Impregnation vessel with convergence side relief and method for heat injection at convergence

Abstract

An impregnation vessel including: a vessel container including an upper inlet to receive cellulosic material; a lower discharge port to discharge the cellulosic material from a discharge section of the vessel container; a convergence section internal to the vessel through which passes a flow of the cellulosic material in the vessel; a cavity between an internal wall of the vessel and the convergence section, wherein the cavity has a lower opening to the cellulosic material in the vessel and an upper section shielded from the flow of cellulosic material in the vessel, and an input port in the vessel and opening to the cavity, wherein the input port is connectable to a source of hot liquid to be added to the cellulosic material in the vessel.

1 . An impregnation vessel comprising:
 a vessel container including an upper inlet to receive cellulosic material;   a lower discharge port to discharge the cellulosic material from a discharge section of the vessel container;   a convergence section internal to the vessel through which passes a flow of the cellulosic material in the vessel;   a cavity between an internal wall of the vessel and the convergence section, wherein the cavity has a lower opening to the cellulosic material in the vessel and an upper section shielded from the flow of cellulosic material in the vessel, and   an input port in the vessel and opening to the cavity, wherein the input port is connectable to a source of hot liquid to be added to the cellulosic material in the vessel.   
   
   
       2 . The impregnation vessel as in  claim 1  wherein the convergence section converges in a single direction within the vessel. 
   
   
       3 . The impregnation vessel as in  claim 1  wherein the convergence section converges in orthogonal directions within the vessel. 
   
   
       4 . The impregnation vessel as in  claim 1  wherein the convergence section includes a tapered wall having an upper section sealed to the internal wall of the vessel and a lower section positioned radially inward of the internal wall, wherein the cavity is between the internal wall of the vessel and the tapered wall of the convergence section. 
   
   
       5 . The impregnation vessel as in  claim 1  wherein the convergence section and cavity are below a liquid level in the vessel. 
   
   
       6 . The impregnation vessel as in  claim 1  wherein the source of hot liquid supplies the hot liquid at a temperature above a discharge temperature of the cellulosic material from the vessel. 
   
   
       7 . The impregnation vessel as in  claim 1  wherein the source of hot liquid supplies the hot liquid at a temperature of at least 120 degrees Celsius. 
   
   
       8 . An impregnation vessel comprising:
 a vessel container including an upper inlet to receive cellulosic material;   a lower discharge port to discharge the cellulosic material from a discharge section of the vessel container;   a one-dimensional convergence section internal to the vessel through which passes a flow of the cellulosic material in the vessel;   a cavity between an internal wall of the vessel and the convergence section, wherein the cavity has a lower opening to the cellulosic material in the vessel and an upper section shielded from the flow of cellulosic material in the vessel, and   an input port in the vessel and opening to the cavity, wherein the input port is connectable to a source of hot liquid to be added to the cellulosic material in the vessel and the hot liquid is added to the cavity at a temperature above an average temperature of the cellulosic material in the vessel.   
   
   
       9 . The impregnation vessel as in  claim 8  wherein the one-dimensional convergence section includes a tapered wall having an upper section sealed to the internal wall of the vessel and a lower section positioned radially inward of the internal wall, wherein the cavity is between the internal wall of the vessel and the tapered wall of the convergence section. 
   
   
       10 . The impregnation vessel as in  claim 8  wherein the convergence section and cavity are below a liquid level in the vessel. 
   
   
       11 . The impregnation vessel as in  claim 8  wherein the source of hot liquid supplies the hot liquid at a temperature above a discharge temperature of the cellulosic material from the vessel. 
   
   
       12 . The impregnation vessel as in  claim 8  wherein the source of hot liquid supplies the hot liquid at a temperature of at least 120 degrees Celsius. 
   
   
       13 . A method for heating cellulosic material in an impregnation vessel having an internal convergence, the method comprising:
 introducing cellulosic material to an upper inlet port in the impregnation vessel;   adding a heated liquid to the vessel and forming a liquid level in a upper section of the vessel;   heating the cellulosic material with the heated liquid as the cellulosic material flows downward through the vessel;   detecting the flow of the cellulosic material below the liquid level and in the vessel through the internal convergence;   introducing a hot liquid to a cavity in the vessel and behind the convergence, wherein the hot liquid is introduced to the cavity at a temperature above a temperature of the heated liquid;   adding the hot liquid from the cavity to the flow of cellulosic material downstream of the internal convergence;   heating the flow of cellulosic material downstream of the internal convergence with the hot liquid, and   discharging the cellulosic material from a discharge port in a lower section of the vessel below the cavity and internal convergence.   
   
   
       14 . The method in  claim 13  wherein the cellulosic material is continuously introduced to and discharged from the vessel. 
   
   
       15 . The method in  claim 13  wherein the convergence section convergences in a single direction within the vessel. 
   
   
       16 . The method in  claim 13  wherein the convergence section includes a tapered wall having an upper section sealed to the internal wall of the vessel and a lower section positioned radially inward of the internal wall, and the cavity is between the internal wall of the vessel and the tapered wall of the convergence section, and the hot liquid added to the cavity is shielded by the tapered wall. 
   
   
       17 . The method in  claim 13  wherein the convergence section converges in orthogonal directions and the flow is funneled to a circular discharge from the convergence. 
   
   
       18 . The method as in  claim 13  wherein the hot liquid is added to the cavity at a temperature above a discharge temperature of the cellulosic material from the vessel. 
   
   
       19 . The method as in  claim 13  wherein the hot liquid is at a temperature of at least 120 degrees Celsius when added to the cavity. 
   
   
       20 . The method as in  claim 13  further comprising conveying the discharged cellulosic material to a digester vessel. 
   
   
       21 . The method as in  claim 20  wherein the hot liquid includes hot black liquor extracted from the digester vessel. 
   
   
       22 . The method as in  claim 20  wherein the hot liquid includes hot black liquor extracted from a lower section of the digester vessel. 
   
   
       23 . The method as in  claim 13  further comprising supplying the introduced cellulosic material from a chip bin.