WQD2011 – BREAKTHROUGH PROCESS IMPROVEMENT – SILVER WINNER – Dubal - Increase Current Efficiency of Potline 3 (PL-3)
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WQD2011 – BREAKTHROUGH PROCESS IMPROVEMENT – SILVER WINNER – Dubal - Increase Current Efficiency of Potline 3 (PL-3)

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Breakthrough Process Improvement case study – Silver Prize winning submission by Dubal during 3rd Continual Improvement & Innovation Symposium organized by Dubai Quality Group's Continual ...

Breakthrough Process Improvement case study – Silver Prize winning submission by Dubal during 3rd Continual Improvement & Innovation Symposium organized by Dubai Quality Group's Continual Improvement Subgroup to celebrate World Quality Day 2011.

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WQD2011 – BREAKTHROUGH PROCESS IMPROVEMENT – SILVER WINNER – Dubal - Increase Current Efficiency of Potline 3 (PL-3) WQD2011 – BREAKTHROUGH PROCESS IMPROVEMENT – SILVER WINNER – Dubal - Increase Current Efficiency of Potline 3 (PL-3) Presentation Transcript

  • Increase Current Efficiency ofPotline 3 (P/L-3)
  • Introduction Dubai Aluminium Company Limited (DUBAL)• Based in Jebel Ali, Dubai• Annual Production of > 1 million tonnes of aluminium• >4000 Employees• 8 Potlines consisting of 1573 aluminium cells• One of the few smelters in world to produce primary high purity metal for use in electronics and aerospace industries. 2
  • Project Background• Smelting converts alumina (ore) into aluminum metal through electrolysis process ― By using Direct Current (DC) ― Current Efficiency (CE) is the ratio of electrical direct current that results in actual metal production• Therefore, improvement in Current Efficiency remains one of the strategic objectives of any Aluminium smelter 3
  • Define Phase 1. Define 2. Measure 3. Analyze 4. Improve 5. ControlProblem Statement:• Potline 3 Current Efficiency is at 92.9% for H1 2009 which is below target since increase of current amperage to 200 kA,• resulting in decreased plant hot metal output.Project Target: Increase average Potline 3 current efficiency to target of 93.1% for 2010. 4
  • 1. Define 2. Measure 3. Analyze 4. Improve 5. ControlProject Scope:In Scope: Out of Scope:Potline 3 Process Parameters All other Potlines and ProceduresUnit of measurement: Potline 3 Current EfficiencyOperational Definition: Monthly Average CE from iRPMS (Smelting Database System) 5
  • 1. Define 2. Measure 3. Analyze 4. Improve 5. ControlTeam Charter: S.No Name Functional Role Project Responsibilities 1 Daniel Whitfield Manager – Projects D18 Team Leader. Snr Process Control 2 Andries Louw Engineer – Potrooms Data analysis and report making. 3 Mohamed Tawfik Boraie H.O.D: PC-CL Data analysis and report making. Snr. Planner – Prodn 4 Saif Mohamed Services Data analysis and report making. 5 Najeeba Al-Jabri Snr Manager Data collection and implementation of solutions. 6 Tariq Majeed Supt Potroom Operations Data collection and implementation of solutions. Act, Manager, Line 3, 7 & 7 Devadiga H.R. 9 Data collection and implementation of solutions. Snr. Manager - PC PR & 8 Maryam Al-Jallaf CL Data collection and implementation of solutions. Snr Process Control 9 Adam Sherrif Engineer – Potrooms Data collection and implementation of solutions. 6
  • 1. Define 2. Measure 3. Analyze 4. Improve 5. ControlStake Holder Model : ARMI Chart Approver Resource Member Interested PartyVP-Smelter Ops. Manager D-18 Andries Louw VP-Casthouse P/L-3 Superintendent Mohamed Tawfik Boraie VP-Marketing P/L-3 Technicians Saif Mohamed VP-Finance P/L-3 Operators Najeeba Al Jabri VP-Power & Desal. P/L-3 Process Technician Tariq Majeed Devadiga H.R. Maryam Al-Jallaf Adam Sheriff 7
  • 1. Define 2. Measure 3. Analyze 4. Improve 5. ControlProject Schedule 8
  • Measure Phase 1. Define 2. Measure 3. Analyze 4. Improve 5. Control• Current efficiency is key measure of process performance, and is regularly reported and monitored• It is difficult to be measured directly; therefore, inferred from actual metal production as below: Actual Hot Metal Production Current Efficiency = -------------------------------------- Theoretical Hot Metal Production• Three months average taken to ensure reasonable accuracy of the data 9
  • 1. Define 2. Measure 3. Analyze 4. Improve 5. Control Measurement System Analysis• Actual Metal Production =Total Weight of Metal delivered to Casthouse  Casthouse scales regularly calibrated and checked – Verified Calibration Records and is OK• Theoretical Metal Production = f (Amperage supplied by Power Plant)  Power Plant amperage supply tested on monthly basis – Found Ok• Review of existing plant system for measuring and reporting current efficiency showed no significant concerns over accuracy or precision 10 Measurement System – Found Satisfactory
  • Analyze Phase 1. Define 2. Measure 3. Analyze 4. Improve 5. Control Current Efficiency – Back Reaction Flow Chart Tool (s) Applied: Carbon Anode Current Dusting Spike bypasses electrolyte - Process Flow Diagram Cell Excessive Cell ExcessOverfeeds Sludge Becomes heat Unstable generation Low Bath Temp / High AlF3High Bath Al solubility in Al mixes Oxidation Low Temp / bath back into of Al to CurrentLow AlF3 increases electrolyte Al2O3 Efficiency CellUnderfeeds Excessive Anode Effects Possible causes for low Current Efficiency  Bath temperature/AlF3  AgeBath Height Too Low  Anode Effects  Alumina FeedingExcessive  Metal and Bath height Anode Airburn  Base Resistance Set Point (BRSP)  Noise/stabilityBRSP Set too low Cell ACD Reduced  Operational problems 11  Anode Problems
  • 1. Define 2. Measure 3. Analyze 4. Improve 5. Control Tool (s) Applied: Multi-Variable Linear Regression • In multi-variable linear regression, there are several independent variables up to N. Yi = βo + β1xi + β2xi + … where i = 1, …. N. Variable P-value • P-value shows the significance of the Bath Temperature 0.000 correlation (p-value of 0.05 = 95% AlF3 0.034 statistical significance or confidence). As Age 0.038 much P-value closer to 0.0 as much as the AEF 0.066 parameter is statistically significant TRSP 0.094 UF Duration 0.275 • Strongest correlation between bath Time Unstable 0.305 temperature and AlF3 (interrelated Dumps 0.451 variables) BRSP 0.537 Needs more investigation Metal Height 0.554 Bath Height 0.583• Age refers to life of reduction cell, Average Resistance 0.608 and hence it is an unassignable Volts 12 0.736 cause Noise 0.746
  • 1. Define 2. Measure 3. Analyze 4. Improve 5. ControlBath Temperature • Based on accumulative experience, it is proven that increase of 5oC in bath temperature can lead to 1% drop in current efficiency 976 Linear regression covers the relationship: 974 CE = (-0.2259 x bath temperature) + 309.13 972 (R2= 0.9543)Bath Tem perature (C) 970 968 966 964 962 960 84 86 88 90 92 94 96 98 100 Current Efficiency (%) 13
  • 1. Define 2. Measure 3. Analyze 4. Improve 5. Control Base Resistance Set Point (BRSP) • Relationship between BRSP/ACD and CE well established• Initial analysis looked BRSP and CE. • Some correlation < 14.75 µ No big correlation above ~14.75 µ 100 98 C u rren t E fficien cy (% ) 96 94 92 90 88 86 84 13.5 14.0 14.5 15.0 15.5 16.0 16.5 BRSP (micro-ohms) 14
  • 1. Define 2. Measure 3. Analyze 4. Improve 5. Control Poor Performing CellsTool (s) Applied: Cumulative chart 100% 90% Loss of Current Efficiency (% ) 80% 70% ~20% of cells represent 47% of total CE loss (Actual CE – Target CE). 60% 50% 40% 30% 20% 10% 0% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Number of Cell (%) 15
  • 1. Define 2. Measure 3. Analyze 4. Improve 5. Control Validated Root Causes/ Parameters  Root Cause 1: High Bath Temperature  Root Cause 2: Low Base Resistance Set Point (BRSP)× Age – Life of Cell: Difficult to address this cause 16
  • Improve Phase 1. Define 2. Measure 3. Analyze 4. Improve 5. ControlRoot Cause 1: Action plan for high bath temp and low CE pots Responsib Completion S. No. Action Point ility Date Adjust Bath Chemistry to improve Current Daniel 1 Dec. 2009 Efficiency Whitfield Current Efficiency Vs Bath Temp 95.0 968 y = 0.052x + 92 94.5 966 R2 = 0.6879 Current Efficiency (%) 94.0 964 Bath Temp (°C) 93.5 962 93.0 960 92.5 958 92.0 Bath Temperature Current Efficiency 956 91.5 Linear (Current Efficiency) 91.0 954 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 1 3 17 Week No. (2009 - 2010)
  • 1. Define 2. Measure 3. Analyze 4. Improve 5. Control Root Cause 2: Action plan for low Base Resistance Set Point (BRSP)• Established Control Limits so that BRSP not to be lowered below 14.5 µ without careful monitoring of the current efficiency• Critical BRSP Limit of 14.75 µ.• Increased the BRSP in low CE/BRSP cells• Example of “action plan for implementation” as a result of weekly meetings is given below Cell CE - 4wks CE - 16wks CE - 52wks Action Person Target Date 146 89.3 90.6 92.9 Increase BRSP by 0.1µcheck dumpweight AS/MSW 07/01/2010 198 90.3 91 92 Check BFT, Cu tab and dumpweight MSW 10/01/2010 271 92.5 91 91.9 Improving in last 28 days, no action 20/01/2010 149 89.3 91.1 93 Increase BRSP by 0.05µcheck Cu tab MSW 07/01/2010 117 92 91.2 90 Under Fe attack FM NA 102 93 91.3 91.5 Increase BRSP by 0.1µ AS 07/01/2010 • Average increase of 0.34 µ in 25 cells, 18 average increase of 1.5% CE
  • 1. Define 2. Measure 3. Analyze 4. Improve 5. ControlCurrent efficiency after improvement actions 95.5 201 Project 95.0 Start 200 94.5 199 Current Efficiency (%) Amperage (kA) 94.0 198 93.5 197 93.0 196 Monthly CE 92.5 195 3-month Running Average 92.0 Target CE 194 Amperage 91.5 193 07 -0 8 -0 8 l-0 9 -1 0 -1 0 -1 1 -1 1 v- n c n g b p No Ju De Ju Ja Au 19 Fe Se
  • Control Phase 1. Define 2. Measure 3. Analyze 4. Improve 5. Control System established for identifying and improving poor CE cells • List of poor performing cells in Potline 3 developed, updated and released on weekly basis for setting up proper action plans. • Work Instruction was developed to diagnose and action poor performing cells Before the project After the Project Summary for L3 CE, June 2009 Distribution of L3 CE, June 2009 Summary for L3 CE, Feb 2010 Distribution of L3 CE, Feb 2010 86 88 90 92 94 96 98 84 87 90 93 96Sample size 227 227 DifferenceMean 92.32 % 93.70 % +1.38%STD. Dev. 2.47 % 1.71 % -0.76% 201st Quartile 91.4 % 92.7 % +1.3%
  • 1. Define 2. Measure 3. Analyze 4. Improve 5. Control• Potline 3 monitoring on daily basis by Potline Engineers and Technicians through potroom monitoring and reporting system (Smelter Analytics)• Fine-tuning and changes to pots operating targets 21
  • Project Success & Benefits 94.2 94 Actual CE%C u rre n t E f f ic ie n c y ( % ) 93.8 Target CE%  Increased average 93.6 Potline 3 current 93.4 efficiency 93.2 93 92.8 92.6  Improved overall 92.4 Potline performance 92.2 2009, 2nd Half 2010, 1st Half 2010, Full year 2011, YTD  Project yielded re-occurring financial benefits of AED 1.47 millions per annum 22
  • Project ClosureLearnings and Roll-over:• Documentation of the project report• Use of statistical tools and gained better understanding w.r.t. Smelting Process• Roll-over of the successful initiatives from projects – to sister Potline 1 – Achieved similar increase in current efficiencyRecognitions:• All team members received gift and cash award• Project selected for Share Best Practice Session – to 200+ employees• Nominated for CII Symposium 23
  • Why this Project is an ExcellentImprovement Example?• Achieved one of the best current efficiencies in D-18 type of cell design (at higher Amperage of 200kA)• Combination of technical as well as statistical methods by using DMAIC approach• Project experiences rolled-over to Potline of similar cell design and resulted in improvements• Quantum contribution to company’s process performance• Environmentally beneficial 24
  • Thank you 25