VATIS UPDATE Article

The Republic of Korean electricity company Gunjang Energy has installed a new flue gas desulphurization unit, called Seagull, at its existing power plant at Gunsan city. The circulating fluidized bed (CFB) boiler size was 275 MW and it needed to fulfil strict emission requirements which came into force in January 2015. Therefore, a suitable flue gas desulphurization (FGD) technology to meet this limit became mandatory. Gunjang Energy wanted to install the most economical FGD technology for these demands, and therefore selected circulating dry scrubber (CDS) technology.

The basic principle underlying a CDS is the removal of gaseous components and a downstream filter for dust removal. The flue gas from the upstream boiler flows through the CDS and then a filter, and is released into the atmosphere via induced draft fans and stack. The main component for the removal of waste gases is the CDS with the high solid concentration situated inside it. These solids contain the dust brought in by the raw gas, a metered quantity of hydrated lime as the absorbent, and over 90 per cent of FGD product, recirculated from the downstream arranged filter. Figure 1 shows the arrangement of the whole CDS system.

The FGD is located downstream of the air preheater in the power plant arrangement. The CDS system itself consists of a CDS absorber, a low pressure fabric filter with eight chambers for dedusting downstream of the CDS absorber, the connecting ductwork including the recirculation duct, the ID fans downstream of the fabric filter and the connection to the stack. All equipment has been installed in a compact and space-saving way.