METHOD AND APPARATUS FOR MIXING A FIRST MEDIUM TO A SECOND MEDIUM AND A BLEACHING PROCESS APPLYING SAID METHOD

摘要

The present invention relates to a mixing of gas into a medium. The method and apparatus in accordance with the present invention are especially applicable in the bleaching plants of the wood process- ing industry for mixing gaseous bleaching chemicals into pulp and to bleaching process of pulp, in which the mixing method and apparatus in accordance with the present invention are applied. An excellent ap- plication is mixing ozone-containing gas into a fiber suspension flow- ing in a pipe line and an ozone bleaching process. The previously known methods and apparatuses have not been able to mix satisfactori- ly large volumes of gas, about 50 % of the total volume of the flow, into the medium flow. In the method in accordance with the present inven- tion the mixing is carried out in a strong shear force field efficiently and uniformly, whereafter the fiber network of the medium is allowed to form rapidly and in a controlled manner so that gas is not allowed to separate in the flow as bubbles, but remains in the plug flow in the fib- er network.