Grain CCGT Power Station: Upgrade of Water-Steam Cycle On-Line Monitoring for Flexible Operation May 2019

Sarah Gerry, Station ChemistGrain CCGT Power Station

Contents

Uniper UK: Grain CCGT Power Station – location & operations.

Water-Steam Cycle (WSC) On-Line Instruments – pre-upgrade issues.

Water-Steam Cycle (WSC) On-Line Instruments – post-upgrade success. (a) Instruments (b) Flexible Operation

Summary & Conclusion – Measurement of Success

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Uniper in the UK

Power Generation: One of the five largest companies (~ 6.5GW installed capacity) Power generation assets: ~4.5GW gas-fired and 2GW coal-fired

Energy Trading: ~ 6% of gas traded at NBP (~1,000TWh) 24/7 Power Dispatch Service

Gas Storage: Fast cycle gas storage facility Meets daily demand of 7,000,000 homes

Engineering Services: Multidisciplinary engineering and technical services More than 600 customers in 40 countries around the world

Engineering Academy: Delivered 600 courses to 4,000 delegates in 2016 Currently training 65 apprentices (internal and external)

3

Uniper UK Sites – location of Grain

CardiffLondon

Belfast

Edinburgh

Offices and Workshops

Compton House (BBP)

Engineering Centre and Engineering Academy(Ratcliffe-on-Soar)

Hams Hall Workshops

Gas Storage

Holford

Gas –Fired Stations

Cottam Development Centre (CDC)

Connah’s Quay

Enfield and Taylor’s Lane

Grain

Killingholme

Coal-Fired Stations

Ratcliffe-on-Soar

1

4

5

1

2

24

5

6

7

8

9

6

78

9

10

10

3

3

11

11

London Office

Units 6-8

OCGT 1 & 4

Unit 1

Unit 4

CHP Link (2x 3km)

National GridGrain LNG

Grain Site Plan - operations

Units 6-8

OCGT 1 & 4

Unit 1

Unit 4

CHP Link (2x 3km)

National GridGrain LNG

2016

Grain CCGT Power Station - operations

• 3 Combined Cycle Single Shaft Units (Gas & Steam Turbine)

• Maximum electricity output: 468MW per unit• CHP export – up to 341 MW

• Thermal efficiency (CCGT only): 58.8%• Thermal efficiency (CCGT + CHP): 81%

• ALSTOM GT26 Gas Turbine• Direct Sea Water Cooled• Fuel - Natural Gas • Water treatment plant creates demineralised

water from sea water for boiler make up

WSC: online instruments pre-upgrade Issues

Issues:1. Difficulty adhering to the Chemistry

specs/limits with the current instrument set up. –IAPWS/EPRI/VGB standards Water Chemistry Guidelines.

2. Labour intensive; spending 3 times a week grab sampling and analysing due to instrument issues. (Issue run-up).

3. Big justification; carry-over experienced from tri-sodium phosphate. Presented a number of consequential issues.

WSC: online instruments pre-upgrade Issues

8

Analysis of white deposits shown suggest them to be sodium phosphate, the chosen pH buffer. Although it is believed that this carry-over is primarily due to a combination of drum level control and poor mechanical steam/water separation, it highlights a need for improved continuous boiler chemistry monitoring to more precisely control boiler phosphate dosing and blowdown, in order to minimise the associated risk of boiler corrosion and tube failure.

WSC: online instruments pre-upgrade Issues

Issues:1. pH and Conductivity; did not correlate. pH was linked to dosing at the time.2. Silica’s; loss of performance when units two shifting.3. Dissolved oxygens; down time caused by manual valve switching between feed

and condensate samples.4. Online sodium instrument; loss of performance when unit two shifting.

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WSC: online instruments post-upgrade Success

Vision1. Visited CQ and Ratcliffe Power

Stations for advice and experience.

2. Attendance of BIAPWS and took new ideas for Degasser instruments and applied this to the new unit labs.

3. Took snagging items from commissioning and ensured compliance. Wrote a ‘Specification’.

4. Trial of instruments before bought to compare instrument readings against previous instruments and lab results.

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LP Boiler Condy &

pH

IP Boiler Condy &

pH

HP Boiler Condy &

pH

LP Steam Condy & Sodium

IP Steam Condy & Sodium

HP Steam Degassed Condy &

Sodium

LP, IP & HP Steam

Silica

Condensate Degassed Condy,

Sodium & DO

Feedwater Condy &

DO

LP, IP & HP Boiler

Silica

Unit Laboratory Main Sampling Wall Arrangement

Unit Laboratory Left Hand Wall Arrangement

They fit!

WSC: online instruments post-upgrade Success

Key elements;1. Back Pressure Regulators –

onload/offload flow regulators.2. Additional Sodium instruments –

continuously monitoring.3. Additional of Degasser instrument

– improved start-up time.4. pH new type – low conductivity

and no static.5. Flooring - colour coded for unit

designation. Work on correct unit.6. Sample Tray – everything off floor.7. Dissolved oxygen – separated

them out so no switching.8. Resin column – configuration

changed, constantly back up rinse.11

Instruments – Diagnostics screen

• Designed a diagnostic page for chemistry trends (no spot checks).

• Logic changed for pH to conductivity for auto dosing regime.

• pH still required for an indicator of a condenser leak.

• Explanation of the Diagnostics page………………….

• - operator engagement.

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Pre-commissioning page

Instruments - Lab

1. The ion chromatograph within the chemistry lab amongst other lab instruments are utilised for the unit lab chemistry analysis.

2. After columns for sample sources will show a ‘figure’, but the contaminant still needs to be quantified and understood in case of actions; e.g. blowdown.

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Flexible Operation – flushing system

Location: Unit Lab - Cooler side photos• Demin solenoid valve – stainless

material (no leaching) and linked to feed pump function group.

Flushing instruments:• Prevents instruments from ‘dry out’. • Ensures calibrations can be carried

out whilst the unit is offload.• Quicker ‘start up’ availability of

instrument as continuously on, reliable readings.

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Flexible Operation – flushing system

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Summary & Conclusion

Measurement of Success: 100% Compliance within spec for Unit Chemistry. Installation of drum furniture based on continuous monitoring. Further Improvements: CQ imbedded actions screens on DCS Diagnostic

screens for operators to follow smoothly.

Fantastic Project Management by Engineers and Operators assigned. Excellent Team Work between all parties on a daily basis. Everyone understood the Goals. Manufacture training –sign off. Cascaded Training via Chemistry Team to

operations, engineers, apprentices. Procurement contracts set ups, Maintenance

excellence via frequency led SAP PMs.

Sarah GerryStation Chemist

Grain CCGT Power Station 16

Thank you for Listening, Any Questions?

17

Thank you!

If you need any further information, please contact:

sarah.gerry@uniper.energy

Uniper UK Limited, Grain CCGT Power Station, Power Station Road, Isle of Grain, Rochester, Kent, ME3 0AR

www.uniper.energy

Uniper disclaimer:This presentation may contain forward-looking statements based on current assumptions and forecasts made by Uniper SE management and other information currently available to Uniper. Various known and unknown risks, uncertainties and other factors could lead to material differences between the actual future results, financial situation, development or performance of the company and the estimates given here. Uniper SE does not intend, and does not assume any liability whatsoever, to update these forward-looking statements or to conform them to future events or developments.