Increased efficiency in cogeneration power plant expansion

In 2019, client Ratch Group recognized the need to expand its existing 110 MW combined cycle cogeneration power plant in Pathum Thani, central Thailand, to meet the increasing needs of the local electricity grid and industrial customers in the vicinity.

Ratch Group mandated Tractebel as owner’s engineer to realize the expansion, alongside project partners EGCO, Jurong Engineering Limited and Thai Jurong Engineering Limited. Our energy experts in Thailand were responsible for basic engineering, engineering, procurement and construction (EPC) tender specifications and evaluation, contract negotiation, technical support for permitting and project management during construction.

Ratch combined cycle cogeneration power plant in Pathum Thani, Thailand

Feeding the grid for a decade

The original power plant is a combined cycle cogeneration natural gas plant of 2-2-1 configuration (two gas turbines and two heat recovery steam generators (HRSG) feeding one steam turbine) with installed capacity of 110 MW of power and 10 tons per hour (TPH) of process steam. Under a Power Purchase Agreement (PPA) with the Electricity Generating Authority of Thailand (EGAT), 90 MW is supplied to the grid and the surplus electricity and steam are sold to nearby industrial customers. The power plant has been operational since late 2013.

More energy, more efficiency

Expansion works began in March 2021 with the aim of increasing capacity from 110 MW to 140 MW. Tractebel oversaw the addition of four gas engine generators, four heat recovery steam generators (HRSG) and the associated plant equipment. The total installed capacity of the expansion is 31.2 (4 x 7.8) MW and 5-10 TPH of process steam. This configuration greatly improved plant efficiency, as it now operates continuously at or near baseload, the minimum amount of power needed to feed the grid. The expansion plant operates during peak periods only, and the engines start one by one according to energy demand. This allows the plant to operate at maximum efficiency at all times.

Opening ceremony for the Ratch extension in Thailand

“Despite the challenges of executing this expansion project during COVID-19 and the supply chain crisis, our team, together with our partners, succeeded in achieving commercial operation on schedule in late 2022. We are pleased that local businesses, and therefore the economy, will benefit from an increased energy source. Most of all we are proud to have designed the expansion for maximum efficiency, thereby significantly reducing fuel consumption per kWh of electricity produced.”

Suparerk Wangtiprak, Project Manager, Tractebel in Thailand

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