Slotted anodes project

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Slotted anodes project

  1. 1. | Slotted Anodes
  2. 2. | Corporate Overview – Vedanta Resources Plc. 1 Vedanta Aluminium Ltd is an associate company of the London Stock Exchange listed, FTSE 100 diversified resources group Vedanta Resources Plc. Originally incorporated in 2001, VAL is a leading producer of metallurgical grade alumina and other aluminium products, which cater to a wide spectrum of industries. ABOUT Vedanta Aluminium Limited, Jharsuguda VAL has invested in a 0.5 MTPA aluminium smelter and 1215 MW captive power plant supported by highly modern infrastructure at Jharsuguda, Orissa. In addition to this, construction of 1.25 MTPA aluminium smelter expansion project at Jharsuguda is under process. The company intends to expand the fully integrated aluminium smelting capacity to around 2.75 MTPA in near future. Jharsuguda is also the site of the 2400 MW Independent Power Plant being set up by group company Sterlite Energy Ltd to meet the growing demand for power from both urban and rural consumers.
  3. 3. | Process Flow – Aluminium Production 2
  4. 4. | 3 Prebake Pot
  5. 5. | To produce 1 kg of aluminium the following amounts of raw materials are needed: 2 kg 0.415 Kg 20 g 2 g Alumina Carbon Aluminium fluoride Cryolite + = 13 - 15 kWh 1 kg Electrical energy Aluminium + + + 4 kg bauxite + CO2 + CO + HF + CF4 + Coke + Other gases Raw material Consumption – Production of Aluminium
  6. 6. | Cost Sensitivity 5 2980.6  Power is the most important cost driver.  Pot Voltage can be decreased to decrease the DC power consumption
  7. 7. | Reasons for High Voltage drop across the Electrolyte 6  During Aluminium smelting, CO2 gases are evolved.  CO2 bubbles get accumulated under the anode – forms a high resistance film.
  8. 8. | Impact of reduction of bubble resistance. 7  Minimizing of the anode gas bubble voltage drop - One of the most economical ways to reduce energy consumption.  Modification of the anode surface/Introducing slots can effectively reduce both the bubble voltage drop and anode overvoltage Anode Surface Slots Reduces Energy Consumption and Green House Gas emissions
  9. 9. | 8 Risk Assessment – Press Forming Disadvantages  Makes green anodes more fragile  Variable anode quality (decrease in anode density, increase in air permeability -  tendency to carbon dust, Spikes which ultimately leads to reduction in CE  Limitation to increase the slot height.  Wide slots are made using the slot plates.  Packing Coke tends to clog the slots, requiring more cleaning.  Reduces the mass of carbon and the life of anodes  Scrap Generation increases in GAP and bake oven. Advantages ▪ Negligible Capital and Operating costs Crack initiation from a slot in a green anode, damaged during handling Anode breakage influenced by slot location. Excessive consumption at slots during cell operation. Slot slumping during baking Spikes during Cell Operation POSSIBLE FAILURE MODE
  10. 10. | Slotted Anode Configuration 9 2 Longitudinal Slots with variable Slope
  11. 11. | Conceptualization & Design Engineering 11  Anode surface slots were not present in the initial design by O&M.  In house design engineering - Calculate the appropriate slot height and slope  Straight slots may be a problem in gas evacuation.  Design of experiment and data analysis was performed  Result was slanted slots are better in case of gas evacuation  Press forming which is the most common method – sometimes lead to the formation of Low density green anodes - results to excess coke dusting.  recipe for preparation of green anodes analysed with varied anode density.  Optimum Density and minimum coke dusting - Specific anode preparation recipe formulated  Design modifications have been made in the anode forming equipment (Vibro- compactor). Slot blades of variable height and slope was fabricated into the equipment.  Packing coke is used as the heat transfer mode in bake oven when green anodes are heated to form baked anodes which if not removed will lead to excess coke dusting in pots  Slot cleaning machine was installed in bake oven to remove this packing coke.
  12. 12. | Trial & Full Implementation - Impact on Energy consumption 12 14547 14587 14521 14422 14411 14608 14551 14376 14344 14303 14282 May-12 Jun-12 Jul-12 Aug-12 Sep-12 Oct-12 Nov-12 Dec-12 Jan-13 Feb-13 Mar-13 Normal Anodes used Normal Anodes  Slotted Anodes – trail Slotted Anodes – After Stabilization Period Normal Anodes  Slotted Anodes – Full Implementation stabilization Period 322.5 324.0 323.3 324.1 324 324 324.2 324.55 325.4 325.66 325.89 May-12 Jun-12 Jul-12 Aug-12 Sep-12 Oct-12 Nov-12 Dec-12 Jan-13 Feb-13 Mar-13 Normal Anodes used Normal Anodes  Slotted Anodes – trail Slotted Anodes – After Stabilization Period Normal Anodes  Slotted Anodes – Full Implementation stabilization Period Consumption increased due to external factors
  13. 13. | Slotted Anode Trial (Line 1-Section 7) Trial period – 27th July to 25th Oct Benefit realized • Reduction in Pot Voltage - a net reduction of 11 mV • Reduction in AEF - net reduction of 0.19 no./pot day. • Reduction in Noise - a net reduction of 1.66 mV. • Net saving in Power Consumption of 35.2 kWh/MT. (190 MU/Year) • Reduction in PFC & CO2 Emissions – Net reduction by 50% in trial section All benefits shown are excluding the benefits realised in section 8.
  14. 14. | Pot room Parameter Analysis for Slotted Anodes on Full line Implementation Implementation period – 23rd Oct’12 to 13th Jan’13 Benefits observed • Reduction in Pot Voltage - a net reduction of 21 mV. • Reduction in AEF - 0.09 no./pot day. • Reduction in Noise - a net reduction of 3.9 mV • Net saving in Power Consumption of 67.3 kWh/MT. (344 MU/Year) • Amperage Ramp – Net increase of 3.1 KA. Production Volume Increased by 0.106 T/Day • Reduction in PFC & CO2 Emissions – Net reduction by 30% in whole pot line.
  15. 15. | Intangible Gains - Impact on Environment 15  Conservation of non renewable resources of energy.(Coal & Oil)  Power consumption reduced by 344 MU/Year.  Emissions of green house gases (PFC) has been reduced by 50%.  Manpower productivity has improved.  Anode effect frequency has been decreased to a large extent - productivity has increased.  Reduction trend was seen in consumption of green poles  AEF had reduced by 50%.  Elimination of Safety and health hazard  reduced anode effect frequency and immediate auto quenching methods - operators are now less exposed to hot furnace conditions.
  16. 16. | Future Readiness of Slotted Anodes 17 Increasing Slot Depth Slot Cutting Other Energy Reduction initiatives
  17. 17. | Other Smelters Slot Heights 18 Benefits of Slotted Anodes enjoyed by other smelters: • For a slot depth equal to half the anode’s life, the voltage benefit is estimated between 35-66mV for Rio Tinto Aluminium managed plants.[2] • Voltage reduction of 45mV/pot by implementation of Slotted Anodes (HINDALCO, Renukoot)[3] It can be seen that increasing slot depth from 10 to 20cm is worth approximately 20mV in reduced bubble resistance Smelter Slot Height (mm) Anode Height (mm) % Slot Height NALCO * (Press forming) 120,100 560 21.40% HINDALCO 180,160 645 27.90% BALCO 182,176 580 31.40% ALBA 215,190.5 650 33.10% MOZAL 250,230 650 38.50% EMAL (Phase-1) 250,200 650 38.50% Hill Side 290,270 650 44.60% EMAL (Phase-2)* 320,300 685 46.70% VAL (Press Forming) 207.5,200 575 36.00% VAL (Slot Cutting) 300,280 575 52.00% * Note: NALCO and EMAL Phase-2 are using On line Slot cutting technique
  18. 18. | 19 Online Slot Cutting High Capital Cost Life time of Saw Blade Advantages  No Variation in anode quality  Higher Slot height than press forming  More slots possible, more closely spaced  Increases active area Disadvantage  Initial investment on Slot Cutting Machine and operating cost  Life time of a saw blade is a potential problem (45000 Anodes per blade is reported as per Brochot – Supplier of Machine to NALCO)  Handling and recycling of granular carbon dust.  Scrap Generation increases in bake Oven. On Line Anode Slot Cutting
  19. 19. | 20 THANK YOU !!!!!

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