Abstract: A membrane separation process and system for removing a component from a fluid stream. An auxiliary membrane module or set of modules is installed across the pump that drives the main membrane unit, so that the permeate streams from the main and auxiliary membrane units are mixed and pass together through a common driving pump. The concentration of the mixed permeate stream is allowed to build up by circulating the stream through the auxiliary unit. When the concentration has reached a desired level, the mixed stream can be tapped and the product stream drawn off.

Abstract: A process for treating a gas stream to remove or recover a condensable component. The process involves a condensation step followed by a membrane concentration step. The process is useful in treating raw gas streams containing low concentrations of the condensable component, in treating small-volume raw gas streams, as an alternative to processes that require multistage membrane separation systems, in treating raw gas streams that have the potential to form explosive mixtures, or in situations where the treated gas stream composition must meet narrow target specifications.

Abstract: A process for treating a gas stream to remove or recover a condensable component. The process involves a condensation step and a membrane concentration step. The condensation step may be followed by the membrane step, or vice versa. The process can be designed to yield only two product streams: one, the condensed liquid, ready for use, reuse or discard, and two, a residue gas stream which im most cases will be clean enough for direct discharge or reuse. This result is achieved by recycling other streams within the process. Recovery of 90% or more of the condensable component can be achieved. The process offers substantial energy savings compared with condensation alone.

Abstract: A separation process for recovering organic components from liquid streams. The process is a combination of pervaporation and decantation. In cases where the liquid stream contains the organic to be separated in dissolved form, the pervaporation step is used to concentrate the organic to a point above the solubility limit, so that a two-phase permeate is formed and then decanted. In cases where the liquid stream is a two-phase mixture, the decantation step is performed first, to remove the organic product phase, and the residue from the decanter is then treated by pervaporation. Embodiments using two decanters, particularly suited to handling feed streams containing multiple organic compounds of different properties, are included.

Abstract: A pervaporation process and system for removing a component from a liquid stream. The process includes a pervaporation separation step and a recovery step. An auxiliary membrane module or set of modules is installed across a condenser and/or recovery unit on the downstream side of the main pervaporation unit. This module takes as its feed a stream from the recovery unit and returns a component-enriched stream to the inlet of the condenser or recovery unit. The module can be sized to produce a discharge stream containing the component in about the same concentration as the feed to be treated. This discharge stream can then be mixed with the feed without adverse effect on the efficiency of the system.

Abstract: A system and process useful for a gas separation operation. The system includes three components: a membrane unit, a pump, blower, ejector or the like to provide gas flow to the membrane unit and a gas holding vessel. The system and process can be used to treat any type of gas flow, but have particular advantages for handling streams where the gas flow varies substantially over time.

Abstract: A process for treating a gas stream to remove or recover a condensable component. The process involves a condensation step and a membrane concentration step. The condensation step may be followed by the membrane step, or vice versa. The process can be designed to yield only two product streams: one, the condensed liquid, ready for use, reuse or discard, and two, a residue gas stream, which in most cases will be clean enough for direct discharge or reuse. This result is achieved by recycling other streams within the process. Recovery of 90% or more of the condensable component can be achieved. The process offers substantially energy savings compared with condensation alone.

Abstract: A method for designing and making composite membranes having a microporous support membrane coated with a permselective layer. The method involves calculating the minimum thickness of the permselective layer such that the selectivity of the composite membrane is close to the intrinsic selectivity of the perselective layer. The invention also provides high performance membranes with optimized properties.

Abstract: A life-support system including a shelter, combined with equipment for sustaining a breathable atmosphere within the shelter. The breathable atmosphere is sustained by providing a supply of fresh air to the shelter, and removing carbon dioxide from the shelter. To provide the air supply, air containing a toxic agent is fed to a membrane separation unit. The membrane unit has a high selectivity to the permeation of oxygen over toxic agent and produces an oxygen-enriched permeate stream, while rejecting almost all of the toxic agent. The oxygen-enriched air is then passed through a unit containing a sorbent, such as activated carbon, to remove any remaining traces of toxic material before being fed to the shelter.

Abstract: A membrane process and system for removing condensable vapors from gas streams is disclosed. The process includes a membrane separation step and a condensation or other recovery step. An auxiliary membrane module or set of modules is installed across the pump and condenser on the downstream side of the main membrane unit. This module takes as its feed the vent gas from the condenser, and returns a vapor-enriched stream upstream of the pump and condenser. The module can be sized to produce a discharge stream containing the vapor in about the same concentration as the feed to be treated. This discharge stream can then be mixed with the feed without adverse effect on the efficiency of the system.

Abstract: A process for treating gas streams containing a sterilant gas and a diluent gas, such as sterilizer exhaust streams. The process involves a sterilant removal step and a diluent removal step. The sterilant removal step can be absorption, catalytic oxidation or some other chemical reaction. The diluent removal step includes a membrane separation step, and may include a condensation step. The permselective membranes used for the membrane separation step are typically selective for the diluent gas over other gases in the stream. The process removes essentially all the sterilant present in the feed stream, and typically removes 90% or more of the diluent. The process is particularly useful for treating ethylene oxide/CFC-12 mixtures.

Abstract: A spiral-wound pervaporation module, designed to achieve optimum permeate flow throughput. The module is of conventional design and construction, in that it incorporates membrane envelopes, within and between which are channels through which the feed and permeate streams flow. The feed and permeate channels are created by spacers on the feed and permeate sides of the membrane layers. The module is unconventional in that the permeate spacer is tailored for optimum permeate flow throughput. The tailoring is based on the discovery that the total permeate flow throughput from a module passes through a maximum as the resistance to vapor transport of the permeate spacer material is progressively decreased. The resistance to vapor transport along the permeate channel is kept below a value at which it has a significant adverse effect on the membrane flux and the membrane separation properties, yet at the same time the total module throughput is within an optimum range.

Abstract: A composite membrane particularly useful for gas separation or pervaporation. The membrane has three layers: a microporous substrate, an intermediate sealing layer, and a top permselective layer. The permselective layer is made by interfacial polymerization directly on the sealing layer. The sealing layer prevents penetration of the interfacial polymerization reagents into the substrate pores during membrane preparation and provides a gutter layer in the finished membrane.

Abstract: A refrigeration process including a refrigeration cycle, and refrigerant purge and recovery operations is disclosed. The refrigeration cycle may be a vapor compression cycle or an absorption cycle, for example. A purge stream is withdrawn from the refrigeration cycle and subjected to treatment by means of a membrane separation unit. The purge-stream treatment operation produces an essentially pure refrigerant stream, suitable for return to the refrigeration cycle, and an air stream, clean enough for direct discharge to the atmosphere. The process is applicable to most refrigerants, but is particularly useful in minimizing atmospheric emissions of chlorofluorocarbons, such as CFC-11 and CFC-12.

Abstract: A fractionation process for treating a gas stream containing organic vapor in a concentration technically or economically difficult to treat by standard waste control methods. Typically this concentration will be about 0.1-10% organic vapor. The process involves running the stream through a membrane system containing one or more membranes selectively permeable to the organic vapor component of the gas stream. The fractionation produces two streams: a product residue stream containing the organic vapor in a concentration less than about 0.5% and a product permeate stream highly enriched in organic vapor content. Both residue and permeate streams are then suitable for treatment by conventional separations or waste control technologies. The low concentration residue stream might be passed to carbon adsorption beds, for example, and the high concentration permeate stream might be subjected to condensation or incineration.

Abstract: A method for designing and making composite membranes having a microporous support membrane coated with a permselective layer. The method involves calculating the minimum thickness of the permselective layer such that the selectivity of the composite membrane is close to the intrinsic selectivity of the permselective layer. The invention also provides high performance membranes with optimized properties.

Abstract: A method for designing and making composite membranes having a microporous support membrane coated with a permselective layer. The method involves calculating the minimum thickness of the permselective layer such that the selectivity of the composite membrane is close to the intrinsic selectivity of the permselective layer. The invention also provides high performance membranes with optimized properties.

Abstract: A membrane process for separating fluorinated hydrocarbon vapors is disclosed. The process employs a permselective membrane that is selectively permeable to fluorinated hydrocarbons over oxygen or nitrogen. The process involves contacting the feed side of the membrane with a gas mixture containing the fluorinated hydrocarbon vapor, and withdrawing from the permeate side a vapor enriched in the fluorinated hydrocarbon component. The driving force for membrane permeation is preferably provided by maintaining a partial vacuum on the permeate of the membrane. Eighty to 99% of the fluorinated hydrocarbon contained in the feedstream can be removed by the process. The permeate may be sufficiently enriched in fluorinated hydrocarbon to permit recovery and reuse. Very high membrane selectivities are not required.

Abstract: An ultrathin, high-flux composite membrane for use in gas separation. The membrane comprises a metal layer, typically 500.ANG. or less thick on a microporous support. The support may be as asymmetric Loeb-Sourirajan type membrane or a two-layer composite of a microporous substrate with a very thin sealing layer. The support gives mechanical strength to the membrane but does not contribute significantly to the selectivity. Optionally the metal layer may be overcoated with a second polymeric sealing layer to plug any defects and to protect the fragile surface from mechanical damage. The membrane is particularly useful in the purfication of hydrogen.