01 VAI CON® Temp und VAI CON®Chem

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VAI-CON® Temp und VAI-CON®Chem– „New Dimensions in 
Continuous and Contactless Measurement“0) 
 
 
 
Authors: 
 
Dr. N. Ramaseder 1) 
DI. J. Steins 1) 
DI. M. Hiebler 1) 
Dr. W. Meyer 2) 
DI. J. Hochörtler 2) 
Dr. J. Schwelberger 3) 
 
 
Abstract 
 
VAI has developed and tested an innovative continuous temperature and analysis system for 
metallurgical vessels with the tradenames VAI-CON® Temp and VAI-CON®Chem. These new 
systems offer a potential for improved process control in steelmaking. They were tested in 
the laboratory and proved its functionality in industrial applications. VAI-CON® Temp offers 
accurate temperature measurements and VAI-CON® Chem provides the chemical analysis 
results for chosen elements during the entire treatment time.Both systems together replace 
the traditional discontinuous temperature measurement techniques and sampling. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
0) 33 º Seminário de Fusão da ABM - Associação Brasileira de Metalurgia e Materiais- De 
 06 a 08 de maio de 2002 - Santos, SP. 
1) VOEST ALPINE Industrieanlagenbau, Linz, Austria 
2) BÖHLER-EDELSTAHL Kapfenberg, Austria 
3) VOEST ALPINE Industria, Belo Horizonte, Brazil
 
VAI-CON® Temp and 
VAI-CON® Chem 
- 2 - 18/4/2002 
 
 
1. Introduction 
 
Already in the late 1960‘ies VAI started with research and development activities for new 
methods for sampling and temperature measurements in metallurgical vessels. A prototype 
of an immersion lance was installed in the LD Steelplant No. 3 at bei VOEST-ALPINE Stahl 
Linz in 1981. Later followed the development of the Slantec-System, a slanted lance system 
vor small converters. Both systems for temperature and sampling are discontinuous and 
require analysis of the sample in the laboratory. 
 
Bases on the known technologies for immersion lances for metallurgical plants and the 
availability for high temperature detectors in 1997 VAI together with VOEST-ALPINE Stahl 
Linz started tests to develop a continuous temperature measuring system. This system was 
was later installed on a 65 t KMS converter at Neue Maxhütte, AOD converters at 
ACCIAIERIE VALBRUNA and KRUPP-THYSSEN-NIROSTA, a vacuum degassing plant at 
BÖHLER-EDELSTAHL, Kapfenberg and also on one LD-converter at VOEST-ALPINE Stahl 
Linz. 
 
In close cooperation with the University of Linz, VAI developed a system for the continuous 
measurement of the chemical composition of steel melts. In December 1998 laboratory tests 
were started on solid and liquid steel samples. By adding alloying elements, the steel 
composition was changed and the analysis of the melt was monitored continuously. 
Consequentlz, a prototype for industrial applications was built and after laboratory tests it 
was installed at the vacuum degassing plant at BÖHLER-EDELSTAHL (see fig. 1). 
 
Due to the good results for both the temperature and chemical analysis systems, these are 
now on the market under the tradenames VAI-CON® Temp and VAI-CON® Chem, 
respectively. 
 
 
 
 
Fig. 1: VAI-CON®Chem Equipment mounted on cover of degassing plant 
 
 
 
 
VAI-CON® Temp and 
VAI-CON® Chem 
- 3 - 18/4/2002 
 
 
2. Description of VAI-CON® Temp and VAI-CON® Chem 
 
The systems are mainly characterized by the following features: 
 
♦ Continuous and contactless measurement of the emitted radiation, in case of VAI-CON® 
Temp the infrared radiation and in case of VAI-CON® Chem the plasma induced 
radiation 
♦ Use of submerged tuyeres and gas purged windos for visual access of the steel bath 
♦ Location of measurement equipment outside the hot area of the production untis 
♦ Injection of CnHm-gas or inert gas through an anular gap of the measuring 
♦ Easy installation of the measureing equipment 
 
The main advantage of the VAI-CON® Temp system is the continuous measurement of the 
steel temperature without interruption of the process. Additionally, information about slag and 
refractory temperatures can be obtained. VAI-CON®Chem provides continuous information 
on the chemical analysis of the steel and slag without process interruptions. 
 
 
2.1 VAI-CON® Temp Measurement System 
 
The VAI-CON® Temp system mainly consists of the following components: 
 
♦ Measuring tuyere 
♦ Lens system 
♦ Safety glass 
♦ Detector 
♦ Adapter with protective housing 
♦ Fiber optic cable 
♦ Data Processor 
♦ Cooling box 
♦ Evaluation Unit 
♦ Process computer 
 
Fig. 2 shows a schematic overview of the temperature measuring system. 
 
N2, Ar
N2, Ar
Lens System
Detector
Adapter
Tuyere
Protective skull
 
Fig. 2 Schematic overview of the temperature measuring system 
 
VAI-CON® Temp and 
VAI-CON® Chem 
 
 
 
In order to measure the temperature continously, inertgas is injected into the steel melt. The 
pulsating cavity formed by the injection in the steel melt emits temperature radiation mainly in 
the infrared which are transmitted throught the measuring tuyere a cussed with a 
special lens on the detector. The signal from the detector is processed and give temperature 
values which are continuoulsy measured and stored, available immediately for process 
control. In other gas than inert gas is used, such as oxygen or air, or even solids, the 
measured temperature does not correspond to the average steel temperature, but the 
reaction temperature in front of the tuyere opening. 
 
 
2.2 VAI-CON® Chem System 
 
The VAI-CON® Chem system mainly consists of the following components: 
 
♦ Submerged measure
♦ Lens and mirror syst
♦ Beam guiding system
♦ Spectrometer 
♦ Laser 
♦ Calibration laser 
♦ camera 
♦ cooled protective ho
♦ Evaluation computer
 
Fig. 3 shows a schematic
 
A pulsed Nd:YAG – las
system of lenses and m
consists of the line rad
radiation spectrum. This 
the entrance of the sp
measureing the line inte
relative intensity of the lin
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Fig. 3: Schema
m
 
Sam
(sol
- 4 - 
ing/process tuyere or gas purged window 
em 
 
using 
 
 overview of the VAI-CON® Chem measuring s
er beam (1064 nm) is focussed onto the sa
irrors and forms a plasma. The radiation emit
iation of the excited atoms and molecules a
radiation is transmitted via a special lens and m
ectrometer. The composition of the sample
nsities of the emission lines of the elements 
es is related directly to the concentration of the
tic overview of the VAI-CON® Chem measuri
Nd:YAG LASER
Lens system 
mirror 
irror 
Fiber optic calbe 
Spektrometer 
Dple 
id/liquid) 
nd fo
18/4/2002 
ystem. 
mple surface with a 
ted from the plasma 
nd a broad thermal 
irror arrangement to 
s is determined bz 
to be analysed. The 
 elements. 
ng system 
etector
 
VAI-CON® Temp and 
VAI-CON® Chem 
- 5 - 18/4/2002 
 
 
VAI-CON® Chem uses the same principle of the tuyere with inert gas injection as the VAI-
CON® Temp system. The steel composition is measured through a submerged tuyere with 
laser induced plasma spectroscopy. The light emitted from the plasma and steel surface is 
focussed on the entrance of the spectrometer. The signal from the spectrometer is 
processed with a software that continuously evaluates the concentration of selected 
elements. The current measuring data (temperature and chemical composition) is displayed 
and stored for later evaluation. 
 
 
 
3. Operational Experience 
 
After first tests in the laboratory on induction furnaces, the concepts were developed into 
prototypes for industrial application. The results of the industrial application tests is described 
below. 
 
 
3.1 Application of VAI-CON® Temp on a KMS-KonverterIn 1997 the VAI-CON® Temp system was used to measure the temperature in one of the 
KMS converters of the steelplant Neue Maxhütte. The KMS converter uses bottom tuyeres 
for oxygen blowing and solid injection. One of these process tuyeres was used fort he 
installation of the VAI-CON® Temp measurement. The results of the continuous VAI-CON® 
Temp measurement was compared with the result of the manual measuring lances in a 
range between 1.570 °C und 1.710 °C. Because during the process phase oxygen was 
blown throught the measuring tuyere, the steel bath temperature could only be measured 
after the end of the oxygen blow, during nitrogen injection. This measurement was done 
approximately 0.5 to 3 minutes before the manual measurement. 
 
A comparison of the results shows that the absolute temperature difference between the 
manual and the VAI-CON® temperature measurements is generally less than 10 °C and the 
standard deviation between the measurements only 5,8 °C. The results are shown in fig. 4. 
 
 
-15
-10
-5
0
5
10
15
0 1 0 2 0 3 0 40 50
Heats
∆∆ ∆∆
T=
T V
AI
-C
O
N®
 T
em
p 
- T
m
an
ue
ll
Steel Temperature Comparison
∆∆∆∆ T = TVAI-CON® Temp - Tmanual
[°
C
]
 
Fig. 4: Temperature difference [∆∆∆∆T] of VAI-CON® Temp and manual measurements 
 
 
 
VAI-CON® Temp and 
VAI-CON® Chem 
- 6 - 18/4/2002 
 
 
3.2 Application of VAI-CON® Temp on an AOD-Konverter 
 
The VAI-CON® Temp system was also successfully installed and tested on AOD-converters 
at ACCIAIERIE VALBRUNA in Italy and at KTN in Germany. Continuous temperature 
measurements were made in both plants for a whole converter campaign. The equipment 
installed is shown in fig. 5. 
 
 
 
Fig. 5: Installation of VAI-CON® Temp on an AOD-converter 
 
During the test campaign the VAI-CON® Temp system was installed directly on an existing 
AOD process tuyere. The temperature of the steel bath was measured continuously, starting 
with the injection of a mixture of oxygen and inert gas and during the end of the heat with the 
injection of inert gas. During the oxygen injection phase , the temperature measured in front 
of the tuyere was in the range between 2000 to 2700°C, corresponding to the reaction 
temperature in front of the tuyere. In the phase when inert gas was injected, the temperature 
of the steel bath was measured in the range between 1.600 to 1.780 °C corresponding to the 
average temperature of the steel bath. Occasional skul formation on the tuyere obstructed 
the direct view throught the tuyere on the steel bath (see fig. 6). 
 
 
Tuyere Open Tuyere Closed
A B
 
Fig. 6: View through open (a) and partially closed (b) tuyere 
 
 
VAI-CON® Temp and 
VAI-CON® Chem 
- 7 - 18/4/2002 
 
In fig. 7 a comparison of the results of the VAI-CON® Temp mesurements and the manual 
measurements are shown. The high temperature values correspond to oxygen injection 
through the tuyere, and during the abrupt interruptions of the oxygen blow injert gas was 
injeted and the steel bath temperature could be measured. The difference between VAI-
CON® Temp and manual measurements is generally below 10 °C, and the standard 
deviation between the measurements is 7 °C. Deviations of more than 10 °C can be 
explained by the fact that the manual measurement was was taken in a colder region on the 
surface or near the refractory lining. 
 
 
!Manual Measurement
! ! ! !
1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
00
:0
2:
15
00
:0
6:
59
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:1
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38
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48
00
:2
8:
40
00
:2
9:
54
Time
Te
m
pe
ra
tu
re
 [°
C
]
 
Fig.7 : Continuous VAI-CON® Temp measurement during an AOD Heat at ACCIAIERIE 
VALBRUNA, Italy 
 
 
3.3 Application of VAI-CON® Temp on an LD-Converter 
 
During various converter campaigns, VAI-CON® Temp was installed to measure the steel 
bath temperature continuously. Initially, a single pipe tuyere was used. Due to frequent 
closing of the tuyere, oxygen or air was used to open the tuyere for the measurements. This 
caused a more rapid refractory erosion near the tuyere with a tuyere life of 300 to 500 heats. 
Therefore a double pipe tuyere with an anular gap was used. The results of the VAI-CON® 
Temp measurements and the manual or sublance measurements agree with small 
deviations. 
 Fig. 8 shows the measurements with VAI-CON® Temp during a typical heat of the LD 
converter. 
 
VAI-CON® Temp and 
VAI-CON® Chem 
- 8 - 18/4/2002 
 
1000
1100
1200
1300
1400
1500
1600
1700
1800
08
:4
5
08
:4
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:4
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:1
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:1
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:1
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:1
5
 
 
Time
Tapping
Charging
Oxygen Blow Tuyere outside steel bath
Slag Temperature
Te
m
pe
ra
tu
re
 [o
C
]
 
Fig. 8: Continuous VAI-CON® Temp-Messungen during an LD converter 
heat, VOEST-ALPINE Stahl Linz 
 
 
3.4 VAI-CON® Temp-Measurements on a vacuum degassing plant 
 
Continuous temperature measurements with VAI-CON® Temp were also made on a vacuum 
degassing plant in the steel plant of BÖHLER-EDELSTAHL in Kapfenberg. The VAI-CON® 
Temp equipment was installed on the cover of vacuum vessel in order to continuously 
measure the steel temperature. The equipment was mounted in a position and angle to view 
the bubbling spot which offers a direcg view of the steel bath. The comparison between VAI-
CON® Temp and manual thermocouple measurements showed a deviation of less than 5 °C. 
 
 
 
3.5 Application of VAI-CON® Chem on a vacuum degassing plant 
 
In spite of difficult measurement conditions in the vauum degassing tank the evaluation of the 
spectra for the elements Chrome and Manganese was satisfactory. For other elements (e.g. 
Carbon) the resolution of the spectrometer was too low to make an accurate analysis 
because the spectral lines of the element were overlapping. Further, the varying freeboard 
and the movement of the steel bath in the bubbling spot have a negative influence on the 
measurements. A consequence of these influences together with the fractions of slag was a 
varying laser intensity on the steel bath surface. When using an immersion lance or a 
submerged tuyere, these variations are eliminated because the distance between the 
focussing mirror and the steel bath are is constant and a mixture of slag and steel is avoided. 
 
Cr-content 
 
Fig. 11shows the comparison of the chrome content of the VAI-CON®Chem measurement 
and the laboratory analysis for 12 consecutive heats. For the evaluation, the relative intensity 
of the chrome 435,5 nm spectral line and the 440,45 nm iron line were used. The error bars 
show the deviation for the single measurements. With a chrome contents of 1,4% – 2,0% the 
maximum deviation from the laboratory result is less than 0,3%. The reason for this deviation 
is the presence of peaks of other elements near the Cr peak. With a spectrometer with higher 
resolution, this deviation can be minimized. 
 
VAI-CON® Temp and 
VAI-CON® Chem 
- 9 - 18/4/2002 
 
0 2 4 6 8 10 12 14 16
0,0
0,2
0,4
0,6
0,8
1,0
1,2
Chrom
I C
r /
 I F
e 
[ 1
 ]
Cr-Gehalt [ % ]
430 432 434 436 438 440
0
2
4
6
8 Fe 440,54nm
Cr 434,5nm
 
 
In
te
ns
itä
t
Wellenlänge[ nm ]
 
Fig.9: Comparison of the Cr content of the VAI-CON®Chem and laboratory analysis on 
the VD-plant at Böhler Kapfenberg 
 
 
Mn-content 
Fig. 10 shows the comparison of the Mn content of the VAI-CON®Chem analysis measured 
directly on the VD plant and the subsequent laboratory analysis for 24 consecutive heats. For 
the comparison, the relative intensity of the 323,07 Mn line and the 322,19 iron line was 
plotted. The error bars show the deviation of the single measurements. At a Mn content of 
1,5% the maximum devation to the laboratory result was 0,12 %. 
0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6
0,4
0,6
0,8
1,0
1,2
1,4
1,6
1,8
2,0
Mangan
 
 
I M
n /
 I F
e 
[ 1
 ]
Mn-Gehalt [ % ]
320 322 324 326
0
2
4
6
8
Fe 322,19nm
Mn 323,07nm
 
 
In
te
ns
itä
t
Wellenlänge [ nm ]
 
Fig. 10: Comparison of the Mn content of the VAI-CON®Chem and laboratory analysis 
on the VD-plant at Böhler Kapfenberg 
 
 
Transition Slag - Steel 
 
Fig. 11 shows a typical transition at the start of bubbling, where slag changes over to steel. 
The spectrum is shown as a function of time in the range 315 to 330 nm. In the range 
between 315 and 320 nm strong Ca lines are appear and in the range of 320 to 325 nm 
strong iron lines are predominant (steel bath). The iron lines appear only after some time due 
to the development of the bubbling spot and the disappearance of the slag in the observed 
region. 
 
VAI-CON® Temp and 
VAI-CON® Chem 
- 10 - 18/4/2002 
 
315 320 325 330
0
2
4
6
8
5
4
3
2
1
Wellenlänge [ nm ] Z
eit
 (c
hr
on
olo
gis
ch
, a
be
r I
nt
er
va
ll v
ar
iab
el)
In
te
ns
itä
t
 
Fig 11: Spectra of a stainless steel as a function of time in a vacuum degassing plant 
(Böhler Edelstahl; Kapfenberg) 
 
 
4. Summary of Advantages 
 
Tests in the laboratory and application of VAI-CON® Temp on KMS-, AOD-, LD- and vacuum 
degassing plants and VAI-CON®Chem on a vacuum degassing plant show various 
advantages of the systems compared to traditional measuring systems: 
 
♦ The chemical analysis and temperature of the steel bath is measured continuously 
which offers the possibility for improved process control 
♦ The deviations from the laboratory results and from the manual or sublance 
measurements are small 
♦ Tapto tap times can be reduced because no process interruption is necessary for the 
measurements 
♦ No reblow is necessary because the temperature is available continuously 
♦ Improved safety in the working place 
♦ Low operation and maintenance costs 
♦ Installation of the system is possible during the regular maintenance periods 
♦ Reproducible temperature and analysis results because the measurements are always 
made on the same place in the same way 
 
 
Conclusion 
 
The continuous temperature (VAI-CON® Temp) and chemical anlysis (VAI-CON® Chem) 
systems developed by VAI were tested in various industrial applications. The systems are 
based on optical measurements of the emitted radiation. The access to the clean steel 
surface can be obtained through existing process tuyeres or special measuring tuyeres. Also 
immersion lances or bubbling spots can be used for optical observation. 
 
In principle, the systems can be applied in all metallurgical untis including LD-, OBM- and 
AOD- converters, electric arc furnaces, hot metal ladles, secondary metallurgy units such as 
ladle furnace, chemical heating and vacuum plants and tundishes. 
Because of its compact size both the VAI-CON® Temp as well as VAI-CON®Chem systems 
can be installed easily and quickly in existing metallurgical vessels without major 
modifications with the sensitive equipment outside the hot zone. A significant advantage 
 
VAI-CON® Temp and 
VAI-CON® Chem 
- 11 - 18/4/2002 
 
compared to traditional methods is the continuous measurement during the whole process 
phase. The systems therefore offer a complete dynamical process control. 
 
 
Acknowledgements 
 
VAI would like to thank VOEST-ALPINE Stahl Linz, Neue Maxhütte (Germany), KRUPP-
THYSSEN-NIROSTA (Germany) and ACCIAIERIE VALBRUNA (Italy) for the possiblity of 
industrial tests of VAI-CON® Temp and BÖHLER-EDELSTAHL GmbH&Co KG for the 
possiblity of industrial tests of VAI-CON®Chem. Special thanks to the Johannes-Kepler-
University for the excellent colaboration for the development and optimization of the new 
continuous analysis system. Further, we want to thank the FFF- Austria for the financial 
support for the development of this measuring system. 
 
 
References 
 
1) K. Primas, F. Kostersitz, A. Patuzzi, Ch. Coessens; Einsatz von Sublanze und 
Prozessmodellen bei der VOEST-ALPINE, Stahl und Eisen 105 (1985), pp. 1081–1085. 
2) N. Ramaseder, W. Pirklbauer, J. Kalisch; Entwicklung eines Systems mit schräger 
Meßlanze zur Blasprozesssteuerung, Stahl und Eisen 113 (1993), 
pp. 49–52 
3) N. Ramaseder, W. Pirklbauer, J. Kalisch; A Slanted Sublance System for Blowing 
Process Control, MPT International 3 (1993), pp. 42–45. 
4) N. Ramaseder, H. Öllinger; Arrangement for Installing and Removing a Lance into and 
from a Metallurgical Vessel, Europ. Patentanmeldung EP 0 444 006 A1 (1991). 
5) N. Ramaseder, E. Fritz; Method and device for measuring electromagnetic waves 
emanating from a melt, Patentanmeldung WO 97/22859 
6) N. Ramaseder, J. Heiss; Kontinuierliche Temperaturmessung in metallurgischen 
Gefäßen für verbesserte Basisautomation, Stahl und Eisen (8/2001) 
 
	Fig. 10: Comparison of the Mn content of the VAI-CON®Chem and laboratory analysis on the VD-plant at Böhler Kapfenberg