Vapor pressure dewatering

A modification to vapor pressure dewatering is the so-called Hi-Bar Steam Pressure Filtration (Bokela GmbH, Karlsruhe, Germany), where pure steam... 

Ruf J, Stahl W. The hot filter-press The new technology of vapor pressure dewatering. In Baumann ER, Weisert L, eds. Advances in EUtration and Separation Technology. Vol. 11. Boston American Filtration Separations Society, 1997, pp 558-562. 

Dry Form Process, The advent of the pressurized refiner led eventually to dry-formed wood fiberboards because high-consistency pulps can be produced. Green wood chips contain equal parts water and dry wood matter and can be pressure refined in saturated steam with little change in moisture content. Fiber from the refiner at fifty percent consistency can be made fluffy and readily suspendable in air. This enables vapor-phase dewatering in hot-air driers to produce a fine, dry fiber that can be formed in air and dry pressed. Without liquid-phase dewatering, solubles formed by the steam cooking of chips remain in the fiber furnish going to the board machine. 

The overhead from the second stage is heated by an exchange with hot solvent. The fired heater further raises the temperature of the solvent/demetallized oil mixture to a point above the critical temperature of the solvent. This causes the demetallized oil to separate. It is then flashed and steam-stripped to remove all traces of solvent. The vapor streams from the demetallized oil and asphalt strippers are condensed, dewatered, and pumped up to process pressure for recycle. The bulk of the solvent goes overhead in the supercritical separator. This hot solvent stream is then effectively used for process heat exchange. The subcritical solvent recovery techniques, including multiple effect systems, allow much less heat recovery. Most of the low grade heat in the solvent vapors from the subcritical flash vaporization must be released to the atmosphere requiring additional heat input to the process. 

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