Condensers control and reclaim VOCs
Technological advances increase recovery of costly product
Condensation is one technology used to reduce volatile organic compound (VOC) emission rates. Its use has been driven in part by the Clean Air Act Amendments of 1990, which state acceptable rates for VOC emissions. Condensation technology allows reclamation of VOCs, providing an economic incentive when costly product is reclaimed as a condensate.
Condenser operation
Condensation in a condenser is a phase change operation in which a vapor contacts a heat transfer surface maintained below the dewpoint temperature of that vapor. A liquid film, known as a condensate, forms on the heat transfer surface. This condensate can be compared to the moisture that develops on the inside of a window in a home on a cold winter day. The window temperature is below the dewpoint temperature; therefore, moisture in the air is condensed onto the cold surface.
When a vent stream consists of a single VOC and no non-condensible gas, then condensation occurs isothermally, that is, at a constant temperature. When non-condensibles or other VOCs with varied volatilities are present, condensation will occur along a temperature change. As the outlet temperature gets colder,more of the VOCs are converted from vapor to liquid.
Non-condensible gases
The most common condenser applications involve a VOC stream that includes non-condensible gases.Non-condensible gases may be air, nitrogen or any other gas that will not condense at the operating temperatures within a condenser. Because of the presence of non-condensible gases, there always is an associated VOC saturation component....