Quick Dry Refractory Castables to Reduce the Downtime of Foundry Furnaces

Transcription

1 Quick Dry Refractory Castables to Reduce the Downtime of Foundry Furnaces Dirk HOLLAND CastTech 2012 Krefeld, 8th November 2012

2 Reduction of Refractory Consumption and the related constraints. Monolithic refractory developments during the last two decades have enabled Foundries to greatly reduce their refractory consumption The associated compromise is often the reduction in plant availability due to longer drying times Some foundries are even forced to invest in additional equipment which are ready lined and pre-dried to speed up the production start after maintenance work One area in which this compromise was very clear was the introduction of Low Cement (LC) and Ultra Low Cement (ULC) Castables for Channel Holding and Pressure Pouring Furnaces

3 Channel Furnace Lining The lining of Channel Holding Furnaces and - Presspours has to be well planned in advance and any necessary installation work must be undertaken during long non-production schedules like summer or winter break. Owing to the scale and complexity of these furnaces, these periods must typically have a duration of 17 to 23 days to allow for refractory setting, curing and drying All this has to be strictly controlled in order to achieve the full benefit of the technology In the event of unplanned maintenance this can only mean a great loss of production for the foundry

4 100 t Channel Furnace Lining Concepts Combined bricks Dry Vibratable Material ULC Castable Drying 5 to 6 days Drying 5 to 6 days Drying 8 to 10 days

5 The Quick Dry - Castable Concept In 2009 Calderys began to develop a completely new type of cement-free refractories, now known as the QD -castable range This new binding system, based on fine mineral components, allows drying times reduction up to 50%, depending on the type of furnace and raw material selection In addition to the reduced drying time after demoulding, no curing is necessary, so that the burner can be started immediately Due to the way QD evacuates water, it can be considered a safer product in terms of reduced explosion risks compared to cement bonded castables

6 Introduction: Quick Dry No Cement Castables QUICK DRY NO CEMENT CASTABLES Flexibility and Ease of installation No curing time Drying times heavily reduced

7 Technology definition: Quick Dry No Cement Castables

8 In Situ Steam Pressure Measurements Radiant Heaters 5000W C thermal insulation (ceramic blocks) 2mm specimen 30x30x12 cm 3 Pressure transducer Thermocouples Balance Massive bloc (30 x 30 x 12 cm3) Unidirectional and Fast heating (110 C/min hot face) Continuous vapour pressure & Temperature measurement

9 Cup test for Channel Holder QD No difference in corrosion between CALDE CAST UT 94 and CALDE CAST NT 92 QD

10 Customer Details Leading German Automotive Foundry ABP IRT 115 Channel Holding Furnace with 1,2 MW inductor Prime melting unit (feed furnace) Küttner unlined Cupola SG Base Iron (Feed Temperature 1540oC Tap Temperature 1480oC) Normal Lining CALDE CAST UT 94 Normal life 2-3 yrs (+450k tons iron) Reason for QD Castable Application Normal installation including wrecking and drying takes ~ 23 days Customer demand is for a 17 days maximum QD Option offered and accepted following success in Press Pour Furnace Repair November 2010

11 Lining Design BATH -Wall Insulation Plate: 10 mm ceramic fibre board Insulation Lining: 100 mm CALDE CAST MW STRONG LITE Safety Lining: 50 mm CALDE GUN M 32 Hot Face Lining: 279 mm CALDE CAST NT 92 QD SPOUTS & COVER LINING Detachable Spouts fully installed with CALDE CAST NT 92 QD INDUCTOR Front Lining: CALDE MIX M S 86 BTI

12 Fitting of Ceramic Felt

13 Gunning of Back Lining and Surface Finishing

14 Former Preparation

15 Pump Casting of CALDE CAST NT 92 QD

16 Former Removal CALDE CAST NT 92 QD

17 Burner Assembly Placement of Thermocouples and air ejectors

18 A good Burner and Supervision are Key for Success

19 Installation Details BATH LINING (Excluding Spouts and Cover) Insulation Layer ~7.5 t CALDE CAST MW STRONG LITE Safety Layer ~7.5 t CALDE GUN M 32 Hot Face Layer 36.8 t CALDE CAST NT 92 QD QD CASTING WATER (Recommended Range = 4.8 to 5.4%) 5.4% 5.0% 4.75% Total Water Installed = 1780 Litre = 4.84% QD CASTING TIME (2 x 800kg Pump) 6200KG per Hour

20 Comparison of typical Heating Curves IRT 125 CALDE CAST NT Channel 92 QD Furnace versus 160 ton Example CALDE CAST UT days saved CALDE CAST NT 92 QD Temperature, C CALDE CAST UT Cement bonded castables (380mm thickness) QD NCC (> 380mm thickness) time, hrs

21 1 Week Production Saved QD INSTALLATION ULCC INSTALLATION OBJECTIVE ACHIEVED!!!

22 QD Range for Foundry Ladles CALDE CAST NB 82 QD (for Iron & Steel) Bauxite based Medium densitiy: 2,82 kg/dm³ high corrosion and abrasion resistance (6,2 cm³ following ASTM) High Cold Crushing Ctrength Very good thermal shock resistance CALDE CAST NA 55 QD (for Iron) Andalusite based low density: 2,51 kg/dm³ >> good thermal insulation Very good thermal shock resistance CALDE CAST NM 62 QD (for Iron) Mullite based Low density: 2,55 kg/dm³ >> good thermal insulation Good corrosion and abrasion resistance CALDE CAST NT 92 QD (for Steel) Tabular Alumina based High density: 2,96 kg/dm³ Excellent corrosion resistance High Cold Crushing Strength

23 Time Saving The curing - air setting is shorter than LCC, about 50%-75% shorter, hourscan be saved Immediate heating after former removal is possible. This means the ladle can be set into drying much quicker Drying cycles are about 60% shorter, and up to 48 hours can be saved compared to Low Cement Castables

24 Energy savings for Ladles thanks to QD Range usage Figures show some example on ladles traditionally lined with LCC and alternatively with QD castables and the significant savings in time and energy. Hours of initial sintering/heat up LCC QD NCC 2 ton transfer ladle ton transfer ladle ton - treatment ladle ton pouring ladle ,5 ton transfer ladle hours saved!

25 Repair of ladle bottom in cold or warm condition by using the QD range Possibility to repair bottom in a cold condition or with residual heat in, can be done and gives the advantage to get back into production in very short time, the drying can be minimised and the repair shows very good result also with respect of the handling and to stressed heat up/sintering. Picture shows a repair in a cold ladle. The ladle can be brought in the preheating station after 4-6 hours and be fired at C/hour with very good result.

26 Advantages of QD Castables in Foundry ladles Less sensitive for thermal cycling Safe drying cycles Flexible in working temperature intervals Easy to repair QD Less demanding preheating Short curing time and drying cycles Lower energy consumption during drying

27 Conclusions AdvantageswiththenewQD -rangeprovenonthefield: Energy savings during dryout / sintering Shorter cycles = shorter turn around time Up to 60 % time saving = up to 60 % gas/energy consumtion Installation advantage No curing time = shorter turn around time Easy installation Favourable thermal shock resistance Advantages for preheating and cold tapping Less sensitive to thermal cycling Leads to prolonged life length Faster turn around: Refractory installation times can be reduced by several days resulting in higher ladle availability and flexibility Overall improved performances!

28 Summary The success of recent furnace projects clearly demonstrates the real benefits of the new QD technology, which has been applied in many variants. The number of references is increasing daily in all areas of the foundry: Press Pour Furnaces, Channel Holding Furnaces, Cupola, CIF, Ladles, and Launders etc. No special equipment or skills are required for the installation and drying of QD materials beyond those required for conventional castables. Savings can be achieved in both downtime and fuel consumption