The use of Waste Heat from Flue Gas in the System of Regeneration of Steam Boiler Supply Water

This study presents an analysis of the process of the use of waste heat from flue gas for the purposes of heating water in the regeneration system of a steam power unit fuelled with brown coal with a power of 900 MW_e. Preparation of flue gas and its initial moistening (increasing the dew point temperature) followed by cooling (condensation of the moisture contained in the flue gas) can ensure intensive heat exchange in the process of heat recovery. Replacing a first regeneration exchanger with the heat recovered from flue gas allows for an increase in steam power unit efficiency by 0.22% and limitation of CO₂ emissions by 22,810 t/year, while reducing the fuel demand by 26,727 tonnes per annum. Depending on the prices of CO₂ emissions permits and prices of brown coal, the proposed heat recovery allows for saving from €500,000 to €1,000,000 per year.