Andritz Oy

Andritz-Ahlstrom Oy

Jan E &Ouml;hman

Risto Honkanen

The present invention relates to a method of treating condensates containing compounds, which are more volatile than water, in an evaporation plant, where liquid, such as effluent liquid from a pulp or paper mill is evaporated in multiple effects and where condensates generated in the evaporation are flashed and purified in a steam stripping column. In the method, the condensates from at least two evaporation effects are combined and flashed together, and the vapor obtained from the flashing is made to contact with a condensate stream to be purified in the stripping column, wherefrom the impurities-containing vapor and the purified condensate stream are discharged.

Method of treating condensates

A method and system for handling foul condensate containing Hazardous Air Pollutants (HAPs) in a cellulose pulp mill has enhanced energy efficiency and lower cooling water usage, while complying with the Cluster Rules and other environmental regulations. The condensate is fed countercurrently to stripping vapor in the stripping column to produce a HAPs vapor and a clean condensate. Part of the clean condensate is fed from the stripping column reboiler, and the HAPs-rich vapor is directed to the reboiler to at least partially condense while vaporizing the clean condensate into the clean vapor (stripping vapor). The pressure of the stripping vapor is increased, such as utilizing a steam ejector, to about 0.1-30 psig and then is used as the stripping vapor in the stripping column. The non-condensed HAPs-rich vapor is fed to an external condenser, and the dirty condensate from the external condenser and the dirty condensate from the reboiler, are returned to the stripping column.

Growing community of inventors

Helsinki, Finland

Jan E Öhman

Growing community of inventors

Helsinki, Finland

Jan E &Ouml;hman

Jan E Öhman