FIGS. 2 and 3 show schematically the arrangement of the
least one sensor or detector 9a, 9b. FIG. 2 shows a detector or
sensor 9a arranged by means of a bracket 10 in the head 4 of the
lance; the sensor or detector is connected to an evaluation and/or
control unit (not shown) by a transmission line, especially a cable
11.
[0054] In the case of the exemplary embodiment according to FIG. 3,
a detector or sensor 9b is used, which is connected to an assigned
radio module 12, by means of which the measurement signals detected
and/or measured by the detector or sensor 9b are transmitted in
wireless fashion, especially by radio, to the evaluation and/or
control unit (not shown). The radio module 12 comprises here a
power source in the form of a battery or energy-harvesting
module.
[0055] The measurement signals acquired by means of the at least
one detector or sensor 9a, 9b are transmitted continuously,
on-line, during the operation of the blowing lance 4 in the blowing
process to the connected evaluation and/or process control unit
(not shown), where they are made available for the purpose of
controlling the operation of the blowing lance 2 and then used in
fact to control the blowing process.
[0056] The at least one detector or sensor 9a, 9b is a pressure
sensor for determining the inlet pressure p.sub.0t. It is also
quite possible, however, for several detectors or sensors 9a, 9b or
multi-function detectors or sensors to be arranged in the head 4 of
the lance, these components being selected from the group
consisting of pressure sensors, temperature sensors, vibration
sensors, and/or light sensors.
[0057] Vibration sensors installed in the head 4 of the lance
detect and/or measure the vibration amplitude A and/or the
vibration frequency .omega. of the blowing lance 2.
[0058] Detectors or sensors 9a, 9b designed as light sensors detect
the optical emissions caused by the ignition of oxygen jets as the
oxygen is being blown into the vessel. The light sensors can be CCD
sensors, CMOS sensors, photodiodes, photodetectors, or cameras
equipped with these sensors or detectors. In the head 4 of the
lance, they detect the radiation or optical emission occurring when
an oxygen jet ignites; or they detect, in the head 4 of the lance,
the change in the radiation intensity or in the optical emissions
occurring when an oxygen jet ignites. The individual detector or
sensor 9a, 9b designed in the form of a light sensor can also be
equipped and aimed in such a way that, as indicated schematically
in FIG. 4, it can detect or recognize the location where the
ignition occurs, i.e. the ignition spot 13. In cases where at least
one, preferably several, aimed optical sensors 9a, 9b are used or
when a camera is used as an optical sensor system, it is possible
to determine not only the time when ignition occurs but also, in
the case of conventionally used multi-orifice blowing lance, the
ignition spot 13. Here, use is made of the effect that, when an
oxygen jet 8b emerging from the head 4 of the lance strikes the
metal bath 3 in the metallurgical vessel 1, an arcing zone is
formed upon ignition of the oxygen jet 8b at the ignition spot 13,
whereas, when an oxygen jet 8a strikes scrap 14 present in the
metal bath 3, an arcing zone is not formed. The point of contact of
the oxygen jet 8b therefore shows a different radiation intensity
and thus optical emission than the contact point of the oxygen jet
8a. Advantage can be taken of this effect to detect the arcing zone
and thus the ignition spot 13.
[0059] While specific embodiments of the invention have been shown
and described in detail to illustrate the inventive principles, it
will be understood that the invention may be embodied otherwise
without departing from such principles.
* * * * *