Surface Flue Gas Condenser are most frequently used when the vapours to be condensed constitute the major portion of the gas stream and only a small amount of non-condensable are be vented.
In such cases, ordinary tubular condenser-type heat exchangers may be used. When non-condensable predominate, finned tubes on the gas side will give better heat transfer unless the condensing material tends to scale the surface.
In such cases, tubular exchangers designed for easy cleaning of the gas side heat transfer surface should be considered.
Flue Gas Condensers can either be vertical or horizontal. Horizontal flue gas condensers are frequently pitched with a slight slope to provide for tube drainage.