Bottom Bubbling 19TH AUG 2014

Bottom Bubbling

TIME LINE PAUL WURTH COUPLINGS.

INHERENT PROBLEMS. POOR MAINTENANCE. DIFFICULT ENSURING

A CONNECTION BETWEEN MALE AND FEMALE COUPLINGS. KEEPING THE STEEL CAR TOPS CLEAN. SEALS DROPPING OUT.

NOT RELIABLE, OPERATORS HAD NO CONFIDENCE WITH THE SYSTEM.

EXPENSIVE TO RUN WITH A POOR PERFORMANCE.

BEDA COUPLING USED AS AN EMERGENCY BACKUP.

NO MOVING PARTS.

EASY TO INSTALL.

INEXPENSIVE COMPARISON TO OTHER SYSTEMS.

RELIABLE.

MALLY AVAILABLE TO INSTALL THE SYSTEM AND MODIFY AS REQUIRED TO MEET OUR PLANT

REQUIREMENTS.

K.I.S.S.

Development.

TRAINING.

ACCESS AND GATE SYSTEMS.

PRE-SHIFT CHECKS FOR PRESSURE AND FLOWS.

RECORDING AND DATA MONITORING SYSTEMS.

PLUG AND LADLE CHECKS FOR BEST PRACTICE.

Development 2

• MODIFICATIONS ON THE 20M LEVEL.

• REDUCE FLUSHING LANCE USAGE BY 50%. APPROX SAVING £ 400,000

• INSTALLED BOTTOM BUBBLING SYSTEM ON THE LMF.

• MODIFICATIONS.

• LADLE 36 TWIN FEED.

MAJOR SUCCESS

9 LADLES, 1508 QUALITY

ROUTED THROUGH TANK, LMF.

ALL LADLES BUBBLED, SEVERAL DURING A HEATING PROGRAM.

CUSTOMER VERY HAPPY WITH THE END PRODUCT.

FUTURE

HYBRID PLUGS WITH STAINLESS STEEL CANS.

FACE WASHING FACILITY TRIAL UNIT EARLY SEPTEMBER .

GENERATING KNOWLEDGE WITH THE LMF PRODUCTION.

• UP DATE ON LMF OPERATIONS

PURGE PLUGS AT SSI UK

October 15 12

• Pressure test the system a minimum of once per shift preferably at the start of the shift. Ladles & Secondary.

• At the Tank – Currently not in service.

PURGE PLUGS AT SSI UK

• Common issues

• If the connections are made and the following is apparent.

• Low flow high pressure - blocked plugs or lines.

• High flow low or no pressure – hole in pipe work/Leaks.

• Pressure test the system if one of the above occurs.

October 15 13

PURGE PLUGS AT SSI UK

• We were operating with mild steel cans on the purge plugs. These are easily oxidise and are unsuitable for face washing.

• Stainless steel cans are now available on the hybrid purge plugs. We are in the process of formulating a plan to allow face washing.

• Traffic light system for face washing. Flow system for face washing, red light low or no flow. Green light minimum required flow achieved. This reduces the possibility of damage due to face washing.

• Just need time scale for traffic light system, then plan of action to introduce face washing.

October 15 14

Technical

FLOW PATTERNS

October 15 16

32

Flow Pattern: Bottom- versus Lance- purging

Bottom Lance

„Dead Area“

Source: 2013 04 VDEh Steel Academy Refractory Technology II, Ladle Metallurgical Tratments & Refractory Stress for a Steel Teeming Ladle Refractory Technology1

Flow Pattern Inductive or RH-Degasser

MIXING EFFICENCY

October 15 17

Use of a scalar transport equation to determine mixing efficiency.Procedure:The vessel is virtually devided into two parts. The value of the lower volume is set to 1, the upper is set to 0. Due to stirring by purging the two volumes will exchange their scalar value. Complete mixing takes place when a value of 0.5 is reached in each part.

MIXING EFFICENCY

October 15 18

PURGE PLUGS AT SSI UK

• Micro stir 10m3 - removal of inclusions.

• Heating of ladle – Use judgement we are all still learning.

• Homogenisation – Definition of good bubble?

• Alloy additions – Again use judgement but a more vigorous bubble required to get alloys in and mixed.

• We are all still learning with bottom bubbling.

October 15 19

VISUAL REFERENCES

October 15 20

Micro bubble

Homogenisation

Lidding of Ladles.

October 15 21

Ladle Number Ladle lidded or on gas? Ladle time on car Temp on car Ladle lidded on car? Waiting Time - 10 minutes W. Time - 15 minutes W. Time - 20 minutes Temperature Lost Start of tap time Allocated vessel

21 LID 12:00 782 NO - - 12:22 - 675 107 12:41 C

7 LID 13:35 648 NO - 13:46 - 595 - 53 13:57 C

35 LID 14:50 875 NO - 15:05 - 830 - 45 B

21 LID 15:15 865 NO - - - - 15:27 B

27 LID 16:25 635 NO - - - - 16:37 B

23 LID 09:45 720 NO 705 - - 15 09:58 B

7 LID 11:30 630 YES 625 625 - 5 11:53 B

9 LID 12:55 720 NO 700 685 670 50 13:26 B

23 LID 14:20 790 NO - - - - 14:27 B

7 LID 15:10 700 NO 690 - - 10 15:35 C

9 LID 14:40 780 NO 760 739 - 41 16:57 C

Information collated from two shifts showing the

temperature loss for different scenarios

Temperature loss after ten minutes – 10 to 15 degrees (with

no lid on the car)

Temperature loss after fifteen minutes – 40 to 50 degrees

(with no lid on the car)

Temperature loss after twenty minutes – Could potentially

be up to 110 degrees lost (with no lid on the car)

Taking the first example – temperature loss after twenty

minutes – 107 degrees and then waited out for another

twenty minutes before the start of the tap time – potentially

another 100 degrees loss

One heat was lidded on the car – only lost 5 degrees whilst

waiting

PROCESS CONTROL - TEMPERATURES