A process and apparatus for producing a hydrogen-enriched product and recovering CO.sub.2 from an effluent stream from a hydrogen production unit are described. The effluent from the hydrogen production unit, which comprises a mixture of gases comprising hydrogen, carbon dioxide, water, and at least one of methane, carbon monoxide, nitrogen, and argon, is sent to a PSA system that produces at least two product streams for separation. The PSA system that produces at least two product streams separates the gas mixture into a high-pressure hydrogen stream enriched in hydrogen, optionally a second gas stream containing the majority of the impurities, and a low-pressure tail gas stream enriched in CO.sub.2 and some impurities. The CO.sub.2-rich tail gas stream is compressed and sent to a CO.sub.2 recovery unit, where a CO.sub.2-enriched stream is recovered. The CO.sub.2-depleted overhead gas stream is recycled to the PSA system that produces at least two product streams.

A gas separation and recovery method is provided. Based on the fact that a gas adsorbent has differing adsorption and desorption characteristics depending on the affinities and pressures of gas species, and gases of different species are desorbed at different timings, a target gas component is separated and recovered from a source gas by a pressure swing adsorption process in such a manner that a desorption step is divided into, for example, two time periods and desorbed gases are recovered separately in the respective time periods. In this manner, when gas 1 and gas 2 having different desorption timings are adsorbed to an adsorbent, a gas rich in gas 1, and a gas rich in gas 2 may be recovered separately from each other. Thus, it becomes possible to separate and recover selectively a target gas component with high concentration.

The present invention relates to a method for obtaining a hydrogen rich gas from an off gas. Further, the invention relates to a system for operating said method.

The present invention relates to a gas-filtering system (1000, 3000, 4000, 5000, 6000) comprising: an input (1100) for the gas, a reactor (1301, 1302, 1303) for filtering the gas at the input (1100) and thus obtaining a filtered gas, an output (1200) for the filtered gas, a vacuum generator (1401, 1402) for generating a vacuum inside the reactor (1301, 1302, 1303), where the vacuum generator (1401, 1402) is configured so as to apply a first predetermined vacuum value (VI) in a first vacuum phase (T2) and so as to apply a second predetermined vacuum value (V2) in a second vacuum phase (T3); the filtering system (1000, 3000, 4000) further comprising a flow controller (1501, 1502, 1503) connected at the output to the reactor (1301, 1302, 1303), where the flow controller (1501, 1502, 1503) is configured so as to block the introduction of the filtered gas into the reactor (1301, 1302, 1303) during the first vacuum phase (T2), and where the flow controller (1501, 1502, 1503) is configured so as to allow the introduction of the filtered gas and/or a second gas into the reactor (1301, 1302, 1303), starting from the output (1200) during the second vacuum phase (T3).

Provided is a pressure swing adsorption type hydrogen manufacturing apparatus that can improve the product recovery rate in a state where the purity of the product is kept from being reduced. A process control unit P controls operation of adsorption towers 1 that generate a product gas by adsorbing, using adsorbents, adsorption target components other than hydrogen components from a source gas, in a state where an adsorption process, a pressure-equalization discharge process, a desorption process, and a pressure-restoration process are successively repeated. The process control unit is configured to control operation of the adsorption towers 1 in such a manner that a prior pressure-equalization process of supplying gas inside an adsorption tower 1 undergoing the pressure-equalization discharge process to an adsorption tower 1 undergoing the pressure-restoration process is performed in an initial stage of a unit processing period, a subsequent pressure-equalization process of supplying gas inside the adsorption tower 1 undergoing the pressure-equalization discharge process to an adsorption tower 1 undergoing the desorption process is performed in a final stage of the unit processing period, a pressurization process of introducing a product gas H to perform pressurization is performed, as the pressure-restoration process, subsequently to the prior pressure-equalization process, and the pressurization process is performed while overlapping with the subsequent pressure-equalization process.

A gas separation and recovery method is provided. Based on the fact that a gas adsorbent has differing adsorption and desorption characteristics depending on the affinities and pressures of gas species, and gases of different species are desorbed at different timings, a target gas component is separated and recovered from a source gas by a pressure swing adsorption process in such a manner that a desorption step is divided into, for example, two time periods and desorbed gases are recovered separately in the respective time periods. In this manner, when gas 1 and gas 2 having different desorption timings are adsorbed to an adsorbent, a gas rich in gas 1, and a gas rich in gas 2 may be recovered separately from each other. Thus, it becomes possible to separate and recover selectively a target gas component with high concentration.

A method for producing oxygen by adsorbing a stream of atmospheric air, using four VPSA, one air compressor and two vacuum pumps, each adsorber undergoing a single pressure cycle including the following steps: a) producing a first stream of gas having an oxygen content T1 while loading the adsorber of the stream of atmospheric air upstream; b) producing a second stream of gas including an oxygen content T2<T1: c) producing a third stream of gas including an oxygen content T3<T2<T1 while simultaneously extracting a nitrogen-enriched residual stream; d) eluting the adsorber, from which the three streams of gas produced in steps a), b), and c) are taken with the second stream of gas produced in step b); e) repressurizing the adsorber consecutively with at least two streams, first and second repressurizing streams, with increasing oxygen content.

Methods and systems for continuous pressure swing adsorption separation of a pressurized feed gas stream, the method including separating hydrocarbons heavier than methane from the pressurized feed gas stream to produce at least two product streams, a first product stream being substantially pure methane, and a second product stream being substantially comprised of components with a greater molecular weight than methane.

A method for producing oxygen by adsorbing a stream of atmospheric air, using a VPSA, including at least one adsorber, each adsorber undergoing a single pressure cycle including the following steps: a) producing a first stream of gas having an oxygen content T1 while loading the adsorber of the stream of atmospheric air upstream; b) producing a second stream of gas including an oxygen content T2<T1: c) producing a third stream of gas including an oxygen content T3<T2<T1 while simultaneously extracting a nitrogen-enriched residual stream; d) eluting the adsorber, from which the three streams of gas produced in steps a), b), and c) are taken with the second stream of gas produced in step b); e) repressurizing the adsorber consecutively with at least two streams, first and second repressurizing streams, with increasing oxygen content.

In various aspects, methods are provided for hydrogen production while reducing and/or mitigating emissions during various refinery processes that produce syngas, such as power generation. Syngas can be effectively separated to generate high purity carbon dioxide and hydrogen streams, while reducing and/or minimizing the energy required for the separation, and without needing to reduce the temperature of the flue gas. In various aspects, the operating conditions, such as high temperature, mixed metal oxide adsorbents, and cycle variations, for a pressure swing adsorption reactor can be selected to minimize energy penalties while still effectively capturing the CO.sub.2 present in syngas.