Crystallization apparatus and method

Claim 2

AN IMPROVED CRYSTALLIZATION APPARATUS, COMPRISING A VESSEL ADAPTED TO CONTAIN A BODY OF SLURRY WHICH INCLUDES CRYSTAL PARTICLES AND LIQUID,MEANS FOR MAINTAINING SUPERSATURATION CONDITIONS IN THE SLURRY BODY TO INDUCE CRYSTALLIZATION THEREIN, MEANS IN SAID CRYSTALLIZATION APPARATUS FOR CIRCULATING SAID ALURRY IN A PREDETERMINED FLOW PATH IN SAID VESSEL AND FOR MAINTAINING SAID CRYSTAL PARTICLES IN SUSPENSION, SAID VESSEL ALSO INCLUDING AT LEAST TWO SEPARATE ELUTRIATION CHAMBERS, EACH OF SAID ELUTRIATION CHAMBERS HAVING AN OUTLET AT ONE END THEREOF FOR REMOVING SLURRY LIQUID AND CRYSTAL PARTICLES WHICH ARE BELOW A PREDETERMINED SIZE ONLY FROM SAID SLURRY BODY, AND MEANS COMMUNICATING WITH EACH OF SAID OUTLETS FOR INDEPENDENTLY REGULATING THE FLOW IN EACH OF SAID ELUTRIATION CHAMBERS TO SELECTIVELY OPERATE ANY ONE OR MORE OF SAID ELUTRIATION CHAMBERS AT A DESIRED FLOW RATE, WHEREBY, THE SIZE AND QUANTITY OF CRYSTAL PARTICLES REMOVED FROM SAID SLURRY BODY THROUGH SAID ELUTRIATION CHAMBERS CAN BE SELECTIVELY AND INDEPENDENTLY REGULATED WITH RESPECT TO EACH OTHER TO PROVIDE PRODUCT CRYSTALS OF IMPROVED SIZE UNIFORMITY.

Claim 3

The improved crystallization apparatus of claim 1 wherein each of said elutriation chambers in sAid apparatus is of substantially uniform cross-section for at least a substantial portion of its height.

Claim 4

An improved crystallization apparatus, comprising a vessel adapted to contain a body of slurry which includes crystal particles and liquid, means in said vessel for maintaining a supersaturation zone in said slurry body to induce crystallization therein, means in said vessel for circulating a substantial portion of said slurry body in a predetermined flow path through said supersaturation zone and for maintaining said crystal particles in suspension in said liquid, a plurality of elutriation chambers in said vessel, each of said elutriation chambers having a substantially uniform cross-section for at least a substantial portion of its height and a lower end which is in open communication with said substantial portion of said slurry body adjacent the predetermined flow path in a generally quiescent zone with respect thereto, each of said elutriation chambers also including an outlet adjacent the upper end thereof, means communicating with each of said outlets for independently regulating the flow rate in each of said elutriation chambers to withdraw a recycle stream of crystal particles and slurry liquid from said zone and to selectively operate any one or more of said elutriation chambers at a desired flow rate, thereby enabling the size and quantity of crystal particles removed from said slurry body to said recycle stream to be selectively and independently regulated with respect to each other, and means for removing crystal particles in said recycle stream prior to the return of said stream to the body of slurry in said vessel.

Claim 5

An improved crystallization apparatus, comprising a vessel adapted to contain a body of slurry which includes crystal particles and liquid, means in said vessel for maintaining a supersaturation zone in said slurry body to induce crystallization therein, means in said vessel for circulating a substantial portion of said slurry body in a predetermined flow path through said supersaturation zone and for maintaining said crystal particles in suspension in said liquid, a plurality of elutriation chambers in said vessel, each of said elutriation chambers having a substantially uniform cross-section for at least a substantial portion of its height and a lower end which is in open communication with said substantial portion of said slurry body adjacent the predetermined flow path in a generally quiescent zone with respect thereto, each of said elutriation chambers also including an outlet adjacent the upper end thereof, means communicating with each of said outlets for independently regulating the flow rate in each of said elutriation chambers to withdraw a recycle stream of crystal particles and slurry liquid from said zone and to selectively operate any one or more of said elutriation chambers at a desired flow rate, thereby enabling the size and quantity of crystal particles removed from said slurry body to said recycle stream to be selectively and independently regulated with respect to each other, and means for removing crystal particles in said recycle stream prior to the return of said stream to the body of slurry in said vessel.

Claim 6

An improved crystallization apparatus, comprising a vessel adapted to contain a body of slurry which includes crystal particles and liquid, first means for maintaining supersaturation conditions in the slurry body to induce crystallization therein, second means in said crystallization apparatus for circulating said slurry in a predetermined flow path in said vessel and for maintaining said crystal particles in suspension, a plurality of elutriation chambers in said apparatus, each of said elutriation chambers having a substantially uniform cross-section for at least a substantial portion of its height and having an inlet at one end thereof and an outlet at the opposite end thereof, said inlet communicating with said body of slurry at a location therein whereby slurry will be received in said elutriation chamber means from a generally quiescent zone with respect to said predetermined flow path, means communicating with each of said elutriation chambers for independently regulating the flow rate in each of said elutriation chambers to selectively operate any one or more of said elutriation chambers at a desired flow rate; whereby, both the size and quantity of crystal particles in said slurry stream removed from said slurry body can be selectively and independently varied with respect to each other to provide product crystals of improved size uniformity.

Claim 7

An improved crystallization apparatus, comprising a vessel adapted to contain a body of slurry which includes crystal particles and liquid, first means for maintaining supersaturation conditions in the slurry body to induce crystallization therein, second means in said crystallization apparatus for circulating said slurry in a predetermined flow path in said vessel and for maintaining said crystal particles in suspension, a plurality of elutriation chambers in said apparatus, each of said elutriation chambers having a substantially uniform cross-section for at least a substantial portion of its height and having an inlet at one end thereof and an outlet at the opposite end thereof, said inlet communicating with said body of slurry at a location therein whereby slurry will be received in said elutriation chamber means from a generally quiescent zone with respect to said predetermined flow path, means communicating with each of said elutriation chambers for independently regulating the flow rate in each of said elutriation chambers to selectively operate any one or more of said elutriation chambers at a desired flow rate; whereby, both the size and quantity of crystal particles in said slurry stream removed from said slurry body can be selectively and independently varied with respect to each other to provide product crystals of improved size uniformity.

Claim 8

The improved crystallization apparatus of claim 4 wherein said vessel includes two separate elutriation chambers, the first of which has a cross-sectional area which is equal to approximately one half the cross-sectional area of said second elutriation chamber.

Claim 9

An improved crystallization apparatus, comprising an enclosed vessel adapted to contain a slurry body of liquid and crystal particles, vacuum means communicating with said vessel for maintaining a supersaturation zone in said slurry body, forced circulation means in said vessel for circulating a substantial portion of said slurry body in a predetermined flow path through said supersaturation zone and for maintaining said crystal particles in suspension, said vessel including a mid-section defined by a generally cylindrical shell and an interior wall co-axially disposed with respect to said cylindrical shell, said interior wall and cylindrical shell defining a channel having a uniform annular cross-section for at least a subStantial portion of its height, and partition members radially disposed between said interior wall and cylindrical shell defining said channel into separate elutriation chambers, each of said elutriation chambers having an inlet adjacent the lower end thereof communicating with said substantial portion of the slurry body adjacent the periphery of said predetermined flow path and having an outlet above said inlet for withdrawing a recycle stream of slurry liquid and crystal particles, variable flow rate means communicating with each of said outlets for withdrawing said recycle stream therefrom at a rate which can be selectively controlled to establish a flow velocity in the elutriation chamber associated with said outlet which will suspend and withdraw through said outlet crystal particles which are below a predetermined size only, valve means in said vessel associated with each of said elutriation chamber outlets enabling any one or more of said elutriation chambers to be selectively openly communicated with said recycle stream for independently, with respect to said variable flow rate means, controlling the volume of slurry liquid and crystal particles removed from said elutriation chambers, and crystal particle solubilizing means in said apparatus for removing said crystal particles below said predetermined size in said recycle stream prior to the return thereof to said vessel.

Claim 10

An improved crystallization apparatus, comprising an enclosed vessel adapted to contain a slurry body of liquid and crystal particles, vacuum means communicating with said vessel for maintaining a supersaturation zone in said slurry body, forced circulation means in said vessel for circulating a substantial portion of said slurry body in a predetermined flow path through said supersaturation zone and for maintaining said crystal particles in suspension, said vessel including a mid-section defined by a generally cylindrical shell and an interior wall co-axially disposed with respect to said cylindrical shell, said interior wall and cylindrical shell defining a channel having a uniform annular cross-section for at least a subStantial portion of its height, and partition members radially disposed between said interior wall and cylindrical shell defining said channel into separate elutriation chambers, each of said elutriation chambers having an inlet adjacent the lower end thereof communicating with said substantial portion of the slurry body adjacent the periphery of said predetermined flow path and having an outlet above said inlet for withdrawing a recycle stream of slurry liquid and crystal particles, variable flow rate means communicating with each of said outlets for withdrawing said recycle stream therefrom at a rate which can be selectively controlled to establish a flow velocity in the elutriation chamber associated with said outlet which will suspend and withdraw through said outlet crystal particles which are below a predetermined size only, valve means in said vessel associated with each of said elutriation chamber outlets enabling any one or more of said elutriation chambers to be selectively openly communicated with said recycle stream for independently, with respect to said variable flow rate means, controlling the volume of slurry liquid and crystal particles removed from said elutriation chambers, and crystal particle solubilizing means in said apparatus for removing said crystal particles below said predetermined size in said recycle stream prior to the return thereof to said vessel.

Claim 11

An improved crystallization apparatus, comprising an enclosed vessel adapted to contain a slurry body of liquid and crystal particles, vacuum means communicating with said vessel for maintaining a supersaturation zone in said slurry body, said vessel including a mid-section defined by a generally cylindrical shell, a first interior wall co-axially disposed with respect to said cylindrical shell and with said cylindrical shell defining a first elutriation chamber having a substantially uniform annular cross-section for at least a substantial portion of its height, a second interior wall co-axially disposed with respect to said first interior wall, said first and second interior walls defining a second elutriation chamber having a substantially uniform cross-section for at least a substantial portion of its height, each of said elutriation chambers having an inlet adjacent the lower end thereof communicating with said substantial portion of the slurry body adjacent the periphery of said predetermined flow path and having an outlet above said inlet for withdrawing a recycle stream of slurry liquid and crystal particles, variable flow rate means communicating with each of said outlets for withdrawing the recycle stream therefrom at a rate which can be selectively controlled to establish a flow velocity in the elutriation chamber associated with said outlet which will suspend and withdraw through said outlet crystal particles which are below a predetermined size only, valve means in said vessel associated with each of said elutriation chamber outlets enabling any one or more of said elutriation chambers to be selectively openly communicated with said recycle stream for independently, with respect to said variable flow rate means, controlling the volume of slurry liquid and crystal particles removed from said elutriation chambers, and solubilizing means in said apparatus for removing said crystal particles below said predetermined size in said recycle stream prior to the return thereof to said vessel.

Claim 12

An improved crystallization apparatus, comprising an enclosed vessel adapted to contain a slurry body of liquid and crystal particles, vacuum means communicating with said vessel for maintaining a supersaturation zone in said slurry body, said vessel including a mid-section defined by a generally cylindrical shell, a first interior wall co-axially disposed with respect to said cylindrical shell and with said cylindrical shell defining a first elutriation chamber having a substantially uniform annular cross-section for at least a substantial portion of its height, a second interior wall co-axially disposed with respect to said first interior wall, said first and second interior walls defining a second elutriation chamber having a substantially uniform cross-section for at least a substantial portion of its height, each of said elutriation chambers having an inlet adjacent the lower end thereof communicating with said substantial portion of the slurry body adjacent the periphery of said predetermined flow path and having an outlet above said inlet for withdrawing a recycle stream of slurry liquid and crystal particles, variable flow rate means communicating with each of said outlets for withdrawing the recycle stream therefrom at a rate which can be selectively controlled to establish a flow velocity in the elutriation chamber associated with said outlet which will suspend and withdraw through said outlet crystal particles which are below a predetermined size only, valve means in said vessel associated with each of said elutriation chamber outlets enabling any one or more of said elutriation chambers to be selectively openly communicated with said recycle stream for independently, with respect to said variable flow rate means, controlling the volume of slurry liquid and crystal particles removed from said elutriation chambers, and solubilizing means in said apparatus for removing said crystal particles below said predetermined size in said recycle stream prior to the return thereof to said vessel.

Claim 13

The improved crystallization apparatus of claim 7 wherein said baffle means includes a third interior wall co-axially dispoed with respect to said second interior wall, said second and third interior walls defining a third elutriation chamber also having a substantially uniform cross-section for at least a substantial portion of its height.

Claim 14

An improved crystallization apparatus comprising a vessel adapted to contain a slurry body of crystals and liquid, said vessel having a recycle inlet and outlet formed therein, a recycle loop communicating said recycle outlet with said recycle inlet, vacUum means communicating with said vessel for maintaining supersaturation conditions in at least a portion of the slurry body contained in said vessel, pump means in said recycle loop for providing forced circulation of said recycle slurry, a slurry removal outlet in said apparatus, a fines removal circuit communicating with said slurry removal outlet, said fines removal circuit including, at least two separate elutriation chambers, each of said elutriation chambers having an outlet at one end thereof for removing slurry liquid and crystal particles which fall below a predetermined size from a slurry stream withdrawn from the slurry body through said slurry removal outlet, means communicating with each of said elutriation chamber outlets to selectively operate any one or more of said elutriation chambers at a desired flow rate; whereby, the size and quantity of crystal particles removed from said slurry body through said elutriation chamber outlets can be selectively and independently regulated with respect to each other to provide product crystals of improved size uniformity.

Claim 15

An improved crystallization apparatus comprising a vessel adapted to contain a slurry body of crystals and liquid, said vessel having a recycle inlet and outlet formed therein, a recycle loop communicating said recycle outlet with said recycle inlet, vacUum means communicating with said vessel for maintaining supersaturation conditions in at least a portion of the slurry body contained in said vessel, pump means in said recycle loop for providing forced circulation of said recycle slurry, a slurry removal outlet in said apparatus, a fines removal circuit communicating with said slurry removal outlet, said fines removal circuit including, at least two separate elutriation chambers, each of said elutriation chambers having an outlet at one end thereof for removing slurry liquid and crystal particles which fall below a predetermined size from a slurry stream withdrawn from the slurry body through said slurry removal outlet, means communicating with each of said elutriation chamber outlets to selectively operate any one or more of said elutriation chambers at a desired flow rate; whereby, the size and quantity of crystal particles removed from said slurry body through said elutriation chamber outlets can be selectively and independently regulated with respect to each other to provide product crystals of improved size uniformity.

Claim 16

The improved crystallization apparatus of claim 9 wherein each of said elutriation chambers is contained in a settling tank wherein crystal particles above a predetermined size are removed through an outlet adjacent the bottom thereof which outlet is in direct communication with a return inlet in said apparatus.

Claim 17

The apparatus of claim 9 wherein said fines removal circuit includes a crystal particle solubilizing means wherein crystal particles below a predetermined size removed through said elutriation chamber outlets can be solubilized prior to return of the liquid slurry to the crystallization apparatus.

Claim 18

An improved crystallization apparatus comprising an enclosed vessel adapted to contain a slurry body of liquid and crystal particles, means in said vessel for maintaining supersaturation conditions in at least a portion of the slurry body contained therein, a recycle outlet formed in said vessel for withdrawing a portion of said slurry body as a recycle stream, said recycle outlet communicating with the suction side of a pump having a discharge side in communication with a recycle inlet formed in said vessel, said recycle inlet in said vessel communicating with associated recycle inlet piping adapted to discharge said recycle slurry into said vessel adjacent the central interior portion of said vessel, at least two elutriation chambers in said vessel, each of said elutriation chambers having an outlet at one end thereof communicating with a fines removal circuit, means communicating with each of said elutriation chamber outlets to selectively operate any one or more of said elutriation chambers at a desired flow rate; whereby, both the size and quantity of crystal particles removed from said slurry body via said elutriation chambers are independently regulated with respect to each other to provide product crystals of improved size uniformity.

Claim 19

An improved crystallization apparatus comprising an enclosed vessel adapted to contain a slurry body of liquid and crystal particles, means in said vessel for maintaining supersaturation conditions in at least a portion of the slurry body contained therein, a recycle outlet formed in said vessel for withdrawing a portion of said slurry body as a recycle stream, said recycle outlet communicating with the suction side of a pump having a discharge side in communication with a recycle inlet formed in said vessel, said recycle inlet in said vessel communicating with associated recycle inlet piping adapted to discharge said recycle slurry into said vessel adjacent the central interior portion of said vessel, at least two elutriation chambers in said vessel, each of said elutriation chambers having an outlet at one end thereof communicating with a fines removal circuit, means communicating with each of said elutriation chamber outlets to selectively operate any one or more of said elutriation chambers at a desired flow rate; whereby, both the size and quantity of crystal particles removed from said slurry body via said elutriation chambers are independently regulated with respect to each other to provide product crystals of improved size uniformity.

Claim 20

An improved crystallization process, comprising a body of slurry which includes crystal particles and liquid in a vessel, maintaining conditions in said vessel for establishing supersaturation in said slurry body to induce crystallization therein, circulating said body of slurry in a predetermined flow path in said vessel at a flow rate sufficient to maintain said crystal particles in suspension, segregating a portion of said slurry body in a plurality of elutriation chambers, each of said elutriation chambers having a lower end in open communication with a main portion of said slurry body adjacent said predetermined flow path, withdrawing a stream of crystal particles and slurry liquid from each of said elutriation chambers through an outlet adjacent an upper end thereof and transmitting said stream to a fines removal circuit, each of said outlets including valve means enabling any one or more of said chambers to be in direct communication with said fines removal circuit, selectively controlling the velocity of slurry in said elutriation chamBers to effect withdrawal of crystal particles below a predetermined size only in said stream, independently controlling the volume of slurry and crystal particles removed in said stream by selectively communicating any one or more of said elutriation chambers with said fines removal circuit, removing the crystal particles in said stream and thereafter returning said stream to said body of slurry in said vessel whereby, both the size and quantity of crystal particles removed from said slurry body in said stream are independently regulated to provide product crystals of improved size uniformity.

Claim 21

An improved crystallization process, comprising a body of slurry which includes crystal particles and liquid in a vessel, maintaining conditions in said vessel for establishing supersaturation in said slurry body to induce crystallization therein, circulating said body of slurry in a predetermined flow path in said vessel at a flow rate sufficient to maintain said crystal particles in suspension, segregating a portion of said slurry body in a plurality of elutriation chambers, each of said elutriation chambers having a lower end in open communication with a main portion of said slurry body adjacent said predetermined flow path, withdrawing a stream of crystal particles and slurry liquid from each of said elutriation chambers through an outlet adjacent an upper end thereof and transmitting said stream to a fines removal circuit, each of said outlets including valve means enabling any one or more of said chambers to be in direct communication with said fines removal circuit, selectively controlling the velocity of slurry in said elutriation chamBers to effect withdrawal of crystal particles below a predetermined size only in said stream, independently controlling the volume of slurry and crystal particles removed in said stream by selectively communicating any one or more of said elutriation chambers with said fines removal circuit, removing the crystal particles in said stream and thereafter returning said stream to said body of slurry in said vessel whereby, both the size and quantity of crystal particles removed from said slurry body in said stream are independently regulated to provide product crystals of improved size uniformity.

Claim 22

An improved crystallization apparatus comprising an enclosed vessel adapted to contain a slurry body of liquid and crystal particles, means in said vessel for maintaining supersaturation conditions in at least a portion of the slurry body contained therein, a recycle outlet formed in said vessel for withdrawing a portion of said slurry body at the recycle stream, said recycle outlet communicating with the suction side of a pump having a discharge side in communication with a recycle inlet formed in said vessel, said recycle inlet in said vessel communicating with associated recycle inlet piping adapted to discharge said recycle slurry in said vessel adjacent the central interior portion of said vessel, said recycle inlet piping including a generally vertically extending pipe portion having substantial length, an interior baffle coaxially disposed with respect to and around said pipe portion, said baffle and pipe portion defining a channel of substantially cross-sectional area for at least a substantial portion of its height, radially extending partitions between said pipe portion and baffle defining said channel into at least two separate elutriation chambers, each of said elutriation chambers having an inlet adjacent the lower end thereof communicating with slurry contained in said vessel and an outlet at least a substantial height above said inlet, variable flow rate means communicating with each of said elutriation chamber outlets for selectively controlling the flow velocity in said elutriation chambers to establish a flow velocity therein for suspending only crystal particles below a predetermined size, and valve means operatively associated with each of said elutriation chamber outlets for selectively operating any one or more of said elutriation chambers simultaneously, whereby both the size and quantity of crystal particles below a predetermined size can be independently regulated to control the residence time in said vessel of said crystal particles below said predetermined size.

Claim 23

An improved crystallization apparatus comprising an enclosed vessel adapted to contain a slurry body of liquid and crystal particles, means in said vessel for maintaining supersaturation conditions in at least a portion of the slurry body contained therein, a recycle outlet formed in said vessel for withdrawing a portion of said slurry body at the recycle stream, said recycle outlet communicating with the suction side of a pump having a discharge side in communication with a recycle inlet formed in said vessel, said recycle inlet in said vessel communicating with associated recycle inlet piping adapted to discharge said recycle slurry in said vessel adjacent the central interior portion of said vessel, said recycle inlet piping including a generally vertically extending pipe portion having substantial length, an interior baffle coaxially disposed with respect to and around said pipe portion, said baffle and pipe portion defining a channel of substantially cross-sectional area for at least a substantial portion of its height, radially extending partitions between said pipe portion and baffle defining said channel into at least two separate elutriation chambers, each of said elutriation chambers having an inlet adjacent the lower end thereof communicating with slurry contained in said vessel and an outlet at least a substantial height above said inlet, variable flow rate means communicating with each of said elutriation chamber outlets for selectively controlling the flow velocity in said elutriation chambers to establish a flow velocity therein for suspending only crystal particles below a predetermined size, and valve means operatively associated with each of said elutriation chamber outlets for selectively operating any one or more of said elutriation chambers simultaneously, whereby both the size and quantity of crystal particles below a predetermined size can be independently regulated to control the residence time in said vessel of said crystal particles below said predetermined size.