There is provided a nitrogen rejection unit for extracting nitrogen and carbon dioxide from a flue gas, the system comprising: a first container for holding a first volume of the flue gas at a first pressure and a first temperature that is below or equal to the condensation temperature of the carbon dioxide and greater than the condensation temperature of nitrogen; an outlet for removing the carbon dioxide as a liquid from the first container; means for transporting gaseous nitrogen from the first container to a second container and means for cooling the nitrogen such that the second container contains nitrogen at a second temperature that is below or equal to its condensation temperature such that at least some of the nitrogen in the second container is in liquid form; and means for guiding the liquid nitrogen from the second container through or around the first container to cool the material within the first container to the first temperature. There is also provided a system for capturing carbon dioxide in a flue gas, a method for extracting nitrogen from a flue gas, and a method for capturing carbon dioxide in a flue gas.

A method for producing liquid nitrogen using a residual gas stream derived from a flue gas of a power plant is provided. The residual gas stream is purified in a front-end purification unit to remove freezable components and then the purified stream is compressed. Following compression, the stream can be divided into a first portion and a second portion, wherein the first portion is cooled and sent to a distillation column, wherein oxygen and argon are separated, thereby leaving an essentially pure gaseous nitrogen stream. The gaseous nitrogen stream can then be liquefied using refrigeration provided by expanding the second portion of the purified stream. In a preferred embodiment, the second portion is expanded in two turbines, and the gaseous nitrogen is compressed in a cold nitrogen booster, which is powered by one of the two turbines. In an additional embodiment, after warming, the expanded second portion of the purified stream can be used to regenerate the front-end purification unit.

A photoelectric hydrogen production energy storage and cold energy recovery coupled dry ice production device and a use method are disclosed. The device comprises a photoelectric conversion liquid hydrogen energy storage unit, photoelectricity participates in electrolysis of water in the storage unit to prepare hydrogen, and surplus hydrogen meeting downstream process requirements is liquefied in the unit; liquid hydrogen is output, so that intermittent photoelectric energy is converted into hydrogen energy to be stored. When hydrogen production through electrolysis of water is insufficient but industrial hydrogen is continuously used, high-grade and low-grade cold energy of low-temperature liquid hydrogen serving as cold sources in the unit is recovered from industrial tail gas purified CO.sub.2 and air separation nitrogen, liquid nitrogen and liquid CO.sub.2 are output and used for the storage unit and dry ice production respectively, and the liquid hydrogen is reheated and supplied to a downstream process.

A blast furnace facility includes a process for capturing and sequestering CO2 generated from the facility process, producing hydrogen from the hot blast furnace gas, and using blast furnace gas as methanol feed. The CO2 rich streams from the facility may be sent to sequestration of some form via a sequestration compressor, thereby reducing the overall emissions from the facility. The other products generated by the facility are used as methanol feedstock and to produce hydrogen.

A blast furnace facility includes a process for capturing and sequestering CO2 generated from the facility process, generating hydrogen from hot blast furnace gas, and using blast furnace gas as methanol feed. The CO2 rich streams from the facility are sent to sequestration of some form via a sequestration compressor, thereby reducing the overall emissions from the facility. The other products generated by the facility are used as methanol feedstock and to produce hydrogen.

A combined plant for cryogenic separation and liquefaction of methane and carbon dioxide in a biogas stream, including a mixing means, a compressor, a first exchanger, a distillation column, a second exchanger, a separating means, an expanding means, and a separator vessel. Wherein, the mixing means is configured such that the recycle gas is the overhead vapour stream, and the first exchanger and the expanding means are combined.

An apparatus for forming solid carbon dioxide blocks comprises a chamber with an internal cavity, a flow control valve including a variable area orifice, an actuator configured to control the area of the variable area orifice and a controller configured to vary the are of the variable area orifice while liquid carbon dioxide is being flashed to solid carbon dioxide snow through the flow control valve. A method of forming carbon dioxide blocks comprises the steps of varying the area of an orifice while flowing liquid carbon dioxide through the orifice under sufficient pressure to flash the liquid carbon dioxide to solid carbon dioxide snow.

Provided herein are systems and methods for the processing of exhaust gases of industrial processes in order to reduce or eliminate emission of pollutants (including carbon dioxide) and store energy in the form of cryogenic liquids. Advantageously, the provided systems and methods utilize advanced heat exchanger systems to reduce or eliminate the net power required for operation. The heat exchangers are used both to reduce effluent gases to liquid temperatures as well as reheat previously cooled and separated gases, which can generate electricity via a turbo generator. The described systems and method may also produce cryogenic liquid products (Argon, Krypton, liquid Oxygen, liquid Nitrogen, etc.).

A method including entraining carbon dioxide (CO.sub.2) in a cement slurry composition and subjecting the cement slurry composition to conditions under which the CO.sub.2 achieves and maintains a supercritical state; and allowing the cement slurry composition to harden to form a hardened cement having CO.sub.2 sequestered therein.

A liquid natural gas (LNG) reforming system of the present invention may include a reformer provided to receive LNG from an LNG tank; a C02 PSA unit connected to the reformer and configured to extract carbon dioxide from off-gas generated from the reformer; a cooler connected to the C02 PSA unit and configured to cool and liquefy the carbon dioxide extracted by the C0.sub.2 PSA unit using the LNG supplied from the LNG tank to the reformer; a storage tank connected to the cooler and provided to store liquid carbon dioxide of the cooler therein; and a circulation pump provided to pump the liquid carbon dioxide from the cooler into the storage tank and circulate a part of the liquid carbon oxide into the cooler.