Q2-1 Reflux Condenser Design

J. W. Palen

Reflux condensers have been used in industry for many years. Sometimes called knockbacks, these condensers allow vapor to enter and condensate to exit at the lower end of the unit. Both the column-top and the component-separator are condensers of this type.

Column-top condensers inserted in the top of distillation columns eliminate the need for vapor piping. Component-separator condensers remove heavier components from a vapor stream exiting at the top of the condenser.

For environmental and economic reasons, use of the latter application, which removes as many hydrocarbons as possible from off-gas streams, has increased. The cryogenics industry uses reflux condensers (referred to as dephlegmators) to separate hydrocarbons from cryogenic components.