Modo-chemetics Ab

Sven-Erik D Henriksson

Claes G Svensson

Torsten A Franzen

Bo A Ahrel

A process is provided for inexpensively producing high yield mechanical cellulose pulp having good paper properties, which comprises preheating particulate lignocellulosic material; defibrating the preheated material under a superatmospheric steam pressure within the range from about 2 to about 4.5 bar above atmospheric pressure in a disc refiner under conditions such that steam is generated during the defibration; continuing the defibration until a cellulose pulp is obtained having a freeness within the range from about 300 to about 700 ml CSF; flash drying the defibrated cellulose pulp while maintaining a superatmospheric steam pressure within the said range during the drying; withdrawing steam generated during the defibration and passing it in indirect heat exchange with steam utilized in the flash drying, so as to utilize in the drying at least 30% of the heat content thereof; and then removing and baling the flash-dried cellulose pulp. Water vapor produced in the flash dryer is condensed and recycled to the disc refiner.

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Vancouver, Canada

Sven-Erik D Henriksson