Hongsa power station

Very large mine mouth, lignite fired power station in Laos uses Wet Limestone FGD and chimney with PennguardTM lined steel flues

Just across the border of Northern Thailand, in the Lao Province of Xayabury, a consortium of two Thai companies, Banpu Power and Ratchaburi Electricity, along with the Lao Government are constructing one of the world’s largest new mine mouth power stations.

When they enter commercial operation in 2015 and 2016, the station’s three 626 MW lignite fired units will produce a combined 1,878 MW of electricity. The majority of this capacity will be destined for Thailand. The remainder will be supplied to electricity users in Laos.

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The new power station and its lignite mine have been constructed in a sparsely populated area with limited infrastructure. Among many other works, the developers had to build a combined 32 km of new roads through the mountainous landscape. Together with the mines, water reservoirs, transmission lines and the power station itself, the combined project investment is close to the equivalent of 4 billion US Dollars.

The lignite used at Hongsa Power Station has a moderate sulfur content of 0.6-0.7%. Wet Limestone Flue Gas Desulfurization (FGD) plants are used to reduce sulfur oxide emissions by 92%. Following desulfurization in the FGD plants, the flue gas is reheated to a temperature above 80°C in rotary gas-to-gas heaters (GGH) and emitted through a 250 m high reinforced concrete chimney.

With operating temperatures well below the sulfuric acid dewpoint, the owner and his EPC contractor, China National Electric Engineering, Co., Ltd. (CNEEC) from Beijing, were well aware of the need to protect the chimney flues against a highly corrosive environment. After evaluating a number of options, it was decided to use three mild steel flues, protected internally by 18,263 m² of PennguardTM linings.