Design Project - Electric Furnace for Steel Making

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Design Project - Electric Furnace for Steel Making

  1. 1. DESIGN OF AN ELECTRIC FURNACE FOR MAKING STEEL BY GROUP 23 : EUGENE TEO GUO SHUN 061933G07 KENVIN TEO SHI YU 061932E07 JOELTEE HAN YUN 060420D07 FIZH TO CHUN YU 060324H07
  2. 2. MS 3005 DESIGN PROJECT List of Contents  1. INTRODUCTION  2. MOTIVATION  3. SCOPE  4. CURRENT OPERATION OF MAKING STEEL  5. LITERATURE REVIEW  6. WHY STAINLESS STEEL?  7. MATERIALS SELECTION  8. DISCUSSIONS  9. RECOMMENDATIONS  10. REVIEW  11. QUESTIONS AND ANSWERS
  3. 3. MS 3005 DESIGN PROJECT Introduction  Steel making can be separated into two categories- primary and secondary  Current trend – using of electric arc furnace (EAF)  Advantages  400 tons of steel in 60 minutes  Mass production= low price  Flexible in stopping according to demand  Disadvantages  Environmental and efficiency  Cost
  4. 4. MS 3005 DESIGN PROJECT Motivation & Scope  The growing Steel processing industry  The gist of making stainless steel lies in the decarburization process.  2 types of decarburization processes  Vacuum oxygen decarburization (VOD)  Argon oxygen decarburization (AOD)  hassle of transferring to another ladle  focus on improving and redesigning two aspects of the existing electric arc furnace  1. The process of vacuum decarburization  2. The stirring of the molten steel to obtain a homogenous melt.
  5. 5. MS 3005 DESIGN PROJECT Current Operation of Making Steel Video
  6. 6. MS 3005 DESIGN PROJECT Literature Review  DESIGN OF AN ELECTRIC FURNACE FOR MAKING STEEL Our group is going to focus on improving the design and manufacturing stainless steel using the Electric Arc Furnace
  7. 7. MS 3005 DESIGN PROJECT Literature Review Methods of making steel (Christopher 2007)  Hits  Focuses on the method of making steel using an electric arc furnace  Manage to come out with an invention make steel at a reduced cost  Generation of source of lime compacted to form a conglomeration of compacts; charged to the furnace in the shortest period of time to avoid energy loss  Misses  Did not explain how different kinds of steel, like stainless steel, are made directly from the electric arc furnace
  8. 8. MS 3005 DESIGN PROJECT Literature Review Making of stainless steel without using electric arc furnace (Clifford 1971)  Hits  patented a design which allowed them to produce stainless steel without the use of an Electric Arc Furnace  Misses  Uses 2 channel furnaces  A channel furnace is employed to mix chromium containing and chromium-free hot metal, producing a converter feed metal of desired temperature and chemical composition.
  9. 9. MS 3005 DESIGN PROJECT Literature Review  Making of stainless steel with an electric arc furnace without using secondary processes (Arturo 1991)  Hits  identified the problems and enhanced the added oxygen process to obtain good reducing conditions  Installation of devices + lance system to introduce oxygen to improve efficiency  Misses  Never looked into reducing the loss of chromium + homogenization of melt
  10. 10. MS 3005 DESIGN PROJECT Literature Review  Electromagnetic Stirring  Commonly used in continuous casting of metals  Prevents the creation of inhomogeneous steel  It agitates the molten core  Balances the temperature gradient between the outer shell and inner core of casted metal  Feasible in homogenizing the stainless steel melt in the steel making process
  11. 11. MS 3005 DESIGN PROJECT Why Stainless Steel?  WHAT is Stainless Steel?  Low carbon steel alloy, 10 wt% of chromium by mass, chromium oxide layer Advantages  1. Corrosion resistance  2. Fire & Heat Resistance  3. Hygiene  4. Aesthetic appearance  5. Strength-to-weight advantage  6. Ease of fabrication  7. Impact Resistance  8. Long term value
  12. 12. MS 3005 DESIGN PROJECT Materials Selection  Stainless Steel chosen for the roof of electric arc furnace typically Properties considered  1. Melting point - high  2. Fracture Toughness - high  3. Specific Heat Capacity - high  4. Thermal Expansion coefficient - high  5. Thermal Conductivity – high  Total number of decisions = N(N-1)/2 = 5(4)/2 = 10 decisions  Weighting factors method  Gathered data from CES software located at MSE computer lab  Scaled data according to criterion  Calculate Performance index
  13. 13. MS 3005 DESIGN PROJECT Materials Selection Table 1 Application of Digital Logic Method Property Decision Number 1 2 3 4 5 6 7 8 9 10 Melting Point 1 1 1 1 Fracture 0 0 1 0 Toughness Specific Heat 1 1 0 0 Capacity Thermal Expansion 1 0 1 0 Coefficient Thermal 0 1 0 0 Conductivity
  14. 14. MS 3005 DESIGN PROJECT Materials Selection Table 2 Weighting Factors Property Positive Decisions Weighting Factors Melting Point 4 0.4 Fracture Toughness 1 0.1 Specific Heat Capacity 2 0.2 Thermal Expansion Coefficient 2 0.2 Thermal Conductivity 1 0.1 Total 10 1
  15. 15. MS 3005 DESIGN PROJECT Materials Selection Table 3 Property of Candidate Materials for EAF Fracture Specific Heat Thermal Expansion Thermal Material Melting Point °F Toughness Capacity Coefficient µ Conductivity ksi.in^1/2 BTU/lb.F strain/°F BTU.ft/h.ft^2.F Wrought 418 Martensite Stainless Steel, tempered at 2597 24.57 0.1075 5.00E+00 13.29 260degC Wrought 403 Ferritic Stainless 2597 47.32 0.1075 5.56E+00 13.29 Steel, intermediate temper Wrought 202 Austenitic Stainless 2552 61.88 0.117 9.17E+00 8.667 Steel, annealed Wrought 301 Austenitic Stainless 2552 61.88 0.1149 9.00E+00 9.013 Steel Wrought 301 Precipitation 2552 61.88 0.1149 9.00E+00 9.013 Hardening Stainless Steel Cast Duplex Stainless Steel CD- 2660 46.41 0.1075 5.56E+00 8.667 4CU
  16. 16. MS 3005 DESIGN PROJECT Materials Selection  As stainless steels are chosen commonly as roof material for the typical electric arc furnace, 5 classes of stainless steels are chosen to be analyzed. Table 4 Scaled Values of properties and performance index Performance Scaled (1) Scaled (2) Scaled (3) Scaled (4) Scaled(5) Wrought 418 Martensite Stainless 39.05 3.97 20 10.91 10 83.93 Steel, tempered at 260degC Wrought 403 Ferritic Stainless Steel, 39.05 7.65 20 12.12 10 88.82 intermediate temper Wrought 202 Austenitic Stainless 38.38 10 21.77 20 6.52 96.66 Steel, annealed Wrought 301 Austenitic Stainless 38.38 10 21.38 19.64 6.78 96.17 Steel Wrought 301 Precipitation Hardening 38.38 10 21.38 19.64 6.78 96.17 Stainless Steel Cast Duplex Stainless Steel CD-4CU 40 7.5 20 12.12 6.52 86.14  Wrought 202 Austenitic Stainless Steel, annealed, should be chosen to be made as the roof of electric arc furnace.
  17. 17. MS 3005 DESIGN PROJECT Discussions - Vacuum Oxygen Decarburization Concept  To produce large steel ingots, rails, ball bearings and other high quality steels.
  18. 18. MS 3005 DESIGN PROJECT Discussions - Vacuum Oxygen Decarburization Concept  The oxidation of liquid steel components under the influence of vacuum would result in the oxygen being used up mainly by the reaction [C] + [O] = {CO}  Use of Ellingham diagram
  19. 19. MS 3005 DESIGN PROJECT Discussions - Vacuum Oxygen Decarburization Concept  A plot of Gibbs Free Energy ΔG against temperature.  The Ellingham diagram shown is for metals which react with oxygen to form oxides.  The position of the line for a given reaction on the Ellingham diagram shows the stability of the oxide as a function of temperature.
  20. 20. MS 3005 DESIGN PROJECT Discussions - Vacuum Oxygen Decarburization
  21. 21. MS 3005 DESIGN PROJECT Discussions - Vacuum Oxygen Decarburization Concept  Carbon unusually useful as a reducing agent.  Ellingham Diagram  This process helps to decarburize the steel with minimum chromium losses.  Complete deoxidizers  then desulfurizing slag  Problem?
  22. 22. MS 3005 DESIGN PROJECT Discussions - Vacuum Oxygen Decarburization Design of the Furnace in incorporating an extensible roof with vacuum  Combine step of Vacuum Oxygen Decarburization
  23. 23. MS 3005 DESIGN PROJECT Discussions - Vacuum Oxygen Decarburization Design of the Furnace in incorporating an extensible roof with vacuum  2 roofs which are interchangeable  Simultaneous addition of oxygen  Use of Vacuum  Eliminates the need for another furnace
  24. 24. MS 3005 DESIGN PROJECT Discussions - Electromagnetic Stirring Importance of Stirring the Molten Melt  Homogenizing of molten melt  Improving heat and mass transfer rates  Reduce processing times  Metallurgical restrictions
  25. 25. MS 3005 DESIGN PROJECT Discussions - Electromagnetic Stirring Current Practice: Gas Stirring  Use of Inert gases Vacuum  2 commonly used methods: Pump Outlet Ladle Lid  gas valve  semi permeable refractory material Safety Height Molten Steel Refractory Material and Ladle Wall Porous Plug Gas Injection or valve for System gas injection
  26. 26. MS 3005 DESIGN PROJECT Discussions - Electromagnetic Stirring Disadvantages of Gas Stirring  Additional processing step  Cost  Inability to cut off gas flow  Violent turbulence  Dangerous ejection of the melt
  27. 27. MS 3005 DESIGN PROJECT Discussions - Electromagnetic Stirring Proposed solution: Electromagnetic stirring  Applied in continuous casting processes  Non-invasive  Adjustable stirring strength  Simplifies furnace process  Variable stirring pattern
  28. 28. MS 3005 DESIGN PROJECT Discussions - Electromagnetic Stirring Electromagnetic stirring: Working principle Three Phase Power Supply
  29. 29. MS 3005 DESIGN PROJECT Discussions - Electromagnetic Stirring Electromagnetic stirring: 2 proposed solutions  Installation of stirrers at top of furnace  Installation of stirrers at side of furnace
  30. 30. MS 3005 DESIGN PROJECT Discussions - Electromagnetic Stirring Proposed solution 1: Installation of Inductor at top of furnace Top Ring Furnace Lid Energizing (toroid) coils Molten Melt X Bottom Refractory Ring Material and Ladle Wall X Top View of Furnace Lid
  31. 31. MS 3005 DESIGN PROJECT Discussions - Electromagnetic Stirring Proposed solution 1: Installation of stirrers at top of furnace Predicted Flow lines Electromagnetic transducer
  32. 32. MS 3005 DESIGN PROJECT Discussions - Electromagnetic Stirring Proposed solution 1: Installation of stirrers at top of furnace Verdict: Unsuitable  Inefficient Stirring pattern generated  Inadequate Stirring strength  Stirring strength will have to rely on a single electrode  Distance of electrode to melt Solution: Installation of stirrers at side of furnace
  33. 33. MS 3005 DESIGN PROJECT Discussions - Electromagnetic Stirring Proposed solution 2: Installation of stirrers at side of furnace Slag Molten Metal H ν F Electromagnetic transducers Electromagnetic transducers
  34. 34. MS 3005 DESIGN PROJECT Discussions - Electromagnetic Stirring Proposed solution 2: Installation of stirrers at side of furnace  Final Solution  Installation of transducer at side of furnace Summary  Placement and number of magnetic stirrers  Ability to control flow strength  Predetermined stirring patterns for optimum performance  Workable idea
  35. 35. MS 3005 DESIGN PROJECT Recommendations  Installation of Heat Exchanger system  Improvements in Refractory Material  Refractory Cooling System
  36. 36. MS 3005 DESIGN PROJECT Review  Summary of the current electric furnace operation present  Literature review  Why stainless steel is chosen  Materials selection of the roof for the EAF (group design)  Ellingham diagram and Vacuum Oxidation Decarburization  Design of the Furnace in incorporating an extensible roof with vacuum  Design of the Furnace by implementing and installing magnetic stirrers – side of furnace versus top of furnace  Recommendations for future work  Last but not least . . .
  37. 37. MS 3005 DESIGN PROJECT Questions & Answers  “Now… who ever said that steel making was a process that is hard to understand...”  “perhaps if your presenter was that informative, more students will be interested to venture into the steelmaking industry!”  Thank you. . .  Questions and Answers

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