Rotary vacuum drum filters

Claim 2

A rotary vacuum drum filter which comprises a tank containing pulp to be subjected to filtration, a filter drum comprising a cylindrical shell having end trunnions whereby said shell is supported for rotation on said tank, external filtrate compartments coextensive with the axis of rotation of the drum, and arranged side by side about the periphery of said shell and entering the pulp at the descending side of the drum, and emerging from the pulp at the ascending side during a filtration cycle, a set of trailing filtrate drainage pipes extending from the trailing ends of the respective compartments, and having delivery ends terminating in a trunnion of said drum, and adapted to withdraw through said trunnion filtrate liquid collecting at the trailing end of said compartments while moving upwardly at said ascending side of the drum and through a first filtrate withdrawal zone extending along at least a substantial portion of the ascending side of the drum, a set of leading drainage pipes extending from the leading ends of said compartments and having filtrate delivery ends terminating in a trunnion of said drum, and adapted for withdrawing filtrate liquid collecting at the leading end of said compartments during their movement downwardly at said descending side of the drum and through a second filtrate withdrawal zone extending along at least a substantial portion of the descending side of the drum, vacuum supply means communicating with the filtrate delivery ends of said trailing pipes and of said leading pipes, for effecting filtrate withdrawal through said trailing pipes during their movement through said first filtrate withdrawal zone, and through said leading pipes during their movement through said second filtrate withdrawal zone, incident to rotation of the drum, first control means for controlling the supply of vacuum from said supply means to said trailing pipes and said leading pipes, so constructed and arranged that the vacuum supply is kept open for the trailing pipes during their movement upwardly through said first filtrate withdrawal zone, and that the vacuum supply is kept closed for the leading pipes during their movement through said first zone, and second control means for controlling the supply of vacuum from said supply means to said trailing pipes and said leading pipes, so constructed and arranged that the vacuum supply is kept open for the leading pipes during their movement downwardly through said second filtrate withdrawal zone, and that said vacuum supply is kept closed for the trailing pipes during their movement downwardly through said second zone.

Claim 3

A rotary vacuum drum filter which comprises a tank containing pulp to be subjected to filtration, a filter drum comprising a cylindrical shell having end trunnions whereby said shell is supported for rotation on said tank, external filtrate compartments coextensive wIth the axis of rotation of the drum, and arranged side by side about the periphery of said shell, and entering the pulp at the descending side of the drum, and emerging from the pulp at the ascending side of the drum during a filtration cycle, a set of trailing filtrate drainage pipes extending from the trailing ends of the respective compartments, and having filtrate delivery ends terminating in the one of said trunnions, and adapted to withdraw through said trunnion filtrate liquid collecting at the trailing end of said compartments while moving upwardly at said ascending side of the drum and through a first filtrate withdrawal zone extending along at least a substantial portion of the ascending side of the drum, a set of leading filtrate drainage pipes extending from the leading ends of said compartments, and having filtrate delivery ends terminating in the other trunnion of the drum, and adapted for withdrawing filtrate liquid collecting at the leading end of said compartments during their movement downwardly at said descending side of the drum and through a second filtrate withdrawal zone extending along at least a substantial portion of the descending side of the drum, first vacuum supply means associated with said one trunnion, for effecting filtrate withdrawal through said trailing pipes while moving through said first filtrate withdrawal zone, incident to rotation of the drum, first control means cooperatively associated with said first supply means and said one trunnion, for controlling the supply of vacuum from said first supply means to said trailing pipes and said leading pipes, said control means being so constructed and arranged that the vacuum supply is kept open for the trailing pipes during their movement upwardly through said first filtrate withdrawal zone, and that the vacuum supply is kept closed for the leading pipes during their movement through said first zone, second vacuum supply means associated with said other trunnion, for effecting filtrate withdrawal through said leading pipes while moving through said second filtrate withdrawal zone, incident to the rotation of the drum, and second control means cooperatively associated with said second supply means and said other trunnion, for controlling the supply of vacuum from said second supply means to said trailing pipes and said leading pipes, said control means being so constructed and arranged that the vacuum supply is kept open for the leading pipes during their movement downwardly through said second filtrate withdrawal zone, and that the vacuum supply is kept closed for the trailing pipes in their movement through said first zone,

Claim 4

A rotary vacuum drum filter which comprises a tank containing pulp to be subjected to filtration, a filter drum comprising a cylindrical shell having end trunnions whereby said shell is supported for rotation on said tank, external filtrate compartments coextensive wIth the axis of rotation of the drum, and arranged side by side about the periphery of said shell, and entering the pulp at the descending side of the drum, and emerging from the pulp at the ascending side of the drum during a filtration cycle, a set of trailing filtrate drainage pipes extending from the trailing ends of the respective compartments, and having filtrate delivery ends terminating in the one of said trunnions, and adapted to withdraw through said trunnion filtrate liquid collecting at the trailing end of said compartments while moving upwardly at said ascending side of the drum and through a first filtrate withdrawal zone extending along at least a substantial portion of the ascending side of the drum, a set of leading filtrate drainage pipes extending from the leading ends of said compartments, and having filtrate delivery ends terminating in the other trunnion of the drum, and adapted for withdrawing filtrate liquid collecting at the leading end of said compartments during their movement downwardly at said descending side of the drum and through a second filtrate withdrawal zone extending along at least a substantial portion of the descending side of the drum, first vacuum supply means associated with said one trunnion, for effecting filtrate withdrawal through said trailing pipes while moving through said first filtrate withdrawal zone, incident to rotation of the drum, first control means cooperatively associated with said first supply means and said one trunnion, for controlling the supply of vacuum from said first supply means to said trailing pipes and said leading pipes, said control means being so constructed and arranged that the vacuum supply is kept open for the trailing pipes during their movement upwardly through said first filtrate withdrawal zone, and that the vacuum supply is kept closed for the leading pipes during their movement through said first zone, second vacuum supply means associated with said other trunnion, for effecting filtrate withdrawal through said leading pipes while moving through said second filtrate withdrawal zone, incident to the rotation of the drum, and second control means cooperatively associated with said second supply means and said other trunnion, for controlling the supply of vacuum from said second supply means to said trailing pipes and said leading pipes, said control means being so constructed and arranged that the vacuum supply is kept open for the leading pipes during their movement downwardly through said second filtrate withdrawal zone, and that the vacuum supply is kept closed for the trailing pipes in their movement through said first zone,

Claim 5

The filter according to claim 2, wherein said first and said second vacuum control means are furthermore so constructed and arranged that mutually adjoining trailing and leading pipes of mutually adjoining filtrate chambers are both open to vacuum suction while passing through a bottom zone extending between the lower ends of said filtrate withdrawal zones.

Claim 6

The filter according to claim 2, wherein said first and said second vacuum control means are furthermore so constructed and arranged that mutually adjoining trailing and leading pipes of mutually adjoining filtrate chambers are open to vacuum suction while passing through a top zone extending between the upper ends of said filtrate withdrawal zones.

Claim 7

The filter according to claim 2, wherein said first vacuum control means comprise a first trunnion valve cooperating with the adjacent ends of the trailing pipes, and constructed and arranged so as to open and close said pipes in the respective filtrate withdrawal zones, and wherein said second control means comprise a second trunnion valve cooperating with the adjacent ends of the leading pipes, said trunnion valve being constructed and arranged so as to open and close said pipes in the respective filtrate withdrawal zones.

Claim 8

The filter according to claim 2, wherein at least one of said trunnions has a closEd inner end and an open outer end, wherein a stationary valve head associated with the open end of said trunnion is constructed and arranged to provide vacuum supply to the interior of the trunnion, wherein one set of said pipes have exposed outer end portions connected to the interior of said trunnion, thus to be subject to the vacuum effect maintained therein, wherein each of said outer end portions of said pipes is provided with an individual valve operable to open or close communication with the vacuum, and wherein stationary cam means are provided effective to operate said valves incident to the rotation of said drum, in such a manner as to admit vacuum suction from said trunnion to the associated filtrate withdrawal zone.

Claim 9

A rotary vacuum drum filter which comprises a tank containing pulp to be subjected to filtration, a filter drum comprising a cylindrical shell having end trunnions whereby said shell is supported for rotation on said tank, external filtrate compartments coextensive with the axis of rotation of the drum, and arranged side by side about the periphery of said shell, and entering the pulp at the descending side of the drum, and emerging from the pulp at the ascending side of the drum during a filtration cycle., a set of trailing filtrate drainage pipes extending from the trailing ends of the respective compartments, and having filtrate delivery ends terminating in one of said trunnions, and adapted to withdraw through said trunnion filtrate liquid collecting at the trailing end of said compartments while moving upwardly at said ascending side of the drum and through a first filtrate withdrawal zone extending along at least a substantial portion of the ascending side of the drum, a set of leading filtrate drainage pipes extending from the leading end of said compartments, and having filtrate delivery ends terminating in said one trunnion of the drum, and adapted for withdrawing filtrate liquid collecting at the leading end of said compartments during their movement downwardly at said descending side of the drum and through a second filtrate withdrawal zone extending along at least a substantial portion of the descending side of the drum, vacuum supply means associated with said one trunnion, for effecting filtrate withdrawal through said trailing pipes while moving through said first filtrate withdrawal zone, and filtrate withdrawal through said leading pipes while moving through said second filtrate withdrawal zone, incident to the rotations of the drum, first control means associated with said trunnion and with said vacuum supply means for controlling the supply of vacuum from said supply means to said trailing pipes and said leading pipes, said control means being so constructed and arranged that the vacuum supply is kept open for the trailing pipes during their movement upwardly through said first filtrate withdrawal zone, and that the vacuum supply is kept closed for the leading pipes during their movement through said first zone, and second control means cooperatively associated with said vacuum supply means and with said trunnion, for controlling the supply of vacuum from said supply means to said trailing pipes and said leading pipes, said control means being so constructed and arranged that the vacuum supply is kept open for the leading pipes during their movement downwardly through said second filtrate withdrawal zone, and that the vacuum supply is kept closed for the trailing pipes during their movement through said second zone.

Claim 10

A rotary vacuum drum filter which comprises a tank containing pulp to be subjected to filtration, a filter drum comprising a cylindrical shell having end trunnions whereby said shell is supported for rotation on said tank, external filtrate compartments coextensive with the axis of rotation of the drum, and arranged side by side about the periphery of said shell, and entering the pulp at the descending side of the drum, and emerging from the pulp at the ascending side of the drum during a filtration cycle., a set of trailing filtrate drainage pipes extending from the trailing ends of the respective compartments, and having filtrate delivery ends terminating in one of said trunnions, and adapted to withdraw through said trunnion filtrate liquid collecting at the trailing end of said compartments while moving upwardly at said ascending side of the drum and through a first filtrate withdrawal zone extending along at least a substantial portion of the ascending side of the drum, a set of leading filtrate drainage pipes extending from the leading end of said compartments, and having filtrate delivery ends terminating in said one trunnion of the drum, and adapted for withdrawing filtrate liquid collecting at the leading end of said compartments during their movement downwardly at said descending side of the drum and through a second filtrate withdrawal zone extending along at least a substantial portion of the descending side of the drum, vacuum supply means associated with said one trunnion, for effecting filtrate withdrawal through said trailing pipes while moving through said first filtrate withdrawal zone, and filtrate withdrawal through said leading pipes while moving through said second filtrate withdrawal zone, incident to the rotations of the drum, first control means associated with said trunnion and with said vacuum supply means for controlling the supply of vacuum from said supply means to said trailing pipes and said leading pipes, said control means being so constructed and arranged that the vacuum supply is kept open for the trailing pipes during their movement upwardly through said first filtrate withdrawal zone, and that the vacuum supply is kept closed for the leading pipes during their movement through said first zone, and second control means cooperatively associated with said vacuum supply means and with said trunnion, for controlling the supply of vacuum from said supply means to said trailing pipes and said leading pipes, said control means being so constructed and arranged that the vacuum supply is kept open for the leading pipes during their movement downwardly through said second filtrate withdrawal zone, and that the vacuum supply is kept closed for the trailing pipes during their movement through said second zone.

Claim 11

The filter according to claim 7, wherein said first and said second vacuum control means are furthermore so constructed and arranged that mutually adjoining trailing and leading pipes of mutually adjoining filtrate chambers are both open to vacuum suction while passing through a bottom zone extending between the lower ends of said filtrate withdrawal zones.

Claim 12

The filter according to claim 7, wherein said first and said second vacuum control means are furthermore so cOnstructed and arranged that mutually adjoining trailing and leading pipes of mutually adjoining filtrate chambers are open to vacuum suction while passing through a top zone extending between the upper ends of said filtrate withdrawal zones.

Claim 13

The filter according to claim 7, wherein one of said trunnions has a terminal tube plate for connection with the outer ends of said trailing pipes and of said leading pipes, arranged in respective concentric zones in said terminal plate, and wherein said control means comprise a trunnion valve constructed and arranged so as to cooperate with the respective concentric zones to provide vacuum suction in the respective filtrate withdrawal zones of the filtration cycle.

Claim 14

The filter according to claim 7, wherein one of said trunnions has a closed inner end and an open outer end, wherein a stationary valve head associated with the open end of said trunnion is constructed and arranged to provide vacuum supply to the interior of the trunnion, wherein said trailing pipes as well as said leading pipes have exposed outer end portions connected to the interior of said trunnion, thus to be subjected to the vacuum effect maintained therein, wherein each of said outer end portions of said trailing and leading pipes is provided with a valve operable to open or close communication with the vacuum, wherein first stationary cam means are provided effective to operate the valves of the trailing pipes incident to the rotation of the drum, in such a manner as to admit vacuum suction from said trunnion to the associated filtrate withdrawal zone at the ascending side of the drum, and second stationary cam means are provided effective to operate the valves of the leading pipes.

Claim 15

The filter according to claim 1, wherein said second control means are constructed and arranged to provide a neutral zone effective to allow for cake discharge at the descending side of the drum.

Claim 16

The filter according to claim 2, wherein said second control means are constructed and arranged to provide a neutral zone effective to allow for cake discharge at the descending side of the drum.

Claim 17

The filter according to claim 3, wherein said second control means are constructed and arranged to provide a neutral zone effective to allow for cake discharge at the descending side of the drum.

Claim 18

The filter according to claim 4, wherein said second control means are constructed and arranged to provide a neutral zone effective to allow for cake discharge at the descending side of the drum.

Claim 19

The filter according to claim 5, wherein said second control means are constructed and arranged to provide a neutral zone effective to allow for cake discharge at the descending side of the drum.

Claim 20

The filter according to claim 6, wherein said second control means are constructed and arranged to provide a neutral zone effective to allow for cake discharge at the descending side of the drum.

Claim 21

The filter according to claim 7, wherein said second vacuum control means are constructed and arranged to provide a neutral zone effective to allow for cake discharge in the filtration cycle at the descending side of the drum.

Claim 22

The filter according to claim 8, wherein said second vacuum control means are constructed and arranged to provide a neutral zone effective to allow for cake discharge in the filtration cycle at the descending side of the drum.

Claim 23

The filter according to claim 9, wherein said second vacuum control means are constructed and arranged to provide a neutral zone effective to allow for cake discharge in the filtration cycle at the descending side of the drum.

Claim 24

The filter according to claim 10, wherein said second vacuum control means are constructed and arranged to provide a neutral zone effective to allow for cake discharge in the filtration cycle at the descending side of said drum.

Claim 25

The filter according to claim 11, wherein said second vacuum control means are constructed and arranged to provide a neutral zone effective To allow for cake discharge in the filtration cycle at the descending side of the drum.

Claim 26

The filter according to claim 1, wherein said second control means are so constructed and arranged as to maintain vacuum suction along the entire descending side of the drum, effective to allow for precoat filter cake scalping operation.

Claim 27

The filter according to claim 2, wherein said second control means are so constructed and arranged as to maintain vacuum suction along the entire descending side of the drum, effective to allow for precoat filter cake scalping operation.

Claim 28

The filter according to claim 3, wherein said second control means are so constructed and arranged as to maintain vacuum suction along the entire descending side of the drum, effective to allow for precoat filter cake scalping operation.

Claim 29

The filter according to claim 4, wherein said second control means are so constructed and arranged as to maintain vacuum suction along the entire descending side of the drum, effective to allow for precoat filter cake scalping operation.

Claim 30

The filter according to claim 5, wherein said second control means are so constructed and arranged as to maintain vacuum suction along the entire descending side of the drum, effective to allow for precoat filter cake scalping operation.

Claim 31

The filter according to claim 6, wherein said second control means are so constructed and arranged as to maintain vacuum suction along the entire descending side of the drum, effective to allow for precoat filter cake scalping operation.

Claim 32

The filter according to claim 7, wherein said second control means are so constructed and arranged as to maintain vacuum suction along the entire descending side of the drum, effective to allow for precoat filter cake scalping operation.

Claim 33

The filter according to claim 8, wherein said second control means are so constructed and arranged as to maintain vacuum suction along the entire descending side of the drum, effective to allow for precoat filter cake scalping operation.

Claim 34

The filter according to claim 9, wherein said second control means are so constructed and arranged as to maintain vacuum suction along the entire descending side of the drum, effective to allow for precoat filter cake scalping operation.

Claim 35

The filter according to claim 10, wherein said second control means are so constructed and arranged as to maintain vacuum suction along the entire descending side of the drum, effective to allow for precoat filter cake scalping operation.

Claim 36

The filter according to claim 11, wherein said second control means are so constructed and arranged as to maintain vacuum suction along the entire descending side of the drum, effective to allow for precoat filter cake scalping operation.