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
• • 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
  • B01D61/38—Liquid-membrane separation
• • 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
  • B01D2311/13—Use of sweep gas

Definitions

• a process for the separation of a gaseous mixture and an apparatus for carrying out the same is a process for the separation of a gaseous mixture and an apparatus for carrying out the same.
• the present invention relates to a process for the separation of a gaseous mixture, which is different from biogas, to form two streams of which one is depleted and the other is enriched in at least one component of the gaseous mixture.
• the process comprises introducing the gaseous mixture to one side of a liquid membrane having higher affinity to at least one component of the gaseous mixture.
• the liquid membrane is immobilized in a porous support having good affinity to the membrane forming liquid.
• the first stream is obtained as a retentate and the second stream is obtained as a permeate.
• the invention also relates to an apparatus for carrying out said process.
• the apparatus comprises a membrane separator, which is divided by a liquid membrane immobilized in/on a porous support, into a retentate space and a permeate space.
• the retentate space is connected with supply fittings for the gaseous mixture and discharge fittings for the retentate stream whereas the permeate space is connected with discharge fittings for the permeate stream.
• Membrane separations seem to be promising for the separation of a plurality of different gaseous mixtures.
• the term membrane separation is used to designate a process in which a mixture is separated on the basis of different permeability of individual components across a selective membrane by means of which two spaces are separated from one another.
• the transport of the components across the membrane l is influenced by their physical and chemical properties, and the interactions of the components between each other and the membrane, itself.
• porous membranes the components are most frequently separated on the basis of their particle size.
• the transport properties are particularly dependent on the solubility of the components within the membrane or optional possibility of chemical interactions between the individual components and the membrane, and the diffusion coefficients of the components in the membrane.
• Immobilized ionic membranes comprise ionic liquids which, owing to their high selectivity and molecular diffusion, as well as negligible vapour tension, represent ideal materials for the preparation of liquid membranes.
• the main diadvantage of the liquid membranes consists in that their stability depends on miscibility with the separated materials which are not always capable of resisting to the long-termed (or even operational) duty.
• ionic liquids more or less absorb moisture, which leads to relatively quick breakdown of the membrane structure and stability.
• a suitable liquid for the separation has to comply with the requirement that the separated gases be at least by one order of magnitude more soluble in the selected liquid than the gas which is the predominant component of a gaseous mixture. Hence, the selection of a liquid for the impregnation of a porous membrane is a key factor.
• the subject matter of the present invention is a process for the separation of a gaseous mixture, which is different from biogas, to form two streams of which one is depleted and the other is enriched in at least one component of said gaseous mixture, which comprises introducing said gaseous mixture to one side of a liquid membrane having higher affinity to at least one component of said gaseous mixture, said liquid membrane being immobilized in a porous support having good affinity to the membrane forming liquid, wherein the first stream is obtained as a retentate and the second stream is obtained as a permeate.
• the improvement of said process lies in that the liquid losses from said membrane, which are caused by driving away said liquid in said permeate stream, are compensated by saturating said introduced gaseous mixture with the vapour of said liquid at a temperature which is higher than the temperature at which said membrane separation takes place whereupon said vapour is condensed when said gaseous mixture is cooled in said membrane.
• any materials having high affinity to the selected liquid in the pores of which the vapour of the liquid with which the introduced gaseous mixture has been saturated can spontaneously condense as soon as it is cooled to the temperature below its dew point.
• Such materials can include polymer porous membranes e.g. made of polytetrafluoroethylene, polyatnide or other polymers or ceramic membranes e.g. on the basis of alumina.
• the permeation takes place into sweeping gas.
• reduced pressure can be maintained on the permeate side of a permeation cell.
• the subject matter of the present invention also includes an apparatus for carrying out said process.
• Said apparatus comprises a membrane separator, which is divided by a liquid membrane immobilized in a porous support, into a retentate space and a permeate space.
• Said retentate space is connected with supply fittings for said gaseous mixture and discharge fittings for said retentate stream whereas said permeate space is connected with discharge fittings for said permeate stream.
• the improvement of said apparatus lies in that a saturator for saturating said gaseous mixture with said vapour of the used liquid is inserted into the supply tubing for said introduced gaseous mixture.
• the solubility of the separated gases in the separation liquid may be substantially different. This can be achieved by appropriate selection of the separation liquid.
• the gaseous mixture introduced to the membrane is saturated with the separation liquid. The saturation takes place at a temperature which is higher than the temperature in the membrane separator in which the liquid membrane immobilized in the pores of the support is located. The temperature difference between the introduced gaseous mixture and the liquid membrane is such that spontaneous condensation of the liquid in the pores may take place. In this way the membrane can be prevented from drying which would impair the stability and the separation properties of the system.
• the proposed separation method is advantageous in that it requires simple arrangement which is associated with reduced capital and operational expenditures, and it provides safe operation of the separation unit resulting from continuous regeneration of the membrane liquid in the course of the separation process.
• the attached figure contains a schematic diagram of an example of the apparatus according to the invention.
• a gaseous mixture consisting of a ternary mixture of 70% vol. methane, 30% vol.. carbon dioxide a 900 ppm sulfane is introduced from a pressure container 1 of the gaseous mixture over a flow controller 3 of the gaseous mixture into a saturator 5, in which the gaseous mixture is saturated with vapour, and then into a membrane separator 6.
• the temperature in the saturator 5 of the gaseous mixture with steam is higher than the temperature in the membrane separator 6, in which a water impregnated porous support of hydrophilized polytetrafluoroethylene is mounted. Partial gas flows through this condensing water membrane at the pressure over the
• the temperature difference is such that spontaneous water condensation in the pores of the porous membrane may take place.
• the driving force of the separation process is the different concentration of individual gas components and the pressure difference across the membrane.
• the permeation takes place into the carrier gas, which is nitrogen, introduced below the membrane from a pressure container 2 of the carrier gas over the carrier gas flow controller 4.
• Optimal total pressure over the membrane is controlled by a reverse pressure controller 7. E x a m l e
• the typical composition of waste gas from an industrial process is as follows: 25 % vol. 0 2 and 75 % vol. C0 2 .
• a gaseous mixture having two different compositions mentioned in Table 3 are used.
• the gaseous mixture is introduced from a pressure container l_of the gaseous mixture over a gaseous mixture flow controller 3 at a velocity of 10 ml/min into a saturator 5 of the gaseous mixture with steam, and then into a membrane separator 6.
• the saturator 5 is supplied with tap water.
• the temperature in the saturator 5 of the gaseous mixture with steam is higher (27 °C) than the temperature in the membrane separator 6_(14 °C).
• a porous mesh with pores 3 ⁇
• an attached membrane 10 of hydrophilized teflon having pores 0.1 ⁇ , thickness 30 ⁇ and porosity 80 %), impregnated with water, is mounted, in the membrane separator 6.
• the effective area of the membrane having the radius of 13 cm is 132,7 cm 2 .
• the permeation is carried out into the carrier gas, which is nitrogen.
• the conducted experiments show that C0 2 can be efficiently removed with the use of a porous membrane of hydrophilic teflon (Table 3) in which water condensation takes place. Partial gas flows through thisracwater membrane" at the pressure over the membrane 350 kPa are shown in Table 3.
• the temperature difference (13 °C) is such that spontaneous water condensation in the pores of the porous membrane may take place.
• the driving force of the separation process is the different concentration of individual gas components and the overall pressure over and under the membrane.
• the permeation takes place into the carrier gas, which is nitrogen, introduced below the membrane from a pressure container 2 of the carrier gas over the carrier gas flow controller 4.
• Optimal total pressure over the membrane is controlled by a back pressure regulator 7.
• the invention is exemplified on an illustrative separation of the mixture CH 4 /CO 2 /H 2 S a 0 2 /C0 2 with the use of a water membrane immobilized in hydrophilized porous polytetrafluoroethylene as a support.
• the present invention is however not limited to the use of the exemplified separation.
• the improvement of a separation process which can be achieved with the use of the principle of "a condensing membrane" (i.e.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Analytical Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Water Supply & Treatment (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Gas Separation By Absorption (AREA)

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• 2010
  • 2010-06-02 CZ CZ20100438A patent/CZ303107B6/cs unknown
• 2011
  • 2011-05-13 WO PCT/CZ2011/000051 patent/WO2011150898A2/en active Application Filing
  • 2011-05-13 EP EP11764670.3A patent/EP2576011A2/de not_active Withdrawn

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