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VDEh-Betriebsforschungsinstitut GmbH
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Workshop R&D on Electrical Arc Furnace:
state-of-the-art of RFCS-supported projects
Sensors and Measurement Techniques
for Process Control
Dalmine, March 12th, 2015
Herbert Köchner, VDEh-Betriebsforschungsinstitut (BFI), Düsseldorf, Germany
1 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
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Table of contents
2 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
Temperature/Foam/Analysis
Off gas/Emissions
Purging/Cooling
Source: MPT Int. 1/14
Energy input
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Introduction
Major drivers for innovation related with the electric arc furnace are:
Improvement of energy efficiency
Improvement of ressource efficiency
Improvement of steel quality
Improvement of safety
3 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
“Necessity is the mother of invention” (Platon)
1919 Present
Source: Tenova State of the art in EAF technologies,
2nd VDEh-AIM Joint Meeting on Metallurgical Fundamentals
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Evaluated RFCS research projects directly dealing with
EAF sensor based process control
4
Contract
Report
Title Participants Date
Start / End
Topic regarding sensors
RFSR-CT-
2004-00008
Control by camera of the EAF
operations in airtight
conditions
CSM, BFI, AM R&D,
CORUS UK, MORE
SRL
2004-07-01
to
2007-12-31
To observe the scrap-melting process under slag-
door closed conditions, a camera-based technology
to observe furnace events during meltdown has been
developed. The camera system is able to see through
combustion gases by selecting its wavelength to be in
the mid-infrared spectral band.
No 7210-
PR/204
Innovative continuous online
determination of steel melt
temperature by direct optical
measurement in the melt
BFI, AG Dillinger
Hütte, CRM, Aceralia
2000-07-01
to
2003-12-31
Based on a detailed analysis of the state of the art a
fibre optical measurement technique was
promising to meet the demands of the requested
applications. The measurement principle is to feed a
standard low cost optical fibre continuously into the
steel bath and to analyse the radiation transmitted
through the fibre for information on bath temperature.
RFSR-CT-
2013-00002
Determining process
conditions for online
monitoring of temperature
and carbon content in the
electric arc furnace to
optimise end point control
BFI, FERRIERE
NORD S.P.A.,
POLITECNICO DI
MILANO,
SAARSCHMIEDE
2013-07-01
to
2016-06-30
Online measurement systems for continuous
monitoring of the process status during EAF
treatment and end point control will be developed and
applied. At one furnace an accretion free melt access
will be created for fibre-optical temperature
measurement. At another furnace a measurement
system for combined optical determination of carbon
content and temperature will be developed using a
lance access.
12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
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Steel bath temperature sensor technologies
5 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
manual
Thermocouple
Type MMT10-1200-Fe
17,8 manipulator
Thermocouple
Type MLTS-1200-Fe-P
28,5
1. Paper tube
2. Thermocouple type S
3. Ceramic housing
4. Protection cap steel
5. Paper cap
1. Paper tube
2. Thermocouple type S
3. Ceramic housing
4. Protection cap steel
5. Paper cap
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Optical steel bath temperature sensors
Immersed fibre-optical steel bath
temperature measurement is:
Independent of emissivity
Continuous measurement of melt
temperature during fibre feeding
Fast response time by optical
measurement
No influence by melt bath surface or
slag cover
available also during heating
operation, because insensitive against
electromagnetic fields
Precise temperature control to reach
the desired target temperature
6 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
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Optical temperature measurement sensors (EAF)
RFCS-No 7210-PR/204
Optical fibre temperature measurement based
on lance/manipulator technique
Two flexible hoses connected to the probe (one
for the fibre and shield gas, and one for cooling
gas) and the lance / manipulator
Results:
The probe withstood the harsh conditions
inside the furnace during 11.5 minutes, i.e.
much longer than the application period for
liquid steel temperature measurement in the
EAF (last 5 - 6 minutes of each heat);
That the probe could have been used for an
additional measurement;
The measured temperature signal shows a
clear trend up, as expected
7 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
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Optical temperature measurement sensors (Induction furnace)
RFCS-No 7210-PR/204
BFI developed an optical temperature
measuring system based on manual
lances, especially in small-to-medium
sized foundries
Technical data of mobile, lance based
optical temperature measurement system
DynTemp® H:
Temperature measurement range:
1250°C to 1800°C
Reproducibility of detector: ± 0,1% + 1 K
Response time: 0,5 s
Device dimensions:
0,8 m x 0,8 m x 0,35 m
8 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
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Optical temperature measurement sensors (EAF/LF)
Optical fibre temperature measurement based
on lance/manipulator technique
No influence of slag and oxides
No electromagnetic influence on
measurement
Flexible measurement duration up to
several minutes
Tailored measurement probes
Temperature measurement without
interrupting the heating process
Temperature measurement range:
1500°C to 1700°C
9 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
temperature
measuring
instrument
manipulator
lance
Measurement
probe
PTG
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Optical temperature measurement sensors (EAF/LF)
Measurement accuracy of the new process control
DynTemp® is better than 2 K compared to
thermocouple measurements
Shorter heating times can be detected, using the
continuous temperature measurement (new process
control), compared to thermocouple spot
measurements (conventional process control)
For a typical heat of 100 t more than 300 kWhel can
be saved
10 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
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Optical temperature measurement sensors (EAF/LF)
With efficient bottom stirring, homogeneous temperature of liquid steel in ladles
Local DynTemp® measurement, reproducibility better than 2 K
Continuous temperature measurement up to 90 s 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH 11
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Optical temperature measurement sensors (EAF/LF)
Improved process stability with continuous temperature measurement by DynTemp®
compared to short term measurement with thermocouple measurement and/or model
Without proper stirring for homogenization of liquid steel bath :
temperature fluctuations up to +/- 30 K observed
12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH 12
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Optical temperature measurement sensors (BOF)
RFCS-No 7210-PR/204
BFI has developed a robust continuous
optical measurement system based on
a consumable optical fibre fed through
the bottom gas system into the liquid
steel bath.
The system measures the actual steel
bath temperature during the blowing
process to determine accurately the
required end of blowing.
13 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
Flexible Fiber guiding tube
Shielding box
liquid steel
Bottom nozzle
Data acquisitionand control
Bottom gasFeeding control
Pyrometer
Piping for bottom gasand fibre transport
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Optical temperature measurement sensors (BOF)
Main benefits are:
Short response time (< 0,1 s)
Continuous online monitoring
Easy application
Improved process control
Raising output
Savings in oxygen consumption and time
14 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
0 5 10 15 20 25
tem
pera
ture
in
°C
1400
1450
1500
1550
1600
1650
1700
1750
1800
continously measured temperature during blowing
theorecical temperature developing
manual thermocouple measurement
end o
f oxy
gen
blo
win
g
conve
rter
tiltin
g
conve
rter
tiltin
g
conve
rter
at
upright
positio
n
conve
rter
tiltin
g a
tcasting p
ositio
n
measure
ment
sta
rt
time in min
reference datafor correlation
15% to 25% of tap15% to 25% of tap--toto--tap time are used for temperature measurement,tap time are used for temperature measurement,
waiting for analysis or for a necessary reblownwaiting for analysis or for a necessary reblown15% to 25% of tap15% to 25% of tap--toto--tap time are used for temperature measurement,tap time are used for temperature measurement,
waiting for analysis or for a necessary reblownwaiting for analysis or for a necessary reblown
0 5 10 15 20 25 30 35 40 45
Time in minutes
lime addition
scrap charging
hot metal charging
main blowing time
post stirring
temperature and
sampling
waiting for analysis
reblown
tapping
deslagging
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Optical temperature measurement sensors (EAF)
RFSR-CT-2013-0002 Fibre-optical continuous temperature measurement
(BFI DynTemp®) using
Lance
Bottom nozzle
Monitor continuously the liquid steel temperature
during the refining phase
Determine process conditions to perform
representative measurements in dynamic
inhomogeneous melts
Develop enhanced dynamic process control based
on novel measurements
Develop strategies and model-based set point
calculations for exact determination of control
parameters for accurate EAF end point control
Evaluate availability, performance and limitations of
continuous measurement
15 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
Ferriere Nord
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EAF bottom gas purging systems
In EAF steelmaking where metallurgical
constraints exist, bottom gas purging provides
cost benefits by:
lncreased thermal and temperature
homogeneity in the steel melt
Decreased melting time of scrap and DRI.
lncreased heat transfer during the
superheating period.
Decreased specific electrical energy demand.
lncreased chemical homogeneity in
the steel melt
Decreased oxygen consumption.
16 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
Furnace control
system Elec. control box
Gas control box
Operation
control box
Gas inlet
Year
C
usto
mer
Source: Benefits of Electric Arc Furnace Bottom Gas Purging Systems, RHI Bulletin 2013
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Oxygen sensor technologies
17 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
manual
Oxygen Probe
Type MIN-OXL-S-170
Low Level
18,0 manipulator
Oxygen Probe
Type MIN-OX-28B-120
High level
28,5
1. Paper tube
2. EMK-Unit type S
3. Steel protection cap
4. Paper protection cap
1. Paper tube
2. EMK-Unit type B
3. Steel protection cap
4. Paper protection cap
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Vibration and sound sensors
The evaluation of structure-borne sound
emissions in EAFs yields essential
information about
foaming slag behavior,
scrap shielding of the arcs
condition of scrap bulk
Condition-based Scrap Melt-down control
module (CSM)
Foaming slag control module, also called
SIMELT Foaming Slag Manager (FSM)
help to improve energy efficient operations
18 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
Vibration sensor 3
Vibration sensor 2
Vibration
sensor 1
Electrodes
Determination of
slag heights
Source: Results of foaming slag and scrap meltdown control SIMELT CSM/FSM based on
structure-borne sound in Electric Arc Furnace operation, AISTech 2012
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Vibration and sound sensors
Use of the sensors leads to a smoother and
forward-looking operation yielding in
reduced heat load and a large reduction of
transformer tap changes.
Further on, a slight decrease in power-on
time can be realized.
19 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
Number of total transformer tap changes before and after
the SIMELT CSM installation, showing a pronounced
decrease.
Specific power-on time in minutes per mt before and after
the SIMELT CSM installation
Low shielding of the furnace walls is detected before thermal load occurs. Low
shielding is compensated by asymmetrical power control
Source: Results of foaming slag and scrap meltdown control SIMELT CSM/FSM based on
structure-borne sound in Electric Arc Furnace operation, AISTech 2012
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Infrared sensors
RFSR-CT-2004-00008
The developed camera-based technology is an
infrared camera for observing the process inside
an EAF operating with closed slag door.
Recordings have provided new and interesting
insights into the EAF melting process. Images
showing:
the melting characteristics of different size
scrap pieces; scrap-drop events; scrap melting
completion
time; thermal contours after end-of-arcing; the
extent and duration of slag foaming; and details
of the
tapping operation (including the size of the hot
heel), have been demonstrated and these
direct online
views of operations inside the furnace to
provide the operator with improved control of
the process.
20 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
Start of melting phase Dust clouds while melting
phase Slag surface
Electrode
Metal bath
View angle
Camera
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Electromagnetic bath level measurement sensors
Compared with other solutions the
EMLI-FBL has the following
advantages:
Once the system is installed, the bath
level measurements are made
automatically at no extra cost.
Several measurements are
automatically performed during each
heat, providing true and repeatable
results.
Enhanced safety as it does not require
the operators to perform extra
procedures and expose themselves to
danger in order to collect a bath
measurement.
21 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
Source: Electromagnetic bath level measurement system improves EAF melting process control, AISTech 2014
Green trace denotes
sensor position
during immersion
sequence and blue
trace shows bath
level detection.
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Conclusions
Research and innovation is a key driver for energy and ressource efficient EAF technology
Improved process control requires more sensor and measurement data
Until now, only few RFCS projects were directly related to sensors and measurement techniques
for the EAF
Continuous measurement allows further improved understanding of actual process conditions also
during fast processes such as heating or mixing
Online monitoring and real time sensors for improved EAF control is a requirement for future
steelmaking
As in daily life, sensors become increasingly important to supply real time process information
22 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH
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Thank you very much for your attention !
Contact:
Dr.-Ing. Herbert Köchner
VDEh-Betriebsforschungsinstitut
Dept. Process Measuring and Testing Technology
Tel.: +49 211 6707 892
23 12.03.2015 · Herbert Köchner · © VDEh-Betriebsforschungsinstitut GmbH