the timken company’s steel business · pdf filefia| tech hop 2010 1 energy savings...

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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)


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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


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


Trials supported reducing burners in the soak zones

Results:

No impact to product quality

Significant fuel savings

Heat Treat


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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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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

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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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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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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• Heat Treat Furnace Energy Savings Projects1. Reducing the number of burners


• Rotary Furnace Energy Savings Projects1. Tuning 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


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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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• 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


Tuning on-line billet temperature model and level 2 control system

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Making Thermod billet temperature calculation closer to actual temperature.

Attaching a logger to the billet with thermocouples recording temperatures

every 5 seconds.


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• 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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• 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


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• 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.


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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


Material type effect is negligible

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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


Predicted temperature was off by over 400°F at times

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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


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Quality

Production

Energy Savings

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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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Furnaces are slightly pressurized in order to reduce cold air infiltration

Cold air infiltration negatively affects billet temperature uniformity


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• Billet spacing• Zone #4 excess air• Zone #5 excess air • Enthalpy Profile • Furnace pressure

Responses were:

Eccentricity (P)

Fuel Consumption (S)

Productivity (S)


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• 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


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• 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


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• 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


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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


Warm POC


Courtesy of Bloom Eng.

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Regenerative Burners Cycle B



Courtesy of Bloom Eng.

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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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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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Other projects:

Shut down Zones

Added Insulation

Better Control of Air/Fuel

…….

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Questions?

the timken company’s steel business · pdf filefia| tech hop 2010 1 energy savings...

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