High consistency pressure screen and method of separating accepts and rejects

Claim 2

Pressure screen apparatus comprising : a housing including an inlet for receiving a slurry of paper stock, an accepts outlet and a rejects outlet; a hollow cylindrical screen in said housing including a profiled inner surface and an outer surface; mounting means mounting said screen to the interior of said housing and defining an accepts chamber about said screen which is in communication with said accepts outlet and is sealed from said inlet so that said inlet communicates with said accepts outlet via said screen and said accepts chamber; drive means including a rotary output; and a rotor connected to said rotary output and mounted within and spaced from said screen between said inlet and said rejects outlet, said rotor comprising outer wall means including a non circular outer surface which includes a blunt lead section facing in the direction of rotation.

Claim 3

The pressure screen apparatus of claim 1, wherein said outer surface of said rotor comprises : first and second semicylindrical sections each including an elongate first edge and an elongate second edge, said lead section connecting said elongate first edges; and a second blunt lead section connecting said elongate second edges.

Claim 4

The pressure screen apparatus of claim 2, wherein said rotor further comprises : a hollow cylinder; end plates mounting said hollow cylinder within said outer wall concentric with the axis of rotation and sealing said outer wall means; a drive shaft within said hollow cylinder and extending through one of said end plates; and a drive connection connecting said shaft to said hollow cylinder.

Claim 5

In a pressure screen of the type in which a slurry of paper stock is fed through an inlet and towards an accepts outlet, through a profile screen and towards a rejects outlet between the screen and the rotor, the improvement wherein said rotor comprises: an elongate generally cylindrical body including a pair of elongate semicylinders radially offset from one another; and a pair of members connecting said semicylinders and defining a pair of blunt lead edges with respect to the direction of rotation.

Claim 6

In a pressure screen of the type in which a slurry of paper stock is fed through an inlet and towards an accepts outlet, through a profile screen and towards a rejects outlet between the screen and the rotor, the improvement wherein said rotor comprises: an elongate generally cylindrical body including a pair of elongate semicylinders radially offset from one another; and a pair of members connecting said semicylinders and defining a pair of blunt lead edges with respect to the direction of rotation.

Claim 7

In a pressure screen of the type in which a slurry of paper stock is fed through an inlet and towards an accepts outlet, through a profile screen and towards a rejects outlet between the screen and a rotor, the improvement wherein said rotor comprises : an elongate generally cylindrical body including a plurality of arcuate sections radially offset from one another; and a plurality of members connecting said sections and defining a plurality of blunt lead surfaces with respect to the direction of rotation.

Claim 8

In a pressure screen of the type in which a slurry of paper stock is fed through an inlet and towards an accepts outlet, through a profile screen and towards a rejects outlet between the screen and a rotor, the improvement wherein said rotor comprises : an elongate generally cylindrical body including a plurality of arcuate sections radially offset from one another; and a plurality of members connecting said sections and defining a plurality of blunt lead surfaces with respect to the direction of rotation.

Claim 9

Pressure screen apparatus comprising : a housing including an inlet for receiving a slurry of paper stock, an accepts outlet, and a rejects outlet; a hollow cylindrical profile screen mounted in and sealed to said housing adjacent said accepts outlet between said inlet and said rejects outlet; drive means; and a rotor connected to said drive means and mounted within said screen spaced from the inner surface of said screen and including blunt surface means on the periphery of said rotor facing in the direction of rotation and effective during rotation to continuously vary the rotor-screen spacing about the inner surface of said . screen.

Claim 10

Pressure screen apparatus comprising : a housing including an inlet for receiving a slurry of paper stock, an accepts outlet, and a rejects outlet; a hollow cylindrical profile screen mounted in and sealed to said housing adjacent said accepts outlet between said inlet and said rejects outlet; drive means; and a rotor connected to said drive means and mounted within said screen spaced from the inner surface of said screen and including blunt surface means on the periphery of said rotor facing in the direction of rotation and effective during rotation to continuously vary the rotor-screen spacing about the inner surface of said . screen.

Claim 11

A pressure screen apparatus comprising : a generally cylindrical hollow housing including sidewall means, an end wall having an opening therein, an inlet for receiving a flow of paper stock slurry located adjacent one end of said housing, an accepts outlet centrally located in said sidewall means, and a rejects outlet adjacent the other end of said housing; drive means including a rotatable drive shaft extending through said opening and sealed to said housing; a pair of spaced rings connected to the inner surface of said housing on each side of said accepts outlet between said inlet and said rejects outlet; a cylindrical profile screen connected to said rings to isolate said accepts outlet from said inlet ; and a rotor connected to said drive shaft and located within said screen, said rotor comprising a profiled surface including means effective to cause turbulence of the slurry and to provide a stock and screen-cleaning pulsation cycle of approximately + 50% positive and -50% negative in the accepts direction of flow.

Claim 12

A pressure screen apparatus comprising : a generally cylindrical hollow housing including sidewall means, an end wall having an opening therein, an inlet for receiving a flow of paper stock slurry located adjacent one end of said housing, an accepts outlet centrally located in said sidewall means, and a rejects outlet adjacent the other end of said housing; drive means including a rotatable drive shaft extending through said opening and sealed to said housing; a pair of spaced rings connected to the inner surface of said housing on each side of said accepts outlet between said inlet and said rejects outlet; a cylindrical profile screen connected to said rings to isolate said accepts outlet from said inlet ; and a rotor connected to said drive shaft and located within said screen, said rotor comprising a profiled surface including means effective to cause turbulence of the slurry and to provide a stock and screen-cleaning pulsation cycle of approximately + 50% positive and -50% negative in the accepts direction of flow.

Claim 13

The apparatus of claim 7, wherein : said rotor comprises an outer surface which comprises at least one arcuate surface of decreasing radius connected to itself by a blunt surface facing into the direction of travel and forming said means for creatihg turbulence.

Claim 14

The apparatus of claim 7, wherein: said rotor comprises an outer surface which comprises at least two arcuate surfaces connected together by at least two blunt surfaces capable of capturing an accelerating stock up to rotor speed and constituting said means for creating turbulence.

Claim 17

The method of claim 10, wherein the step of changing the spacing is further defined as : cyclically changing the spacing between the outer surface of the rotor and the inner surface of the screen over the entire length of the rotor.