Reactive twin-screw extrusion valve

Abstract

A system for the production of carbonized biomass that includes an infeed for accepting biomass feed material and an associated twin screw extruder. A water heater is connected with respect to at least one inlet along a length of the twin screw extruder and a pressure sustaining valve is connected at an outlet of the twin screw extruder.

What is claimed is: 
     
         1 . A system for the production of extruded product comprising:
 an infeed for accepting material;   a twin screw extruder connected with respect to the infeed, the twin screw extruder having a length between the infeed and an outlet; and   a dual-function variable restriction valve connected with respect to a die plate positioned between the infeed and the outlet, the dual-function variable restriction valve permitting a quasi-steady-state process to be carried out within the extruder while controlling delivery of the extruded product to ambient conditions, the dual-function variable restriction valve including a valve plunger having an adjustable tension relative to the die plate, wherein the adjustable tension is adjustable based upon process parameters within the extruder.   
     
     
         2 . The system of  claim 1  further comprising a feedback control system that responsively adjusts the adjustable tension based upon process pressure upstream of the die plate. 
     
     
         3 . The system of  claim 1  wherein the dual-function variable restriction valve further comprises a sleeve bearing and a valve seal follower connected to the valve plunger. 
     
     
         4 . The system of  claim 1  further comprising a hand wheel connected with respect to the dual-function variable restriction valve. 
     
     
         5 . The system of  claim 1  further comprising a linear driver motor connected with respect to the valve plunger and a feedback control system. 
     
     
         6 . The system of  claim 5  wherein the linear driver motor is capable of operating the valve plunger at a sufficient rate to maintain a generally constant pressure within the reaction zone. 
     
     
         7 . The system of  claim 1  further comprising a load cell connected with respect to the valve plunger. 
     
     
         8 . The system of  claim 1  wherein the twin screw extruder includes a plurality of mixing elements and a plurality of reversing elements. 
     
     
         9 . The system of  claim 8  wherein the reversing elements are interspersed within the twin screw extruder upstream and downstream of the die plate to provide flow restrictions and/or pressure boundaries within the twin screw extruder. 
     
     
         10 . The system of  claim 1  wherein the twin screw extruder includes at least one reversing element and an increasing pitch on a mixing element between the infeed and the at least one reversing element. 
     
     
         11 . The system of  claim 1  further comprising a water heater connected with respect to at least one inlet along the length of the twin screw extruder. 
     
     
         12 . The system of  claim 11  wherein the liquid water inlet is positioned immediately following a first dynamic seal created between a mixing element and a reversing element within the twin screw extruder. 
     
     
         13 . The system of  claim 11  wherein the at least one inlet generally corresponds with a pressure boundary within the twin screw extruder 
     
     
         14 . The system of  claim 1  wherein the twin screw extruder includes an increasing pitch mixing element extending from the infeed. 
     
     
         15 . The system of  claim 1  wherein at least three reversing elements are positioned within the twin screw extruder resulting in at least three flow restrictions and/or pressure boundaries. 
     
     
         16 . The system of  claim 1  wherein the dual-function variable restriction valve is regulated by a servo-actuated feedback-control system that uses pressure and temperature measurements within a reaction section of the twin-screw extruder to stabilize a pressure within the reaction section. 
     
     
         17 . The system of  claim 16  wherein the feedback-control system stabilizes pressure within the reaction section to within 5% to 10% of a process average value ranging between 25 and 100 bar. 
     
     
         18 . The system of  claim 1  wherein the dual-function variable restriction valve is regulated by a servo-actuated feedback-control system that uses pressure and temperature measurements within a reaction section of the twin-screw extruder to maintain an average Specific Mechanical Energy of the twin-screw extruder to a desired value. 
     
     
         19 . The system of  claim 18  wherein the desired value is within 5% of a process average value ranging between 20 and 80 Watt-hours/kilogram. 
     
     
         20 . The system of  claim 1  wherein the process parameters within the extruder include a temperature range of 200-300° C. 
     
     
         21 . The system of  claim 1  wherein the process parameters within the extruder include a pressure range of 100-350 bar. 
     
     
         22 . A system for the production of hydrothermally carbonized biomass comprising:
 a supply of lignocellulosic biomass feed material;   an infeed for accepting the lignocellulosic biomass feed material;   a twin screw extruder connected with respect to the infeed, the twin screw extruder having a length between the infeed and an outlet;   an high-pressure, high-temperature, on-demand hot water heater adapted to provide hot water at greater than 230° C. connected with respect to at least one inlet along the length of the twin screw extruder, wherein the at least one inlet generally corresponds with a pressure boundary within the twin screw extruder; and   a dual-function variable restriction valve connected with respect to a die plate positioned between the infeed and the outlet, the valve including a valve plunger having an adjustable tension relative to the die plate, wherein the adjustable tension is adjustable based upon process parameters within the extruder, and wherein the hydrothermally carbonized biomass is provided at the outlet.