Abstract: An automatic lacer wraps bundles of polymeric fibers with thread, before the bundles are woven into a fabric mat and placed in a housing to form a gas-separation membrane module. A fiber bundle passes through a spool which is previously wound with thread on its outer surface. The thread is attached to the fiber bundle, so that when the bundle is moved through the spool, the thread is pulled from the spool, and automatically becomes wound around the bundle. Threads from two or more spools may be wrapped around the fiber bundle simultaneously. Lacing of the fiber bundles reduces the amount of tangling in the loom feeder, and improves the quality of modules made from the fiber bundles.

Abstract: An integrated fiber membrane module for air dehydration and air separation includes dehydration and separation units disposed concentrically in a generally cylindrical module. Air flows through the outer dehydration unit, becomes dried, and is then directed, in an opposite direction, through the separation unit. The permeate gas from the separation unit serves as a sweep gas for the dehydration unit. A portion of dried gas produced by the dehydration unit may be used as a sweep gas for the separation unit, and also for the dehydration unit. The module makes it feasible to dry and separate air using a device which occupies relatively little space, and which is therefore especially suited for use in aircraft and in other cramped environments.

Abstract: An air dehydration membrane module is provided with a sweep gas which is taken from the waste gas of a pressure swing adsorption (PSA) unit. No additional compressor is required, other than the compressor forming part of the PSA unit. In another embodiment, the sweep gas includes the combination of dried product gas, taken from the dehydration membrane module, and a supplemental gas, which may be ambient air, or permeate gas from an air separation membrane, or waste gas from a PSA unit. An air ejector combines the streams, without the use of an additional compression step, and the combined gas is used as a sweep stream for the dehydration module. The invention also includes the method of selecting an optimum point at which the sweep gas is injected into the module.

Abstract: A shipboard system provides dry, oil-free utility air and inert gas for use on a marine vessel. A compressor converts ambient air into a pressurized air stream. The air stream is cooled by heat exchange with sea water in the vicinity of the vessel. The air stream is then dried in a dehydration membrane module, and some of the product of the dehydration module is taken for use as utility air. The remainder of the dried air is passed through an air separation module which includes a polymeric membrane. The product of the air separation module includes a nitrogen-enriched gas which is used as an inert gas on the vessel. The compressor is the only mechanically moving component of the system.

Abstract: Compressed natural gas is produced by a compressor, located near a natural gas well. The compressor being driven by a gas engine. A portion of the compressed natural gas is diverted, and passed through a dehydration membrane, and also through a gas-separation membrane which selects for carbon dioxide. The result is a natural gas stream which is relatively dry, and relatively free of carbon dioxide. This stream is used as fuel for the gas engine which drives the compressor. The permeate gases from the membrane may be recycled. The system enables the natural gas to be compressed efficiently, by providing a conditioned fuel gas for driving the compressor.

Abstract: An automatic lacer wraps bundles of polymeric fibers with thread, before the bundles are woven into a fabric mat and placed in a housing to form a gas-separation membrane module. A fiber bundle passes through a spool which is previously wound with thread on its outer surface. The thread is attached to the fiber bundle, so that when the bundle is moved through the spool, the thread is pulled from the spool, and automatically becomes wound around the bundle. Threads from two or more spools may be wrapped around the fiber bundle simultaneously. Lacing of the fiber bundles reduces the amount of tangling in the loom feeder, and improves the quality of modules made from the fiber bundles.

Abstract: A tubesheet is formed at the end of a module containing polymeric material for gas separation, by immersing the end of the module in an epoxy material, or its equivalent. A vacuum, or partial vacuum, applied at or near the opposite end of the module, tends to draw the epoxy material towards the source of the vacuum, and results in a tubesheet having a desired thickness, even though the epoxy material may have relatively high viscosity. The method produces effective tubesheets, while minimizing the degree to which the tubesheet covers the otherwise useful surface area of the polymeric material. The method thus produces gas-separation modules having enhanced productivity.

Abstract: An air-separation system, useful in high-temperature environments, produces a superheated compressed air stream which is sufficiently cool to be applied to an air-separation membrane. Ambient air is compressed, and then cooled by a fan. The cooled compressed air, after being filtered, is passed through a heat exchanger where it is heated by thermal contact with incoming compressed air. The cooled compressed air thus becomes superheated, and can then be conveyed into a polymeric membrane module without damaging the polymer. A valve enables some of the compressed air to bypass the heat exchanger, thus controlling the degree to which the cooled compressed air stream is heated.

Abstract: A gas separation module includes fibers formed of a membrane which exhibits selectivity between gaseous components to be separated. The fibers are partially coated with a solution which enhances their selectivity, the fibers being uncoated in the vicinity of their feed ends. The partially coated fibers provide a good compromise between the goals of improved selectivity and enhanced product flow. The gaseous component that permeates through the membrane is made to flow in a direction opposite that of the main gas feed, due to a baffle that directs the permeate in the desired direction. The invention also includes a method and apparatus for making the partially coated module.

Abstract: A gas-separation module allows a sweep gas to be introduced at selectively variable locations, and in selectively varying amounts, along the length of the module. The sweep gas enters the module through a perforated conduit. A slotted sleeve, disposed within the conduit, selectively blocks and unblocks perforations in the conduit. Rotation of the sleeve causes slots to come into, or out of, registration with the perforations. The sleeve permits varying amounts of sweep gas to be introduced at different locations along the length of the module. Rotation of the sleeve changes the profile of introduction of sweep gas, and can be used to optimize the performance of the module for each of a set of different pressure conditions.

Abstract: A portable system for air separation or air dehydration, or both, is carried on a truck or equivalent vehicle. The air separation system includes, at a minimum, a feed compressor and a gas separation membrane. The air dehydration system includes a feed compressor and an air dehydration membrane. The feed compressor receives power from the engine of the vehicle, only when the vehicle is not moving under its own power. Heat from the vehicle engine may also be used to heat the compressed air stream to prevent the formation of water. The system can also be used to perform air dehydration and air separation simultaneously. The system is substantially self-contained, and can be easily driven from one location to another, simply by driving the vehicle to another location. The invention is especially useful in providing air separation or air dehydration services, or both, for relatively brief periods, at multiple locations.

Abstract: A solid polymer is recovered from a solution by the addition of a water-based solution containing a surfactant. The solutions are mixed and heated, so that the organic solvent containing the polymer is driven off, and the solid polymer can be recovered. The solid polymer is generally recovered in the form of small particles, which can be easily moved, as part of a slurry, and then dried. The process produces no hazardous waste. The by-products of the process can be re-used or discarded through ordinary channels.

Abstract: Oxygen, or other gas, of moderate purity is produced in a fiber membrane module. A diluent gas, such as air, is introduced into the module, on the shell side of the fibers, so as to mix with oxygen which has permeated through the fibers. The diluent gas not only reduces the concentration of oxygen in the product stream, to make oxygen of moderate purity, but also reduces the partial pressure of oxygen on the shell side of the fibers, thus enhancing the permeation of oxygen through the fibers. The invention can therefore enhance the productivity of the module, and/or reduce the energy required to operate the module.

Abstract: A gas separation module includes fibers formed of a membrane which exhibits selectivity between gaseous components to be separated. The fibers are partially coated with a solution which enhances their selectivity, the fibers being uncoated in the vicinity of their feed ends. The partially coated fibers provide a good compromise between the goals of improved selectivity and enhanced product flow. The gaseous component that permeates through the membrane is made to flow in a direction opposite that of the main gas feed, due to a baffle that directs the permeate in the desired direction. The invention also includes a method and apparatus for making the partially coated module.

Abstract: A tubesheet is formed at the end of a module containing polymeric material for gas separation, by immersing the end of the module in an epoxy material, or its equivalent. A vacuum, or partial vacuum, applied at or near the opposite end of the module, tends to draw the epoxy material towards the source of the vacuum, and results in a tubesheet having a desired thickness, even though the epoxy material may have relatively high viscosity. The method produces effective tubesheets, while minimizing the degree to which the tubesheet covers the otherwise useful surface area of the polymeric material. The method thus produces gas-separation modules having enhanced productivity.

Abstract: A gas-separation module allows a sweep gas to be introduced at selectively variable locations, and in selectively varying amounts, along the length of the module. The sweep gas enters the module through a perforated conduit. A slotted sleeve, disposed within the conduit, selectively blocks and unblocks perforations in the conduit. Rotation of the sleeve causes slots to come into, or out of, registration with the perforations. The sleeve permits varying amounts of sweep gas to be introduced at different locations along the length of the module. Rotation of the sleeve changes the profile of introduction of sweep gas, and can be used to optimize the performance of the module for each of a set of different pressure conditions.

Abstract: An air dehydration membrane is made of a hydrophilic polymer having a permeability for water vapor which is greater than its permeability for air, and having low selectivity between oxygen and nitrogen. The membrane has a hydrophilic coating, which itself may be a polymer. The coating does not affect the selectivity of the coated membrane with respect to oxygen and nitrogen, but does increase selectivity of the membrane with respect to water vapor. A preferred material for the membrane is polysulfone. Preferred materials for the coating are poly vinyl alcohol and Triton X-100. The membrane is selected such that the dominant mechanism for gas flow through the membrane is Knudsen flow. The membranes are made at low cost, and can outperform existing commercial membranes in either volumetric productivity or product recovery.

Abstract: A system for making dry, hydrocarbon-free compressed air includes a compressor, a membrane drier, and a carbon bed connected in series. A moisture separator may also be included to remove liquid water from the stream. A filter may be placed after the carbon bed to remove residual carbon dust. The output of the system can be connected to operate virtually any pneumatic device, such as a control valve or pneumatically-operated instrument. Because the chemical content of the compressed air is not changed, it remains breathable, and does not create a safety hazard.

Abstract: A portable system for air separation or air dehydration, or both, is carried on a truck or equivalent vehicle. The air separation system includes, at a minimum, a feed compressor and a gas separation membrane. The air dehydration system includes a feed compressor and an air dehydration membrane. The feed compressor receives power from the engine of the vehicle, only when the vehicle is not moving under its own power. Heat from the vehicle engine may also be used to heat the compressed air stream to prevent the formation of water. The system can also be used to perform air dehydration and air separation simultaneously. The system is substantially self-contained, and can be easily driven from one location to another, simply by driving the vehicle to another location. The invention is especially useful in providing air separation or air dehydration services, or both, for relatively brief periods, at multiple locations.

Abstract: Methods of synthesizing high molecular weight polycarbonate polymers are described. Also described are polycarbonates produced by these methods.