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A type, which zone in the pulping warmth developed use of the steam pressure in the production of fibrous material for the production of fibre boards to reduce to a minimum
A type, which zone in the pulping warmth developed use of the steam pressure in the production of fibrous material for the production of fibre boards to reduce to a minimum
Method and apparatus for minimizing steam consumption in the production of pulp used for the manufacture of fiberboard and the like, in which chips of cellulosic material are ground in a defibrator or refiner in an environment of saturated steam above 100 DEG C and corresponding steam pressures. The chips are normally presteamed with atmospheric steam separated from the pulp at the discharge end of the defibrating process to a temperature between 90 DEG C and 100 DEG C and compressed and dewatered to a dryness of at least 50% and then passed into a preheater which forms part of the defibrating or refining apparatus, where the compressed and dewatered chips are heated to the desired defibrating or refining temperature, usually ranging between 130 DEG C and 200 DEG C, by a portion of the high-temperature high-pressure steam generated by the heat of friction in the grinding space of the defibrator, which portion, upon discharge from the grinding housing, is separated from the pulp and recirculated under increased pressure above the discharge pressure. If the other portion of the discharged atmospheric steam, upon separation from the pulp, should not have sufficient heat content to presteam the raw chips to the desired temperature, fresh pressurized steam may be added to the recirculated portion of the steam to impart to the other portion of the discharged steam the required capacity.
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