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Energy Savings Initiatives
The Timken Company’s Steel Business
Mike Seifert and Nathan Abboud
March 24, 2010
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Energy Savings InitiativesThe Timken Company’s Steel Business
• Overview of Energy Savings at Timken over the Years
• Heat Treat Furnace Energy Savings Projects
1. Reducing the number of burners
2. Installing high velocity burners
• Rotary Furnace Energy Savings Projects
1. Tuning on-line billet temperature model and level 2 control system
2. Optimizing on-line billet temperature model and level 2 control system
3. Replacing conventional burners in the high fired zones with regenerative ones
4. Redesigning recuperator by adding more surface area
5. Increasing oxygen enrichment
Outline of Topics to be Discussed
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Alloy Steel - US
MCF per Shipped Ton
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
1990s ~ 17% improvement1980s ~ 40% improvement
Faircrest Steel Plant
HSP Continuous Caster
HSP Continuous Mill
CI
2000s ~ 45% improvement (excl. 2009)
Energy Savings InitiativesThe Timken Company’s Steel Business
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Heat Treat Furnace Energy Savings Projects
• Historically the furnaces were designed for production & quality
• Energy efficiency was not the primary driver
• Team of Manufacturing, Process Improvement, Combustion, & Met
QA was formed
Heat Treat
Roller Hearth Furnaces
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Heat Treat Furnace Energy Savings Projects
Heat Treat
Roller Hearth Furnaces
An idea was generated that we may be able to reduce the number
of burners
Numerous trials were run monitoring temperature profiles of the
product and the furnace
Product samples were cut and examined to assure no impact to
the product properties
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Heat Treat Furnace Energy Savings Projects
Heat Treat
Roller Hearth Furnaces
Trials supported reducing burners in the soak zones
Results:
No impact to product quality
Significant fuel savings
Heat Treat
Roller Hearth Furnaces
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Heat Treat Furnace Energy Savings Projects
2.00
2.50
3.00
3.50
4.00
4.50
7RM
CF/to
n
02/0
1/20
05
04/0
1/20
05
06/0
1/20
05
08/0
1/20
05
10/0
1/20
05
12/0
1/20
05
02/0
1/20
06
04/0
1/20
06
06/0
1/20
06
08/0
1/20
06
Date
Avg=3.0927
LCL=2.2893
UCL=3.8961
Individual Measurement of 7RMCF/ton
Control Chart
This control chart shows the Results
Net reduction of 25%
Reducing the number of burners
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Heat Treat Furnace Energy Savings Projects
One of our car furnaces had lower velocity 1950 vintage burners
Another car had a higher mix 1979 vintage burner
Heat Treat
Car Furnaces
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Heat Treat Furnace Energy Savings Projects
Heat Treat
Car Furnaces
These two car furnaces at GSP were rebuilt with high velocity
burners to improve throughput in addition to energy
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Heat Treat Furnace Energy Savings Projects
Installing high velocity burners
4 Car MCF/ton
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
3.25
3.50
Ja 0
7Ju
l
Ja 0
8Ju
l
Jan-
09
4 car
As high as 33% savings for some heat treat cycles
Before
changes
After
changes
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Heat Treat Furnace Energy Savings Projects
MCF /Ton
Other projects:
Reduced Cycle Times
Improved Furnace Pressure
Control
Shut down Zones
Added Insulation
Better Control of Air/Fuel
…
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Energy Savings InitiativesThe Timken Company’s Steel Business
• Overview of Energy Savings at Timken over the Years
• Heat Treat Furnace Energy Savings Projects1. Reducing the number of burners
2. Installing high velocity burners
• Rotary Furnace Energy Savings Projects1. Tuning on-line billet temperature model and level 2 control system
2. Optimizing on-line billet temperature model and level 2 control system
3. Replace conventional burners in the high fired zones with regenerative ones
4. Redesign recuperator by adding more surface area
5. Increase oxygen enrichment
Outline of Topics to be Discussed
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• Projects needed dedicated resources
• Finite element analysis knowledge was essential
• DOE (Design of Experiment) expertise was required
• Commitment from operations for the trials was needed
• Trials were designed to run within standard operating ranges
Rotary Furnace Energy Savings Projects
Key factors for success:
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Energy Savings InitiativesThe Timken Company’s Steel Business
• Overview of Energy Savings at Timken over the Years
• Heat Treat Furnace Energy Savings Projects1. Reducing the number of burners
2. Installing high velocity burners
• Rotary Furnace Energy Savings Projects1. Tuning on-line billet temperature model and level 2 control system
2. Optimizing on-line billet temperature model and level 2 control system
3. Replace conventional burners in the high fired zones with regenerative ones
4. Redesign recuperator by adding more surface area
5. Increase oxygen enrichment
Outline of Topics to be Discussed
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• True knowledge of billet temperatures allows optimum pre-heat conditions
to be set
• Scale layer minimized so mill yields increase
• Areas of non-uniform heating that cause eccentricity of tubing identified
• Vital information for verification of mathematical furnace models
Rotary Furnace Energy Savings Projects
Tuning on-line billet temperature model and level 2 control system
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Rotary Furnace Energy Savings Projects
Making Thermod billet temperature calculation closer to actual temperature.
Attaching a logger to the billet with thermocouples recording temperatures
every 5 seconds.
Tuning on-line billet temperature model and level 2 control system
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Rotary Furnace Energy Savings Projects
Tuning on-line billet temperature model and level 2 control system
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Rotary Furnace Energy Savings Projects
Tuning on-line billet temperature model and level 2 control system
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Tuning on-line billet temperature model and level 2 control system
Rotary Furnace Energy Savings Projects
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Rotary Furnace Energy Savings Projects
Tuning on-line billet temperature model and level 2 control system
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Rotary Furnace Energy Savings Projects
Tuning on-line billet temperature model and level 2 control system
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Rotary Furnace Energy Savings Projects
Tuning on-line billet temperature model and level 2 control system
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Rotary Furnace Energy Savings Projects
Tuning on-line billet temperature model and level 2 control system
• Design of experiment goal was to run a minimum number of trials to
identify the variables causing the most amount of error between
calculated and actual billet temperature.
• These trials were later analyzed and used to refine the model and
reduce the error.
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Rotary Furnace Energy Savings Projects
• Assuming:
– The error from factor interactions is negligible
– Only diameter spacing and time are the main factors
• DOE half factorial predicts the main effects of 3 control factors with
a total of 6 runs
RUN DIA SPACING TIME (MPI)
1 10.5 1.25 15
2 6 1.25 15
3 6 0.25 15
4 10.5 0.25 15
5 6 1.25 25
6 6 0.25 25
Tuning on-line billet temperature model and level 2 control system
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Rotary Furnace Energy Savings Projects
• Zone temperature range is 1700°F to 2350°F. It varies within the same run. Thus, its effect was captured.
• Time usually varies from 15 MPI TO 25 MPI. Only 6” billet
was tested at 15 MPI and 25 MPI. The 10.5” billet can not
be tested at 25 MPI due to Datapaq limitations
• View factor is a function of spacing. Only spacing was
tested.
• Emissivity varies with scale thickness and scale thickness
varies with time. Only time was tested.
• According to DEFORM model already developed, material
type has negligible effect.
Tuning on-line billet temperature model and level 2 control system
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Rotary Furnace Energy Savings Projects
Material Type Effect, 10.5" Billet, 15 mpi
0100200300400500600700800900
1000110012001300140015001600170018001900200021002200230024002500
0
500
100
0
150
0
200
0
250
0
300
0
350
0
400
0
450
0
500
0
550
0
600
0
650
0
700
0
750
0
800
0
850
0
900
0
t (s)
T (F
)
zone
top_1026
bot_1026
top_52100
bot_52100
top_1090
bot_1090
Tuning on-line billet temperature model and level 2 control system
Material type effect is negligible
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Rotary Furnace Energy Savings Projects
BILLET OD: 6", BILLET SPACING: 1.5", TIME IN FURNACE: 15 MPI
0
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
2100
2200
2300
0
180
360
540
720
900
1080
1260
1440
1620
1800
1980
2160
2340
2520
2700
2880
3060
3240
3420
3600
3780
3960
4140
4320
4500
4680
4860
5040
5220
5400
Thermod_zone
Datapaq_zone
Thermod_top
Datapaq_top1
Datapaq_top2
Thermod_center
Datapaq_center1
Datapaq_center2
Thermod_bottom
Datapaq_bottom1
Datapaq_bottom2
Tuning on-line billet temperature model and level 2 control system
Predicted temperature was off by over 400°F at times
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Rotary Furnace Energy Savings Projects
New view factors were calculated to account for furnace geometry and
billet spacing variations
Furnace thermocouples were relocated to reflect true zone temperature
Difference between actual billet temperature and calculated billet
temperature was significantly reduced
Tuning on-line billet temperature model and level 2 control system
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Energy Savings InitiativesThe Timken Company’s Steel Business
• Overview of Energy Savings at Timken over the Years
• Heat Treat Furnace Energy Savings Projects1. Reducing the number of burners
2. Installing high velocity burners
• Rotary Furnace Energy Savings Projects1. Tuning on-line billet temperature model and level 2 control system
2. Optimizing on-line billet temperature model and level 2 control system
3. Replace conventional burners in the high fired zones with regenerative ones
4. Redesign recuperator by adding more surface area
5. Increase oxygen enrichment
Outline of Topics to be Discussed
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Rotary Furnace Energy Savings Projects
Quality
Production
Energy Savings
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Rotary Furnace Energy Savings Projects
If the billet temperature is non-uniform, the tube is eccentric. Eccentric tubes often result in an out-of-tolerance wall size.
Optimizing on-line billet temperature model and level 2 control system
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Rotary Furnace Energy Savings Projects
Furnaces are slightly pressurized in order to reduce cold air infiltration
Cold air infiltration negatively affects billet temperature uniformity
Optimizing on-line billet temperature model and level 2 control system
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Rotary Furnace Energy Savings Projects
• Billet spacing• Zone #4 excess air• Zone #5 excess air • Enthalpy Profile • Furnace pressure
Responses were:
Eccentricity (P)
Fuel Consumption (S)
Productivity (S)
Optimizing on-line billet temperature model and level 2 control system
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Rotary Furnace Energy Savings Projects
• A resolution 5 fractional factorial design of experiment with center
points was conducted using JMP
• Ran a four month trial
• Towards the end of the trial, results started to show that lower
eccentricity can be achieved with , increased spacing, increased
excess air, and higher furnace pressure
Optimizing on-line billet temperature model and level 2 control system
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Rotary Furnace Energy Savings Projects
• The trial was augmented with additional settings in order to determine the
optimal settings for this process.
• The trial was continued to completion with these additional runs.
• Optimal spacing was determined (Greater than normal practice)
• We optimized excess air (which was a higher setting)
• Furnace pressure was not changed
Optimizing on-line billet temperature model and level 2 control system
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Rotary Furnace Energy Savings Projects
Optimizing on-line billet temperature model and level 2 control system
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Rotary Furnace Energy Savings Projects
• In Summary:
• A design of experiment using JMP (statistical software) was conducted to
optimize furnace settings and achieve uniformly heated billets.
• Since then, eccentricity has been at a record low. Tubes concentricity
significantly improved allowing us to process new orders with a tighter wall
size tolerance.
• Monitoring fuel, we did see a reduction in fuel.
• Productivity was maintained
Optimizing on-line billet temperature model and level 2 control system
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Energy Savings InitiativesThe Timken Company’s Steel Business
• Overview of Energy Savings at Timken over the Years
• Heat Treat Furnace Energy Savings Projects1. Reducing the number of burners
2. Installing high velocity burners
• Rotary Furnace Energy Savings Projects1. Tuning on-line billet temperature model and level 2 control system
2. Optimizing on-line billet temperature model and level 2 control system
3. Replace conventional burners in the high fired zones with regenerative ones
4. Redesign recuperator by adding more surface area
5. Increase oxygen enrichment
Outline of Topics to be Discussed
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Rotary Furnace Energy Savings Projects
Regeneration uses a pair of burners which cycle to alternately
heat the combustion air or recover and store the heat from the
furnace exhaust gases.
Replaced 21 burners with 9 burners at #4 Rotary in 2006
Air preheat temperatures within 300°F - 500°F of the furnace are
achieved resulting in exceptionally high thermal efficiency.
Result was 32% in natural gas saving
Replace conventional burners in the high fired zones with regenerative ones
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Hot air
Hot POC
Regenerative Burners Cycle AGas
Rotary Furnace Energy Savings Projects
Warm POC
Replace conventional burners in the high fired zones with regenerative ones
Courtesy of Bloom Eng.
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Regenerative Burners Cycle B
Rotary Furnace Energy Savings Projects
Replace conventional burners in the high fired zones with regenerative ones
Courtesy of Bloom Eng.
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Rotary Furnace Energy Savings Projects
Redesign recuperator by adding more surface area
A recuperator is a special purpose counter-flow heat exchanger used
to recover waste heat from exhaust gases. Optimization of heat
recuperator size for heat recovery applications is extremely significant in
order to get maximum savings from these systems.
Courtesy US Department of Energy Efficiency
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Rotary Furnace Energy Savings Projects
Increase oxygen enrichment
Substitution of commercial oxygen for combustion air, which contains
only 20.9% O2, reduces the volume of heat-absorbing nitrogen flowing
through the combustion process and therefore reduces the flue gas loss.
2005: 3% enrichment
2006: 7% enrichment
Result was 10% in natural gas saving
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Rotary Furnace Energy Savings Projects
Other projects:
Shut down Zones
Added Insulation
Better Control of Air/Fuel
…….
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Questions?