Abstract: Processes for removing water from organic solvents, such as ethanol. The processes include distillation in two columns operated at sequentially higher pressure, followed by treatment of the overhead vapor by one or two membrane separation steps.

Abstract: A fuel system for an energy conversion device includes a deoxygenator system with an oxygen permeable membrane formed from a multiple of layers. The layers include a sealant layer, an oxygen permeability layer and a porous backing layer. The layered composite oxygen permeable membrane maximizes the oxygen transfer rate and minimizes the fuel leakage rate.

Abstract: A process and corresponding apparatus for dehydrating gas, especially natural gas. The process includes an absorption step and a membrane pervaporation step to regenerate the liquid sorbent.

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 removing an undesirable vapor from a pump exhaust by a membrane separation process. The process takes advantage of the pressure difference between the inlet and outlet sides of the pump to provide the driving force for membrane permeation. The process of the invention can reduce the emission of pollutants or impurities from pumps to a very low level, such as 10% or less of its previous value, with little extra expenditure of energy.

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 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. The condensed permeate from the pervaporation unit is sufficiently concentrated in the organic component to be fed back to the decanter. The process can be tailored to produce only two streams: an essentially pure organic product stream suitable for reuse, and a residue stream for discharge or reuse.

Abstract: A protective material having a membrane layer and a sorbent layer. The membrane is a thin-film composite membrane permeable to water vapor but relatively impermeable to organic vapors. The sorbent layer includes activated carbon or other sorbent or reactive material, and captures traces of organic vapor that permeate the membrane layer. The material is particularly useful in intermediate-level protective clothing.

Abstract: A membrane for gas separation or pervaporation. The membrane is a composite of a microporous support membrane and an ultrathin permselective membrane, the permselective membrane being made from a polyamide-polyether block copolymer having the general form: ##STR1## where PA is a saturated aliphatic polyamide segment, PE is a polyether segment, and n is a positive integer. The membrane is particularly useful in separating polar gases from non-polar gases.

Abstract: A pervaporation process for separating organic contaminants from evaporator condensate streams is disclosed. The process employs a permselective membrane that is selectively permeable to an organic component of the condensate. The process involves contacting the feed side of the membrane with a liquid condensate stream, and withdrawing from the permeate side a vapor enriched in the organic component. The driving force for the process is the in vapor pressure across the membrane. This difference may be provided for instance by maintaining a vacuum on the permeate side, or by condensing the permeate. The process offers a simple, economic alternative to other separation techniques.

Abstract: A multilayer composite fabric material consisting of a woven or non-woven fabric support, a microporous membrane layer, and an ultrathin permselective surface coating, and optionally an intermediate sealing layer and a protective top layer; the material being freely permeable to water vapor but impermeable to toxic organic vapors.The material is suitable for fabricating protective clothing for use in industrial and military hazardous chemical enviornments.

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.