EP0909209A1 - Procede de pervaporation et module de mise en oeuvre dudit procede - Google Patents

Procede de pervaporation et module de mise en oeuvre dudit procede

Info

Publication number
EP0909209A1
EP0909209A1 EP97926950A EP97926950A EP0909209A1 EP 0909209 A1 EP0909209 A1 EP 0909209A1 EP 97926950 A EP97926950 A EP 97926950A EP 97926950 A EP97926950 A EP 97926950A EP 0909209 A1 EP0909209 A1 EP 0909209A1
Authority
EP
European Patent Office
Prior art keywords
pervaporation
carrier medium
permeate
membrane
feed
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.)
Withdrawn
Application number
EP97926950A
Other languages
German (de)
English (en)
Inventor
René DANZIGER
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Krebs and Co AG
Original Assignee
Krebs and Co AG
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Krebs and Co AG filed Critical Krebs and Co AG
Publication of EP0909209A1 publication Critical patent/EP0909209A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/36—Pervaporation; Membrane distillation; Liquid permeation
    • B01D61/362—Pervaporation

Definitions

  • the present invention relates to a pervaporation method according to the preamble of patent claim 1 and a module for carrying out the method according to the preamble of patent claim 11.
  • Pervaporation is a membrane separation process by means of which one or more components of a fluid mixture are separated.
  • One or more components of the fluid mixture diffuse through a permselective membrane, one side of which the fluid mixture, also called feed or feed, flows over, preferably in comparison to the other component or components.
  • the fraction diffused through the membrane is the permeate, while the remaining fraction is referred to as retentate.
  • the driving force of pervaporation is chemical
  • p ⁇ is the vapor pressure of the component i to be pervaporated on the feed side of the membrane at the feed temperature T
  • p r is the absolute pressure on the permeate side of the membrane
  • y is the mole fraction of component l in the carrier medium.
  • vapor permeation Another method of separating fluid mixtures is vapor permeation. In principle, it is the same Physical procedure as for pervaporation, with the difference that the fluid mixture to be separated, the feed, is not in liquid form, but as vapor. In the following we only speak of pervaporation, but what has been said also applies to vapor permeation.
  • a carrier medium is used on the permeate side.
  • the carrier medium is also called sweep gas or sweep steam.
  • the term p r m of the above formula then corresponds to the pressure of the carrier medium and is approximately constant.
  • sweep gas is used exclusively, whereby sweep steam is also meant.
  • the carrier medium reduces the partial pressure of the permeated components.
  • the carrier medium is a steam or a gas, for example air or nitrogen.
  • a vacuum pump and a refrigeration system are not required for pervaporation with a carrier medium. Such a method is therefore more energetically advantageous. However, it is difficult to achieve good efficiency with this operating mode and with the modules known today.
  • EP-A-0 '657' 205 uses the second operating mode with the sweep gas.
  • a method for removing small amounts of organic substances from a contaminated water stream by means of pervaporation in a hollow fiber module is disclosed, the permeate side of the membrane being flowed over by a condensable sweep gas which flows in countercurrent to the fluid mixture.
  • the sweep gas is at a temperature higher than the temperature of the fluid mixture is warmed so that part of the sweep gas condenses on the permeate side and the heat of condensation is conducted to the feed so that it has a more constant temperature.
  • the disadvantage of this method is that the condensed sweep gas interferes with the membrane surface. Another disadvantage is that it is low in efficiency.
  • the drop in temperature of the fluid mixture when the membrane overflows is at least partially compensated for.
  • the molar fraction y of the permeated component is greatest towards the feed end and thus towards the permeate end of the membrane, which is disadvantageous due to the chemical potential difference ⁇ ⁇ . affects.
  • a combination of a distillation device or a rectification column with a pervaporation module is also known.
  • the combination of distillation or rectification and pervaporation is advantageous in the separation of azeotropic mixtures, since ⁇ a does not require any further chemical sweetener to be disposed of as entrainer.
  • the use of an entrainer led to an additional separation, which would require an additional rectification column and thus more energy.
  • EP-A-0 '572' 355 an industrially usable device for performing pervaporation is known from EP-A-0 '572' 355, the content of which is part of this description.
  • the device according to EP-A-0 '572' 355 consists of several plate-shaped pervaporation cassettes which are provided with at least one permeate outlet and the two largest surfaces e of which are flushed with the fluid mixture and which are spaced apart from one another are provided with a permeable membrane. Each pervaporation chamber lies between two plate-shaped heating cassettes directly adjacent to it.
  • the pervaporation cassettes and the heating cassettes are self-supporting, m-closed cassettes, which are kept in contact-free spacing with respect to one another in a closed flow-through container, so that the fluid mixture to be pervaporated in the gap between a heating and a pervaporation cassette along the outer surfaces of the pervaporation cassette from the feed. is led to the retentate exit.
  • the advantage of this device is that a high throughput is achieved in comparison to the volume of the device and that the temperature of the fluid mixture remains constant over the entire membrane surface.
  • This device is preferably used in accordance with the first pervaporation mode, which uses vacuum.
  • the entire membrane Due to the meandering guidance of the carrier medium, generated by the ribs of the membrane's carrier device, the entire membrane is at least approximately covered with a flat surface, whereby the permeating portion is increased and the efficiency is improved.
  • the carrier medium is preferably heated, as a result of which the losses in the enthalpy of vaporization of the permeating component are compensated for, so that the temperature conditions in the entire pervaporation device, in particular on the permeate side, are kept constant. Heating of the fluid mixture during the overflow of the membrane is generally not necessary.
  • the heating of the carrier medium can take place outside the pervaporation device, but it can also be integrated in the pervaporation device.
  • the temperature of the carrier medium depends on the fluid mixture and the membrane used, but is preferably higher than the temperature of the fluid mixture, that is to say the feed.
  • the invention The method according to the invention can be used in the most varied of module devices, in particular in the module described in EP-A-0 '572' 355 with pervaporation cassettes, in tube modules, capillary modules or hollow fiber modules.
  • the method according to the invention simplifies, on the one hand, the device for carrying out the method, and, on the other hand, avoids the difficulty of permeate-side condensation in a vacuum, since condensation can now be carried out at ambient pressure.
  • the main direction of propagation of the carrier medium is at least approximately co-current or cross-current to the direction of propagation of the fluid mixture.
  • cross current in particular, both terms p and y influencing the chemical potential difference are also. considered.
  • any condensate from the carrier medium does not drip onto the membrane and does not impair the efficiency.
  • any condensate drips onto the ribs for deflecting the carrier medium.
  • the ribs preferably have corresponding depressions for receiving the condensate.
  • a module device having Pervaporationshuntn in cassette form is similar or equal to the value However, as used in EP-0'572'355 type described.
  • the module therefore consists of a self-contained container with a feed-side and a permeate-side chamber, which are separated by a membrane arranged in the container.
  • This embodiment enables simple construction of entrances and exits.
  • the membrane preferably being oriented at least approximately horizontally and the permeate-side chamber being arranged under the associated feed-side.
  • the combination according to the invention of distillation or rectification with pervaporation enables an azeotropic mixture to be separated without the addition of a further substance as the carrier medium.
  • This method can also be used without a meandering course of the sweep gas.
  • the temperature of the carrier medium generally corresponds to the temperature of the fluid mixture.
  • Figure la is a schematic representation of a pervaporation device according to the invention.
  • FIG. 1b shows a perspective view of a pervaporation cassette of the pervaporation device according to FIG.
  • FIG. 1c shows a further embodiment of a pervaporation cassette
  • FIG. 2 shows a view of the pervaporation cassette according to FIG. 1 with ribs from the front;
  • FIG. 3 shows a longitudinal section through the pervaporation cassette according to FIG. 1 m enlarged view
  • FIG. 4 shows a cross section through the pervaporation cassette according to FIG. 1 along the line A-A;
  • FIG. 5 shows a cross section through the pervaporation cassette according to FIG. 1 along the line BB;
  • FIG. 6 shows a perspective illustration of a further embodiment of a pervaporation device;
  • FIG. 7 shows a schematic illustration of a further embodiment of a pervaporation device
  • Figure 8 is a schematic representation of a combination of rectification with pervaporation.
  • FIG. 1 a shows a pervaporation device according to the invention, called a module, which can also be used for vapor permeation. It consists of a cylindrical pass-through container 1, in which support devices for at least one membrane are held in the form of self-supporting, plate-shaped pervaporation cassettes 2, whereby for maintenance purposes they can be removed individually from the pass-through container, which is shown in FIG is therefore visible to a complete circle of missing pervaporation cassettes.
  • the pervaporation chambers 2 are arranged in a star shape in the flow container 1 and therefore each have the shape of a wedge-shaped cylinder cutout, which has the same height as a corresponding, corresponding fictitious cylinder.
  • Cylinder-shaped flow containers are primarily used for pervaporation processes which work with a pressure that deviates from the ambient pressure.
  • the same structure of a pervaporation device described above can, however, also be achieved with differently shaped flow containers, the shape of the pervaporation cassettes being adapted to the corresponding shape of the container.
  • the pervaporation cassette can also have the shape of a cuboid known from EP-A-0 '572' 355.
  • the Pervaporationskassetten 2 are abstandet be ⁇ in fürlaufbehaltnis 1 and arranged ceremoniesrungsok each other.
  • a permeable membrane 3 is fastened flat on both largest surfaces of each per ⁇ vaporation cassette 2 to be flushed by the fluid mixture, the membranes 3 being at least approximately vertically aligned when the pervaporation cassettes 2 are installed.
  • the surface of the membrane 3 directed outwards to the adjacent pervaporation cassette is the feed side, and the surface facing the inner space of the cassette is the permeate side.
  • Partitions can be arranged in the flow container 1 between the individual pervaporation cassettes or the pervaporation cassettes 2 can, as shown here, be arranged directly spaced apart from one another.
  • the flow zone 1 has a central tube, which serves as feed inlet 10.
  • the central tube passes through the flow container 1 along its central axis, the inlet running from the bottom to the top.
  • a retentate outlet 11 is arranged in the bottom of the flow container 1.
  • the two connections, feed inlet and retentate outlet, are interchanged, so that the fluid mixture runs from the bottom to the top over the membrane. This is particularly advantageous if means for evenly distributing the fluid mixture are provided in the bottom of the flow container.
  • Each Pervaporationskassette 2 has a minimum precisely where a Fermeatausgang 13A, which is in the installed state in the upper region of the Pervaporationskassette 2 ⁇ is arranged and preferably is in the from the center axis cyl DER remote area.
  • These permeate outlets 13A preferably open into a common channel which surrounds the jacket of the flow container 1 and which has a common permeate outlet 13B. For better readability of the drawing, only every second permeate outlet 13A is shown in FIG. 1, although each cassette has its own permeate outlet.
  • each pervaporation cassette 2 there is at least one carrier medium passage 12 which leads into the interior of the cassette.
  • the carrier medium passage 12 is preferably formed by an inlet channel arranged in the interior of the cassette, which is separated from the interior accessible to the permeate.
  • FIGS. 1b and 1c Different arrangements of the carrier medium entrance 12 are shown in FIGS. 1b and 1c. Both figures show Trager- mediumemgange 12 in the form of a Emlasskanales which extends over at least approximately the entire height of the pervaporation ⁇ cassette 2 extends and proceeds from top to bottom. Lb shows proceeds the Emiasskanal 12 m which faces the Zylmderstoffachse narrowed area of the Pervaporationskassette 2.
  • Ribs 20 are arranged for deflecting the Tragermediums on the inside of Pervaporationskassetten so that the transmitter ⁇ medium is passed over the Per ⁇ meat side of the membrane 3 as flat covering meandering.
  • Each pervaporation ⁇ cassette 2 consists for this purpose of a frame construction with two halves. These two halves are preferably sym ⁇ cally designed so that, for example in the production of injection molded only one form is necessary. The two halves are connected to one another by means of struts which simultaneously form the ribs 20 for the deflection of the carrier gas. In Figures 2 and 3, these are shown as ribs / struts 20. It can be seen from FIGS.
  • each pervaporation chamber consists of individual elements 21, which in turn are connected to one another via the ribs 20. However, they can have other ribs.
  • This structure has the advantage that production is simplified. Smaller and therefore more cost-effective injection molds can be used in particular in the case of ⁇ er production using the injection molding process.
  • the cassette interior can be divided by the individual elements into a plurality of pervaporation chambers, each of which has a single permeate outlet.
  • each pervaporation chamber has at least one passage opening 22, which connects the pervaporation chamber to a common connection channel 23 which transitions into the permeate outlet.
  • the carrier medium is guided through the ribs 20 in a meandering manner.
  • the main direction of propagation of the carrier medium runs in preferred embodiments in the opposite direction to the direction of propagation of the fluid mixture. In other embodiments, it also runs in a plane parallel to the membrane plane, but in a direction parallel or perpendicular to the direction of propagation of the fluid mixture, so that the carrier medium spreads in cocurrent or in crossflow to the fluid mixture.
  • the permeate / carrier medium mixture collected in the interior of the cassette is conducted away or suctioned off via the permeate outlet 13A.
  • FIG. 6 shows another exemplary embodiment of the module according to the invention. Since the method according to the invention can be carried out at least approximately at ambient pressure, a round cross section is no longer absolutely necessary for the module.
  • the carrier device shown here thus consists of a cuboid-shaped container 4 which, apart from a feed and a carrier medium outlet 40, 42 and a retentate and a permeate outlet 41, 43, is self-contained.
  • a chamber 44 on the feed side is located in the container 4 and a permeate-side chamber 45, which are separated by a membrane 5.
  • the feed inlet 40 and the retentate outlet 41 form a connection from the outside to the feed side chamber 44 and the carrier medium outlet 42 and the permeate outlet 43 to the permeate side chamber 45.
  • Ribs for meandering guidance of the carrier medium are in turn arranged on the permeate side of the carrier device.
  • the main direction of propagation of the carrier medium can take the directions already described above with respect to the direction of propagation of the feed
  • This support device can already form the entire module as a single element.
  • a plurality of carrier devices are stacked one above the other, the membrane being oriented horizontally and the permeate-side chamber lying below the associated feed-side chamber.
  • FIG. 7 shows a further embodiment of a module according to the invention. It essentially consists of the cuboid-shaped container 4 shown in FIG. 6, in which container a plurality of diaphragms 5 arranged parallel to one another are now arranged, which divide the container 4 into several feed-side and permeate-side chambers 44, 45. This sandwich construction is very space-saving.
  • FIG. 1 A preferred variant of the method according to the invention is shown schematically in FIG.
  • an approximately azeotropic mixture is separated by the combination of distillation or rectification with pervaporation.
  • a mixture of water and ethanol is separated.
  • part of the condensate is returned to the latter, for example by means of pumps P.
  • the amount of condensate which arises at the beginning of the process in this partial condensation should at least be sufficient to ensure a sufficiently large reflux for the rectification column 6 and to produce the distillate, called the top product.
  • the remaining part is fed as a fluid mixture or pervaporation feed into a downstream pervaporation device 8, more precisely over the feed side of a membrane.
  • the part of the steam remaining after the first heat exchanger 7 serves as a carrier medium for the pervaporation and is passed at least via a carrier medium inlet into the pervaporation device 8, more precisely over the permeate side of the membrane, where it mixes with the permeate.
  • the carrier medium permeate mixture is then condensed in a second heat exchanger 9. This condensate is returned to the rectification column or in the distillation direction, be it by mixing with the column feed or by imports onto a column bottom which has the same or a similar composition as the condensate.
  • the steam used as carrier medium is preferably passed through a third heat exchanger 7 ′ before entering the pervaporation device 8, where it is heated. This prevents condensation of the carrier medium.
  • valves of the heat exchangers are used to control this system consisting of rectification column and pervaporation device, whereby the amounts of condensate obtained are selected.
  • This process can be carried out with all pervaporation modules that are suitable for pervaporation using a carrier medium.
  • the module described in EP-A-0 '572' 355, the modules according to the invention described above, and tubular modules, capillary modules and hollow fiber modules are particularly suitable.

Landscapes

  • Engineering & Computer Science (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

Dans un procédé de pervaporation pour séparer au moins un constituant contenu dans un mélange fluidique à l'aide d'une membrane perméable (3) comportant une face d'alimentation et une face de perméat, le mélange fluidique est guidé par l'intermédiaire de la face d'alimentation de la membrane (1) et un milieu support, notamment un gaz de balayage, est guidé par l'intermédiaire de la face de perméat. Le constituant (au moins au nombre de un) est transporté de la face d'alimentation à la face de perméat de la membrane (3) et forme conjointement avec le milieu support, un mélange perméat-milieu support. A cet effet, le milieu support est guidé à l'aide de nervures disposées sur le dispositif support de la membrane de manière à décrire des méandres, jusqu'au mélange fluidique, par l'intermédiaire de la face de perméat. Ce procédé s'utilise notamment en combinaison avec une colonne de rectification, la vapeur des produits obtenue en haut de la colonne servant de milieu support.
EP97926950A 1996-06-28 1997-06-27 Procede de pervaporation et module de mise en oeuvre dudit procede Withdrawn EP0909209A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
CH162396 1996-06-28
CH1623/96 1996-06-28
PCT/CH1997/000255 WO1998000225A1 (fr) 1996-06-28 1997-06-27 Procede de pervaporation et module de mise en oeuvre dudit procede

Publications (1)

Publication Number Publication Date
EP0909209A1 true EP0909209A1 (fr) 1999-04-21

Family

ID=4214778

Family Applications (1)

Application Number Title Priority Date Filing Date
EP97926950A Withdrawn EP0909209A1 (fr) 1996-06-28 1997-06-27 Procede de pervaporation et module de mise en oeuvre dudit procede

Country Status (3)

Country Link
EP (1) EP0909209A1 (fr)
AU (1) AU3163097A (fr)
WO (1) WO1998000225A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TW200505554A (en) * 2003-04-22 2005-02-16 Mykrolis Corp Pleated construction for effecting gas transfer membrane
DE102004013647A1 (de) * 2004-03-19 2005-10-06 Wolfgang Heinzl Verfahren und Vorrichtung zur Destillation von Lösungen

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2411238A (en) * 1943-07-08 1946-11-19 Syivania Ind Corp Process and apparatus for dialyzing solutions
US4244820A (en) * 1978-05-16 1981-01-13 Gelman Instrument Company Fluid purification system
DE8801980U1 (de) * 1988-02-09 1988-04-28 GKSS-Forschungszentrum Geesthacht GmbH, 2054 Geesthacht Vorrichtung zum Filtern und Trennen von Strömungsmedien
US5096584A (en) * 1990-01-29 1992-03-17 The Dow Chemical Company Spiral-wound membrane separation device with feed and permeate/sweep fluid flow control
AU5741094A (en) * 1992-12-08 1994-07-04 Osmotek, Inc. Osmotic concentration

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9800225A1 *

Also Published As

Publication number Publication date
WO1998000225A1 (fr) 1998-01-08
AU3163097A (en) 1998-01-21

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