design project - electric furnace for steel making
DESCRIPTION
Design Project Presentation SlidesTRANSCRIPT
DESIGN OF AN ELECTRIC FURNACE FOR MAKING STEEL
BY GROUP 23 : EUGENE TEO GUO SHUN 061933G07
KENVIN TEO SHI YU 061932E07JOELTEE HAN YUN 060420D07FIZH TO CHUN YU 060324H07
MS 3005 DESIGN PROJECTList 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
MS 3005 DESIGN PROJECTIntroduction
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
MS 3005 DESIGN PROJECTMotivation & 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.
MS 3005 DESIGN PROJECTCurrent Operation of Making Steel
Video
MS 3005 DESIGN PROJECTLiterature Review
DESIGN OF AN ELECTRIC FURNACE FOR MAKING
STEELOur group is going to focus on
improving the design and manufacturing stainless steel using the Electric Arc Furnace
MS 3005 DESIGN PROJECTLiterature 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
MS 3005 DESIGN PROJECTLiterature 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.
MS 3005 DESIGN PROJECTLiterature 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
MS 3005 DESIGN PROJECTLiterature 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
MS 3005 DESIGN PROJECTWhy 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
MS 3005 DESIGN PROJECTMaterials 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
MS 3005 DESIGN PROJECTMaterials 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 Toughness
0 0 1 0
Specific Heat Capacity
1 1 0 0
Thermal Expansion Coefficient
1 0 1 0
Thermal Conductivity
0 1 0 0
MS 3005 DESIGN PROJECTMaterials 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
MS 3005 DESIGN PROJECTMaterials Selection
Table 3 Property of Candidate Materials for EAF
Material Melting Point
°F
Fracture Toughness ksi.in^1/2
Specific Heat Capacity BTU/lb.F
Thermal Expansion
Coefficient µ strain/°F
Thermal Conductivity
BTU.ft/h.ft^2.F
Wrought 418 Martensite Stainless Steel, tempered at
260degC 2597 24.57 0.1075 5.00E+00 13.29
Wrought 403 Ferritic Stainless Steel, intermediate
temper 2597 47.32 0.1075 5.56E+00 13.29
Wrought 202 Austenitic Stainless Steel, annealed
2552 61.88 0.117 9.17E+00 8.667
Wrought 301 Austenitic Stainless Steel
2552 61.88 0.1149 9.00E+00 9.013
Wrought 301 Precipitation Hardening Stainless Steel
2552 61.88 0.1149 9.00E+00 9.013
Cast Duplex Stainless Steel CD-4CU
2660 46.41 0.1075 5.56E+00 8.667
MS 3005 DESIGN PROJECTMaterials 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.
Wrought 202 Austenitic Stainless Steel, annealed, should be chosen to be made as the roof of electric arc furnace.
Table 4 Scaled Values of properties and performance index Performance
Scaled (1) Scaled (2) Scaled (3) Scaled (4) Scaled(5)
Wrought 418 Martensite Stainless Steel, tempered at 260degC
39.05 3.97 20 10.91 10 83.93
Wrought 403 Ferritic Stainless Steel, intermediate temper
39.05 7.65 20 12.12 10 88.82
Wrought 202 Austenitic Stainless Steel, annealed
38.38 10 21.77 20 6.52 96.66
Wrought 301 Austenitic Stainless Steel
38.38 10 21.38 19.64 6.78 96.17
Wrought 301 Precipitation Hardening Stainless Steel
38.38 10 21.38 19.64 6.78 96.17
Cast Duplex Stainless Steel CD-4CU
40 7.5 20 12.12 6.52 86.14
MS 3005 DESIGN PROJECTDiscussions - Vacuum Oxygen Decarburization
Concept To produce large steel ingots, rails, ball bearings and other
high quality steels.
MS 3005 DESIGN PROJECTDiscussions - 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
MS 3005 DESIGN PROJECTDiscussions - 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.
MS 3005 DESIGN PROJECTDiscussions - Vacuum Oxygen Decarburization
MS 3005 DESIGN PROJECTDiscussions - 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?
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
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
MS 3005 DESIGN PROJECTDiscussions - Electromagnetic Stirring
Importance of Stirring the Molten Melt Homogenizing of molten melt Improving heat and mass transfer rates Reduce processing times Metallurgical restrictions
MS 3005 DESIGN PROJECTDiscussions - Electromagnetic Stirring
Current Practice: Gas Stirring Use of Inert gases 2 commonly used methods: gas valve semi permeable refractory material
Safety Height
Vacuum Pump OutletLadle Lid
Molten Steel
Porous Plug or valve for gas injection
Gas Injection System
Refractory Material and Ladle Wall
MS 3005 DESIGN PROJECTDiscussions - Electromagnetic Stirring
Disadvantages of Gas Stirring Additional processing step
Cost Inability to cut off gas flow Violent turbulence
Dangerous ejection of the melt
MS 3005 DESIGN PROJECTDiscussions - Electromagnetic Stirring
Proposed solution: Electromagnetic stirring Applied in continuous casting processes Non-invasive Adjustable stirring strength Simplifies furnace process Variable stirring pattern
MS 3005 DESIGN PROJECTDiscussions - Electromagnetic Stirring
Electromagnetic stirring: Working principle
Three Phase Power Supply
MS 3005 DESIGN PROJECTDiscussions - Electromagnetic Stirring
Electromagnetic stirring: 2 proposed solutions Installation of stirrers at top of furnace
Installation of stirrers at side of furnace
Proposed solution 1: Installation of Inductor at top of furnace
Bottom Ring
Molten Melt
Refractory Material and Ladle Wall
Furnace Lid
X
X
MS 3005 DESIGN PROJECTDiscussions - Electromagnetic Stirring
Energizing (toroid)
coils
Top Ring
Top View of Furnace Lid
MS 3005 DESIGN PROJECT Discussions - Electromagnetic Stirring
Proposed solution 1: Installation of stirrers at top of furnace
Electromagnetic transducer
Predicted Flow lines
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
MS 3005 DESIGN PROJECT Discussions - Electromagnetic Stirring
Proposed solution 2: Installation of stirrers at side of furnace
Electromagnetic transducers
Slag
Molten Metal
F
H
ν
Electromagnetic transducers
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
MS 3005 DESIGN PROJECTRecommendations
Installation of Heat Exchanger system
Improvements in Refractory Material
Refractory Cooling System
MS 3005 DESIGN PROJECTReview
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 . . .
MS 3005 DESIGN PROJECTQuestions & 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