Engineering Services for the Optimisation of Chlor-Alkali Plants

Transcription

1 Engineering Services for the Optimisation of Chlor-Alkali Plants Amanda Lancaster Process Technology Manager INEOS Technologies Electrochemical Technology Business 1

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 BICHLOR Cellroom Engineering services to meet the challenge 2 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.

3 The Challenge of Chlor-Alkali Achieving Optimum Performance 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 Primary purification Secondary purification Hydrogen Treatment H2 Pressure / DP control Brine resaturation Pure brine storage and heat conditioning Chlorine Treatment Cl2 Sulphate removal Electrolysis Catholyte handling and dilution NaOH Dechlorination Anolyte handling / chlorate destruction Catholyte heat conditioning 3

4 The Challenge of Chlor-Alkali - Why is it not so Easy Corrosive fluids Explosive gases Stray currents Exotic materials Fragile components Electrochemistry! Chemical sensitivity Toxicity 4

5 For Big Challenges.... talk to someone who s been there before 5

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 6

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 BICHLOR Cellroom Brine purity and salt selection Stray Currents Keeping the plant online Keeping the plant safe 7

8 It s all about Power Ideal Power Consumption Ideal power consumption P o w e r Years 8

9 It s all about Power the Reality Power consumption over time P o w e r Current efficiency Pressure Temperature Ohmic loss Overpotential dy dx Quality of operation Operability Time 9

10 It s all about Power a Marathon not a Sprint Power consumption over time P o w e r Time 10

11 It s all about Power a Marathon not a Sprint Power consumption over time P o w e r Time 11

12 Early Performance can be Easily Lost 20 mv start up voltage benefit Saving = 0.1 million 4mV/month voltage rise penalty Penalty = 0.9 million 100 ktpa plant 4 year cycle European power price 12

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 13 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.

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 14

15 Staying in Control of Pressure - Typical System Hydrogen from other electrolysers PIC PdIC dp = 25 mbar B Vent to hydrogen stack dp = 15 mbar Chlorine from other electrolysers PIC P = 185 mbar A Hydrogen to plant Chlorine treatment A Chlorine to compression Brine feed Electrolyser 1 Vent to hydrogen stack XZ XZ B P = 205 mbar Vent to chlorine absorption Caustic feed PdIC N 2 purge N 2 or air purge Catholyte header Anolyte header PIC Anolyte from other electrolysers Anolyte tank Vent to chlorine header Vent to hydrogen header Catholyte from other electrolysers Catholyte tank 15

16 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 Chlorine V01 (10 BiChlor Electrolysers) Stream 01 Hydrogen PIC 01A dpic 11A PIC 01B dpic 11B dp02 (Headers and coolers) 205 mbarg dp = +15 mbar dp = + 25 mbar SD1 V02 (Headers and coolers) P02 (-20 mbarg) PCV 01B P12 (0 mbarg) dpcv 11B 185 mbarg dp03 (Headers, dryer, filter) V03 (Headers, dryer, filter) Stream 02 Stream 03 SD1 PCV 01A P13 (165 mbarg) SD1 P03 (xxx barg) V11 (10 BiChlor Electrolysers) dp12 (Headers and cooler) V12 (Headers and cooler) dp13 (Headers, filter) V13 (Headers, filter) dpcv 11A PV 12 Stream 11 Stream 12 Stream 13 16

17 Staying in Control of Pressure Dynamic Modelling Model validated against a less than optimal pressure swing during a plant trip 17

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. 18

19 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) Anode Face Membrane Cathode Face + Damaging cation solubility (typical) _ Cation flow

20 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 20

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 21

22 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 22

23 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? Buffering and redundancy Staying on line during upsets Configuration and overcapacity If one unit is off-line can another make up? 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 23

24 Keeping the Plant Safe Designing for inherent safety. Isolations Working at height Hydrogen in chlorine Maintenance outside of cellroom 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 24

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 Strengths Knowledge Client INEOS Contractors Optimise Communicate 25 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.

26 Where can INEOS add value? Plant performance assessment Plant capacity assessment Process Definition Process Design Optioneering and financial analysis Feasibility studies Expert process engineering PDPs Front End Engineering Hazard studies and technical risk SIL/LOPA Vendor analysis and selection Layout analysis Detailed Engineering Procurement and Construction Dynamic modelling Troubleshooting Technology knowledge Commissioning Operating skills 26

27 Where can we help you? Thank you for your time and attention Amanda Lancaster Tel: amanda.lancaster@ineos.com 27