The present invention is a process for removing carbon dioxide from a compressed gas stream including cooling the compressed gas in a first heat exchanger, introducing the cooled gas into a de-sublimating heat exchanger, thereby producing a first solid carbon dioxide stream and a first carbon dioxide poor gas stream, expanding the carbon dioxide poor gas stream, thereby producing a second solid carbon dioxide stream and a second carbon dioxide poor gas stream, combining the first solid carbon dioxide stream and the second solid carbon dioxide stream, thereby producing a combined solid carbon dioxide stream, and indirectly exchanging heat between the combined solid carbon dioxide stream and the compressed gas in the first heat exchanger.

Light gases such as helium are extracted from a carbon dioxide-containing feed stream by distillation. Costly dehydration steps are avoided by pumping the liquid bottoms stream leaving the distillation column without vaporization so as to ensure that any water present in the feed remains in solution with the bulk stream leaving the process. This prevents any liquid phase water causing corrosion or solid ice or hydrates forming to plug the flow.

In a method for separating a mixture containing carbon dioxide, the mixture is cooled in a heat exchanger and partially condensed and a first liquid is separated from the mixture in a first system operating at low temperature comprising at least one first phase separator and a gas from the first system is treated in a membrane system to produce a permeate and a non-permeate, the gas from the first system being divided into two portions, a first portion being sent to the membrane system without being heated and a second portion being heated to at least an intermediate temperature of the heat exchanger and then sent to the membrane system without being cooled.

Various illustrative embodiments of a system and process for recovering high-quality biomethane and carbon dioxide product streams from biogas sources and utilizing or sequestering the product streams are provided. The system and process synergistically yield a biomethane product which meets gas pipeline quality specifications and a carbon dioxide product of a quality and form that allows for its transport and sequestration or utilization and reduction in greenhouse gas emissions. The system and process result in improved access to gas pipelines for products, an improvement in the carbon intensity rating of the methane fuel, and improvements in generation of credits related to reductions in emissions of greenhouse gases.

A plant for the production of liquefied methane having, arranged in series, a means for the generation of methane from hydrogen and carbon dioxide, a means for drying the gas mixture produced by the methane generation means, a purification means configured to remove carbon dioxide from the gas mixture dried in the drying means, a liquefier configured to liquefy the methane contained in the gas mixture purified in the purification means, and a liquefied gas storage facility configured to store the methane liquefied by the liquefier.

Various illustrative embodiments of a system and process for recovering high-quality biomethane and carbon dioxide product streams from biogas sources and utilizing or sequestering the product streams are provided. The system and process synergistically yield a biomethane product which meets gas pipeline quality specifications and a carbon dioxide product of a quality and form that allows for its transport and sequestration or utilization and reduction in greenhouse gas emissions. The system and process result in improved access to gas pipelines for products, an improvement in the carbon intensity rating of the methane fuel, and improvements in generation of credits related to reductions in emissions of greenhouse gases.

A carbon dioxide electrolytic device in an embodiment includes: an electrochemical reaction cell including: a first accommodation part that accommodates gas or a first electrolytic solution containing CO.sub.2; a second accommodation part that accommodates a second electrolytic solution containing H.sub.2O; a diaphragm provided between the first and second accommodation parts; a cathode that is in contact with the gas or the first electrolytic solution; and an anode that is in contact with the second electrolytic solution; a first supply part that supplies the gas or the first electrolytic solution to the first accommodation part; a second supply part that supplies the second electrolytic solution to the second accommodation part; and a carbon dioxide separation part that is connected to a discharge portion of a discharge containing O.sub.2 and CO.sub.2 from the second accommodation part and includes a cryogenic separation device to separate CO.sub.2 from a gas component in the discharge.

A cryogenic carbon capture system includes a flue gas cooling device in fluid communication with a heat engine. The flue gas cooling device receives a fluid stream that is downstream from the heat engine and a cooled liquid coolant stream so that the fluid stream is cooled by the cooled liquid coolant stream and a cooled flue gas stream is formed. A cryogenic carbon capture unit receives at least a portion of the cooled flue gas stream and separates carbon dioxide from the first portion of the cooled flue gas stream so that a clean flue gas stream and a carbon dioxide stream are formed. A liquid coolant cooling device receives the clean flue gas stream and a liquid coolant stream and cools the liquid coolant stream using the clean flue gas stream so that the cooled liquid coolant stream is formed and provided to the flue gas cooling device. The heat engine is in fluid communication with the cryogenic carbon capture system and receives a portion of a split stream that is downstream from the flue gas cooling device as an exhaust gas recirculation stream and an air stream.

A CO2 separation and liquefaction system such as might be used in a carbon capture and sequestration system for a fossil fuel burning power plant is disclosed. The CO2 separation and liquefaction system includes a first cooling stage to cool flue gas with liquid CO2, a compression stage coupled to the first cooling stage to compress the cooled flue gas, a second cooling stage coupled to the compression stage and the first cooling stage to cool the compressed flue gas with a CO2 melt and provide the liquid CO2 to the first cooling stage, and an expansion stage coupled to the second cooling stage to extract solid CO2 from the flue gas that melts in the second cooling stage to provide the liquid CO2.

A system captures carbon dioxide from a flue gas of a power generation facility by using cold heat of liquefied natural gas and utilizes the captured carbon dioxide for mining natural gas, using heat of the flue gas to regasify the LNG. Solidified dry ice is captured from gaseous carbon dioxide contained in the flue gas, and the captured dry ice is used as filler when mining natural gas. The system includes a mining facility, a vehicle to transport LNG liquefied by the mining facility; and a facility for regasifying the transported LNG and capturing dry ice from the carbon dioxide. In the regasification and capture facility, the flue gas exchanges heat with the LNG, thereby regasifying the LNG at an increased temperature and capturing the dry ice from the carbon dioxide. The captured dry ice is transported to the mining facility, which uses it for mining the natural gas.