METHODS FOR PRODUCING HIGH-FREENESS PULP
First Claim
1. A method of producing a mechanical pulp from lignocellulosic material in a pulping system comprisinga pretreatment subsystem comprising a pressure separated feeding device, a high compression device, and an impregnator, anda production subsystem comprising a variable speed pressurized conveyor and a primary mechanical refiner,the method comprising the following steps:
- providing lignocellulosic material to the pressure separated feeding device and then transferring the lignocellulosic material to the high compression device;
wherein the step of destructuring the lignocellulosic material in the high compression device results in a destructured lignocellulosic material in which over 50% of the destructured lignocellulosic material by weight passes through a 16 mm screen perforation;
transferring the lignocellulosic material from the high compression device to the impregnator and impregnating the lignocellulosic material;
transferring the lignocellulosic material to the variable speed pressurized conveyor, wherein a residence time of the variable speed pressurized conveyor is 20 seconds or less, and wherein the variable speed pressurized conveyor operates at a pressure between 7.5 and 12 bar (gauge) and preheats the lignocellulosic material with steam;
transferring the lignocellulosic material to the primary mechanical refiner; and
mechanically refining the lignocellulosic material in the primary mechanical refiner at a pressure between 7.5 and 12 bar (gauge) to obtain a high freeness pulp.
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Accused Products
Abstract
Methods of producing mechanical pulps from lignocellulosic material including partial defibration of lignocellulosic material in a chip press followed by liquid impregnation, preheating the lignocellulosic material for 20 seconds or less at a pressure between 7.5 and 12 bar (gauge) prior to mechanically refining the lignocellulosic material in a primary mechanical refiner at a pressure between 7.5 and 12 bar (gauge), thus obtaining a high freeness pulp.
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Citations
21 Claims
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1. A method of producing a mechanical pulp from lignocellulosic material in a pulping system comprising
a pretreatment subsystem comprising a pressure separated feeding device, a high compression device, and an impregnator, and a production subsystem comprising a variable speed pressurized conveyor and a primary mechanical refiner, the method comprising the following steps: -
providing lignocellulosic material to the pressure separated feeding device and then transferring the lignocellulosic material to the high compression device;
wherein the step of destructuring the lignocellulosic material in the high compression device results in a destructured lignocellulosic material in which over 50% of the destructured lignocellulosic material by weight passes through a 16 mm screen perforation;transferring the lignocellulosic material from the high compression device to the impregnator and impregnating the lignocellulosic material; transferring the lignocellulosic material to the variable speed pressurized conveyor, wherein a residence time of the variable speed pressurized conveyor is 20 seconds or less, and wherein the variable speed pressurized conveyor operates at a pressure between 7.5 and 12 bar (gauge) and preheats the lignocellulosic material with steam; transferring the lignocellulosic material to the primary mechanical refiner; and mechanically refining the lignocellulosic material in the primary mechanical refiner at a pressure between 7.5 and 12 bar (gauge) to obtain a high freeness pulp. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of producing a mechanical pulp from lignocellulosic material in a pulping system comprising
a pretreatment subsystem comprising a pressure separated feeding device, a high compression device, and an impregnator, and a production subsystem comprising a variable speed pressurized conveyor and a primary mechanical refiner, the method comprising the following steps: -
providing lignocellulosic material to the pressure separated feeding device and then transferring the lignocellulosic material to the high compression device;
wherein the step of destructuring the lignocellulosic material in the high compression device results in a destructured lignocellulosic material in which over 50% of the destructured lignocellulosic material by weight passes through a 16 mm screen perforation;transferring the lignocellulosic material from the high compression device to the impregnator and impregnating the lignocellulosic material; transferring the lignocellulosic material to the variable speed pressurized conveyor, wherein a residence time of the variable speed pressurized conveyor is 20 seconds or less, and wherein the variable speed pressurized conveyor operates at a pressure between 7.5 and 12 bar (gauge) and preheats the lignocellulosic material with steam; transferring the lignocellulosic material to the primary mechanical refiner; and mechanically refining the lignocellulosic material in the primary mechanical refiner at a speed greater than or equal to 2000 rpm and at a pressure between 7.5 and 12 bar (gauge) to obtain a high freeness pulp. - View Dependent Claims (21)
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Specification