Importance

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Abstract

A method for treating a fiber pulp suspension, which comprises transporting the fiber pulp suspension from a maintenance vessel, in which there is atmospheric pressure or at most 1 bar overpressure and in which the pulp suspension is at a temperature which does not exceed 95.degree. C., to a bleaching reactor and introducing the suspension into the bottom part of the reactor, which is at least 10 m high and at the top of which there is an overpressure which exceeds the steam saturation pressure, in which reactor the pulp is subjected to a bleaching treatment under pressure at a reaction temperature exceeding 100.degree. C., in addition to which the pulp suspension, during the transportation from the maintenance vessel to the reactor, is heated to at least reaction temperature. The pulp suspension is pumped to a mixer with the aid of a first pump which provides 1.5-3 bar overpressure. Low-pressure steam, which is at a pressure of 3-8 bar above atmospheric pressure and a temperature of 135-155.degree. C., is mixed into the pulp suspension in the mixer so that the temperature of the suspension is increased to the desired reaction temperature. After that, the pressure is increased still further with the aid of a second pump 18 after the mixer, so that the heated and pressurized pulp suspension can be pumped into the bottom part of the reactor. The invention also relates to equipment for implementing the method.

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First Claim