Apparatus and method for thickening and washing suspensions containing fibrous material

Claim 2

An apparatus according to claim 1, wherein said one side of said filter medium is the outer side thereof.

Claim 3

An apparatus according to claim 1, wherein said face of said pressing baffle is, at least adjacent said trailing end of said pressing baffle, provided with low-coefficient of friction material.

Claim 4

An apparatus according to claim 1, wherein said pressing baffle extends along said one side of said filter medium for an arcuate distance greater than about 60* and less than about 120* of the drum circumference.

Claim 5

An apparatus according to claim 1, further comprising stationary baffle means extending along said one side of said filter medium spaced therefrom and substantially immediately preceeding said pressing baffle in said predetermined rotary direction.

Claim 6

An apparatus according to claim 6, wherein said pressing baffle and said stationary baffle means together extend along said one side of said filter medium for an arcuate distance greater than about 100* and less than about 180* of the drum circumference.

Claim 7

An apparatus according to claim 1, wherein said bias causing means comprises a biasing chamber on the opposite side of said pressing baffle from said filter medium, and means for supplying pressurized fluid to said biasing chamber whereby the pressurized fluid biases said pressing baffle towards said filter medium.

Claim 8

An apparatus according to claim 8, wherein said washing fluid supplying means comprises means for supplying pressurized fluid from said biasing chamber to said one side of said filter medium following said trailing end of said pressing baffle.

Claim 9

An apparatus according to claim 8, wherein said washing fluid supplying means comprises means for supplying washing fluid independently of said biasing chamber.

Claim 10

An apparatus according to claim 8, wherein said biasing fluid supplying means is connected to said biasing chamber adjacent said leading end of said pressing baffle.

Claim 11

An apparatus according to claim 1, wherein said pressing baffle includes a flexible portion adjacent its said trailing end, and at least the major part of the remainder of the length of said pressing baffle circumferentially of said drum is provided with reinforcing rib means.

Claim 12

An apparatus according to claim 1, wherein said face of said pressing baffle is at least generally concave, said one side of said filter medium is the outer side thereof, said pressing baffle includes a flexible portion adjacent its said trailing end, said bias causing means comprises a biasing chamber on the opposite side of said pressing baffle from said filter medium and means for supplying pressurized fluid to said biasing chamber whereby the pressurized fluid biases said pressing baffle towards said filter medium.

Claim 13

An apparatus according to claim 13, wherein said washing fluid supplying means comprises means for supplying pressurized fluid from said biasing chamber to said one side of said filter medium following said trailing end of said pressing baffle.

Claim 14

An apparatus according to claim 13, wherein said biasing fluid supplying means is connected to said biasing chamber adjacent said leading end of said pressing baffle.

Claim 15

An apparatus according to claim 13, wherein said face of said pressing baffle is, at lesat adjacent said trailing end of said pressing baffle, provided with low-coefficient of friction material.

Claim 16

An apparatus according to claim 13, wherein said pressing baffle extends along said one side of said filter medium for an arcuate distance greater than about 60* and less than about 120* of the drum circumference.

Claim 17

An apparatus according to claim 13, further comprising stationary baffle means extending alon said one side of said filter medium spaced therefrom and substantially immediately preceeding said pressing baffle in said predetermined rotary direction.

Claim 18

An apparatus according to claim 18, wherein said pressing baffle and said stationary baffle means together extend along said one side of filter medium for an arcuate distance greater than about 100* and less than about 180* of the drum circumference.

Claim 19

An apparatus according to claim 13, wherein the major part of the length of said pressing baffle circumferentially of said drum is provided with a plurality of reinforcing ribs.

Claim 20

An apparatus according to claim 1, further comprising a second pressing baffle extending along said one side of said filter medium intermediate said trailing end of said pressing baffle and said discharge means, said second pressing baffle having a face opposing said one side of said filter medium spaced therefrom to bound a space arcuately along said one side of said filter medium, said second pressing baffle being movable towards-and-away from said filter medium and adapted to gradually converge towards said one side of said filter medium in said predetermined rotary direction to cause said space between said second pressing baffle and said one side of said filter medium to gradually narrow in said predetermined rotary direction, and means for causing said second pressing baffle to be resiliently biased to so gradually converge towards said predetermined rotary direction.

Claim 21

An apparatus according to claim 21, wherein the bias causing means for said second pressing baffle comprises means defining a second biasing chamber on the opposite side of said second pressing baffle from said filter medium, and means for supplying pressurized fluid to such second biasing chamber whereby the pressurized fluid resiliently causes said second pressing baffle to gradually converge towards said filter medium in said predetermined rotary direction.

Claim 22

An apparatus according to claim 21, further comprising a press roll adjacent said one side of said filter medium closely spaced after said second pressing baffle in said predetermined rotary direction and intermediate said second pressing baffle and said discharge means.

Claim 23

An apparatus according to claim 21, further comprising motor means for biasing from said filter medium the end portion of said second pressing baffle trailing in said predetermined rotary direction.

Claim 24

In an apparatus for processing a suspension containing fibrous material, a first drum adapted to be rotatably driven in a first predetermined rotary direction and having a first circumferential porous filter medium for collecting fibrous material, a second drum adapted to be rotatably driven in a second predetermined rotary direction opposite to said first predetermined rotary direction and having a second circumferential porous filter medium for collecting fibrous material, said drums being circumferentially spaced apart by a therebetween nip, discharge means for removing collected fibrous material from each of said filter mediums, a first pressing baffle extending along the outer side of said first filter medium for a substantial portion of the circumference of said first drum and spaced around said first drum from the said discharge means for said first filter medium, a second pressing baffle extending along the outer side of said second filter medium for a substantial portion of the circumference of said second drum and spaced around said second drum from the said discharge means for said second filter medium, each of said pressing baffles having a leading end leading in the predetermined rotary direction of the rotation of its respective corresponding said drum and a trailing end trailing in such predetermined rotary direction, siad nip being intermediate said trailing ends of said pressing baffles and said discharge means, each of said pressing baffles having a face opposing the outer side of its respective corresponding said filter medium spaced therefrom to bound a space arcuately along such outer side of such filter medium for a substantial portion of the circumference of the respective corresponding said drum, each of said pressing baffles being pivotally mounted adjacent its leading end for movement towards-and-away from its respective corresponding said filter medium and including a substantial portion adjacent its said leading end restrained from flexing, each of said pressing baffles being adapted to gradually convege towards the outer side of its respective corresponding said filter medium in the predetermined rotary direction of the rotation of the corresponding said drum such that each of said space gradually narrows in the predetermined rotary direction of the rotation of the said drum for causing substantial liquid flow from said spaces through said filter mediums, means for causing each of said pressing baffles to be resiliently biased to so gradually converge towards its respective corresponding said filter medium in the predetermined rotary direction of the rotation of the corresponding said drum, means for supplying pressurized washing fluid to the outer side of each of said filter mediums following the trailing end of the respective corresponding said pressing baffle and before said nip in the predetermined rotary direction of the rotation of the drum whereby, during an arcuate portion of the rotation of each said drum intermediate the trailing end of its respective said pressing baffle and said nip, fibrous material collected on the filter medium of the drum is washed by such washing fluid, and inlet means for supplying pressurized suspension containing fibrous material to said outer sides of said filter medium, said inlet means comprising means for supplying the pressurized suspension to each said filter medium following the said discharge means for the filter medium and before the said leading end of the corresponding said pressing baffle in the predetermined rotary direction of the rotation of the drum.

Claim 25

An apparatus according to claim 25, further comprising pressinb baffle means intermediate said nip and each of said pressing baffles.

Claim 26

An apparatus according to claim 25, wherein each of said pressing baffles extends along the corresponding drum for an arcuate distance greater than about 60* and less than about 120* of the drum circumference.

Claim 27

An apparatus according to claim 25, further comprising first stationary baffle means extending along said first drum spaced therefrom and substantially immediately preceeding said first pressing baffle in said first predetermined rotary direction, and second stationary baffle means extending along said second drum spaced therefrom and substantially immediately preceeding said second pressing baffle in said second predetermined rotary direction.

Claim 28

An apparatus according to claim 28, wherein said first stationary baffle means and said first pressing baffle together extend along said first drum for an arcuate distance greater than about 100* and less than about 180* of the circumference of said first drum, and said second stationary baffle means and said second pressing baffle together extend along said second drum for an arcuate distance greater than about 100* and less than about 180* of the circumference of the latter.

Claim 29

An apparatus according to claim 28, further comprising pressing baffle means intermediate the trailing end of each said pressing baffle and said nip for pressing fibrous material on said filter mediums.

Claim 30

An apparatus according to claim 30, wherein said pressing baffle means comprises individual baffles for said drums, and further comprising means for biasing such baffles towards their respective drums.

Claim 31

An apparatus according to claim 25, wherein each said pressing baffle includes a flexible portion adjacent its said trailing end.

Claim 32

An apparatus according to claim 25, wherein the major portion of the length of each said pressing baffle circumferentially of Its respective said drum is restrained from flexing, and each said pressing baffle includes a freely flexible portion adjacent its trailing end.

Claim 33

An apparatus according to claim 25, wherein said inlet means is arranged to supply the pressurized suspension whereby the suspension passes along each said filter medium in the predetermined rotary direction of the driven rotation of the respective drum.

Claim 34

An apparatus according to claim 25, wherein said face of each said pressing baffle is, at least adjacent the baffle trailing end, provided with low-coefficient of friction material.

Claim 35

An apparatus according to claim 35, wherein each said pressing baffle extends along its repsective said filter medium for an arcuate distance greater than about 60* and less than about 120* of the circumference of the respective drum.

Claim 36

An apparatus according to claim 36, further comprising stationary baffle means extending along the outer side of each said filter medium spaced therefrom and immediately preceeding the respective said pressing baffle in the predetermined rotary direction of the driven rotation of the corresponding drum.

Claim 37

An apparatus according to claim 37, wherein each said pressing baffle and its respective said stationary baffle means together extend along said one side of the filter medium for an arcuate distance greater than about 100* and less than about 180* of the circumference of the corresponding drum.

Claim 38

An apparatus according to claim 25, wherein said bias causing means for each said pressing baffle comprises a biasing chamber on the opposite side of the pressing baffle from said filter medium, and means for supplying pressurized fluid to said biasing chamber whereby the pressurized fluid biases the pressing baffle towards said filter medium.

Claim 39

An apparatus according to claim 39, wherein each said washing fluid supplying means comprises means for supplying pressurized fluid from one of said biasing chambers.

Claim 40

An apparatus according to claim 25, further comprising actuator means for moving each said pressing baffle towards the corresponding filter medium.

Claim 42

A method according to claim 42, further comprising the step of pressing the fibrous material collected on said filter medium after its said washing.

Claim 43

A method according to claim 42, wherein said pressing baffle is so resiliently biased by pressurized liquid, and further comprising the step of employing such pressurized biasing liquid for said washing of the collected fibrous material.

Claim 44

A method according to claim 42, further comprising the step of pressing the fibrous material collected on said filter medium by another said dRum after its said washing.

Claim 45

A method according to claim 45, wherein said pressing baffle is so resiliently biased by pressurized liquid, and further comprising the step of employing such pressurized biasing liquid for said washing of the collected fibrous material.