engineering services for the optimisation of chlor alkali ... · engineering services for the...
TRANSCRIPT
1
Engineering Services
for the Optimisation of
Chlor-Alkali Plants
Amanda Lancaster
Process Technology Manager
INEOS Technologies Electrochemical Technology Business
This document is the property of INEOS Technologies (Vinyls) Limited and the information it contains is strictly confidential
and may not be copied, used or disclosed without the express permission of Ineos Technologies (Vinyls) Limited.2
Agenda
• The challenge of chlor-alkali
• INEOS experience and expertise
• Key areas for optimum cellroom design
– Long term performance - power
– Pressure
– Brine purity and salt selection
– Stray currents
– Keeping the Plant Online
– Keeping the Plant Safe
• Engineering services to meet the challenge
BICHLOR™ Cellroom
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The Challenge of Chlor-Alkali – Achieving Optimum Performance
Electrolysis
Hydrogen
Treatment
Chlorine
Treatment
Pressure / DP
control
Catholyte
handling and
dilution
Anolyte handling
/ chlorate
destruction
Dechlorination
Sulphate
removal
Brine
resaturation
Pure brine
storage and heat
conditioning
Catholyte heat
conditioning
Primary
purification
Secondary
purification
NaOH
Cl2
H2
Key to successful, long term operation of a membrane cellroom, as well as good
technology selection, is the correct design of the unit operations surrounding the
electrolyser
4
The Challenge of Chlor-Alkali - Why is it not so Easy
Explosive gases
Electrochemistry!
Stray currents
Exotic materials
Fragile components
Chemical sensitivityToxicity
Corrosive fluids
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Meeting the Challenge for Over a Century!!
INEOS have over 100 years experience of
operating all chlor-alkali technologies
INEOS currently operate membrane technology
on 3 major European sites
INEOS have been at the forefront of membrane
cell technology since it’s inception
INEOS have installed chlor-alkali technology at
over 100 sites worldwide
INEOS are experts in chlor-alkali design, engineering and operation
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Key Areas for Optimum Cellroom Design
• For optimum long term performance==
– Minimise power consumption
– Maximise performance on day 1
– Ensure high performance maintained day 2+
• Key design areas to achieve optimum performance
– Cellroom pressure
– Brine purity and salt selection
– Stray Currents
• Keeping the plant online
• Keeping the plant safe
BICHLOR™ Cellroom
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It’s all about Power – Ideal Power Consumption
Ideal power consumptionIdeal power consumptionIdeal power consumptionIdeal power consumption
0000 2222 4444 6666 8888 10101010
YearsYearsYearsYears
Po
we
r
Po
we
r
Po
we
r
Po
we
r
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It’s all about Power – the Reality
Power consumption over timePower consumption over timePower consumption over timePower consumption over time
TimeTimeTimeTime
Po
we
r P
ow
er
Po
we
r P
ow
er
Current efficiencyCurrent efficiencyCurrent efficiencyCurrent efficiency
PressurePressurePressurePressure
TemperatureTemperatureTemperatureTemperature
Ohmic lossOhmic lossOhmic lossOhmic loss
OverpotentialOverpotentialOverpotentialOverpotential
dydydydydxdxdxdx
Quality of operationQuality of operationQuality of operationQuality of operation
OperabilityOperabilityOperabilityOperability
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It’s all about Power – a Marathon not a Sprint
Power consumption over timePower consumption over timePower consumption over timePower consumption over time
TimeTimeTimeTime
Po
we
r P
ow
er
Po
we
r P
ow
er
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It’s all about Power – a Marathon not a Sprint
Power consumption over timePower consumption over timePower consumption over timePower consumption over time
TimeTimeTimeTime
Po
we
r P
ow
er
Po
we
r P
ow
er
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Early Performance can be Easily Lost
20 mV start up voltage benefit
4mV/month voltage rise penalty
Saving = €0.1 million
Penalty = €0.9 million
100 ktpa plant
4 year cycle
European power price
This document is the property of INEOS Technologies (Vinyls) Limited and the information it contains is strictly confidential
and may not be copied, used or disclosed without the express permission of Ineos Technologies (Vinyls) Limited.13
Keeping the Power Down - Pressure
High pressures can be beneficial=.
• Reduce day 1 power consumption
• Reduce plant capital cost
• Enable operation at altitude
• Reduce utility usage
But they can also==
• Increase day 2+ power consumption if transients are not managed
Sometimes low pressure has other advantages===.
• Reuse of low pressure equipment (mercury or monopolar conversions)
• Simple pressure control system
• Less vulnerable to pressure / differential pressure excursions
Is high or low pressure right for you!!.?
BICHLOR™ is designed to operate at high current density and low or high
cellroom pressures and is robust to excursions
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Staying in Control of Pressure
INEOS operate plants at high pressures and can mitigate risks
•Easy to control pressure and differential pressure during steady operation
•Not so easy to control pressure during transient events (e.g. trips)
•Removal / re-instatement of a single electrolyser from a multi-electrolyser cellroom
•Pressure protection and relief systems to cover all sources of overpressure (and
underpressure) during all modes of operation
Risk of pressure and differential pressure excursions if the design of the pressure
control system isn’t right
Excessive pressure excursions can
reduce electrolyser performance
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Staying in Control of Pressure - Typical System
Vent to chlorine absorption
Chlorine to compression
Hydrogen to plant
Vent to hydrogen stack
Electrolyser 1
Chlorinetreatment
PdIC
PIC
PIC
PIC PdIC
N2 purge
Catholyte header
Anolyte header
Vent tohydrogenstack
Anolyte tank
Catholytetank
XZ XZ
Hydrogen from otherelectrolysers
Chlorine from otherelectrolysers
Anolyte from otherelectrolysers
Catholyte from otherelectrolysers
Vent to chlorine header
Vent to hydrogen header
dP = 15mbar
dP = 25mbar
N2 or air purge
P = 185 mbar
P = 205 mbar
Brine feed
Caustic feed
B
A
A
B
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Staying in Control of Pressure – Getting it Right
Keys to good pressure and differential pressure control
• Correct valve sizing• Trip logic• Valve settings (stroke times)• Tuning of valves
INEOS are experts in dynamic modelling of cellroom gas systems
• Simulate various transient events
• Optimise control valve selection
• Develop the optimum logic and timed
responses
• Achieve excellent pressure control in
all situations
• Check response of system prior to
start-up
V01
(10 BiChlor
Electrolysers)
V02
(Headers
and coolers)
V03
(Headers,
dryer, filter)
PIC
01B
PIC
01A
dP02
(Headers and
coolers)
dP03
(Headers,
dryer,
filter)
P03
(xxx barg)
P02
(-20
mbarg)
PC
V 0
1B
PCV 01A
V11
(10 BiChlor
Electrolysers)
V12
(Headers
and cooler)
V13
(Headers,
filter)
dPIC
11B
dPIC
11A
dP12
(Headers and
cooler)
dP13
(Headers,
filter)
P13
(165
mbarg)
P12
(0 mbarg)
dP
CV
11B
dPCV 11A PV 12
SD1
185 mbarg
205 mbargSD1
SD1
dP = +15 mbar
dP = + 25 mbar
Stream 02 Stream 03Stream 01
Stream 11 Stream 12 Stream 13
Chlorine
Hydrogen
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Staying in Control of Pressure – Dynamic Modelling
Model validated against a less than optimal pressure swing during a plant trip
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Staying in Control of Pressure – Dynamic Modelling
Model used to evaluate optimal valve stroke times, within the constraints of the installed valves. Subsequent plant trip followed modelling results very well.
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Brine Purity and Salt Selection
Low cost brine plants can reduce capital=..
==.but they can seriously increase day 2+ power increase due to impurity excursions
How will specific impurities behave in the brine loop and electrolyser?
• Precipitation within the membrane (increased voltage, reduced CE)
• Plating on electrodes / attack of electrode coatings (increased over-potential)
1514131211
Anode
Face
Cathode
FaceMembrane
+_
Cation flow
Damaging cation
solubility
(typical)
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Brine Purity and Salt Selection
What do we do in design to minimise damage due to brine impurities?
• Salt and brine selection
• Secondary purification design and resin specification
• Brine purge vs other brine loop purification techniques
• Hg residue for conversion projects
• Cost / benefit analysis of relaxation of specific impurities
• Full characterisation of brine
• Pilot trials for brine purification
INEOS are experienced in operating plants with different salt supplies and
brine purification strategies. We design to avoid the pitfalls
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Electrolyser Stray Currents
Relatively high voltages in membrane cells leads to current leakage via process fluids
• Corrosion of electrolyser components
• Corrosion of up and downstream metallic equipment
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Electrolyser Stray Currents
What do we do to alleviate the problems caused by stray currents?
• Inclusion of sacrificial stray current collectors in cell feeds
and exits
• Positioning of process fluid supply and discharge lines
• High resistance fluid paths
• Grounding electrodes
– Protect up and downstream equipment
– Positioned to minimise stray currents
to earth
– Prolong life of the grounding electrode
• Stray current modelling
INEOS understand the issues of stray currents and know how good
cellroom design can minimise their effects
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Keeping the Plant On-Line
Capital cost saving decisions may impact long term availability and revenue
• Materials of construction
It may cost less but how long will it
last?
• Maintainability
It may look neat but can you get at it?
• Maintenance window
How long to repair/replace an item?
• Configuration and overcapacity
If one unit is off-line can another make
up?
• Buffering and redundancy
Staying on line during upsets
• Refurbishment planning
Does technology supplier look after
you?
As operators INEOS understand the importance of keeping the plant on
line. INEOS technology is designed to be robust and easily maintained.
We help clients throughout the plant life cycle
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Keeping the Plant Safe
Maintenance outside of cellroom
Hydrogen in chlorine
Safety is paramount in the INEOS culture. Our technology is designed for
installation into facilities demanding the highest safety standards in all
operating and maintenance situations
Isolations
Designing for inherent safety!.
Working at height
This document is the property of INEOS Technologies (Vinyls) Limited and the information it contains is strictly confidential
and may not be copied, used or disclosed without the express permission of Ineos Technologies (Vinyls) Limited.25
INEOS will Bring Deep Understanding of Chlor-Alkali to your Project
• Design of wider chlor-alkali plant, whether for a technology conversion or new installation is by now generally understood
• Deep understanding of the chemical engineering science around the electrolysis section of the plant is required to ensure optimal design
• Several key areas, identified here, require very careful consideration to ensure prolonged efficient operation of the plant
• Operating Experience + Technical Expertise � Optimal Cellroom design
ContractorsINEOS
Client
Strengths Knowledge
CommunicateOptimise
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Where can INEOS add value?
Optioneering and
financial analysis
Hazard studies and
technical risk
Vendor analysis
and selection
Dynamic modelling
Plant performance
assessmentProcess Definition
Process Design
Detailed Engineering
Commissioning
Procurement and
Construction
Front End Engineering Expert process
engineering
Operating skillsTechnology knowledge
Layout analysis
Feasibility studiesPlant capacity
assessment
Troubleshooting
SIL/LOPA
PDPs
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Where can we help you?
Thank you for your time and attention
Amanda Lancaster
Tel: + 44 1928 516677
E-mail: [email protected]
www.ineostechnologies.com