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Loy Yang Power Station Control System Upgrade.

Loy Yang Power Station Control System Upgrade. BARRY DUNGEY General Manager Engineering & Maintenance June 2008. Key Project Objectives:. Original control system is of mid 1970’s design with circuit board, relay and wire wrap technology.

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Loy Yang Power Station Control System Upgrade.

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  1. Loy Yang Power Station Control System Upgrade. BARRY DUNGEY General Manager Engineering & Maintenance June 2008

  2. Key Project Objectives: • Original control system is of mid 1970’s design with circuit board, relay and wire wrap technology. • The main driver for the project is the difficulty in supporting obsolete control equipment.( Our policy is to run for approx 5 years following withdrawal of support by our equipment supplier) • The opportunity is also being taken to gain improvements in system performance and reduce business risk exposure. • ( i.e. Alternative control room) • Plant trip rates were increasing with a significant number due to control system faults. • Upgrade will include the installation of a separate plant safety system. • Complete unit cut over to be achieved in 35-40 day outage duration

  3. Number of Trips & Trip Rate.

  4. Project Timeline

  5. Loy Yang Power Expectations • The current control system is fairly tight as it is already being run on a digital platform, hence LYP are not expecting significant direct improvements in efficiency as a result. (Some studies indicate that up to 2% improvement is possible from older systems) • The system will deliver flexibility to do things smarter, fault find easier, and implement future plant logic change easier. • The supplier has provided a guarantee that they will support the new control system for 35 years, hence no further significant upgrades are expected in the remaining life of the plant.

  6. Yokogawa Site Observations • Site surveys noted that the current control strategies are sound. • Boiler thermocouple dynamic response suitably fast to allow for quick movement in loads. • Existing spray valves and actuators not significantly limiting performance • Existing controls have some issues when limits are reached – wind-up, excess output pull-back, etc

  7. Benefits from Yokogawa control design • Integration between steam temperature and combustion controls minimises interaction • “Over-firing” minimised by using transient contribution of superheater sprays to main steam pressure control • Contributes to wider operating range from milling plant • Boiler thermal stress reduced • Flexibility on turbine ramp rates possible • On line efficiency tools improved.

  8. Benefits (Continued) In summary, the current process is about achieving incremental improvements, particularly with: • Start up and shutdown sequences • Better trim controls associated with excess air (oxygen). • Maximising future flexibility with an open system which can accept third party products. • Improved Operator information and diagnostics

  9. Original Coal Handling Plant

  10. Coal Handling Plant (Part)

  11. Coal Handling Plant (Overview Screen)

  12. Major Plant Drive Graphic

  13. Future Control Room Layout

  14. Simulation For Engineering and Training

  15. Optimised Sootblowing • Loy Yang Power has four superheater elements, 2 reheater elements and an economiser within each furnace convection path. • To manage boiler fouling, 74 sootblowers are used to clean the elements using high pressure steam from the Reheat Steam System. • The original design used a time based operation system with two cleaning cycles per day.

  16. Original Sootblower Control Panel

  17. Optimised Sootblowing - NGISB • An optimised sootblowing system (NGISB - Next Generation Intelligent Sootblowing System) has been installed on one unit as a trial. It uses a Synengco supplied NGISB system interfaced to PLC based sootblower controls supplied by Siemens. • The NGISB gathers data from the plant historian at near real time and continuously calculates the ideal sootblower schedule using a thermal boiler model within business rule constraints.

  18. Sootblower Optimisation System Aims • Reduce sootblowing frequency • Maintain boiler attemporator spray flows within the ideal valve control range • Minimise Reheat Spray Flow • Maintain Steam and Metal Temperatures close to target and minimise alarm conditions to maximise thermal efficiency. • “Set and Forget” operation.

  19. Siemens/Synengco Sootblower Control System

  20. Optimised Sootblowing Results • Sootblowing frequency reduced to 32.5% of the original time based schedule. • Annualised Savings per Unit • 24.7 TJ of energy • 8.1 Ml of Cold Reheat Steam • 4,900 Tonnes of CO2

  21. Optimised Sootblowing Results (Continued) • Reducing RH Spray Flow to a minimum has a positive impact on overall steam cycle efficiency – estimated to be 0.3% • Reduced thermal excursions in the boiler due to sootblowing leading to a more stable boiler. • Better than 12 month payback on current costs.

  22. QUESTIONS

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