U.S. patent application number 10/576735 was filed with the patent office on 2007-06-14 for process for keeping a tuyere passing through a metallurgical vessel free of a skull.
Invention is credited to Christoph Carlhoff, Rolf Lamm, Wilhelm Merkens.
Application Number | 20070132161 10/576735 |
Document ID | / |
Family ID | 32404019 |
Filed Date | 2007-06-14 |
United States Patent
Application |
20070132161 |
Kind Code |
A1 |
Carlhoff; Christoph ; et
al. |
June 14, 2007 |
Process for keeping a tuyere passing through a metallurgical vessel
free of a skull
Abstract
The present invention relates to a process for keeping a tuyere
passing through a metallurgical vessel free of a skull by
intermittendly passing an oxygen-containing gas through the tuyere
to dissolve the skull, wherein it is determined that an interval
for passing said oxygen-containing gas through the tuyere needs to
be started by detecting electromagnetic radiation emanating from a
spot in the interior of the melt by means of a dual wavelength
pyrometer and comparing the intensity of the pyrometer signals with
the ratio of the pyrometer signals, and initiating said interval
for passing said oxygen-containing gas through the tuyere, upon the
condition that the combined intensity of the signals falls below a
predetermined threshold value and that the ratio of the signals
remains substantially constant.
Inventors: |
Carlhoff; Christoph;
(Willich, DE) ; Merkens; Wilhelm; (Hueckelhoven,
DE) ; Lamm; Rolf; (Aachen, DE) |
Correspondence
Address: |
George H Fairchild;Minerals Technologies Inc.
1 Highland Avenue
Bethlehem
PA
18017-9482
US
|
Family ID: |
32404019 |
Appl. No.: |
10/576735 |
Filed: |
November 5, 2003 |
PCT Filed: |
November 5, 2003 |
PCT NO: |
PCT/EP03/12349 |
371 Date: |
October 10, 2006 |
Current U.S.
Class: |
266/265 ;
266/47 |
Current CPC
Class: |
G01J 5/08 20130101; F27D
21/02 20130101; G01J 5/084 20130101; G01J 5/0809 20130101; G01J
5/0859 20130101; G01J 5/60 20130101; G01J 5/02 20130101; G01J 5/089
20130101; G01J 5/0818 20130101; G01J 5/0846 20130101; G01J 5/004
20130101; C21C 5/4673 20130101; F27D 19/00 20130101; G01J 5/029
20130101; G01J 5/0806 20130101; C21C 5/48 20130101 |
Class at
Publication: |
266/265 ;
266/047 |
International
Class: |
C21B 7/16 20060101
C21B007/16 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 19, 2002 |
DE |
10259830.4 |
Claims
1. A method of keeping a tuyere passing through a metallurgical
vessel free of a skull, the method comprising intermittently
passing an oxygen-containing gas through the tuyere to dissolve the
skull, wherein it is determined that an interval for passing said
oxygen-containing gas through the tuyere needs to be started by
detecting electromagnetic radiation emanating from a spot in the
interior of the melt by means of a dual wavelength pyrometer and
comparing the intensity of the pyrometer signals with the ratio of
the pyrometer signals, and initiating said interval for passing
said oxygen-containing gas through the tuyere, upon the condition
that the combined intensity of the signals falls below a
predetermined threshold value and that the ratio of the signals
remains substantially constant.
2. The method of claim 1 wherein said threshold value is determined
by using a video camera which is arranged with the pyrometer along
one optical path and by setting into relation the intensity of the
pyrometer signal with the image of the video camera, deciding on
the basis of the video image whether a status of clogging is
reached and determining the corresponding intensity value of the
combined pyrometer signals.
3. A method of measuring electromagnetic radiation emanating from
the interior of a metallurgical vessel, the method comprising
adjusting the optical axis of a measuring unit including a video
detector and an instrument for measuring the electromagnetic
radiation through a tuyere having a first end facing the interior
of the metallurgical vessel and a second end facing the instrument,
wherein said measuring unit is arranged along an optical path, and
the adjustment is carried out on the basis of the video image by
varying the orientation of the measuring unit such that the first
end and second end in the video image form concentric circles.
4. The method of claim 3 wherein said instrument for measuring
electromagnetic radiation is a pyrometer.
5. The method of claim 3 wherein said instrument for measuring
electromagnetic radiation is a spectrometer.
6. A method for measuring the length of a tuyere passing through a
metallurgical vessel having a first end facing the interior of said
metallurgical vessel and a second end facing the exterior of said
metallurgical vessel by means of an autofocus video camera, wherein
the lens system of the autofocus video camera is adjusted so that
the first end of the tuyere facing the interior of said
metallurgical vessel is in focus and the length of said tuyere is
determined on the basis of the distance of the focus and the known
position of said second end of the tuyere with respect to the
camera.
7. An apparatus for carrying out the method of claim 1, the
apparatus comprising: (a) a dual wavelength pyrometer, (b) an
autofocus video camera which is aligned with said dual wavelength
pyrometer along one optical path, and (c) means for varying the
orientation of the optical path.
8. The apparatus of claim 7 further comprising a laser device
suitable for creating a plasma in the interior of said
metallurgical vessel, and wherein the further detector is a
spectrometer capable of detecting electromagnetic radiation
emanating from said plasma.
9. The apparatus of claim 7 which is connected to the interior of
said metallurgical vessel by means of a tube which is passed
through the tuyere.
10. The apparatus of claim 7, further comprising: (d) a further
detector for measuring electromagnetic radiation emanating from the
interior of the vessel.
11. An apparatus for carrying out the method of claim 3, the
apparatus comprising: (a) a dual wavelength pyrometer, (b) an
autofocus video camera which is aligned with said dual wavelength
pyrometer along one optical path, and (c) means for varying the
orientation of the optical path.
12. The apparatus of claim 11 further comprising a laser device
suitable for creating a plasma in the interior of said
metallurgical vessel, and wherein the further detector is a
spectrometer capable of detecting electromagnetic radiation
emanating from said plasma.
13. The apparatus of claim 11 which is connected to the interior of
said metallurgical vessel by means of a tube which is passed
through the tuyere.
14. The apparatus of claim 11, further comprising: (d) a further
detector for measuring electromagnetic radiation emanating from the
interior of the vessel.
15. An apparatus for carrying out the method of claim 6, the
apparatus comprising: (a) a dual wavelength pyrometer, (b) an
autofocus video camera which is aligned with said dual wavelength
pyrometer along one optical path, and (c) means for varying the
orientation of the optical path.
16. The apparatus of claim 15 further comprising a laser device
suitable for creating a plasma in the interior of said
metallurgical vessel, and wherein the further detector is a
spectrometer capable of detecting electromagnetic radiation
emanating from said plasma.
17. The apparatus of claim 15 which is connected to the interior of
said metallurgical vessel by means of a tube which is passed
through the tuyere.
18. The apparatus of claim 15, further comprising: (d) a further
detector for measuring electromagnetic radiation emanating from the
interior of the vessel.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to a process for the keeping free a
tuyere passing through a metallurgical vessel of a skull by
intermittendly passing an oxygen-containing gas through the tuyere
to dissolve the skull.
[0002] A common method to measure the temperature of molten metal
in a container, such as e.g. a metallurgical vessel, is by means of
a pyrometer. Normally, a non-contacting type radiation pyrometer is
arranged at the end of a nozzle base which is part of a gas blowing
tuyere. The tuyere is arranged at the bottom or at the side wall of
the metallurgical vessel. The pyrometer can also be arranged at one
end of a measuring channel introduced into the melt from the top of
the metallurgical vessel. Such arrangements are e.g. disclosed in
DE-OS 964 991, DE-A-4 025 909, EP-A-0 362 577, U.S. Pat. No.
3,161,499, EP-A-0 162 949, DE-OS-2 438 142, U.S. Pat. No. 4,400,097
and JP-A-62 207 814.
[0003] Generally non-reactive gas is blown through the tuyere into
the inside of the melt to keep its opening free. Nevertheless,
skulls may build up in the measuring channel since metal freezes at
the outlet of the tuyere so that the measuring channel is clogged
from time to time. The frozen metal at the outlet of the tuyere may
be dissolved by means of blowing oxygen through the channel. In
this way the clogging of the tuyere may be prevented. However,
oxygen distorts the measured values considerably and promotes wear
of the measuring channel. Therefore, oxygen must be blown
intermittendly through the channel.
SUMMARY OF THE INVENTION
[0004] The object has been solved by a process for keeping a tuyere
passing through a metallurgical vessel free of a skull by
intermittendly passing an oxygen-containing gas through the tuyere
to dissolve the skull, wherein it is determined that an interval
for passing the oxygen-containing gas through the tuyere needs to
be started by detecting electromagnetic radiation emanating from a
spot in the interior of the melt by means of a dual wavelength
pyrometer and comparing the intensity of the pyrometer signals with
the ratio of the pyrometer signals, and initiating the interval for
passing the oxygen-containing gas through the tuyere, upon the
condition that the combined intensity of the signals falls below a
predetermined threshold value and that the ratio of the signals
remains substantially constant. Preferably the threshold value is
determined by using a video camera which is arranged with the
pyrometer along one optical path and by setting into relation the
intensity of the pyrometer signal with the image of the video
camera, deciding on the basis of the video image whether a status
of clogging is reached and determining the corresponding intensity
value of the combined pyrometer signals.
[0005] Another object has been solved by providing an apparatus
which includes: [0006] (a) a dual wavelength pyrometer, [0007] (b)
an autofocus video camera which is aligned with the dual wavelength
pyrometer along one optical path, [0008] (c) means for varying the
orientation of the optical path, and [0009] (d) optionally a
further detector for measuring electromagnetic radiation emanating
from the interior of the vessel.
[0010] Preferably the apparatus further includes a laser device
suitable for creating a plasma in the interior of the metallurgical
vessel, and wherein the further detector is a spectrometer capable
of detecting electromagnetic radiation emanating from the plasma.
More preferably, the apparatus is connected to the interior of the
metallurgical vessel by means of a tube which is passed through the
tuyere.
DETAILED DESCRIPTION OF THE INVENTION
[0011] FIG. 1 shows a preferred configuration of the apparatus of
the present invention. The apparatus 1 is connected to a container
2 such as a metallurgical vessel containing a melt, preferably a
molten metal. The container 2 is preferably a converter. A blowing
lance may be inserted into the melt from the top for blowing oxygen
into the melt, thereby converting iron into steel. Alternatively,
the oxygen many be blown into the converter through tuyeres at the
bottom and/or side walls of the container 2. The apparatus 1 is
connected to the inner side of the container 2 via a tuyere. The
tuyere forms a measuring channel A through which electromagnetic
radiation emitted from the inner side of the container may pass.
The tuyere has one end facing the interior of the container. The
second end of measuring channel 2 faces a first measuring unit 3
which preferably includes a dual wavelength pyrometer and a video
camera. Preferably a spectrometer 4 and a laser generating unit 5
are also connected to the measuring channel. Most preferably data
processing devices 6 are connected to the measuring unit 3.
[0012] FIG. 2 schematically shows a detailed cross sectional and
bottom views of the measuring channel (which indicated as A in FIG.
1). Electromagnetic radiation may pass unhindered through the
unobstructed measuring channel 7, as schematically shown in the
bottom view 8. Once clogging occurs at the top of measuring channel
9, the passage of electromagnetic radiation is hindered, as
schematically shown in bottom view 9. Measuring unit 3 can not
anymore detect the intensity of electromagnetic radiation of the
whole area of the channel.
[0013] FIG. 3 shows in detail, how the measuring channel (indicated
as A in FIG. 1) can be formed. Preferably a set of two concentric
tubes is used. The measuring channel preferably includes an outer
tube 11 and an inner tube 12 such that different gases or gas
mixtures can blown into the container. For example a gas stream 13
comprising nitrogen-gas and/or argon, and methane may be passed
through the inner tube 12, whereas a gas stream comprising
nitrogen-gas and/or argon, and oxygen may be passed through the
outer tube. Inner tube 12 also forms the measuring channel. Thereby
oxygen cannot affect measuring.
[0014] FIG. 4 schematically shows a preferred embodiment of
measuring unit 3 (FIG. 1). It includes an adjustable lens 15, two
adjustable mirrors in combination with two pyrometer detectors 16,
17 and a detector 18 for collecting a video signal. Adjustable lens
15 is preferably an autofocus lens and driven by a motor (not
shown).
[0015] The process for determining the interval for passing the
oxygen-containing gas through the tuyere is started by detecting
electromagnetic radiation emanating from a spot in the interior of
the melt by means of a dual wavelength pyrometer and comparing the
intensity of the pyrometer signals with the ratio of the pyrometer
signals. The interval for passing the oxygen-containing gas through
the tuyere is initiated upon the condition that the combined
intensity of the signals falls below a predetermined threshold
value and that the ratio of the signals remains substantially
constant. The threshold value needs to be pre-determined only once
visually on the basis of the image of the video signal. On the
basis of the image it is decided whether the status of clogging is
reached, and the corresponding intensity of the combined pyrometer
signals is determined. This threshold value is then used for
automatic initiation of the interval for passing the
oxygen-containing gas through the tuyere.
[0016] The concept that resides in the use of a dual wavelength
pyrometer instead of a standard pyrometer. In addition to the
information about the intensity of each of the two wavelengths that
are measured, a quotient of two wavelengths can be calculated. This
creates additional information, which can be used to determine the
point in time at which oxygen has to be blown through the measuring
tuyere. If only the intensity of one wavelength is measured it is
not possible to decide whether the change in the intensity is
caused by a change of the temperature of the melt or because a
skull is being formed at the end of the tuyere. By measuring the
intensities of two wavelengths and correlating them with each
other, e.g. by forming the quotient of both values, information can
be obtained about the reason of such a change. For example, if the
values of the measured intensities both fall but the quotient of
these values is about constant, it can be assumed, that the tuyere
is being clogged by a skull, whereas, e.g., in case the values of
the measured intensities both fall but the ratio of both
intensities is changing, it can be assumed, that the temperature of
the melt is changing.
[0017] Therefore it is an advantage of the process according to the
present invention, that oxygen is not unnecessarily blown through
the measuring channel only because the intensity of the pyrometer
signal falls below a predetermined threshold value.
[0018] It has surprisingly turned out that with such embodiment it
is also possible to adjust the optical axis of the instrument for
measuring electromagnetic radiation, such as the pyrometer and the
spectrometer.
[0019] To adjust the one or more measuring devices, with a dual
wavelength pyrometer and/or a spectrometer being preferred,
its/their optical axis/axes is/are moved until the near end of the
measuring channel and the perspective image of its far end is
depicted in a regular fashion according to the geometry of the
measuring channel, e.g. a regular tubular measuring channel will
result in a circular image. This adjustment is preferably performed
using the video camera. For this purpose the video camera and the
instrument for measuring electromagnetic radiation are arranged
along one optical path.
[0020] The adjustment is carried out on the basis of the video
image by varying the orientation of the instrument(s) and the video
camera such that the first end and second end in the video image
form concentric circles is another object of the present
invention.
[0021] The optimal position of the measuring device(s), i.e. the
dual wavelength pyrometer and/or the spectrometer is reached when
the geometries of both ends of the measuring channel depict
concentric images, i.e. in case of the above mentioned (as an
example) tubular measuring channel concentric circles would have to
be obtained. To visualize the "near end" of the measuring channel,
i.e. the end of the measuring channel that is directed to the
measuring device(s) and the camera, it is advisable to use an
auxiliary source of light.
[0022] It has surprisingly been found out that with the present
configuration it is also possible to measure the length of the
tuyere passing through the metallurgical vessel 3. This information
is important because it is an indication of the wear of the lining
of the container. The information is also needed for focussing the
laser beam.
[0023] For this purpose, the lens system of the autofocus video
camera is adjusted so that the first end of the tuyere facing the
interior of the metallurgical vessel is in focus. The length of the
tuyere is determined on the basis of the distance of the focus and
the known position of the second end of the tuyere with respect to
the camera.
[0024] With this information, the laser beam can be focussed in
such a way, that a intensity that is sufficient to form a plasma,
the radiation of which can be detected by the spectrometer, is only
present at the surface of the melt to be analyzed or inside the
melt, but is not inside the gas cavity formed by the gas blowing
through the measuring channel.
* * * * *