Evaporation System Optimization
Condensate Segregation
Condensate segregation is the process whereby volatile organic compounds (VOC) and TRS are disproportionately concentrated into a smaller fraction of condensate. The objective is to minimize the mass flow of foul condensate to the effluent treatment system while maximizing the recapture of clean process condensates for re-use within the mill.
The most effective process for this is two-stage condensing, while a second process is flash distillation of an existing condensate. Two-stage condensing requires that a vapour be condensed in series on two distinct surfaces. These surfaces may be in one body or may be in two separate vessels. The second method, flash distillation, flashes the saturated condensate from a higher pressure to a lower pressure. The more volatile VOC and TRS components distil more readily than water and are thereby preferentially contained in the vapour stream.
Condensate segregation may be utilized in virtually all foul-vapour condensing applications. One of the earliest applications was two-stage condensing for turpentine recovery. Two separate condensers are used, with hot process condensate from the first condenser containing little methanol and no TRS or turpentine. The cooler secondary condensate will contain the bulk of the turpentine, TRS and VOC.