CA1145683A - Gas phase separation system - Google Patents
Gas phase separation systemInfo
- Publication number
- CA1145683A CA1145683A CA000349976A CA349976A CA1145683A CA 1145683 A CA1145683 A CA 1145683A CA 000349976 A CA000349976 A CA 000349976A CA 349976 A CA349976 A CA 349976A CA 1145683 A CA1145683 A CA 1145683A
- Authority
- CA
- Canada
- Prior art keywords
- mixture
- membrane
- cell
- gas
- chambers
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/22—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion
Abstract
ABSTRACT OF THE DISCLOSURE
The relative concentration of the components of a mixture of gasses is altered in a system which includes a cell having chambers separated by a semi-permeable membrane and a means for creating a pressure differential across the membrane. The mixture flows through the inlet means and around the cell in countercurrent reflux flow. An altered mixture is retrieved through an outlet means. The cell may be formed from modular units which can be arranged to achieve a tapered cell configuration so that the flow rate around the system is substantially constant.
The relative concentration of the components of a mixture of gasses is altered in a system which includes a cell having chambers separated by a semi-permeable membrane and a means for creating a pressure differential across the membrane. The mixture flows through the inlet means and around the cell in countercurrent reflux flow. An altered mixture is retrieved through an outlet means. The cell may be formed from modular units which can be arranged to achieve a tapered cell configuration so that the flow rate around the system is substantially constant.
Description
~45683 This invention relates generally to the field of gas phase separation by the passage of gasses across a membrane and more specifically to concentrating selected gasses in a mixture of gasses.
The separation of gasses across a membrane is not new.
Patents to Frey (U.S. Patent No. 2,159,434) and Stahly (U.S.
Patent No. 2,388,095) disclose gas separation devices which apply with pressure a mix~ure of gasses to one side of a semi-permeable membrane. The membrane allows one gas to pass in preference to another. It is also well known that the product gas from one such device can be processed through subsequent serially-connected such devices to further concentrate the gas.
Tapering of such separation devices is known. The textbook Nuclear Chemical Enqineering, by Benedict and Pigford, p.
391, (McGraw-Hill, New York, 1957) describes tapering a plurality of such gas separation devices which are connected in cascade fashion to distribute a gas flow rate evenly through a gas separation system. Tapering and cascade systems are described in Introduction To Nuclear Enqineerinq, by Stephenson, pp. 362-368 (McGraw-Hill, New York, 1958). The article "Taperization of Step Cascade for Uranium Enrichment by Gaseous Diffusion Procesq", by Higashi and Myamoto (?ournal of Nuclear Science and Technology, January 1976, pp. 30-34) also describes cascading and tapering.
Cascading to achieve tapering is also described in Introduction to Nuclear Engineering, by Murray (George Allen, Unwin Ltd., London, pl~. 68-79).
Countercurrent reflux is well known in distillation, extraction and gas absorption processes. Countercurrent reflux without backmixing in gas diffusion devices is described by 30 Pfefferle (~.S. Patent No. 3,144,313). Pfefferle's device '''''` 1 f~
. .
, ., .
~` , '.'' ~145683 separates a selected gas from a mixture of gasses across a membrane which has a high diffusion rate for the selected gas.
Pfefferle describes a device which operates at relatively high temperatures (300 to 400C) and pressures ~2.75 x 106 to 3.45 x 106 Pa) and which uses a metallic membrane.
Gas diffusion devices which employ hollow fibers or tubes as membranes to separate feed and recovery chambers are known from Pfefferle (U.S. Patent No. 3,144,313) and Skarstrom et al. (U.S.
Patent No. 3,735,558).
Practical applications of gas diffusion devices are many and varied. They include oxygen enrichment for inhalation therapy, sweetening of natural gas, stack gas cleaning, nitrogen enrichment to reduce fire hazards, and the like. In most such applications, economy and efficiency of operation are important to the commercial advancement of such devices. Devices which operate at relatively low temperatures and pressures and which require relatively little energy input are desirable.
Gas separation devices which avoid numerous cascading steps are desirable.
It is a principal object of this invention to concentrate a selected gas or gasses in a mixture of gasses.
It is another object of this invention to concentrate a gas or gasses at relatively low temperatures and pressures.
It i9 still another object of this invention to concentrate a gas or gasses without cascading.
It is yet a further object of this invention to maintain a substantially homogeneous flow rate throughout a countercurrent reflux gas separation system.
It is also an object of this invention to remove moisture from a gas.
:`
~:`
~456~33 These and other objects are accomplished by a system operable at room temperature for altering the relative concentrations of the components of a mixture of fluids moving in the system. The system includes at least one cell having chambers separated by a semi-permeable membrane. The chambers communicate in such a way as to produce countercurrent reflux flow of the mixture and to result in one chamber having a higher pressure than the other. The chambers have a geometry which avoids backmixing, and the membrane has a different permeability constant for at least two of the components of the mixture.
The system also includes a means for creating a pressure differential across the membrane and at least one inlet means for feeding the mixture into the system. At least one outlet means is also included in the system for recovering the mixture after the relative concentrations of its components have been altered. The means for creating a pressure differential may create any such suitable differential, although a pressure differential of less than about 3.45 x 105 Pa is preferred.
The means for creating a pressure differential between the chambers may be a pressure reducer positioned in the communication between the chambers. It may also be a relatively high pres~ure feed mixture or a compressor which communicates ; between the chambers or both.
The outlet means is positioned in the system to recover an altered mixture having increased amounts of either most permeable gas or the least permeable gas, or both. The inlet means can be positioned at any suitable location in the system, but it is preferably located at a point where the concentration of gasses in the system matches the concentration of gasses in the inlet mixture.
.
1~5683 In the relatively low pressure, room temperature system of the present invention, any suitable semi-permeable membrane material may be used. Representative useful materials include cellulose acetate, polytetrafluoroethylene, cellulose triacetate, cellulose acetate-styrene, cellulose acetate butyrate, polyethylmethacrylate, cellulose propionate, polypropylene, epoxy, ethyl cellulose, ethylene vinyl-acetate, methyl cellulose, nitrocellulose, polyvinylchloride, polyvinyl acetate, nitroso rubber, polyamide, polybutadiene, polyvinylchloride, poly(butadiene methylmethacrylate), polytbutadiene styrene), polycarbonate, polydialkylsiloxane resins, silicone rubbers, polyethylene-acrylonitrile, polyethylenimine-polyvinylbutyral, polyethylene, polyestermethane, polyethylene terephthalate and the like.
Silicone materials are often preferred because of their permeability and relative chemical inertness. An especially preferred material is a poly(alphamethylstyrene-co-dimethyl-siloxane) copolymer (described in U.S. Patent No. 4,107,227) which has many of the permeability characteristics of silicone rubber but which has shaping and handling characteristics typical of plastics. In the preferred embodiment, the membrane is a hollow fiber.
A cell may be formed ~rom a plurality of interconnected ` modular units. Each such unit includes chambers separated by a membrane. In the preferred embodiment, the modular units are interconnected in a tapered configuration so as to form a system in which the rate of movement of the mixture is substantially constant throughout the system.
FIG. 1 shows schematically and in cross-section a system according to the present invention.
,:
:
;~
'~
~145~83 FIG. 2 shows schematically the relative membrane area required to obtain substantially even flow in the system of FIG. l.
FIG. 3 shows schematically and in cross-section an arrangement of modular units which together form the system of claim l having a membrane area approximating that shown in FIG. 2.
~ IGS. 4 and 5 show alternative embodiments of the system of the present invention.
Referring more specifically to FIG. l, there is shown a system according to this invention for altering the relative concentrations of the components of a mixture of fluids moving in the system. The system includes cell l which has a high pressure chamber 2 and a low pressure chamber 3 separated by a membrane 4.
Chambers 2 and 3 communicate through pressure reducer 25 at one end and compressor 5 at the other.
Each chamber 2 and 3 has a geometry which avoids backmixing of a gas flowing through the system. Such a geometric limitation usually requires that the chambers have a small ao cross-section. In a representative embodiment, eor example, cell l is a bundle of hollow microfibers packed in a tube, each hollow microfiber having an I.D. of 0.239 mm. and an O.D. of 0.610 mm..
The inside of the microfibers forms chamber 2 and the area outside the fibers but inside the tube forms chamber 3.
An inlet means 6 allows entry of a mixture of gasses into the system. Inlet means 6 may be a pressurized feed. The pressurized feed creates a pressure differential across the membrane with the aid of pressure reducer 25. Inlet means 6 can be located anywhere along either side of cell l, but it is most preferahl~ located at about the p int where the concentration of .~
,: .
~4~;83 gasses in the mixture moving through the system is about the same as the concentration of gasses entering the system.
In the embodiment of FIG. 1, the pressure differential across the membrane can be provided by compressor S which increases the gas pressure as it moves from chamber 3 to chamber
The separation of gasses across a membrane is not new.
Patents to Frey (U.S. Patent No. 2,159,434) and Stahly (U.S.
Patent No. 2,388,095) disclose gas separation devices which apply with pressure a mix~ure of gasses to one side of a semi-permeable membrane. The membrane allows one gas to pass in preference to another. It is also well known that the product gas from one such device can be processed through subsequent serially-connected such devices to further concentrate the gas.
Tapering of such separation devices is known. The textbook Nuclear Chemical Enqineering, by Benedict and Pigford, p.
391, (McGraw-Hill, New York, 1957) describes tapering a plurality of such gas separation devices which are connected in cascade fashion to distribute a gas flow rate evenly through a gas separation system. Tapering and cascade systems are described in Introduction To Nuclear Enqineerinq, by Stephenson, pp. 362-368 (McGraw-Hill, New York, 1958). The article "Taperization of Step Cascade for Uranium Enrichment by Gaseous Diffusion Procesq", by Higashi and Myamoto (?ournal of Nuclear Science and Technology, January 1976, pp. 30-34) also describes cascading and tapering.
Cascading to achieve tapering is also described in Introduction to Nuclear Engineering, by Murray (George Allen, Unwin Ltd., London, pl~. 68-79).
Countercurrent reflux is well known in distillation, extraction and gas absorption processes. Countercurrent reflux without backmixing in gas diffusion devices is described by 30 Pfefferle (~.S. Patent No. 3,144,313). Pfefferle's device '''''` 1 f~
. .
, ., .
~` , '.'' ~145683 separates a selected gas from a mixture of gasses across a membrane which has a high diffusion rate for the selected gas.
Pfefferle describes a device which operates at relatively high temperatures (300 to 400C) and pressures ~2.75 x 106 to 3.45 x 106 Pa) and which uses a metallic membrane.
Gas diffusion devices which employ hollow fibers or tubes as membranes to separate feed and recovery chambers are known from Pfefferle (U.S. Patent No. 3,144,313) and Skarstrom et al. (U.S.
Patent No. 3,735,558).
Practical applications of gas diffusion devices are many and varied. They include oxygen enrichment for inhalation therapy, sweetening of natural gas, stack gas cleaning, nitrogen enrichment to reduce fire hazards, and the like. In most such applications, economy and efficiency of operation are important to the commercial advancement of such devices. Devices which operate at relatively low temperatures and pressures and which require relatively little energy input are desirable.
Gas separation devices which avoid numerous cascading steps are desirable.
It is a principal object of this invention to concentrate a selected gas or gasses in a mixture of gasses.
It is another object of this invention to concentrate a gas or gasses at relatively low temperatures and pressures.
It i9 still another object of this invention to concentrate a gas or gasses without cascading.
It is yet a further object of this invention to maintain a substantially homogeneous flow rate throughout a countercurrent reflux gas separation system.
It is also an object of this invention to remove moisture from a gas.
:`
~:`
~456~33 These and other objects are accomplished by a system operable at room temperature for altering the relative concentrations of the components of a mixture of fluids moving in the system. The system includes at least one cell having chambers separated by a semi-permeable membrane. The chambers communicate in such a way as to produce countercurrent reflux flow of the mixture and to result in one chamber having a higher pressure than the other. The chambers have a geometry which avoids backmixing, and the membrane has a different permeability constant for at least two of the components of the mixture.
The system also includes a means for creating a pressure differential across the membrane and at least one inlet means for feeding the mixture into the system. At least one outlet means is also included in the system for recovering the mixture after the relative concentrations of its components have been altered. The means for creating a pressure differential may create any such suitable differential, although a pressure differential of less than about 3.45 x 105 Pa is preferred.
The means for creating a pressure differential between the chambers may be a pressure reducer positioned in the communication between the chambers. It may also be a relatively high pres~ure feed mixture or a compressor which communicates ; between the chambers or both.
The outlet means is positioned in the system to recover an altered mixture having increased amounts of either most permeable gas or the least permeable gas, or both. The inlet means can be positioned at any suitable location in the system, but it is preferably located at a point where the concentration of gasses in the system matches the concentration of gasses in the inlet mixture.
.
1~5683 In the relatively low pressure, room temperature system of the present invention, any suitable semi-permeable membrane material may be used. Representative useful materials include cellulose acetate, polytetrafluoroethylene, cellulose triacetate, cellulose acetate-styrene, cellulose acetate butyrate, polyethylmethacrylate, cellulose propionate, polypropylene, epoxy, ethyl cellulose, ethylene vinyl-acetate, methyl cellulose, nitrocellulose, polyvinylchloride, polyvinyl acetate, nitroso rubber, polyamide, polybutadiene, polyvinylchloride, poly(butadiene methylmethacrylate), polytbutadiene styrene), polycarbonate, polydialkylsiloxane resins, silicone rubbers, polyethylene-acrylonitrile, polyethylenimine-polyvinylbutyral, polyethylene, polyestermethane, polyethylene terephthalate and the like.
Silicone materials are often preferred because of their permeability and relative chemical inertness. An especially preferred material is a poly(alphamethylstyrene-co-dimethyl-siloxane) copolymer (described in U.S. Patent No. 4,107,227) which has many of the permeability characteristics of silicone rubber but which has shaping and handling characteristics typical of plastics. In the preferred embodiment, the membrane is a hollow fiber.
A cell may be formed ~rom a plurality of interconnected ` modular units. Each such unit includes chambers separated by a membrane. In the preferred embodiment, the modular units are interconnected in a tapered configuration so as to form a system in which the rate of movement of the mixture is substantially constant throughout the system.
FIG. 1 shows schematically and in cross-section a system according to the present invention.
,:
:
;~
'~
~145~83 FIG. 2 shows schematically the relative membrane area required to obtain substantially even flow in the system of FIG. l.
FIG. 3 shows schematically and in cross-section an arrangement of modular units which together form the system of claim l having a membrane area approximating that shown in FIG. 2.
~ IGS. 4 and 5 show alternative embodiments of the system of the present invention.
Referring more specifically to FIG. l, there is shown a system according to this invention for altering the relative concentrations of the components of a mixture of fluids moving in the system. The system includes cell l which has a high pressure chamber 2 and a low pressure chamber 3 separated by a membrane 4.
Chambers 2 and 3 communicate through pressure reducer 25 at one end and compressor 5 at the other.
Each chamber 2 and 3 has a geometry which avoids backmixing of a gas flowing through the system. Such a geometric limitation usually requires that the chambers have a small ao cross-section. In a representative embodiment, eor example, cell l is a bundle of hollow microfibers packed in a tube, each hollow microfiber having an I.D. of 0.239 mm. and an O.D. of 0.610 mm..
The inside of the microfibers forms chamber 2 and the area outside the fibers but inside the tube forms chamber 3.
An inlet means 6 allows entry of a mixture of gasses into the system. Inlet means 6 may be a pressurized feed. The pressurized feed creates a pressure differential across the membrane with the aid of pressure reducer 25. Inlet means 6 can be located anywhere along either side of cell l, but it is most preferahl~ located at about the p int where the concentration of .~
,: .
~4~;83 gasses in the mixture moving through the system is about the same as the concentration of gasses entering the system.
In the embodiment of FIG. 1, the pressure differential across the membrane can be provided by compressor S which increases the gas pressure as it moves from chamber 3 to chamber
2.
Outlet 7 for altered mixture 11 enriched in the least permeable gas is located at one end of the system. Outlet 8 is provided at the other end of the system to collect altered mixture 12 enriched in the most permeable gas.
A plurality of outlets such as outlets 7 and 8, or one such outlet, could be placed anywhere along either side of the cell to collect any desired mixture of gasses.
In operation of the embodiment of FIG. 1, a pressurized feed mixture 9 of gasses enters the system at inlet 6 and moves around the system in the direction shown by the arrows.
Amounts of the most permeable component 10 pass through membrane 4 as mixture 9 moves along chamber 2. As mixture 9 approaches the end of chamber 2, its relative concentrations of least permeable and most permeable components has changed because of the loss of most permeable component 10.
Altered mixture 11 which has a relatively low concentration of component 10 may be recovered at outlet 7.
As mixture 9 moves along chamber 3, countercurrent to its flow in chamber 2, it gathers additional amounts of most permeable component 10 so that an altered mixture 12 containing a relatively high ratio of most permeable component 10 may be collected at outlet 8.
In most operations, the volume of the gas stream recirculated through cell 1 may exceed considerably that of feed ., .
.~ .
1~5~33 stream 9, however, at steady state operation, the volume of altered mixtures 11 and 12 will total the volume of feed mixture 9.
It can readily be seen that such a flow pattern would normally result in a greater volume of mixture 9 being present near the compressor end of cell 1 where most permeable gas 10 tends to accumulate. For example, in a system for concentrating oxygen in air, condensed air twhich is 21.1% 2) is introduced at inlet 6 at a rate of about 0.137 cc/sec under a pressure of 172.1 cm Hg (the system operates at a temperature of about 23.1C.). At inlet 6, mixture 9 already in cell 1 is flowing in the direction shown by the arrows at a rate of about 0.093 cc/sec.
By the time mixture 9 gets to the end of chamber 2, a distance of 2.11 m in a 35-member bundle of silicone rubber hollow microfibers, it has a pressure of only 171.5 cm Hg because of passage of 2 through membrane 4. The gas stream has an oxygen concentration of only 15.1% at the end of chamber 2. About 0.0972 cc/sec of the oxygen reduced (nitrogen-enriched) altered mixture 11 is drawn off at outlet 7 in this example.
None of the gas stream passes through the pressure reducer 25, but at a point in chamber 3 opposite inlet valve 6 the gas flow i9 0.133 cc/sec and the 2 concentration is about 25.9%.
The pressure in chamber 3 i9 7~. 92 cm Hg.
By the time the gas stream reaches the end of chamber 3 (a distance of about 4.24 m), it has a flow rate of 0.284 cc/sec ` and an altered oxygen concentration of about 36.8~. About 0.0401 cc/sec of the oxygen enriched altered mixture 12 is taken at outlet 8 and about 0.244 cc/sec is reintroduced into chamber 2 at a pressure of about 172.6 cm Hg. Because of passage of most permeable gas 10 (oxygen) through membrane 4, mixture 9 has a .
. .
~456~3 reduced pressure of about 172.1 cm Hg after it travels the 2.13 m back to inlet 6.
FIG. 2 shows schematically a sheet membrane 14 which is ~haped to correspond with the changing volume of flow of mixture 9 as it circulates around cell 1 of FIG. 1 in countercurrent fashion to that there is a homogeneous rate of flow. As mixture 9 enters chamber 2 at inlet 6, much of most permeable component 10 passes through membrane 4 and adds to the volume of the portion of mixture 9 which is already in chamber 3. The volume of mixture 9 is continually reduced as it passes along chamber 2 because of the continual passage of portions of most permeable component 10 through membrane 4.
Sheet membrane 14 of FIG. 2 is constructed to correspond with the changes in volume of mixture 9 so as to result in a substantially uniform flow of mixture 9.
A ~ystem accord ing to the present lnvention can be constructed to correspond to the ~hap~ of sheet membrane 14, with an outlet for altered mixture 11 enr~ched with the least permeable product and outlet 8 for altered mixture 12 enriched with the most permeable product.
However, the construction of such a system presents practical construction difficulties which do not make it a preferred embodiment. Such difficulties are largely overcome by the representative embodiment shown schematically in FIG. 3.
Cell 15 is constructed of modular units 16. Each unit 16 comprises a high pressure chamber 17 and a low pressure chamber 18 separated by a membrane 19. Units 16 are interconnected in such a way as to result in a membrane surface area and configuration approximating that shown in FIG. 2 so that the rate of flow is substantially constant at all parts of cell 15.
~14S683 In cell 15, a mixture of gasses is introduced at inlet 20. It moves through chambers 17 and 18 and through membrane 19 as in FIG. 1. In the embodiment of FIG. 3 the gas moves at a substantially uniform rate throughout the system because of the tapering effect, provided by the arrangement of modular units 16.
A gas mixture having an altered concentration of components can be removed at outlet 21 (for mixtures having a reduced concentration of the most permeable component) or at outlet 22 (for mixtures having an increased concentration of the most permeable component).
Pressure reducer 23 and compressor 24 function in the same manner as pressure reducer 25 and compressor 5 of FIG. 1.
FIG. 4 shows schematically and in cross-section an embodiment of the present invention wherein the pressure differential is accomplished by a pressurized feed of mixture 27 through inlet 26, as mixture 27 moves through high pressure chamber 28 to pressure reducer 29, most permeable component 30 moves through semi-permeable membrane 31. In low pressure chamber 32 most permeable component 30 joins mixture 27 in countercurrent reflux flow.
An altered mixture 32 having a high concentration of the most permeable gas can be collected or discharged at outlet 33.
Similarly, in this embodiment altered mixture 34 is collected at outlet 35. Altered mixture 34 has been stripped of some of its concentration of most permeable gas 30, leaving it with an enriched concentration of the least permeable gas.
Referring more specifically to FIG. 5, there is shown yet another embodiment of the present invention. The pressure differential across membrane 36 is accomplished by compressor 37 which draws feed mixture 38 (such as air) into low pressure ". 9 :
., .
.
, chamber 3~ at inlet 41, increases its pressure and moves it into high pressure chamber 40 in countercurrent flow. Most permeable component 42 of mixture 38 moves through membrane 36 in the direction shown by the arrows and countercurrent flow of mixture 38 results in an altered mixture 43 which is enriched in the most permeable component. Altered mixture 43 may be collected at outlet 44. An altered mixture 45, which is usually considered as residue in this embodiment may be collected at outlet 46.
The present invention has been disclosed in the above teachings and drawings with sufficient clarity and conciseness to enable one skilled in the art to make and use the invention, to know the best mode for carrying out the invention and to distinguish it from other inventions and from what is old. Many variations and obvious adaptations of the inventions will readily come to mind, and these are intended to be contained within the scope of the invention as claimed below.
.
Outlet 7 for altered mixture 11 enriched in the least permeable gas is located at one end of the system. Outlet 8 is provided at the other end of the system to collect altered mixture 12 enriched in the most permeable gas.
A plurality of outlets such as outlets 7 and 8, or one such outlet, could be placed anywhere along either side of the cell to collect any desired mixture of gasses.
In operation of the embodiment of FIG. 1, a pressurized feed mixture 9 of gasses enters the system at inlet 6 and moves around the system in the direction shown by the arrows.
Amounts of the most permeable component 10 pass through membrane 4 as mixture 9 moves along chamber 2. As mixture 9 approaches the end of chamber 2, its relative concentrations of least permeable and most permeable components has changed because of the loss of most permeable component 10.
Altered mixture 11 which has a relatively low concentration of component 10 may be recovered at outlet 7.
As mixture 9 moves along chamber 3, countercurrent to its flow in chamber 2, it gathers additional amounts of most permeable component 10 so that an altered mixture 12 containing a relatively high ratio of most permeable component 10 may be collected at outlet 8.
In most operations, the volume of the gas stream recirculated through cell 1 may exceed considerably that of feed ., .
.~ .
1~5~33 stream 9, however, at steady state operation, the volume of altered mixtures 11 and 12 will total the volume of feed mixture 9.
It can readily be seen that such a flow pattern would normally result in a greater volume of mixture 9 being present near the compressor end of cell 1 where most permeable gas 10 tends to accumulate. For example, in a system for concentrating oxygen in air, condensed air twhich is 21.1% 2) is introduced at inlet 6 at a rate of about 0.137 cc/sec under a pressure of 172.1 cm Hg (the system operates at a temperature of about 23.1C.). At inlet 6, mixture 9 already in cell 1 is flowing in the direction shown by the arrows at a rate of about 0.093 cc/sec.
By the time mixture 9 gets to the end of chamber 2, a distance of 2.11 m in a 35-member bundle of silicone rubber hollow microfibers, it has a pressure of only 171.5 cm Hg because of passage of 2 through membrane 4. The gas stream has an oxygen concentration of only 15.1% at the end of chamber 2. About 0.0972 cc/sec of the oxygen reduced (nitrogen-enriched) altered mixture 11 is drawn off at outlet 7 in this example.
None of the gas stream passes through the pressure reducer 25, but at a point in chamber 3 opposite inlet valve 6 the gas flow i9 0.133 cc/sec and the 2 concentration is about 25.9%.
The pressure in chamber 3 i9 7~. 92 cm Hg.
By the time the gas stream reaches the end of chamber 3 (a distance of about 4.24 m), it has a flow rate of 0.284 cc/sec ` and an altered oxygen concentration of about 36.8~. About 0.0401 cc/sec of the oxygen enriched altered mixture 12 is taken at outlet 8 and about 0.244 cc/sec is reintroduced into chamber 2 at a pressure of about 172.6 cm Hg. Because of passage of most permeable gas 10 (oxygen) through membrane 4, mixture 9 has a .
. .
~456~3 reduced pressure of about 172.1 cm Hg after it travels the 2.13 m back to inlet 6.
FIG. 2 shows schematically a sheet membrane 14 which is ~haped to correspond with the changing volume of flow of mixture 9 as it circulates around cell 1 of FIG. 1 in countercurrent fashion to that there is a homogeneous rate of flow. As mixture 9 enters chamber 2 at inlet 6, much of most permeable component 10 passes through membrane 4 and adds to the volume of the portion of mixture 9 which is already in chamber 3. The volume of mixture 9 is continually reduced as it passes along chamber 2 because of the continual passage of portions of most permeable component 10 through membrane 4.
Sheet membrane 14 of FIG. 2 is constructed to correspond with the changes in volume of mixture 9 so as to result in a substantially uniform flow of mixture 9.
A ~ystem accord ing to the present lnvention can be constructed to correspond to the ~hap~ of sheet membrane 14, with an outlet for altered mixture 11 enr~ched with the least permeable product and outlet 8 for altered mixture 12 enriched with the most permeable product.
However, the construction of such a system presents practical construction difficulties which do not make it a preferred embodiment. Such difficulties are largely overcome by the representative embodiment shown schematically in FIG. 3.
Cell 15 is constructed of modular units 16. Each unit 16 comprises a high pressure chamber 17 and a low pressure chamber 18 separated by a membrane 19. Units 16 are interconnected in such a way as to result in a membrane surface area and configuration approximating that shown in FIG. 2 so that the rate of flow is substantially constant at all parts of cell 15.
~14S683 In cell 15, a mixture of gasses is introduced at inlet 20. It moves through chambers 17 and 18 and through membrane 19 as in FIG. 1. In the embodiment of FIG. 3 the gas moves at a substantially uniform rate throughout the system because of the tapering effect, provided by the arrangement of modular units 16.
A gas mixture having an altered concentration of components can be removed at outlet 21 (for mixtures having a reduced concentration of the most permeable component) or at outlet 22 (for mixtures having an increased concentration of the most permeable component).
Pressure reducer 23 and compressor 24 function in the same manner as pressure reducer 25 and compressor 5 of FIG. 1.
FIG. 4 shows schematically and in cross-section an embodiment of the present invention wherein the pressure differential is accomplished by a pressurized feed of mixture 27 through inlet 26, as mixture 27 moves through high pressure chamber 28 to pressure reducer 29, most permeable component 30 moves through semi-permeable membrane 31. In low pressure chamber 32 most permeable component 30 joins mixture 27 in countercurrent reflux flow.
An altered mixture 32 having a high concentration of the most permeable gas can be collected or discharged at outlet 33.
Similarly, in this embodiment altered mixture 34 is collected at outlet 35. Altered mixture 34 has been stripped of some of its concentration of most permeable gas 30, leaving it with an enriched concentration of the least permeable gas.
Referring more specifically to FIG. 5, there is shown yet another embodiment of the present invention. The pressure differential across membrane 36 is accomplished by compressor 37 which draws feed mixture 38 (such as air) into low pressure ". 9 :
., .
.
, chamber 3~ at inlet 41, increases its pressure and moves it into high pressure chamber 40 in countercurrent flow. Most permeable component 42 of mixture 38 moves through membrane 36 in the direction shown by the arrows and countercurrent flow of mixture 38 results in an altered mixture 43 which is enriched in the most permeable component. Altered mixture 43 may be collected at outlet 44. An altered mixture 45, which is usually considered as residue in this embodiment may be collected at outlet 46.
The present invention has been disclosed in the above teachings and drawings with sufficient clarity and conciseness to enable one skilled in the art to make and use the invention, to know the best mode for carrying out the invention and to distinguish it from other inventions and from what is old. Many variations and obvious adaptations of the inventions will readily come to mind, and these are intended to be contained within the scope of the invention as claimed below.
.
Claims (4)
1. A system operable at room temperature for altering the relative concentration of the components of a mixture of fluids moving in the system, the system comprising:
(a) at least one cell having chambers separated by a semi-permeable membrane, the chambers communicating in such a way as to produce countercurrent reflux flow of the mixture and to result in one chamber having a higher pressure than the other, the chambers having a geometry which avoids backmixing the membrane having a different permeability constant for at least two of the components of the mixture;
(b) means for creating a pressure differential across the membrane;
(c) at least one inlet means for feeding the mixture into the system; and (d) at least one outlet means for recovering the mixture from the system after the relative concentrations of its components have been altered.
(a) at least one cell having chambers separated by a semi-permeable membrane, the chambers communicating in such a way as to produce countercurrent reflux flow of the mixture and to result in one chamber having a higher pressure than the other, the chambers having a geometry which avoids backmixing the membrane having a different permeability constant for at least two of the components of the mixture;
(b) means for creating a pressure differential across the membrane;
(c) at least one inlet means for feeding the mixture into the system; and (d) at least one outlet means for recovering the mixture from the system after the relative concentrations of its components have been altered.
2. The system of claim 1 wherein the communication between the chambers includes a pressure reducing means.
3. The system of claim 1 wherein the cell is formed from a plurality of interconnected modular units, each unit comprising chambers separated by a membrane.
4. The system of claim 3 wherein the units are interconnected to form in effect a tapered configuration in such a way that the rate of movement is substantially constant throughout the system.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US5358879A | 1979-06-29 | 1979-06-29 | |
| US53,588 | 1979-06-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1145683A true CA1145683A (en) | 1983-05-03 |
Family
ID=21985275
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000349976A Expired CA1145683A (en) | 1979-06-29 | 1980-04-16 | Gas phase separation system |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS567603A (en) |
| CA (1) | CA1145683A (en) |
| DE (1) | DE3016305A1 (en) |
| FR (1) | FR2464088A1 (en) |
| GB (1) | GB2053021A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2139110B (en) * | 1982-12-27 | 1987-05-20 | Gen Electric | Water vapor exchange system |
| JPH0691929B2 (en) * | 1985-09-30 | 1994-11-16 | 帝人株式会社 | Gas separation method |
| FR2636858B1 (en) * | 1988-09-08 | 1990-11-02 | Air Liquide | METHOD AND INSTALLATION FOR SEPARATING A COMPONENT WITH INTERMEDIATE PERMEABILITY OF A GASEOUS MIXTURE |
| FR2683737B1 (en) * | 1991-11-18 | 1994-08-05 | Air Liquide | PROCESS AND PLANT FOR THE PRODUCTION BY PERMEATION OF A LIGHT IMPURE GAS FROM A GAS MIXTURE CONTAINING THIS LIGHT GAS. |
| CN100488710C (en) * | 2003-06-03 | 2009-05-20 | 山特维克知识产权股份有限公司 | Indexable cutter and methods for producing the same |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT649908A (en) * | 1960-04-01 | |||
| IL38187A0 (en) * | 1970-12-10 | 1972-01-27 | Israel State | Improved reverse osmosis process and apparatus for the product of concentrated solutions |
| US4080289A (en) * | 1975-02-28 | 1978-03-21 | Hitachi, Ltd. And Hitachi Plant Engineering And Construction Co., Ltd. | Apparatus for treating waste water or solution |
-
1980
- 1980-04-16 CA CA000349976A patent/CA1145683A/en not_active Expired
- 1980-04-28 DE DE19803016305 patent/DE3016305A1/en not_active Ceased
- 1980-06-17 JP JP8207680A patent/JPS567603A/en active Pending
- 1980-06-26 GB GB8021008A patent/GB2053021A/en not_active Withdrawn
- 1980-06-27 FR FR8014379A patent/FR2464088A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| FR2464088A1 (en) | 1981-03-06 |
| GB2053021A (en) | 1981-02-04 |
| DE3016305A1 (en) | 1981-01-08 |
| JPS567603A (en) | 1981-01-26 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |