Method and system for controlling the addition of oxygen gas and alkali during oxygen gas delignification

摘要

The method and system is for the acid gas delignification of cellulose pulp in a gas/fluid suspension. The oxygen gas delignification takes place in a reactor system with one or several oxygen gas reactors. Delignification chemicals are added at least before the first oxygen gas reactor such that oxygen gas remains present during the complete reaction process in the reactors. Alkali in an amount that ensures that the pH lies above 9 is also added. The temperature of the cellulose pulp is measured at two different positions (T 1 , T 2 , . . . , Tn) viewed in the direction of flow of the pulp though the system. The measurements are used to control the charged amount of the delignification chemicals to the oxygen gas delignification. The first temperature measurement (T 1 ) is carried out at a position in association with the first addition of oxygen gas.