A device for cleaning of flue gases through condensation in small scale firing with fuel pellets having a substantially vertical glue gas cooler (12). The flue gas cooler (12) comprises an inner (4) and an outer (3) pipe, being substantially mutually concentric, arranged with a space (2) between them in a radial direction. In the space between the inner (4) and outer (3) pipe there is a helical pipe (5) for a flowing cooling medium. The flue gases are led through the space (2) between the inner (4) and outer (3) pipe for cooling and condensation.
A method for cleaning of flue gases in small-scale firing with fuel pellets comprising the steps of leading the flue gases into a space (2) between an inner (4) and outer (3) pipe, which are mutually substantially concentric and having a helical pipe (5) arranged in the space (2) between the inner (4) and outer (3) pipe, cooling of the flue gases to condensation, partly so that the condensate forms a liquid film or droplets on cooled surfaces (5), and partly so that the condensate forms droplets falling freely in the flue gases, whereupon the condensate water is collected and remaining flue gases are led out of the space (2) between the inner (5) and outer (3) pipe.