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US 5,207,902 AGranted
Method for separating a liquid mixture
AssigneesRyoka Techno Engineering & Construction Co., Mitsubishi Kasei Corporation
InventorFuruto Seiryo
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AssigneesRyoka Techno Engineering & Construction Co., Mitsubishi Kasei Corporation
InventorFuruto Seiryo
Estimating the term…
A apparatus for separating water by pervaporation from a liquid mixture comprising isopropanol and water, which comprises (a) heating the liquid mixture, then supplying the heated mixture to a pervaporation membrane module unit using a polyimide-type separating membrane to conduct separation of the liquid mixture, recycling a part or whole of the liquid not permeated through the membrane to a feed liquid mixture, supplying a fresh feed liquid mixture to an optional place in the circulation route, and withdrawing the liquid mixture from an optional place in the circulation route, (b) controlling the amount of the liquid to be recycled among the liquid not permeated through the membrane to a level of at least 10 times by volume the amount of the fresh feed liquid mixture, and (c) controlling the difference between the liquid temperature at the inlet of the membrane module unit and the liquid temperature at the outlet of the membrane module unit to a level of at most 20.degree. C.
An apparatus for separating water by pervaporation from a liquid mixture comprising isopropanol and water, which comprises (a) means for heating the liquid mixture, then supplying the heated mixture to a pervaporation membrane module unit using a polyimide-type separating membrane to conduct separation of the liquid mixture, recycling a part or whole of the liquid not permeated through the membrane to a feed liquid mixture, supplying a fresh feed liquid mixture to an optional place in the circulation route, and withdrawing the liquid mixture from an optional place in the circulation route, (b) a means for controlling the amount of the liquid to be recycled among the liquid not permeated through the membrane including structure designed for enabling a level of at least 10 times by volume the amount of the fresh feed liquid mixture, and (c) a means for controlling the difference between the liquid temperature at the inlet of the membrane module unit and the liquid temperature at the outlet of the membrane module unit including structure designed for enabling to a level of at most 20.degree. C.
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Pervaporation: comprising multiple pervaporation steps
Separation; Purification; Use of additives, e.g. for stabilisation: by physical treatment
Separation
Acyclic or carbocyclic compounds
Term ended 27 Dec 2011 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
The present invention relates to a method for separating a liquid mixture by pervaporation. More particularly, the present invention relates to a method for recovering isopropanol of high purity by removing water from a water-containing isopropanol after being used for cleaning precision parts such as semiconductors.
2. Discussion of Background
FIG. 1 is a process flowchart of one embodiment of the present invention and represents also a process flowchart of Example 1.
FIG. 2 is a process flowchart showing an embodiment wherein the place at which fresh feed liquid mixture is supplied to the circulation route and the place at which a concentrated liquid of the component hardly permeable through the membrane is withdrawn is different from FIG. 1.
FIG. 3 illustrates an embodiment wherein a residual liquid is supplied to another pervaporation module unit and represents also a process flowchart of Example 2.
In the drawings, each of reference numerals 1, 17, 33, 49 and 65 indicates a heater for the liquid mixture, each of numerals 2, 18, 34, 50 and 66 indicates a module unit, each of 2a, 18a, 34a, 50a and 66a indicates a pervaporation membrane, each of numerals 3, 19, 35, 51 and 67 indicates a condenser for the permeated component, each of numerals 4, 20, 36, 52 and 68 indicates a vacuum pump at the secondary side, each of numerals 5, 21, 37 and 53 indicates a pump for recycling the liquid mixture, each of numerals 6, 22 and 38 indicates a valve to prevent reverse flow, and numeral 90 indicates a purge gas recycling device.
Firstly, the pervaporation membrane module unit to be used in the present invention, will be described.
As the membrane module unit, any module unit useful for pervaporation, may be employed, and it is selected depending upon the liquid to be separated.