Energy Savings Initiatives

Energy Savings Initiatives The Timken Company s Steel Business Mike Seifert and Nathan Abboud March 24, 2010 1

Energy Savings Initiatives The Timken Company s Steel Business Outline of Topics to be Discussed 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 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 2

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 Energy Savings Initiatives The Timken Company s Steel Business Faircrest Steel Plant Alloy Steel - US MCF per Shipped Ton HSP Continuous Caster HSP Continuous Mill CI 1980s ~ 40% improvement 1990s ~ 17% improvement 2000s ~ 45% improvement (excl. 2009) 3

Heat Treat Furnace Energy Savings Projects Heat Treat Roller Hearth Furnaces 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 4

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 5

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 6

Heat Treat Furnace Energy Savings Projects Reducing the number of burners Control Chart Individual Measurement of 7RMCF/ton 4.50 4.00 UCL=3. 8961 7RMCF/ton 3.50 3.00 Avg=3. 0927 2.50 2.00 02/01/2005 04/01/2005 06/01/2005 08/01/2005 10/01/2005 12/01/2005 02/01/2006 04/01/2006 06/01/2006 08/01/2006 LCL=2. 2893 Date This control chart shows the Results Net reduction of 25% 7

Heat Treat Furnace Energy Savings Projects Heat Treat Car Furnaces One of our car furnaces had lower velocity 1950 vintage burners Another car had a higher mix 1979 vintage burner 8

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 9

Heat Treat Furnace Energy Savings Projects Installing high velocity burners 4 Car MCF/ton Before changes 3.50 3.25 3.00 2.75 2.50 2.25 2.00 1.75 1.50 4 car 1.25 1.00 0.75 0.50 0.25 0.00 After changes Ja 07 Jul Ja 08 Jul Jan-09 As high as 33% savings for some heat treat cycles 10

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 11

Energy Savings Initiatives The Timken Company s Steel Business Outline of Topics to be Discussed 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 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. Replace conventional burners in the high fired zones with regenerative ones 4. Redesign recuperator by adding more surface area 5. Increase oxygen enrichment 12

Key factors for success: 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 13

Tuning on-line billet temperature model and level 2 control system 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 15

Tuning on-line billet temperature model and level 2 control system Making Thermod billet temperature calculation closer to actual temperature. Attaching a logger to the billet with thermocouples recording temperatures every 5 seconds. 16

Tuning on-line billet temperature model and level 2 control system 17

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. 23

Tuning on-line billet temperature model and level 2 control system 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 24

Tuning on-line billet temperature model and level 2 control system 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. 25

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 T (F) Tuning on-line billet temperature model and level 2 control system Material type effect is negligible Material Type Effect, 10.5" Billet, 15 mpi 2500 2400 2300 2200 2100 2000 1900 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0 zone top_1026 bot_1026 top_52100 bot_52100 top_1090 bot_1090 t (s) 26

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 Tuning on-line billet temperature model and level 2 control system Predicted temperature was off by over 400 F at times BILLET OD: 6", BILLET SPACING: 1.5", TIME IN FURNACE: 15 MPI 2300 2200 2100 2000 1900 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0 Thermod_zone Datapaq_zone Thermod_top Datapaq_top1 Datapaq_top2 Thermod_center Datapaq_center1 Datapaq_center2 Thermod_bottom Datapaq_bottom1 Datapaq_bottom2 27

Tuning on-line billet temperature model and level 2 control system 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 28

Quality Production Energy Savings 30

Optimizing on-line billet temperature model and level 2 control system If the billet temperature is non-uniform, the tube is eccentric. Eccentric tubes often result in an out-of-tolerance wall size. 31

Optimizing on-line billet temperature model and level 2 control system Furnaces are slightly pressurized in order to reduce cold air infiltration Cold air infiltration negatively affects billet temperature uniformity 32

Optimizing on-line billet temperature model and level 2 control system Billet spacing Zone #4 excess air Zone #5 excess air Enthalpy Profile Furnace pressure Responses were: Eccentricity (P) Fuel Consumption (S) Productivity (S) 33

Optimizing on-line billet temperature model and level 2 control system 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 34

Optimizing on-line billet temperature model and level 2 control system 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 35

Optimizing on-line billet temperature model and level 2 control system 36

Optimizing on-line billet temperature model and level 2 control system 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 37

Replace conventional burners in the high fired zones with regenerative ones 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 39

Replace conventional burners in the high fired zones with regenerative ones Gas Regenerative Burners Cycle A Hot air Hot POC Courtesy of Bloom Eng. Warm POC 40

Replace conventional burners in the high fired zones with regenerative ones Regenerative Burners Cycle B Courtesy of Bloom Eng. 41

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 42

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 43

Other projects: Shut down Zones Added Insulation Better Control of Air/Fuel. 44

Questions? 45