Turpentine is a wood extractive found in most coniferous woods. During the pulping process wood chips are heated and lignin is dissolved which drives turpentine into the liquid/vapor space within the digester. In the batch cooking process, the vapor space of the digester is vented (relieved); it is these vapors that are condensed for turpentine recovery.

In a continuous process, the spent pulping liquor is extracted from the pulp at high temperature and flashed to atmospheric pressure; it is these vapors that contain turpentine.

The A. H. Lundberg Associates, Inc. turpentine condensing system can be either one or two stages. In a two-stage system the primary condenser condenses mostly water with some methanol while the second stage condenser condenses the blow-through containing turpentine from the primary condenser. Mills are required to maximize methanol recovery thus a two-stage system provides little benefit other than slightly better turpentine recovery and generation of hotter process water, since the primary condensate containing methanol must be processed.

A standard Lundberg Associates system includes a pressure vacuum relief valve, a cyclone entrainment separator, one or two condensers, a gas cooler, a horizontal flooded decanter with weir box, and a flooded horizontal storage tank. The cyclone separator removes both fiber and entrained black liquor since the black liquor may cause emulsification of the condensate in the decanter. The A. H. Lundberg turpentine condensers are vertical tube side condensing units. In a two stage system the primary condenser will be co-current, while the secondary or single stage condenser will be counter-current.

The gas cooler may be either shell and tube or a packed column, with a preference towards indirect contact to minimize foul condensate to be handled. The turpentine decanter is a horizontal flooded unit that avoids a vapor space. The adjustable weir box maintains a turpentine layer in the top of the decanter and the adjustability of the unit permits all the turpentine to be decanted if the decanter needs to be maintained. In a new system the decanter is typically mounted on top of the horizontal storage tank to allow gravity overflow of the turpentine to storage.

The storage tank is a flooded unit containing only water and turpentine. The turpentine displaces the water in the storage tank during normal operation. When the storage tank needs to be unloaded the turpentine inlet is temporarily shut off, a water pad is put on the tank, and the turpentine is pushed to transport.