Immobilized-interface solute-transfer apparatus

• US RE34,828 E
• Filed: 10/24/1991
• Issued: 01/17/1995
• Est. Priority Date: 08/28/1984
• Status: Expired due to Term

• Current Assignee: The Trustees of The Stevens Institute of Technology (Stevens Institute Of Technology)
• Original Assignee: The Trustees of The Stevens Institute of Technology (Stevens Institute Of Technology)
• Inventors: Sirkar, Kamalesh
• Primary Examiner(s): Therkorn, Ernest G.
• Application Number:
  US07/781,864
• Time in Patent Office: 1,181 Days
• Field of Search: 210/90, 210/109, 210/111, 210/137, 210/321.65, 210/321.64, 210/321.75
• US Class Current: 210/137
• CPC Class Codes: B01D 11/0415 in combination with membranes
• CPC Class Codes: B01D 2313/50 Specific extra tanks
• CPC Class Codes: B01D 61/246 Membrane extraction
• CPC Class Codes: B01D 61/28 Apparatus therefor
• CPC Class Codes: B01D 61/32 Controlling or regulating
• CPC Class Codes: B01D 63/043 with separate tube sheets

Abstract

An immobilized-interface solute-transfer unit for transferring solute from a feed solution to an extractant liquid comprises a fluid-tight housing and a porous membrane which divides the housing into a feed solution chamber and an extractant chamber. The housing has feed solution inlet and outlet ports which communicate with the feed solution chamber, and extractant inlet an outlet ports which communicate with the extractant chamber. The solute-transfer unit also includes a pressure difference controller for maintaining a difference between a liquid pressure of a feed solution in the feed solution chamber and a liquid pressure of an extractant in the extractant chamber substantially within a predetermined pressure range so that an interface between the feed solution and the extractant is substantially immobilized at the membrane. The solute-transfer unit is particularly adapted for transferring a solute from a feed solution to an extractant, which feed solution and extractant are immiscible with one another when in direct contact.

Claims

2. extractant..]. 13. An immobilized-interface solute-transfer unit for transferring a solute from a feed solution to an extractant liquid, the solute-transfer unit comprising:

(a) A fluid-tight housing;

(b) a first porous membrane located in and connected to the housing, the first porous membrane being preferentially wettable by one of the feed solution and the extractant liquid, the first porous membrane dividing the housing into a feed solution chamber and an extractant chamber, the housing having a feed solution inlet port and a feed solution outlet port which communicate with the feed solution chamber and an extractant inlet port and an extractant outlet port which communicate with the extractant chamber;

(c) feed-solution/extractant pressure difference control means for maintaining a difference between a liquid pressure of a feed solution in the feed solution chamber and a liquid pressure of an extractant in the extractant chamber substantially within a predetermined pressure range so that an interface between the feed solution and the extractant is substantially immobilized at the first porous membrane to effectively prevent the formation of a dispersion of feed solution and extractant in either chamber on opposing sides of the membrane;

(d) a second porous membrane located in and connected to the housing the second porous membrane being preferentially wettable by one of the extractant liquid and a back-extractant, the second porous membrane being located in the extractant chamber and dividing the chamber into an intermediate extractant subchamber and a back extractant subchamber, the extractant inlet and outlet ports being in communication with the intermediate extractant subchamber, the housing having a back extractant inlet port and a back extractant outlet port which communicate with the back extractant subchamber; and

(e) back-extractant/pressure difference control means for maintaining a difference between a liquid pressure of a back extractant in the back extractant subchamber and a liquid pressure of an intermediate extractant in the intermediate extractant subchamber substantially within a predetermined pressure range so that the interface between the back extractant and the intermediate extractant is substantially immobilized at the second porous membrane to effectively prevent the formation of a dispersion of back-extractant and extractant in either subchamber on

3. opposing sides of the second porous membrane. 14. The immobilized-interface solute-transfer unit according to claim 13 in which the extractant inlet port is connected to a source of extractant liquid.

4. The membrane-separation unit according to claim 13 in which

(b.1) The porous membrane is in the shape of a hollow tube, the interior of the tube defining a feed-solution chamber;

and

(d.1) the second porous membrane is in the shape of a hollow tube, the

5. interior of the tube defining a back extractant subchamber. 16. A membrane solute-transfer unit for transferring solute from a liquid feed solution to a liquid extractant, the solute-transfer unit comprising:

(a) a solute-transfer unit housing having extractant inlet port means for introducing a liquid extractant into an interior of the housing and extractant outlet port means for discharging the extractant from the interior of the housing, the housing having feed-solution inlet and outlet port means for introducing and discharging a feed solution from the interior of the housing, and the housing having auxiliary-extractant inlet port means for introducing a liquid auxiliary extractant into the interior of the housing and auxiliary-extractant outlet port means for discharging the auxiliary extractant from the interior of the housing;

(b) a plurality of hollow solute-transfer tubes, the solute-transfer tubes extending through the interior of the solute-transfer unit housing from the extractant inlet port means to the extractant outlet port means, the walls of the tubes being made of a porous membrane material the porous membrane material being preferentially wettable by one of the feed solution and the extractant liquid, interiors of the tubes communicating at an inlet end with the extractant inlet port means for receiving the liquid extractant and at an outlet end with the extractant outlet port means for discharging the extractant;

(c) extractant/feed-solution pressure difference control means for maintaining a difference between a liquid pressure of the extractant in the interior of the solute-transfer tubes and a liquid pressure of the feed solution in the interior of the separation unit housing exterior of the solute-transfer tubes substantially within a predetermined pressure range so that an interface between the feed solution and the extractant is substantially immobilized at the porous membrane wall of the solute-transfer tubes to effectively prevent the formation of a dispersion of feed solution and extractant in either the interior of the solute-transfer tubes or in the interior of the separation unit housing exterior of the solute-transfer tubes;

(d) a plurality of hollow auxiliary-extractant solute-transfer tubes, the auxiliary extractant solute-transfer tubes extending through the interior of the solute-transfer unit housing from the auxiliary-extractant inlet port means to the auxiliary-extractant outlet port means, the wall of the tubes being made of a porous membrane material, the porous membrane material being preferentially wettable by one of the auxiliary-extractant and the feed solution, interiors of the tubes communicating at an inlet end with the auxiliary-extractant inlet port means for receiving the auxiliary extractant and at an outlet end with the auxiliary-extractant outlet port means for discharging the auxiliary extractant; and

(e) auxiliary-extractant/feed-solution pressure-difference control means for maintaining a difference between a liquid pressure of the auxiliary-extractant in the interior of the auxiliary-extractant solute-transfer tubes and a liquid pressure of the feed solution in the interior of the separation unit housing exterior of the auxiliary-extractant solute-transfer tubes substantially within a predetermined pressure range so that an interface between the feed solution and the auxiliary extractant is substantially immobilized at the porous membrane wall of the auxiliary-extractant solute-transfer tubes to effectively prevent the formation of a dispersion of feed solution and auxiliary-extractant in either the interior of the auxiliary-extractant solute-transfer tube or in the interior of the separation unit housing

6. exterior of the auxiliary-extractant solute-transfer tubes. 17. The membrane solute transfer unit according to claim 16 in which the extractant inlet and outlet port mans is connected to a source of liquid

7. extractant. 18. A membrane solute transfer unit for transferring solute from a liquid feed solution to a liquid extractant, the solute-transfer unit comprising:

a solute-transfer unit housing having feed-solution inlet port means for introducing a feed solution into an interior of the housing and feed solution outlet port means for discharging the feed solution from the interior of the housing, the housing having extractant inlet and outlet port means for introducing and discharging an extractant from the interior of the housing, the housing having back-extractant inlet port means for introducing a liquid back extractant into the interior of the housing and back-extractant outlet port means for discharging the back extractant from the interior of the housing;

(b) a plurality of hollow solute-transfer tubes, the solute-transfer tubes extending through the interior of the solute-transfer unit housing from the feed-solution inlet port means to the feed-solution outlet port means, the walls of the tubes being made of a porous membrane material, the porous membrane material being preferentially wettable by one of the feed solution and the extractant liquid, interiors of the tubes communicating at an inlet end with the feed-solution inlet port means for receiving the feed-solution and at an outlet end with the feed solution outlet port means for discharging the feed solution;

(c) feed-solution/extractant pressure difference control means for maintaining a difference between a liquid pressure or a feed solution in the interior of the solute-transfer tubes and a liquid pressure of an extractant in the interior of the separation unit housing exterior of the solute-transfer tubes substantially within a predetermined pressure range so that an interface between the feed solution and the extractant is substantially immobilized at the porous membrane wall of the solute-transfer tubes to effectively prevent the formation of a dispersion of feed solution and extractant in either the interior of the solute-transfer tubes or in the interior of the separation unit housing exterior of the solute-transfer tubes;

(d) a plurality of hollow back-extractant solute-transfer tubes, the back-extractant solute-transfer tubes extending through the interior of the solute-transfer unit housing from the back-extractant inlet port means to the back-extractant outlet port means, the walls of the tubes being made of a porous membrane material the porous membrane material being preferentially wettable by one of the extractant liquid and the back-extractant, the back-extractant solute-transfer tubes commingling with the solute-transfer tubes, interiors of the back-extractant solute-transfer tubes communicating at an inlet end with the back-extractant inlet port means for receiving the back-extractant liquid and at an outlet end with the back-extractant outlet port means for discharging the back extractant; and

(e) back-extractant/extractant pressure difference control means for maintaining a difference between a liquid pressure of a back-extractant liquid in the interior of the back-extractant solute-transfer tubes and a liquid pressure of the extractant in the interior of the separation unit housing exterior of the back-extractant solute-transfer tubes substantially within the predetermined pressure range so that an interface between the back extractant and the extractant is substantially immobilized at the porous membrane wall of the back-extractant solute-transfer tubes to effectively prevent the formation of a dispersion of back-extractant and extractant in either the interior of the back-extractant solute-transfer tubes or in the interior of the separation

8. unit housing exterior of the back-extractant solute-transfer tubes. 19. The membrane solute-transfer unit according to claim 18 in which the extractant inlet port means is connected to a source of liquid extractant and the auxiliary-extractant inlet port means is connected to a source of

9. liquid auxiliary extractant. .Iadd.20. An immobilized-interface solute-transfer unit for transferring a solute from a feed solution to an extractant liquid, the solute-transfer unit comprising:

(a) a fluid-tight housing;

(b) a porous membrane located in and connected to the housing, the porous membrane including pores having effective pore diameters in the range of from about 20 nm to about 10 μ

m, the porous membrane being preferentially wettable by one of the feed-solution and liquid extractant, the porous membrane dividing the housing into a feed solution chamber and an extractant chamber, the housing having a feed solution inlet port and a feed solution outlet port which communicate with the feed solution chamber and an extractant inlet port and an extractant outlet port which communicate with the extractant chamber;

(c) pressure difference control means for maintaining a difference between a liquid pressure of a feed solution in the feed solution chamber and a liquid pressure of an extractant in the extractant chamber substantially within a predetermined pressure range so that an interface between the feed solution and the extractant is substantially immobilized at the membrane, to effectively prevent the formation of a dispersion of feed solution and extractant in either chamber on opposing sides of the membrane..Iaddend. .Iadd.21. The membrane solute-transfer unit according to claim 20 in which the porous membrane is in the shape of a hollow tube, the interior of the tube defining one of the feed solution chamber and the

10. extractant chamber..Iaddend. .Iadd.22. The membrane separation unit according to claim 20 in which the porous membrane is composed of a hydrophilic material selected from the group consisting of porous regenerated cellulose, porous cellulose acetate, porous cellulose acetate-nitrate, porous cellulose triacetate, microporous glass and porous porcelain..Iaddend. .Iadd.23. The membrane separation unit according to claim 20 in which the porous membrane is composed of a hydrophobic material selected from the group consisting of porous polyethylene, porous polypropylene and porous polytetrafluoroethylene..Iaddend. .Iadd.24. The membrane-separation unit according to claim 20 in which the porous membrane is approximately planar in shape and the unit further comprises:

(d) a membrane reinforcing screen connected to the housing and located adjacent to the porous membrane on a side of the membrane facing a chamber maintained in operation at a pressure lower than the pressure of the chamber on the opposing side of the membrane..Iaddend. .Iadd.25. The membrane unit according to claim 20 in which the pressure control means includes;

(c.1) a feed-solution pressure sensor in communication with the feed-solution chamber for detecting a liquid pressure in the chamber;

(c.2) an extractant pressure sensor in communication with the extractant chamber for detecting a liquid pressure in the chamber;

(c.3) a pressure-difference regulator having a head pressure-sensor input, a base pressure-sensor input and a control signal output, the head pressure-sensor input being connected to one of the feed-solution pressure sensor and the extractant pressure sensor and the base pressure-sensor input being connected to the other of the feed-solution pressure sensor and the extractant pressure sensor, the pressure-difference regulator being adapted to generate a pressure control signal at the control-signal output which varies in response to changes in the difference between the pressure sensed at the head pressure-sensor input and the base pressure-sensor input; and

(c.4) a pressure control valve having a valve control input connected to the control-signal output of the pressure-difference regulator, the pressure control valve being in fluid communication with one of the feed solution chamber and the extractant chamber and being adapted to change the liquid pressure in the chamber with which it communicates in response to changes in a control signal at the valve control input..Iaddend. .Iadd.26. The immobilized-interface solute-transfer unit according to claim 20 in which the extractant inlet port is connected to a source of extractant liquid..Iaddend. .Iadd.27. A membrane solute-transfer unit for transferring solute from a liquid feed solution to a liquid extractant, the solute-transfer unit comprising;

(a) A solute-transfer unit housing having feed-solution inlet port means for introducing a feed solution into an interior of the housing and feed solution outlet port means for discharging the feed solution from the interior of the housing, the housing having extractant inlet and outlet port means for introducing and discharging an extractant from the interior of the housing;

(b) a plurality of hollow solute-transfer tubes, the solute-transfer tubes extending through the interior of the solute-transfer unit housing from the feed-solution inlet port means to the feed-solution outlet port means, the walls of the tubes being made of a porous membrane material, the porous membrane material including pores having effective pore diameters in the range of from about 20 nm to about 10 μ

m, the porous membrane material being preferentially wettable by one of the feed-solution and liquid extractant interiors of the tubes communicating at an inlet end with the feed-solution inlet port means for receiving the feed-solution and at an outlet end with the feed solution outlet port means for discharging the feed solution; and

(c) pressure difference control means for maintaining a difference between a liquid pressure of a feed solution in the interior of the solute-transfer tubes and a liquid pressure of an extractant in the interior of the separation unit housing exterior of the solute-transfer tubes substantially within a predetermined pressure range so that an interface between the feed solution and the extractant is substantially immobilized at the porous membrane wall of the solute-transfer tubes to effectively prevent the formation of a dispersion of feed solution and extractant in either the interior of the solute-transfer tubes or in the interior of the separation unit housing exterior of the solute-transfer

1. to changes in a control signal at the valve control input..]. .[.7. The immobilized-interface solute-transfer unit according to claim 1 in which the extractant inlet port is connected to a source of extractant liquid..]. .[.8. A membrane solute-transfer unit for transferring solute from a liquid feed solution to a liquid extractant, the solute-transfer unit comprising:

(a) a solute-transfer unit housing having feed-solution inlet port means for introducing a feed solution into an interior of the housing and feed solution outlet port means for discharging the feed solution from the interior of the housing, the housing having extractant inlet and outlet port means for introducing and discharging an extractant from the interior of the housing;

(b) a plurality of hollow solute-transfer tubes, the solute-transfer tubes extending through the interior of the solute-transfer unit housing from the feed-solution inlet port means to the feed-solution outlet port means, the walls of the tubes being made of a porous membrane material, the porous membrane material including pores having effective pore diameters in the range of from about 7 nm to about 10 μ

m, the porous membrane material being preferentialy wettable by one of the feed-solution and liquid extractant interiors of the tubes communicating at an inlet end with the feed-solution inlet port means for receiving the feed-solution and at an outlet end with the feed solution outlet port means for discharging the feed solution; and

(c) pressure difference control means for maintaining a difference between a liquid pressure of a feed solution in the interior of the solute-transfer tubes and a liquid pressure of an extractant in the interior of the separation unit housing exterior of the solute-transfer tubes substantially within a predetermined pressure range so that an interface between the feed solution and the extractant is substantially immobilized at the porous membrane wall of the solute-transfer tubes to effectively prevent the formation of a dispersion of feed solution and extractant in either the interior of the solute-transfer tubes or in the interior of the separation unit housing exterior of the solute-transfer tubes..]. .[.9. The membrane solute-transfer unit according to claim 8 in which the extractant inlet and outlet port means in connected to a source of liquid extractant..]. .[.10. A membrane solute-transfer unit for transferring solute from a liquid feed solution to a liquid extractant, the solute-transfer unit comprising;

(a) a solute-transfer unit housing having extractant inlet port means for introducing a liquid extractant into an interior of the housing and extractant outlet port means for discharging the extractant from the interior of the housing, the housing having feed-solution inlet and outlet port means for introducing and discharging a feed solution from the interior of the housing;

(b) a plurality of hollow solute-transfer tubes, the solute-transfer tubes extending through the interior of the solute-transfer unit housing from the extractant inlet port means to the extractant outlet port means, the walls of the tubes being made of a porous membrane material, the porous membrane material including pores having effective pore diameters in the range of from about 7 mm to about 10 μ

m, the porous membrane material being preferentially wettable by one of the feed-solution and liquid extractant interiors of the tubes communicating at an inlet end with the extractant inlet port means for receiving the liquid extractant and at an outlet end with the extractant outlet port means for discharging the extractant; and

(c) pressure difference control means for maintaining a difference between a liquid pressure of the extractant in the interior of the solute-transfer tubes and a liquid pressure of the feed solution in the interior of the separation unit housing exterior of the solute-transfer tubes substantially within a predetermined pressure range so that an interface between the feed solution and the extractant is substantially immobilized at the porous membrane wall of the solute-transfer tubes to effectively prevent the formation of a dispersion of feed solution and extractant in either the interior of the solute-transfer tubes or in the interior of the separation unit housing exterior of the solute-transfer tubes..]. .[.11. The membrane solute-transfer unit according to claim 7 in which the pores of the porous membrane material of the solute-transfer tubes are of a size substantially to prevent cellular debris in a feed solution from passing from the feed solution exterior of the solute-transfer tubes to the interior of the solute-transfer tubes, and the solute-transfer unit further comprises;

(d) gas-permeable membrane means for introducing oxygen into the feed solution in the interior of the separation-unit housing..]. .[.12. The membrane solute-transfer unit according to claim 10 in which the extractant inlet port means is connected to a source of liquid

11. tubes..Iaddend. .Iadd.28. The membrane solute-transfer unit according to claim 27 in which the extractant inlet and outlet port means in connected

12. to a source of liquid extractant..Iaddend. .Iadd.29. A membrane solute-transfer unit for transferring solute from a liquid feed solution to a liquid extractant, the solute-transfer unit comprising:

(a) a solute-transfer unit housing having extractant inlet port means for introducing a liquid extractant into an interior of the housing and extractant outlet port means for discharging the extractant from the interior of the housing, the housing having feed-solution inlet and outlet port means for introducing and discharging a feed solution from the interior of the housing;

(b) a plurality of hollow solute-transfer tubes, the solute-transfer tubes extending through the interior of the solute-transfer unit housing from the extractant inlet port means to the extractant outlet port means, the walls of the tubes being made of a porous membrane material, the porous membrane material including pores having effective pore diameters in the range of from about 20 nm to about 10 μ

m, the porous membrane material being preferentially wettable by one of the feed-solution and liquid extractant interiors of the tubes communicating at an inlet end with the extractant inlet port means for receiving the liquid extractant and at an outlet end with the extractant outlet port means for discharging the extractant; and

(c) pressure difference control means for maintaining a difference between a liquid pressure of the extractant in the interior of the solute-transfer tubes and a liquid pressure of the feed solution in the interior of the separation unit housing exterior of the solute-transfer tubes substantially within a predetermined pressure range so that an interface between the feed solution and the extractant is substantially immobilized at the porous membrane wall of the solute-transfer tubes to effectively prevent the formation of a dispersion of feed solution and extractant in either the interior of the solute-transfer tubes or in the interior of the separation unit housing exterior of the solute-transfer tubes..Iaddend. .Iadd.30. The membrane solute-transfer unit according to claim 29 in which the extractant inlet port means is connected to a source of liquid extractant..Iaddend.