WO2009005455A1 - Method and device for purifying water by membrane distillation - Google Patents

Method and device for purifying water by membrane distillation Download PDF

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Publication number
WO2009005455A1
WO2009005455A1 PCT/SE2008/050773 SE2008050773W WO2009005455A1 WO 2009005455 A1 WO2009005455 A1 WO 2009005455A1 SE 2008050773 W SE2008050773 W SE 2008050773W WO 2009005455 A1 WO2009005455 A1 WO 2009005455A1
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WO
WIPO (PCT)
Prior art keywords
water
wall
membrane
sheet
caused
Prior art date
Application number
PCT/SE2008/050773
Other languages
French (fr)
Inventor
Aapo SÄÄSK
Original Assignee
Scarab Development Ab
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 Scarab Development Ab filed Critical Scarab Development Ab
Publication of WO2009005455A1 publication Critical patent/WO2009005455A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D1/00—Evaporating
    • B01D1/0011—Heating features
    • B01D1/0029—Use of radiation
    • B01D1/0035—Solar energy
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0057—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes
    • B01D5/006—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes with evaporation or distillation
    • 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
    • B01D61/364—Membrane distillation
    • 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
    • B01D61/366—Apparatus therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
    • B01D63/08—Flat membrane modules
    • B01D63/087—Single membrane modules
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • C02F1/14—Treatment of water, waste water, or sewage by heating by distillation or evaporation using solar energy
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/447—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by membrane distillation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2311/00—Details relating to membrane separation process operations and control
    • B01D2311/04—Specific process operations in the feed stream; Feed pretreatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2311/00—Details relating to membrane separation process operations and control
    • B01D2311/06—Specific process operations in the permeate stream
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2313/00—Details relating to membrane modules or apparatus
    • B01D2313/22—Cooling or heating elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2313/00—Details relating to membrane modules or apparatus
    • B01D2313/36—Energy sources
    • B01D2313/365—Electrical sources
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/20—Controlling water pollution; Waste water treatment
    • Y02A20/208—Off-grid powered water treatment
    • Y02A20/212—Solar-powered wastewater sewage treatment, e.g. spray evaporation

Definitions

  • the present invention relates to a method for producing clean water and an arrangement for this method.
  • a membrane distillation arrangement is an arrangement that comprises a number of parallel membrane distillation units in the form of sheets. Each unit comprises a first sheet through which water cannot pass, a membrane parallel with the sheet and a second sheet through which water cannot pass parallel with the membrane. Only water in the gaseous phase, i.e. water vapour, can pass through the membrane. Warm water flows between the first sheet and the membrane. The second sheet is colder than the water that is flowing. The difference in temperature between the water and the colder sheet leads to the water being vaporised, passing through the membrane and condensing onto the second, colder wall. The surface tension of the water ensures that the water cannot pass through the membrane.
  • mem- brane distillation unit is described in the Swedish patent 8002233-8.
  • Membrane distillation can be used in many fields, whereby all non-volatile substances, except for clean water, remain in the water that is to be cleaned.
  • the condensed water is thus free from salt, particles, bacteria, viruses, etc.
  • the present invention concerns a method in which it is not necessary to pump warm water to the membrane distillation unit as is the case in the prior art since the water is heated in situ in the equipment.
  • the present invention thus relates to a method for producing clean water, where the water that is to be cleaned is caused to undergo membrane distillation by means of one or several units comprising a first wall that is impermeable to water and that has the form of a sheet, a membrane through which water in the gaseous phase can pass, and through which water in fluid phase cannot pass, and a second wall in the form of a sheet, which walls are located on different sides of and at a certain distance from the membrane, where water is led in between the first wall and the membrane and where the second wall is caused to be colder than the water, and it is characterised in that the first wall is caused to be an electrically heated sheet.
  • the invention relates to an arrangement of the type and with the characteristic features that are specified in claim 4.
  • FIG. 1 shows schematically a membrane distillation unit according to the prior art
  • FIG. 2 shows schematically a membrane distillation unit according to the invention
  • FIG. 3 shows a modified embodiment according to the invention .
  • the principle that is used in the present invention is shown in Figure 1.
  • the invention concerns a method for producing clean water.
  • Water that is to be cleaned is caused to undergo membrane distillation by means of one or several membrane distillation units, where each unit 1 comprises a first wall 2 that is impermeable to water and that has the form of a sheet, a membrane 3 through which water in the gaseous phase can pass, and through which water in fluid phase cannot pass, and a second wall 4 in the form of a sheet.
  • the walls 2, 4 are located on different sides of and at a certain distance from the membrane 3.
  • Water is led into the space 5 between the first wall 2 and the membrane 3, as is illustrated by the arrow 6.
  • the second wall 4 is caused to be colder than the water. Since the second wall 4 is colder than the water, water vapour that has passed through the membrane condenses onto the second wall 4 and is transported away as illustrated by the arrow 7.
  • the second wall 4 can be maintained at a temperature below that of the warmed water by cooling using, for example, un- heated water, or it may be provided with cooling flanges, or another suitable arrangement.
  • the first wall 2 is, according to the invention, caused to be an electrically heated sheet 8.
  • the electrically heated sheet is of suitable known type that generates heat when electricity flows through it.
  • Figure 2 shows a membrane distillation unit 1 in side view, where a sheet 8 that is heated by electricity constitutes the first wall 2. The position of the membrane 3 is shown by the dashed line 10. Water is fed into the unit 1 through a pipe 11, which water flows out from the unit through a pipe 12. Condensed water flows out from the unit through a pipe 13.
  • Heat from the heated sheet is transferred to the water whereby the temperature of the water rises, which leads to more water vapour passing through the membrane to condense onto the second wall 4.
  • the membrane may be placed also on both sides of the electrically heated sheet.
  • a membrane 16, 17 is caused to be located on each side of the first wall 18, and where on each side of the two membranes 16, 17 and at a certain distance from these are placed second walls 19, 20 respectively. Water that is to be cleaned is thereby led in between the first wall 18 and each of the two membranes 16, 17. Water in the gaseous phase condenses onto each of the two second walls 19, 20 and is removed from the arrangement.
  • the water that is to be cleaned is caused to flow through the said unit or units in a closed circuit, where the closed circuit is caused to be filled with water that is to be cleaned at the same rate as water in the gaseous phase passes through the membrane.
  • the second wall 4 may be of plastic or metal.
  • the membrane 3 is of a polymer material.
  • the electrically heated sheets are of suitable known type, of, for example, a plastic material that encloses an electrical resistive element.
  • first wall may be given a cylindrical form and the membrane thereby also a cylindrical form as also the second wall, where the walls and the membrane are located concentrically relative to each other.

Landscapes

  • Engineering & Computer Science (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Organic Chemistry (AREA)
  • Environmental & Geological Engineering (AREA)
  • Hydrology & Water Resources (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Heat Treatment Of Water, Waste Water Or Sewage (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

A method for producing clean water, in which water that is to be cleaned is caused to undergo membrane distillation by means of one or several units (1) comprising a first wall (2) that is impermeable to water and that has the form of a sheet, a membrane (3) through which water in the gaseous phase can pass, and through which water in fluid phase cannot pass, and a second wall (4) in the form of a sheet, which walls are located on different sides of and at a certain distance from the membrane (3), where water is led in between the first wall (2) and the membrane (3), and where the second wall is caused to be colder than the water. The invention is characterised in that the first wall (2) is caused to be an electrically heated sheet.

Description

Method and device for purifying water by membrane distillation
The present invention relates to a method for producing clean water and an arrangement for this method.
Many places in the world suffer from a lack of clean water. Arrangements for cleaning water from contaminants are known.
Such an arrangement is a unit for membrane distillation. Membrane distillation, abbreviated "MD", has been known for cleaning water since the 1980s. A membrane distillation arrangement is an arrangement that comprises a number of parallel membrane distillation units in the form of sheets. Each unit comprises a first sheet through which water cannot pass, a membrane parallel with the sheet and a second sheet through which water cannot pass parallel with the membrane. Only water in the gaseous phase, i.e. water vapour, can pass through the membrane. Warm water flows between the first sheet and the membrane. The second sheet is colder than the water that is flowing. The difference in temperature between the water and the colder sheet leads to the water being vaporised, passing through the membrane and condensing onto the second, colder wall. The surface tension of the water ensures that the water cannot pass through the membrane. Such a mem- brane distillation unit is described in the Swedish patent 8002233-8.
Membrane distillation can be used in many fields, whereby all non-volatile substances, except for clean water, remain in the water that is to be cleaned. The condensed water is thus free from salt, particles, bacteria, viruses, etc.
One problem that arises when membrane distillation is to be used is that large quantities of warm water must pass along the membrane in order that sufficient quantities of vapour are to be produced from the latent energy of heat in the water .
The present invention concerns a method in which it is not necessary to pump warm water to the membrane distillation unit as is the case in the prior art since the water is heated in situ in the equipment.
The present invention thus relates to a method for producing clean water, where the water that is to be cleaned is caused to undergo membrane distillation by means of one or several units comprising a first wall that is impermeable to water and that has the form of a sheet, a membrane through which water in the gaseous phase can pass, and through which water in fluid phase cannot pass, and a second wall in the form of a sheet, which walls are located on different sides of and at a certain distance from the membrane, where water is led in between the first wall and the membrane and where the second wall is caused to be colder than the water, and it is characterised in that the first wall is caused to be an electrically heated sheet.
Furthermore, the invention relates to an arrangement of the type and with the characteristic features that are specified in claim 4.
The invention is described in more detail below, partially in association with an embodiment of the invention shown in the attached drawing, where:
- Figure 1 shows schematically a membrane distillation unit according to the prior art - Figure 2 shows schematically a membrane distillation unit according to the invention
- Figure 3 shows a modified embodiment according to the invention .
The principle that is used in the present invention is shown in Figure 1. The invention concerns a method for producing clean water. Water that is to be cleaned is caused to undergo membrane distillation by means of one or several membrane distillation units, where each unit 1 comprises a first wall 2 that is impermeable to water and that has the form of a sheet, a membrane 3 through which water in the gaseous phase can pass, and through which water in fluid phase cannot pass, and a second wall 4 in the form of a sheet. The walls 2, 4 are located on different sides of and at a certain distance from the membrane 3. Water is led into the space 5 between the first wall 2 and the membrane 3, as is illustrated by the arrow 6. The second wall 4 is caused to be colder than the water. Since the second wall 4 is colder than the water, water vapour that has passed through the membrane condenses onto the second wall 4 and is transported away as illustrated by the arrow 7.
The second wall 4 can be maintained at a temperature below that of the warmed water by cooling using, for example, un- heated water, or it may be provided with cooling flanges, or another suitable arrangement.
The first wall 2 is, according to the invention, caused to be an electrically heated sheet 8. The electrically heated sheet is of suitable known type that generates heat when electricity flows through it. Figure 2 shows a membrane distillation unit 1 in side view, where a sheet 8 that is heated by electricity constitutes the first wall 2. The position of the membrane 3 is shown by the dashed line 10. Water is fed into the unit 1 through a pipe 11, which water flows out from the unit through a pipe 12. Condensed water flows out from the unit through a pipe 13.
Heat from the heated sheet is transferred to the water whereby the temperature of the water rises, which leads to more water vapour passing through the membrane to condense onto the second wall 4.
Only a single unit has been described above. Two or more units can be connected in series or in parallel with respect to the flows of water, depending on the capacity desired.
The membrane may be placed also on both sides of the electrically heated sheet. According to one preferred embodiment, illustrated in Figure 3, a membrane 16, 17 is caused to be located on each side of the first wall 18, and where on each side of the two membranes 16, 17 and at a certain distance from these are placed second walls 19, 20 respectively. Water that is to be cleaned is thereby led in between the first wall 18 and each of the two membranes 16, 17. Water in the gaseous phase condenses onto each of the two second walls 19, 20 and is removed from the arrangement.
According to one preferred embodiment, the water that is to be cleaned is caused to flow through the said unit or units in a closed circuit, where the closed circuit is caused to be filled with water that is to be cleaned at the same rate as water in the gaseous phase passes through the membrane. The second wall 4 may be of plastic or metal. The membrane 3 is of a polymer material. The electrically heated sheets are of suitable known type, of, for example, a plastic material that encloses an electrical resistive element.
A number of embodiments have been described above. It is, however, obvious that the unit can be given another design, even though its fundamental construction is the one that is described above.
For example, the first wall may be given a cylindrical form and the membrane thereby also a cylindrical form as also the second wall, where the walls and the membrane are located concentrically relative to each other.
Thus, the present invention is not be to considered as being limited to the embodiments described above, since it can be varied within the scope defined by the attached patent claims .

Claims

Claims
1. A method for producing clean water, in which water that is to be cleaned is caused to undergo membrane distillation by
5 means of one or several units (1) comprising a first wall (2; 18) that is impermeable to water and that has the form of a sheet, a membrane (3; 16, 17) through which water in the gaseous phase can pass, and through which water in fluid phase cannot pass, and a second wall (4) in the form of a
W sheet, which walls are located on different sides of and at a certain distance from the membrane (3; 16, 17), where water is led in between the first wall (2; 18) and the membrane (3; 16, 17), and where the second wall is caused to be colder than the water, characterised in that the first wall (2;
15 18) is caused to be an electrically heated sheet.
2. A method according to claim 1, characterised in that the water that is to be cleaned is caused to flow through the said unit (1) or units in a closed circuit and in 0 that the closed circuit is caused to be filled with water that is to be cleaned at the same rate as water in the gaseous phase passes through the membrane (3; 16, 17).
3. A method according to claim 1 or 2, characterised 25 in that a membrane (16, 17) is caused to be placed on each side of the first wall (18) and in that on each side of the two membranes (16, 17) and at a certain distance from these are placed second walls (19, 20) respectively.
30 4. An arrangement for producing clean water, in which water that is to be cleaned undergoes membrane distillation by means of one or several units comprising a first wall (2) that is impermeable to water and that has the form of a sheet, a membrane (3) through which water in the gaseous phase can pass, and through which water in fluid phase cannot pass, and a second wall (4) in the form of a sheet, which walls are located on different sides of and at a certain distance from the membrane (3), where it is intended that water is to be led in between the first wall (2) and the membrane (3), and where the second wall (4) is arranged such that it is colder than the water, characterised in that the first wall (2) comprises a sheet arranged to be heated by electricity.
5. An arrangement according to claim 4, characterised in that membranes (16, 17) are placed on each side of the first wall (18) and in that on each side of the two membranes (16, 17) and at a certain distance from these are located second walls (19, 20), respectively.
PCT/SE2008/050773 2007-07-02 2008-06-25 Method and device for purifying water by membrane distillation WO2009005455A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0701601-7 2007-07-02
SE0701601A SE0701601L (en) 2007-07-02 2007-07-02 Process for producing pure water and a device therefor

Publications (1)

Publication Number Publication Date
WO2009005455A1 true WO2009005455A1 (en) 2009-01-08

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PCT/SE2008/050773 WO2009005455A1 (en) 2007-07-02 2008-06-25 Method and device for purifying water by membrane distillation

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WO (1) WO2009005455A1 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3878054A (en) * 1964-12-09 1975-04-15 Pactide Corp Distillation apparatus and process
WO1987000160A1 (en) * 1985-07-04 1987-01-15 Svenska Utvecklings Ab Apparatus for desalinating salt water by membrane distillation
JPS6377503A (en) * 1986-09-17 1988-04-07 Mitsubishi Kasei Corp Liquid separator for thermopervaporation
JPH07768A (en) * 1993-06-15 1995-01-06 Hitachi Ltd Membrane distillation device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3878054A (en) * 1964-12-09 1975-04-15 Pactide Corp Distillation apparatus and process
WO1987000160A1 (en) * 1985-07-04 1987-01-15 Svenska Utvecklings Ab Apparatus for desalinating salt water by membrane distillation
JPS6377503A (en) * 1986-09-17 1988-04-07 Mitsubishi Kasei Corp Liquid separator for thermopervaporation
JPH07768A (en) * 1993-06-15 1995-01-06 Hitachi Ltd Membrane distillation device

Also Published As

Publication number Publication date
SE0701601L (en) 2009-01-03

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