Chip feed and steaming system and method for batch digester

Abstract

A method for chemically digesting cellulosic fibrous material including: adding a liquor to cellulosic fibrous material to form a slurry in a chip feed system; transporting the slurry from the chip feed system to a batch digester vessel; determining when a chip level rises above an extraction screen in the batch digester vessel; after the chip level rises above the extraction screen, extracting liquor from the batch digester vessel while the transport continues of the slurry into the batch digester vessel; adding cooking liquor to slurry in the batch digester vessel; ceasing the transport of the slurry into the batch digester vessel and thereafter converting the cellulosic material in the vessel to a pulp, and discharging the pulp from the batch digester vessel before restarting the transporting of the slurry into the digester vessel.

1 . A method for chemically digesting cellulosic fibrous material comprising:
 adding a liquor to cellulosic fibrous material to form a slurry in a chip feed system;   transporting the slurry from the chip feed system to a batch digester vessel;   determining when a chip level rises above an extraction screen in the batch digester vessel;   after the chip level rises above the extraction screen, extracting liquor from the batch digester vessel while the transport continues of the slurry into the batch digester vessel;   ceasing the transport of the slurry into the batch digester vessel and thereafter converting the cellulosic material in the vessel to a pulp, and   discharging the pulp from the batch digester vessel before restarting the transporting of the slurry into the digester vessel.   
     
     
         2 . The method as in  claim 1  wherein heat energy is added to the cellulosic fibrous material or the slurry before the slurry is transported into the batch digester vessel. 
     
     
         3 . The method as in  claim 1  further comprising adding a cooking liquor to the slurry before the slurry enters the batch digester vessel. 
     
     
         4 . The method as in  claim 1  further comprising extracting liquor from the batch digester vessel during the transport of the slurry into the vessel. 
     
     
         5 . The method as in  claim 1  wherein the transportation of the slurry, the conversion to the pulp in the vessel and the discharging from the vessel are performed sequentially and repeatedly. 
     
     
         6 . The method as in  claim 1  further comprising pressurizing the slurry by passing the slurry through a high pressure transfer device. 
     
     
         7 . The method as in  claim 1  wherein the high pressure transfer device is at least one chip pump which pressurizes the slurry. 
     
     
         8 . The method as in  claim 1  further comprising adding steam heat to the cellulosic material or slurry in a chip feed system. 
     
     
         9 . The method as in  claim 8  where the steam heat is added at a lower end of a chip tube coupled to an inlet of a high pressure transfer device. 
     
     
         10 . The method as in  claim 9  further comprising transferring heat from liquor extracted from the batch digester vessel to the liquor added in the chip feed system. 
     
     
         11 . The method of  claim 1  further comprising adding a cooking liquor to the cellulosic fibrous material in the batch digester vessel and the chip feed system. 
     
     
         12 . The method as in  claim 1  wherein a liquor to cellulosic material ratio on a weight basis is in a range of five to eight as the slurry flows through a high pressure transfer device of the chip feed system, and in a range of three to five during the conversion of the cellulosic material to the pulp in the batch digester vessel. 
     
     
         13 . A method batch digesting method for pulping cellulosic fibrous material, the method comprising:
 adding a liquor to cellulosic fibrous material to form a slurry in a chip feed system;   transporting the slurry from the chip feed system to an upper inlet to a batch digester vessel;   as the slurry is being transported into the batch digester vessel and after a liquid or chip level in the vessel rises above an extraction screen in the vessel, extracting liquor from the batch digester vessel;   ceasing the transport of the slurry into the batch digester vessel;   while the transport of the slurry is ceased, converting the cellulosic material in the vessel to a pulp, and   discharging the pulp from the batch digester vessel.   
     
     
         14 . The method of  claim 13  wherein each of the steps of transporting, ceasing and converting are performed sequentially and separately. 
     
     
         15 . The method of  claim 14  wherein the steps of transporting, ceasing and converting are repeated. 
     
     
         16 . The method as in  claim 13  wherein heat energy is added to the cellulosic fibrous material or slurry before the slurry is transported to the upper inlet of the batch digester vessel. 
     
     
         17 . The method as in  claim 13  further comprising adding a cooking liquor to an impregnation vessel of the chip feed system and before the slurry enters the batch digester vessel. 
     
     
         18 . The method as in  claim 13  further comprising transferring heat from liquor extracted from the batch digester vessel to the liquor added in the chip feed system. 
     
     
         19 . The method of  claim 13  further comprising adding a cooking liquor to the cellulosic fibrous material in the chip feed system and the batch digester vessel. 
     
     
         20 . The method as in  claim 13  wherein a liquor to cellulosic material ratio on a weight basis is in a range of five to eight as the slurry flows through a high pressure transfer device of the chip feed system, and in a range of three to five during the conversion of the cellulosic material to the pulp in the batch digester vessel.