摘要:
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.
摘要:
A process for treating natural gas or other methane-rich gas to remove excess nitrogen. The invention relies on membrane separation using methane-selective membranes, but does not require the membranes to be operated at very low temperatures. We have found that, by using a two-step membrane system design, and controlling the operating pressures for the membrane steps within certain ranges, the capital and operating costs of the process can be kept within economically acceptable limits.
摘要:
A pervaporation apparatus and process adapted to handle a diverse range of feed stream compositions and volumes. The apparatus includes a pervaporation unit and condenser, one or more tanks and a control system to direct liquid flows within the apparatus according to the chosen processing scheme. The apparatus and process can achieve separation performance comparable to a one-stage, two-stage, two-step or more complicated pervaporation system, including those in which two-phase permeates are produced.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.When modules in accordance with the invention are made, the increase in throughput per unit membrane area that is obtained more than compensates for the loss in membrane area brought about as a result of the use of a thicker permeate spacer. The modules are particularly advantageous for containing high-flux, high-separation membranes, and for low-pressure pervaporization processes.
摘要:
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.
摘要:
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.
摘要:
Disclosed herein are 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.