Amercentrale power station unit 9

Large coal-fired power station increases its efficiency by eliminating flue gas reheat and converting its chimney to a PennguardTM lined wet stack.

Essent, a member of the German utility group RWE, is one of the Netherlands’ leading electricity producers. Essent’s Amercentrale 8 and 9 power stations in the southwest of the Netherlands are among the largest coal-firing plants in the country. Commissioned in 1994, Amercentrale 9 has a 640 MW supercritical coal-fired boiler and it produces a further 350 MW of district heating. In recent years it has co-fired biomass, and this now accounts for 35% of the total fuel input.

Amercentrale 9 has used a flue gas desulphurization (FGD) system from the outset, and this included a steam reheater downstream of the FGD system, which increased the temperature of the flue gas going into the chimney from around 45°C to around 60°C.

Amer 9

1997 – Brick lining under attack, lower part chimney

In 1997, three years into operation, acidic puddles were found on concrete supports in the lower third of the chimney – evidence of leakage through the brick. Fortunately this was spotted quickly, and a solution delivered: PennguardTM lining was installed up to a height of 75 m, covering 1,500 m² or 40% of the internal surface to prevent any further leakage.

2013 – Gas reheater eliminated

After some 20 years of operation, the steam reheater of Amercentrale 9 had come to the end of its useful life. Essent then considered the options of replacing the reheater, or converting the chimney to a ‘wet stack’, carrying 45°C, water saturated flue gas.

It was important to consider not only the initial investment needed for this, but also any impact on running costs.

An in-depth study by Essent and its parent company RWE Group found that there was little difference in the necessary capital investment between the two options.

However, converting to a wet stack had a notable advantage: not operating a reheater would deliver a significant increase of overall power station efficiency. It was also found that lining the remaining 2,518 m² of brick flue with PennguardTM was achievable within an already scheduled 31-day outage.