Method and apparatus to distribute the inflow of liquors in a Batch Digester

Abstract

Method and apparatus for introducing liquors into a batch digester to produce enhanced or plug-flow of the liquors through the bed of cellulosic material. Wash out liquor can be introduced into the digester during the discharging in a manner to add wash out liquor into the digester and to prevent formation of a vortex of material during discharge.

1 . A method of discharging delignified cellulosic material from a batch digester at the end of a cook cycle after removal of hot liquor from the digester comprising the steps of: 
 introducing a shower of clean out liquor into said digester at a location above said material, said shower distributing said liquor substantially evenly across a cross-sectional area of said digester, and    withdrawing said pulp from said digester while maintaining a flow of liquor sufficient to maintain consistency of said pulp until said digester is empty.    
     
     
         2 . A method according to  claim 1  including the step of placing means in said digester proximate a clean-out port of said digester to minimize or eliminate vortex flow of said delignified alkaline material as it discharges from said digester.  
     
     
         3 . A method according to  claim 2  including the step of installing anti-vortex vanes in said digester.  
     
     
         4 . A method according to  claim 2  including the step of installing anti-vortex vanes in said digester, said anti-vortex vanes including means to introduce liquor into said digester at any time during one of the charging, delignification, or discharging phase of the cooking cycle.  
     
     
         5 . In a batch digester of the type having a generally cylindrical section and a bottom generally conical section said conical section having an outlet located proximate said apex of said conical section, the improvement comprising a shower device placed in an upper location of said cylindrical section of said digester said device adapted to distribute wash out liquor evenly across cellulosic material within said digester.  
     
     
         6 . In a batch digester of the type having a generally cylindrical section and a bottom generally conical section said conical section having an outlet located proximate said apex of said conical section, the improvement comprising installing a distribution channel for liquid inside said digester at a location proximate a transition from said cylindrical section to said conical section said distribution channel installed adjacent an inner surface of said digester and having means to direct a plurality of streams upwardly and generally parallel to a vertical center line of said digester to enhance plug-flow of pulping liquors introduced into said digester during a liquor charging phase of a cooking cycle.  
     
     
         7 . A batch digester according to  claim 6  including means in said distribution channel to direct a plurality of streams in a downward direction to assist in discharging pulp during a discharge phase of a cooking cycle by one of diluting and/or directing pulp flow.  
     
     
         8 . In a batch digester of the type having a generally cylindrical section and a bottom generally conical section said conical section having an outlet located proximate said apex of said conical section, the improvement comprising at least two distribution channels on the inner surface of said conical section said distribution channels containing means to direct streams of liquors generally upwardly and generally parallel to vertical center-line of said digester to enhance plug-flow of pulping liquors introduced into said digester.  
     
     
         9 . A method for enhancing plug-flow of pulping liquors introduced into a batch digester for delignifying cellulosic materials comprising the steps of: 
 introducing a plurality of streams of said pulping liquor proximate a bottom location of said digester, said streams oriented to flow in a direction generally parallel to a vertical axis of said digester; and    continuing flow of said liquor until said cellulosic material is delignified to a desired consistency.    
     
     
         10 . A method according to  claim 9  including the step of varying the intensity of individual streams with the intensity being greater at the center line of said digester.  
     
     
         11 . A method for enhancing plug flow of pulping liquor introduced into a bottom of a batch digester for counter-current flow through a charge of cellulosic material to be delignified comprising the steps of: 
 placing a flow directing device in said digester at a location proximate s a bottom portion of a vertical portion of said digester, said flow directing device causing said pulping liquor to flow in a direction generally vertical to a center line of said digester; and    continuing flow of said liquor until said cellulosic material is delignified to a desired consistency.