Apparatus for mixing chemicals into pulp at a refiner inlet

#1. Field of the Invention

#Mixing two materials.

#2. Review of the Prior Art

#FIG. 1 is a diagram of a blow line oxygen system using a refiner.

#FIG. 2 is an isometric view of a diffuser used with a refiner to add the oxygen to the refiner.

#FIGS. 3 and 4 are cross sections of refiners, each with the diffuser of FIG. 2.

#The drawings show our invention applied in a blow line refiner.

#FIG. 1 is a diagram of part of a pulp mill. Chips 10, process water 11, steam 12 and pulping chemicals 13 are fed to the pulping section 14 of digester 15. The digester 15 is continuous in operation. The wood chips 10 may be treated prior to entering the digester 15. This is optional. Exemplary of such treatment are presteaming of the chips in a steaming vessel or impregnation of the chips with the digestion chemicals in an impregnation vessel prior to entering the digester. The chemicals 13 entering the digester will depend on the process being used, be it sulfate, sulfite, or soda. The chips will be cooked in the pulping section 14 under conditions appropriate to the chemicals, wood species and type, and size of chip. These conditions are well known.

#The products of the digestion process are the delignified or partially delignified wood chips, the spent pulping chemicals, and the lignin and carbohydrate products which have been removed from the wood chips in the digestion process. A major portion of the spent pulping chemicals and lignin products is removed from the chips prior to further processing. In the continuous digester shown, the chips are washed in the washing section of the digester. This is indicated by process water 16 entering and the effluent stream 17 leaving the washing stage 18 of digester 15. The effluent stream 17 will consist of the lignin and carbohydrates which have been removed from the chips during the digestion process and the spent digestion chemicals. This effluent will be carried to a treating facility. In the case of kraft or sulfate pulp this would be a recovery system in which the liquor is burned to recover the digestion chemicals for reuse.