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Breakthrough Process Improvement case study submitted by Emirates Aluminium 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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2 2
Introduction
Emirates Aluminium Company (EMAL) is a strategic joint venture between
aluminium producer Dubai Aluminium Company (DUBAL) and Mubadala
Development Company (MUBADALA).
The company’s facility at Al Taweelah, halfway between Abu Dhabi and Dubai,
EMAL’s present work force is 2500 employees on rolls.
EMAL will be largest single site Aluminium smelter complex at the end of phase-
2 with a capacity of 1.3 Million Ton of aluminium per year
EMAL produces a wide range of high grade semi finished aluminium products,
like low profile sow , high profile sow, standard ingots, billets, sheet ingots etc.
Supplying to worldwide customers.
3 3
Aluminium Smelting
Process
Power
Plant
Port
DC Power
Alumina
Molten Aluminium
4 4
Project Charter
Anode effect frequency was increasing drastically during and after breakdown in Gas treatment center/ Pot feed system. Which was creating disturbances in Reduction pots.
Huge number of people were involved in quenching the anode effects and stabilizing the pots.
Heavy PFC generation during anode effects, not safe for
employees and environment.
Problem
faced by
EMAL
A
B
C
5
Project Charter
1.The Goal Statement.
To reduce the impact of Pot feed system and Gas treatment center stoppage
during breakdown and power outage on Reduction Pot performance by
improving Alumina quality supplied to pots
2.The teams involved:
5
Teams Roles
Process Control Controlling and monitoring
Operation ( Pot feed system & Pot line) Operating the system
Maintenance Maintaining the system
6
Project Charter
6
• Maintaining the equipment's in good working condition
• Controlling and monitoring the process and equipment's
• Manufacturing Aluminium from Alumina
• Supplying Alumina to Pot lines
Pot feed system
operations
Pot lines Operations
Maintenance Process Control
3.Stakeholders model:
7
Project Charter
7
Problem Identificatio
n
Selection of solution
Trials Plant wide
implementation
Controls and
monitoring
Oct - 2010 April-June 2011 Jan-March 2011 Dec - 2011 June-July 2011
4.The Project Timelines
8
Measure
8
2B039
0.0
10.0
20.0
30.0
40.0
50.0
60.0
10/13/2010
4:48
10/13/2010
9:36
10/13/2010
14:24
10/13/2010
19:12
10/14/2010
0:00
10/14/2010
4:48
10/14/2010
9:36
10/14/2010
14:24
Time
-32
5 %
Feeder 2 Feeder 4
2A144
0.0
10.0
20.0
30.0
40.0
50.0
60.0
10/13/201
0 4:48
10/13/201
0 9:36
10/13/201
0 14:24
10/13/201
0 19:12
10/14/201
0 0:00
10/14/201
0 4:48
10/14/201
0 9:36
10/14/201
0 14:24
Time
-325
%
Feeder 2 Feeder 4
2B045
0.0
10.0
20.0
30.0
40.0
50.0
60.0
10/13/2010
4:48
10/13/2010
9:36
10/13/2010
14:24
10/13/2010
19:12
10/14/2010
0:00
10/14/2010
4:48
10/14/2010
9:36
10/14/2010
14:24
Time
-32
5 %
Feeder 1 Feeder 3
Line-2 Sec -4 Line-2 Sec -8
During pot feed system stoppage Fines content increases in Alumina
9
Measure
9
Line-2 Sec -4 Line-2 Sec -8
• During and after Pot feed system stoppage anode effect frequency increases
drastically .
• This indicates whenever Fine contents increases in alumina it creates
anode effects and disturbs the pot performance.
10
Analyze
A.Problem Statement
• Avoid disturbance in reduction pots by reducing the
Anode effects frequency in reduction pots from 0.4
AE/Day to less than 0.15 AE/Day during and after
breakdown or stoppage of pot feed system and GTC.
• Reduce the fines content in Secondary alumina from 40
% to less than 20% by avoiding segregation of alumina
inside Secondary alumina silo, transport air slides, and
reduction pots.
10
11
Analyze
B. Validation of the Root cause
11
Alumina entering
to Pot hopper/ Silo
Finest particles
settles out and
accumulates here
Alumina entering
to Pot hopper/ Silo
Finest particles
settles out and
accumulates here
•During silo and pot hopper filling fine
alumina gets segregated and
accumulates along the wall of pot
hopper and alumina silo. This is due to
the static, near to full level operation of
the silo and hopper. These areas may
have become inactive by the cohesive
nature of reacted alumina when left
static over long periods of time.
•During any breakdown in GTC or Pot
feed system these fine material starts
entering in to the pot and causes anode
effects which affects pot performance.
12
Improve
12
A. Solution Criteria: The solution should allow the alumina silo to vary between 40-
80% level
The solution should allow the pot to vary 75-100% level
B. Solution evaluation: Trial conducted for one pot for evaluating purpose by stopping
alumina filling manually after every 6Hrs duration .During trial no
change in quality of alumina observed.
13
Improve
C. Solution Selection Process
13
Reacted Alumina Silo
Rotary Feeder Cyclic
Stopping Interval
Through PLC Logic
Modification
Automatic Pot
Hopper Exercising
and Alumina Silo
Feed Modifications
14
Improve
C. Solution Selection Process
14
Sr.No Criteria
Ranking
Engineering
Solution In-House
Solution
1 Easy implementation 1 5
2 Cost involved 1 5
3 Time to implement 2 4
4 Maintenance and control 1 4
5 The results 5 4
Silo Level Trend
85%
83%
Implementation
Reacted Alumina Silo Level Trend
X
Y
85%
35%
Implementation
Reacted Alumina Silo Level Trend
X
Y
85%
35%
Implementation
18
Implementation
18
Reacted alumina rotary feeder is being operated with a continuous 6-hour
cyclic stopping interval.
19 19
Plan
Do Check
Action Results of Trial
2A105 9.9 2A142 39.1
2A094 11.8 2A144 53.4
2A117 10.9 2A146 49.5
2A128 11.4 2A189 18.6
2A136 12.8 2B01 53.4
2A146 13.9 2B039 49.3
2A152 13.4 2B045 38.5
2A164 12 2A142 40.7
2A172 12 2A144 44.1
2A189 12.2 2A146 39
Average 12 2A189 20.2
2B01 35.1
2B039 49.2
2B045 48.6
Average 41.3
Pot No % Fines
Comparison of % fines in the hopper after stoppage of pot feeding system
Pot No % Fines
After Potfeed system stopage for 6 Hrs
(During Trial )
After Potfeed system stopage for 6 Hrs
(During normal operations)
Stoppage of GTC or Pot feed system in normal situation % fines in pot alumina
increases, where as % fines in pot alumina remains unchanged where reacted
alumina rotary feeder cyclic stopping interval has been implemented.
20 20
Plan
Do Check
Action Results of Project
On 23rd April during GTC
breakdown Sec-3, & Sec-4
are not affected as much as
normal sections
AE-frequency in normal sections was 0.365 AE/Pd whereas in Sec-3 & Sec-4 AE-
frequency was 0.167 AE/Pd where reacted alumina rotary feeder cyclic stopping interval
has been implemented. This indicates the change in the quality of alumina.
Plan
Do Check
Action Results of Project
21
The underfeed duration went down in the normal sections where as it was normal in
Sec-3 & Sec-4 where reacted alumina rotary feeder cyclic stopping interval has been
implemented. This indicates the change in the quality of alumina.
On 23rd April during GTC breakdown
Sec-3, & Sec-4 are not affected as
much as normal sections
22 22
Control Plan
Do Check
Action
Alumina Silo level
Rotary
Feeders
Operation
System is controlled by SCADA, and continuously monitored by
operations and Process control
Plan
Do Check
Action Benefits of Projects
• Engineering Solution
• For Automatic Pot hopper Exercise
= $27,810 x 8 sections x 2 Lines
= $444,960
• For Reacted Alumina 700t Silo
Modifications
= $800,618.47
• Total Proposed Project Cost
= $444,960 + $800,618.47
=$1,245,578.47 or
= AED 4,575,321.07
• In-House Control Modification
• Project covered both engineering
proposal to a single cost-effective and
cost avoidance solution.
• Regular man-hours was used in
developing the PLC logic modification
and monitoring the system.
• Control flexibility was incorporated to
enhance mass-balance of the
upstream and downstream process.
23
Total Cost Avoidance: AED 4,575,321.07
24 24
Plan
Do Check
Action Results achieved
Improved work environment in the
Pot lines as emissions reduced
(Environment Protection)
Supply of good quality Alumina to
Potlines will improve Pot performance
AE frequency
reduced during
GTC/Pot feed
stoppage
Eliminated / Avoided
costly engineering
solutions for the
Alumina segregation
problem.
Problem of
Segregation of
Alumina is
eliminated.
25 25
Project Closure Plan
Do Check
Action
Team Recognition: Team was recognized by EMAL management by selecting best
improvement project in June-2011, and team is nominated for
2011 Annual FALAH award.
26 26
Plan
Do Check
Action