Kvaerner Pulping Ab

Kamyr Aktiebolag

Kvaerner Pulping Technologies

Kamyr Atkiebolag

Hakan Dahllof

Martin Ragnar

Rolf Ekholm

Ulf Jansson

Anders Bergovist

Anders Bergvist

A system and process for the oxygen delignification of pulp consisting of a lignocellulose-containing material that has a mean concentration of 8-18% pulp consistency. The oxygen delignification takes place in a first stage with a short dwell time of about 3-6 minutes, at a low temperature of about 85&#xb0; C. and under a low pressure of approximately 0-4 bar. A concluding stage has a longer dwell time of about 50-90 minutes, at a higher temperature of approximately 100&#xb0; C. and under a higher pressure of about 8-10 bar.

Process for the oxygen delignification of pulp in two stages with higher pressure in the second stage

The system is for the oxygen delignification, in at least two reaction stages, of pulp that consists of lignocellulose-containing material having a mean concentration of 8%-18% pulp consistency. The oxygen delignification takes place in a first reaction stage that has a substantially constant low pressure during the whole delignification process. The second delignification stage has a substantially higher pressure and temperature and a longer dwell time. Readily delignifiable constituents in the pulp may react without the pulp being negatively affected so that the delignification process provides a very high degree of selectivity and an improved yield.

System for the oxygen delignification of pulp consisting of lignocellulose-containing material

A system and a process for the oxygen delignification of pulp consisting of lignocellulose-containing material whose mean concentration is 8-18% pulp consistency, in at least two stages. The invention is characterized in that the oxygen delignification takes place in a first stage with a short dwell time of approx. 3-6 minutes, at a low temperature of approx. 85&deg; C. and under a low pressure of approx. 0-4 bar, followed by a concluding stage with a longer dwell time of approx. 50-90 minutes, at a higher temperature of approx. 100&deg; C. and under a higher pressure of approx. 8-10 bar. This makes it possible, in an industrial process, to exploit the kinetics of the oxygen delignification in an optimal manner for the purpose of obtaining a selective oxygen delignification at low installation cost and at low operating cost.

A process for bleaching pulp, in which, after fiber liberation, a first filtrate containing metals, principally in ionic form, is separated off from the pulp, and supplied downstream to the pulp flow after a bleaching stage.

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Edsvalla, Sweden

Hakan Dahllof