Fouling Layer Growth in Black Liquor Falling Film Evaporation

Paper i proceeding, 2007

The fouling behaviour (both local and overall) for black liquor evaporation in a falling film evaporator has been investigated. The experimental results showed that, in the interval of the studied dry solids content, the fouling rates were independent of dry solids content as long as it exceeded a critical limit. The fouling rates were seen to have a strong dependence on circulation flow rate; doubling the circulation flow rate resulted in about halved fouling rates. The local heat flux measurements showed great differences between fouling rates vertically along the heat transfer surface. The fouling was seen to start from the bottom and then expanded upwards.