ANNUAL REPORT UIUC, June 12, Temperature evolution in the spray zones: plant measurements and CON1D prediction

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1 ANNUAL REPORT 2007 UIUC, June 2, 2007 Temperature evolution in the spray zones: plant measurements and COND prediction Huan Li (Ph. D. Student) & Brian G. Thomas Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign Objective Develop accurate model of spray cooling (for use in online control, etc.) Incorporate Leidenfrost effect into spray cooling model Test the accuracy of the Goodrich pyrometers at Riverdale caster Compare COND model with measurents Study transient phenomena during spray water changes University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 2

2 Outline COND model description Plant measurements at Riverdale Comparison of original model with Riverdale measurements Compare improved model (with Leidenfrost) for Riverdale and Nucor cases Nucor experiments: transient case Conclusions University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 3 Continuous casting of steel COND model -ccc.me.uiuc.edu University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 4

3 COND model Simulation domain I shape domain -K. Zheng, concontroller user s manual -cond8.0 user s manual University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 5 COND model Heat transfer coefficient in Spray Zones Spray nozzle cooling Radiation Conducton to the roll ( ) h = A C Q b T n spray water spray 2 2 ( )( ) h = σ ε T + T T + T rad _ spray steel sk amb K sk amb K Natural convetion h = conv W/m K Water Flux Temperature of spray cooling water Ambient Temperature Fraction of heat extraction to rolls Nozaki A*C=0.3925, n=0.55, b= University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 6

4 COND model Heat transfer coefficient in Spray Zones 5 5 Slab Roll Spray nozzle Radiation heat transfer coefficient, h_rad Spray heat transfer coefficient, h_spr Roll heat transfer coefficient, h_roll Distance (mm) h (W/m^2K) ) University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 7 Leidenfrost effect q y p y p p q p DROPLET Ts-00 ( C) VAPOR NUCLEATE BOILING Bubbles form and the droplet evaporates slowly HIGHER SURFACE TEMPERATURE TRANSITION BOILING Marked by violent sizzling. Droplet boils away explosively as soon as it hits the surface FILM BOILING The droplet floats quietly on a vapor cushion, and evaporates very slowly University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 8

5 Considering Leidenfrost by h-multipliers h-multipliers Temperature C 050 University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 9 Spray coefficient C zone no. zone zone 2 zone 3 zone 4 zone 5 C (used in Riverdale without Leidenfrost effect) C (used in Riverdale and Nucor with Leidenfrost) University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 0

6 Surface Temperature Down Strand Surface Temperature ( o C) time (s) mold spray zone (rolls) No. No.5 supporting rolls no spray No.6 No Distance below Meniscus (mm) Example: Riverdale thin slab caster m/min University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi Zone No. () (2) (3) (4) (5) (6) (7) (8) (9) (0) () (2) Zone starts ( ) COND Zone No. Zones in COND file at Riverdale caster # of rolls University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi roll radius(m) End of last spray zone (mm) Spray zones No spray

7 Pyrometer locations Trial (Sep): pyrometer #, #2&shear pyrometer Trial 2(Ovt9): bend&shear pyrometer Trial 3(Mar2): two-color-pyrometers, bend&shear pyro Two-color-pyrometers #, #2 and #3 Pyrometer #2 Pyrometer # bend pyrometer shear pyrometer University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 3 Casting conditions Parameter case case2 case3 case4 case5 Case6 Time 2:07-3:40 Sep 3:50-4:40 Sep 9:0-9:38 Oct9 9:45-0:25 Oct9 3:20-5:00 Mar2 6:30-8:00 Mar2 V cast m/min T pour C T spray C Spray water flow rate L/min/row Zone Zone Zone Zone zone University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 4

8 Casting conditions Same conditions for case~6 Slab thickness (mm) Slab width (mm) Steel composition (%): C 0.2, Mn 0.7, S 0.005, P 0.009, Si 0.04, Cr 0.03, Ni 0.03, Cu 0.03, Mo 0.02, Ti 0.002, Al 0.035, V 0.006, N University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 5 Pyrometer measurement: case and 2 Temperature (F) University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 6

9 Pyrometer measurement: case 5 and 6 Two-color-temperature T: calculated by # &#2 University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 7 Pyrometer measurement: case 5 and 6 Two-color-temperature T2: calculated by #2 &#3 Measured temperature goes up from case5 to case6 University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 8

10 Simulation and comparison case COND: Shell Surface Temperature case(sep-) shear pyrometer pyrometer # pyrometer # University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 9 case 2 Simulation and comparison COND: Shell Surface Temperature case2(sep-) shear pyrometer pyrometer # pyrometer # University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 20

11 Simulation and comparison case 3 case3(oct9) bend pyrometer shear pyrometer University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 2 Simulation and comparison case 4 case4(0ct9) bend pyrometer shear pyrometer University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 22

12 Simulation and comparison case 5 COND: Shell Surface Temperature case5(mar-2) Riverdale installed pyros Goodrich two-color T Goodrich two-color T University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi close up comparison with two-color-temperature Φ65 case5(mar-2) Goodrich two-color T Goodrich two-color T2 total heat transfer coefficient Spray impinging region Φ h (W/m^2K) University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 24

13 Simulation and comparison case 6 COND: Shell Surface Temperature case6(mar-2) Riverdale installed pyros Goodrich two-color T Goodrich two-color T University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi close up comparison with two-color-temperature Φ65 case6(mar-2) Goodrich two-color T Goodrich two-color T2 total heat transfer coefficient Spray impinging region Φ h (W/m^2K) University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 26

14 Comparison of case 5 and 6 COND: Shell Surface Temperature case5(mar-2) case6(mar-2) University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 27 Simulation and comparison The predictions are generally reasonable, being C-43 C higher than pyrometers, (except for case3 at the shear position and case4). Increasing water flow rate (by ~25%) from case 5 to case 6 caused an increase in measured strand temperature (of 30 C in the strand, 3 C at the bend, and 3 C at the shear) Not expected in the model. The model predicted decreases of 50 C, 5 C, and 3 C. Reasons: a gas / water film barrier that decreased heat extraction with increasing water flow. Heat extracted by different rolls might vary with casting conditions such as water flow rate. Further investigation of accuracy of pyrometer measurements is also recommended. University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 28

15 Consider Leidenfrost for Riverdale case ~2 COND: Shell Surface Temperature case(sep-) shear pyrometer pyrometer # pyrometer # COND: Shell Surface Temperature case2(sep-) shear pyrometer pyrometer # pyrometer # University of Illinois at Urbana-Champaign Metals Processing Simulation Lab Distance below meniscus (mm) HLi 29 Consider Leidenfrost for Riverdale case 3~4 case3(oct9) bend pyrometer shear pyrometer case4(0ct9) bend pyrometer shear pyrometer University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 30

16 Consider Leidenfrost for Riverdale case 5~6 COND: Shell Surface Temperature case5(mar-2) Riverdale installed pyros Goodrich two-color T Goodrich two-color T COND: Shell Surface Temperature case6(mar-2) Riverdale installed pyros Goodrich two-color T Goodrich two-color T University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 3 Consider Leidenfrost for Riverdale case 5~ close up comparison with two-color-temperature case5(mar-2) Goodrich two-color T Goodrich two-color T2 total heat transfer coefficient University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi close up comparison with two-color-temperature 0 case6(mar-2) Goodrich two-color T Goodrich two-color T2 total heat transfer coefficient h (W/m^2K) h (W/m^2K)

17 Pyrometer locations at Nucor Pyrometer Pyrometer 2 Pyrometer 3 Pyrometer 4 Pyrometer 5 University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 33 Pyrometer locations at Nucor Model Name and Number Length Focus spot size Location of Pyrometer from meniscus Location of Pyrometer 2 from meniscus Location of Pyrometer 3 from meniscus Location of Pyrometer 4 from meniscus Location of Pyrometer 5 from meniscus Modline 5, 5R-4, 4M5# mm 5.5 mm mm mm 8380 mm 385 mm 3970 mm University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 34

18 Experiments at Nucor Case Number Time 0/3/ /3/ /6/ /3/ Steady/ Transient Steady Steady Steady Transient University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 35 Casting conditions for Nucor case ~3 Parameter Time of Experiment Casting Speed Spray Pattern No. Pouring Temperature Caster Composition (%) case 9:50-0:0 Jan3, m/min o C North case2 5:35-6:0 Jan3, m/min o C South case3 9:45-0:2 Jan3, m/min o C North C 0.247, Mn.09, S 0.009, Al 0.039, Ca 0.008, Si 0.75, P 0.04, Cu 0.087, N (leco) University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 36

19 Consider Leidenfrost for Nucor case COND: Shell Surface Temperature case(nucor) pyrometer # pyrometer #2 pyrometer #3 pyrometer #4 pyrometer # University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 37 Consider Leidenfrost for Nucor case 2 COND: Shell Surface Temperature case2(nucor) pyrometer # pyrometer #2 pyrometer #3 pyrometer #4 pyrometer # University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 38

20 Consider Leidenfrost for Nucor case 3 COND: Shell Surface Temperature case3(nucor) pyrometer # pyrometer #3 pyrometer #4 pyrometer # University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 39 Transient case 4 at Nucor Parameter Time of Experiment Casting Speed Spray Pattern No. Composition of Elements (%) Caster Pouring Temperature Jan. 3, hrs. 42. ipm (3.6 m/min) (0.06 m/s) 4 to 7 C 0.247, Mn.09, S 0.009, Al 0.039, Ca 0.008, Si 0.75, P 0.04, Cu 0.087, N (leco) South o C Case 4 University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 40

21 Case 4 Spray Pattern Change University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 4 Case 4 Spray Pattern Change Pyrometer mm University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 42

22 Conclusions COND model with Leidenfrost effect matches well with both Riverdale and Nucor caster measurements Transient behavior seems to be modeled reasonably University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 43 Ongoing work Further calibration use better h-multipliers for incorporating Leidenfrost effect change flat top heat transfer profile to wedge top profile Study transient cases with spray pattern and casting speed variation University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 44

23 Acknowledgements Continuous Casting Consortium Members (Nucor, Postech, LWB Refractories, Algoma, Corus, Labein, Mittal Riverdale, Baosteel, Steel Dynamics) National Science Foundation GOALI DMI (Online) Other Graduate students, especially K. Zheng, B. Petrus University of Illinois at Urbana-Champaign Metals Processing Simulation Lab HLi 45