A device for separating a gas, such as air, into components, includes a plurality of modules, each module having one or more polymeric membranes capable of gas separation. A set of valves, pipes, and manifolds together arrange the modules in one of two possible configurations. In a first configuration, the modules are arranged in parallel. In a second configuration, the modules are divided into two groups which are arranged in series. The device can be switched from parallel to series, or from series to parallel, simply by changing the positions of a small number of valves, typically three valves. The device can therefore produce gas either of higher purity, or moderate purity, depending on the settings of the valves. The device also includes improved structures for connecting the modules to inlet and outlet manifolds, and also includes devices for temporarily isolating one or more modules from the system.

A membrane is described for purifying or separating hydrogen from a multi-component gas stream such as syngas. This membrane uses a molecular pre-treatment, a transition metal, fluorine containing polymer, carbon fibers and carbon matrix sintered on a supportive screen. The membrane may be a bilayer membrane comprised of a layer containing high surface area carbon and another layer containing lower surface area carbon. Methods for purifying hydrogen are also described.

This invention integrates a membrane with a steam reformer such that a membrane is placed between a raw biogas feed, and a steam reformer to supply a retentate of purified methane feed to the steam reformer and the permeate as fuel to the steam reformer,

An apparatus and process for separating a gas mixture is disclosed. The apparatus includes a plurality of membrane separation stages comprising a first membrane stage, a second membrane stage, and a third membrane stage. Each of the first, second, and third membrane stages are designed to separate a gas stream provided to them into a permeate stream and a retentate stream. The retentate stream provided from the third membrane stage is configured to be withdrawn as a product, further processed, or discarded. The apparatus further includes a gas transport device with an inlet in communication with the gas mixture and an outlet in communication with the first membrane stage. The controller is in communication with at least one measuring device, and the controller adapts a behavior of the gas transport device in response to a measurement of the at least one measuring device.

A biogas upgrading system can include a multiple stage membrane system that is configured to remove oxygen so that the biogas is upgraded to have a higher concentration of methane, a pre-selected oxygen (O.sub.2) concentration (e.g. less than or equal to 0.2 mol %, etc.), and a pre-selected carbon dioxide (CO.sub.2) concentration (e.g. less than or equal to 5 mol %, etc.). The membrane system can be configured to reject O.sub.2 by utilizing a low CO.sub.2/O.sub.2 selectivity that is within a pre-determined range (e.g. less than 5 or less than 4.5). In some embodiments, the upgraded biogas that is output from the system can be entirely made up of methane, carbon dioxide, and oxygen. In other embodiments, the biogas can be almost entirely composed of these components along with a small amount of nitrogen and a trace amount (e.g. less than or equal to 0.2%-0.1%, etc.) of other components.

A method for recovering helium from a feed gas mixture comprising helium, carbon dioxide and at least one of methane and nitrogen, and wherein at least a part of the feed gas mixture is subjected to a separation sequence including a membrane-based separation and an adsorption-based separation forming a helium product, wherein the the membrane based separation is performed using a first membrane separation step and a second membrane separation step, the membrane based separation and the separation sequence includes no further membrane separation steps, the adsorption based separation is performed using a pressure swing adsorption step, at least a part of the feed gas mixture is subjected to the first membrane separation step forming a first retentate and a first permeate. A corresponding arrangement is also provided.

A separation system includes first and second separation parts each having a separation membrane and provided with a fluid supply port, a permeate fluid exhaust port, and a non-permeate fluid exhaust port, an intermediate connecting part for connecting the permeate fluid exhaust port of the first separation part and the fluid supply port of the second separation part, a supply pipe connected to the fluid supply port of the first separation part, in which a mixed fluid flows at a pressure higher than an atmospheric pressure, and a pressure reducing part connected to the permeate fluid exhaust port of the second separation part, for reducing a pressure inside the permeate fluid exhaust port to a pressure lower than the atmospheric pressure. A pressure inside the intermediate connecting part is lower than a pressure inside the supply pipe and not lower than the atmospheric pressure.

A structure and method for carbon capture, e.g., in flue gas. An oxygen-terminated crown pore in graphene can be provided. Exposed carbon atoms on the pore edge can be bonded with oxygen to make a crown pore. When the CO.sub.2 is inside the pore, the electrostatic interaction becomes attractive because the positively charged carbon atom in CO.sub.2 is now exposed to negatively charged oxygen atoms on the crown pore edge. A favorable interaction between CO.sub.2 and the crown pore can be expected.

The invention relates to a specific process and apparatus for separation of gas mixtures with reduced maintenance costs.

A carbon dioxide capture system includes a first heat exchanger that exchanges heat between an exhaust stream and a lean carbon dioxide effluent stream. The carbon dioxide capture system also includes a second heat exchanger in flow communication with the first heat exchanger. The second heat exchanger is configured to cool the exhaust stream such that a condensate is formed, and the second heat exchanger is configured to channel a condensate stream for injection into the lean carbon dioxide effluent stream. A first turboexpander including a first compressor is driven by a first turbine. The first compressor is coupled in flow communication with the first heat exchanger. The first turbine is coupled in flow communication with the first heat exchanger and configured to expand the lean carbon dioxide effluent stream. The carbon dioxide capture system further includes a carbon dioxide membrane unit coupled in flow communication with the first compressor.