engineering services for the optimisation of chlor alkali ... · engineering services for the...

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

3

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

5

For Big Challenges!!!!.

..... talk to someone who’s been there before

6

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

7

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

8

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


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


TimeTimeTimeTime

Po

we

r P

ow

er

Po

we

r P

ow

er

12

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



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

14

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

15

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

18

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

21

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



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

engineering services for the optimisation of chlor alkali ... · engineering services for the...

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