Flue gas cleaning and heat recovery

Using a scrubber increases the global efficiency of the plant while limiting the fuel consumption and pollutants release in the flue gases.Water contained in the flue gas is condensed in the scrubber. Flue gases from boiler contain often a high moisture level, thanks to which they can provide a high source of heat, proportionally to the boiler power output.

For example, the diagram above shows the heat recovery proportionally to the boiler power output from the curves of flue gas cooling. Flue gas belongs to the combustion of wood. In optimal conditions, the heat recovery can be equivalent up to half of the boiler power output.

By using a wet treatment, it is necessary to have a water flow available, which has a temperature low enough to recover the heat.

The heat recovery from combustion flue gases is sometimes limited due to high temperatures of water flow receiving the heat, for instance, district heating with high return temperature, or due to low water flow.

Flue gas cleaning and condensation happen in the fixed bed.

The fixed bed of the scrubber is composed of bed particles allowing an optimal contact between liquid and gas flows. Moreover, both flows circulate at counter current, enabling a high efficiency of heat transfer and chemical reactions.

Using a fixed bed is efficient for dust removal, with a size up to 1 μm, for flue gas cleaning, stripping and humidification/evaporation.

Calculator for estimating the heat recovery from flue gases in a flue gas scrubber.