Method fo feeding fibrous material into a pressurized vessel

Claim 2

Method of feeding fibrous ligno-cellulose raw material through a tubular conduit into a vessel whose interior contains steam pressurized to the range of up to 300 pounds per square inch, said method including the step of compacting said material within a predetermined length of said conduit adjacent to said vessel to a density of at least 45 pounds per cubic foot of oven dry material, while maintaining the moisture thereof at approximately 10 to 50% by weight, simultaneously advancing the compacted material through said length of said conduit to discharge the leading end thereof into said vessel; whereby the compacted material located within said pre-determined length of the conduit forms a closure plug for preventing the escape of pressurized medium from said vessel into said conduit.

Claim 3

Method of feeding fibrous, ligno-cellulose raw material of the type capable of being conveyed in a screw conv-eyor into a pressurized vessel, said vessel containing vapour medium pressurized to approximately 300 pounds per square inch, said method comprising the steps of: (a) feeding said material in a generally free-fall bulk form into an inlet region of a screw conveyor; (b) advancing said material by said screw conveyor to an outlet region of said screw conveyor while simultaneously pre-compacting said material at said outlet region to a first degree of compactness; (c) further advancing said pre-compacted material in a direction generally co-axial with said screw conveyor, into an elongated, tubular conduit such that the material occupies the entire cross-sectional area of a first length of said conduit; (d) further compacting the material located in said length of said conduit, to a bulk density of at least 45 pounds per cubic foot of oven dry material; (e) the moisture content of said material throughout said pre-compacting and said compacting stage being maintained at a natural level of approximately 10 to 50% by weight; (f) further advancing said material through said conduit towards said vessel, at said bulk density of at least 45 pounds per cubic foot of oven dry material, to form from said material a plug advancing through a second length of said conduit; and (g) discharging the leading end of said plug into said pressurized vessel, whereby said plug forms in said conduit a closure separating, in a pressure-tight fashion, the inside of said vessel from said first length of said conduit.

Claim 4

Method of feeding fibrous, ligno-cellulose raw material of the type capable of being conveyed in a screw conv-eyor into a pressurized vessel, said vessel containing vapour medium pressurized to approximately 300 pounds per square inch, said method comprising the steps of: (a) feeding said material in a generally free-fall bulk form into an inlet region of a screw conveyor; (b) advancing said material by said screw conveyor to an outlet region of said screw conveyor while simultaneously pre-compacting said material at said outlet region to a first degree of compactness; (c) further advancing said pre-compacted material in a direction generally co-axial with said screw conveyor, into an elongated, tubular conduit such that the material occupies the entire cross-sectional area of a first length of said conduit; (d) further compacting the material located in said length of said conduit, to a bulk density of at least 45 pounds per cubic foot of oven dry material; (e) the moisture content of said material throughout said pre-compacting and said compacting stage being maintained at a natural level of approximately 10 to 50% by weight; (f) further advancing said material through said conduit towards said vessel, at said bulk density of at least 45 pounds per cubic foot of oven dry material, to form from said material a plug advancing through a second length of said conduit; and (g) discharging the leading end of said plug into said pressurized vessel, whereby said plug forms in said conduit a closure separating, in a pressure-tight fashion, the inside of said vessel from said first length of said conduit.

Claim 5

Method as claimed in claim 2, wherein the degree of a compacting pressure acting on said material during said stage of pre-compacting is gradually increased from a generally free-fall bulk pressure to a pressure below the value of a minimum shear limit of fibres contained in said material, whereby said pre-compacting can be effected by screw conveyor means.

Claim 6

A method as claimed in claim 3, wherein said compacting pressure is generated by subjecting the material within said conduit to a repeated intermittent compressive force oriented coaxially with said screw conveyor in the direction towards said vessel, while subjecting the material to a frictionally retarding action near the walls of said conduit, said intermittent compressive force being applied to said material near the end of said conduit remote from said vessel and along an annular locus whose outside diameter is generally coincident with the inside diameter of said conduit.