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Emerson Process Management has completed a dual-fuel conversion initiative that enables the Termocandelaria power plant to operate using either natural gas or oil.

The project, implemented by Emerson and Mitsubishi Power Systems Americas (MPSA), went into commercial operation in just 11 months, an aggressive timetable that was required in order for Termocandelaria to fulfil its regulatory obligations.

The project marks the latest collaboration between Emerson and MPSA, which in 2008 formed an alliance for turbine retrofit projects.

Termocandelaria, owned by Termocandelaria Power, is a two-unit, 320MW power plant located in Cartagena.

Converting the two Westinghouse 501F turbines from gas-fuel only to dual-fuel operation offered Termocandelaria a low-risk, cost-effective strategy for improving unit start-up reliability.

By being able to start reliably and generate the requested power on demand, Termocandelaria not only maximises its generating revenue but avoids financial penalties that would be incurred if it were not able to fulfil its regulatory obligations with the Colombian authorities.

The Colombian electricity market is served primarily by hydro-electric plants located in the centre of the country.

When there is drought, transmission issues or high demand, these plants are not always able to generate sufficient power to meet the region’s needs.

In these instances, the Colombian government typically calls on power plants utilising other fuel sources, such as Termocandelaria, to provide additional megawatts.

For this project, Emerson co-developed with MPSA a new control strategy for the dual fuel conversion, which included logic for water injection, fuel gas and fuel oil systems.

In addition to the new logic required to accommodate a second fuel source, Emerson also migrated the existing gas-turbine controls from the previous-generation WDPF distributed control system to its Ovation expert control system.

As part of the migration, Emerson converted the existing logic to industry-standard SAMA logic.

This will enable Termocandelaria to more easily modify control schemes in the future as changing circumstances dictate.

From the beginning, Emerson designed the Ovation system to allow a straightforward migration path for users of its WDPF systems.

This proven economical alternative to complete system replacement offers WDPF customers the latest technology while allowing them to retain much of their existing control-system investment, including control logic, graphics, I/O cards, field cabling and terminations.

MPSA was responsible for the dual-fuel conversion, including new combustion-system components, gas and oil fuel supply systems featuring Emerson control valves and instrumentation, as well as civil and electrical design of the expanded balance of plant equipment for water and oil treatment and storage equipment.

MPSA also provided installation and commissioning support for the project to help it achieve a certificate of completion by demonstrating power-supply capabilities on oil fuel.

Water-injected diffusion flame combustors (fuel nozzles, combustor baskets and transition pieces) were supplied to maximise the unit’s output and simplify the fuel-conversion process.

The retrofit also included MPSA’s new dual-fuel system, which utilises a duplex liquid-fuel nozzle to eliminate the need for a flow divider and improve start-up and low-load particulate emissions and opacity.

Purge air systems and Mitsubishi’s high-energy ignition system were also applied to ensure high starting reliability.

The Emerson Ovation expert control system features co-ordinated boiler-turbine control, automated start-up and shutdown sequencing, speciality turbine interface cards, built-in security features and embedded advanced control applications that improve plant reliability and efficiency.

Ovation technology removes the need for power generators to rely on existing turbine suppliers to support a proprietary control system.

Ovation provides a clear window into the turbine control logic, eliminating the need for a third party to ‘unlock the black box’.

Emerson Process Management – Power and Water

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