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.

A bio-renewable conversion process for making fuel from bio-renewable feedstocks is combined with a hydrogen production process that includes recovery of CO.sub.2. The integrated process uses a purge gas stream comprising hydrogen from the bio-renewable hydrocarbon production process in the hydrogen production process.

In a method for separating at least one lighter impurity of a gaseous mixture containing at least 30% mol of carbon dioxide, a liquid (101) enriched with carbon dioxide is drawn off into a vat of a distillation column (25), at least part (27) of the liquid enriched with carbon dioxide is vaporized and then heated to a first temperature higher than the boiling temperature thereof in the exchanger and leaves the exchanger at the hot end thereof, and at least part of the vaporized and heated liquid is sent from the hot end of the exchanger at the first temperature, without being cooled in the exchanger and without having been compressed, to the lower part of the distillation column, where it participates in the distillation while enriching itself.

The invention relates to a method for separating a feed gas containing at least 20 Mol % of CO2 and at least 20 Mol % of methane, by partial condensation and/or by distillation, the gas at a pressure of at least 40 bar abs, including expanding at least one portion of the feed gas in a turbine producing an expanded feed stream at a pressure of less than 90 bar abs, separating at least one portion of the expanded feed stream by partial condensation and/or by distillation thus obtaining a CO.sub.2-depleted gas and a CO.sub.2-enriched liquid, wherein the temperature of the expanded feed gas at the outlet of the turbine is below −56.6° C., and wherein the process does not use an external refrigeration source; and wherein the CO.sub.2-depleted gas is introduced into a supplementary separation step, in order to obtain a stream that is more depleted in CO.sub.2 and a CO.sub.2-rich stream.

Techniques for providing carbon dioxide include generating thermal energy, an exhaust fluid, and electrical power from a power plant; providing the exhaust fluid and the generated electrical power to an exhaust fluid scrubbing system to separate components of the exhaust fluid; capturing heat from a source of heat of an industrial process in a heating fluid; transferring the heat of the industrial process captured in the heating fluid to a carbon dioxide source material of a direct air capture (DAC) system; providing the generated electrical power from the power plant to the DAC system; providing the thermal energy from the power plant to the DAC system; and separating, with the transferred portion of the heat of the industrial process and the provided thermal energy, carbon dioxide from the carbon dioxide source material of the DAC system.

A process for producing liquefied natural gas and liquid carbon dioxide from a natural gas feed gas comprising at least the following steps: Separation of a natural gas feed gas into a CO.sub.2-enriched gas stream and a natural gas stream; Cooling of said natural gas in a heat exchanger; Purification of the in step 1 from compounds containing at least six carbon atoms; At least partial condensation of said gas stream resulting from step 3 to form a two-phase stream; Separation of said two-phase stream resulting from step 4 to form a gas stream and a liquid stream; Condensation of the gas stream resulting from step 5 to form a liquefied gas containing less than 5 ppm by volume of compounds containing at least six carbon atoms; Liquefaction of the CO.sub.2-enriched gas stream resulting from step 1 with a portion of the liquid stream resulting from step 5.

A carbon dioxide capture system includes a first heat exchanger configured to exchange heat between an exhaust stream and a lean carbon dioxide effluent stream. The carbon dioxide capture system also includes a first turboexpander including a first compressor 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. The carbon dioxide membrane unit is configured to separate the exhaust stream into the lean carbon dioxide effluent stream and a rich carbon dioxide effluent stream. The carbon dioxide membrane unit is further configured to channel the lean carbon dioxide effluent stream to the first heat exchanger.

A gas recovery system for a compressor, said gas recovery system being equipped with: a distillation column that brings a supply gas in a liquid state into contact with a mixed gas, thereby cooling and liquefying a process gas in the mixed gas, and heating and gasifying the liquid supply gas; a process gas recovery line that is connected to the lower part of the distillation column and recovers the liquid process gas discharged from the distillation column; and a supply gas recovery line that is connected to the upper part of the distillation column and recovers the gaseous supply gas discharged from the distillation column.

In a method for compressing a gas that is to be separated in a low-temperature CO.sub.2 separation unit using at least one partial condensation step and/or at least one distillation step, the gas that is to be separated has a variable composition and/or variable flow rate, the gas that is to be separated is compressed in a compressor to produce a compressed gas and the inlet pressure of the gas that is to be separated, entering the compressor, is modified according to the CO.sub.2 content and/or the flow rate of the gas that is to be separated so as to reduce the variations in volumetric flow rate of the gas that is to be separated entering the compressor.

Lake Kivu contains ˜50 million tonnes (MT) dissolved biomethane. Efficient use is problematic from massive associated CO.sub.2: ˜600 MT. Conventional extraction scrubs CO.sub.2 with ˜50% overall CH.sub.4 loss, and returns ˜80% CO.sub.2 into the deep lake, preserving a catastrophe hazard threatening >2 M people. Methods and systems are disclosed coupling: (1) efficient CH.sub.4+CO.sub.2 degassing; (2) optional oxyfuel power generation and CO.sub.2 power cycle technologies; and (3) CO.sub.2 capture, processing, storage and use in a utilization hub. The invention optimally allows power production with >2× improved efficiency plus cryo-energy storage and large-scale greentech industrialization. CO.sub.2-utilizing products can include: Mg-cements/building materials, algal products/biofuels, urea, bioplastics and recycled materials, plus CO.sub.2 for greenhouse agriculture, CO.sub.2-EOR/CCS, off-grid cooling, fumigants, solvents, carbonation, packaging, ores-, biomass-, and agro-processing, cold pasteurization, frack and geothermal fluids, and inputs to produce methanol, DME, CO, syngas, formic acid, bicarbonate and other greentech chemicals, fuels, fertilizers and carbon products.