An apparatus is provided for maintaining a steady flow rate and pressure of a carbon dioxide stream at high pressure when a low-pressure source of the carbon dioxide varies with time. Liquid level in an accumulator that is sized to accommodate variations in supply rate is controlled by sub-cooling of liquid entering the accumulator and heating in the accumulator, the sub-cooling and heating being controlled by a pressure controller operable in the accumulator.

The present disclosure relates to systems and methods that provide a low pressure liquid CO.sub.2 stream. In particular, the present disclosure provides systems and methods wherein a high pressure CO.sub.2 stream, such as a recycle CO.sub.2 stream from a power production process using predominately CO.sub.2 as a working fluid, can be divided such that a portion thereof can be expanded and used as a cooling stream in a heat exchanger to cool the remaining portion of the high pressure CO.sub.2 stream, which can then be expanded to form a low pressure CO.sub.2 stream, which may be in a mixed form with CO.sub.2 vapor. The systems and methods can be utilized to provide net CO.sub.2 from combustion in a liquid form that is easily transportable.

Embodiments described herein provide methods and systems for separating a mixed ethane and CO.sub.2. A method described includes generating a liquid stream including ethane and CO.sub.2. The liquid stream is flashed to form an ethane vapor stream and solid CO.sub.2. The solid CO.sub.2 is accumulated in an accumulation vessel and the gas is removed from the top of the accumulation vessel.

A proposed method provides a highly efficient fueled power output augmentation of the liquid air energy storage (LAES) with zero carbon emissions of its exhaust. It combines the production of liquid air using excessive power from the renewable or/and conventional energy sources and an effective recovery of stored air for production of on-demand power in the fueled supercharged reciprocating internal combustion engine (ICE) and associated expanders. A mutually beneficial integration between the LAES and ICE makes possible to recover the ICE exhaust energy for increase in power produced by the LAES expanders and to use a cold thermal energy of air re-gasified at the LAES facility for cryogenic capture of CO.sub.2 emissions from the ICE exhaust.

Systems and methods to separate carbon dioxide from flue gases and sequester carbon dioxide are described here. By using the properties of carbon dioxide and the temperature in a body of water (e.g., the ocean or freshwater body of water) or the temperatures of the ambient atmosphere, gaseous carbon dioxide can be converted to a liquid and separated from other gases. Pressure used to separate carbon dioxide from other gases may also be used to sequester liquid carbon dioxide. The liquid carbon dioxide is inert and can be discharged into the ocean without dissolving in seawater and acidifying the ocean. The liquid carbon dioxide may further be densified to be denser than seawater. The liquid carbon dioxide can then sink to the bottom of the ocean or be injected into ocean sediments or sediments and rocks beneath the ocean floor, inert and sequestered for the long term.

A CO.sub.2 energy storage system includes a storage tank that stores a CO.sub.2 slurry, including dry ice and liquid CO.sub.2, at CO.sub.2 triple point temperature and pressure conditions. The storage system also includes a first pump coupled in flow communication with the storage tank. The first pump is configured to receive the CO.sub.2 slurry from the storage tank and to increase a pressure of the CO.sub.2 slurry to a pressure above the CO.sub.2 triple point pressure. The energy storage system further includes a contactor coupled in flow communication with the first pump. The contactor is configured to receive the high pressure CO.sub.2 slurry from the pump and to receive a first flow of gaseous CO.sub.2 at a pressure above the CO.sub.2 triple point pressure. The gaseous CO.sub.2 is contacted and then condensed by the melting dry ice in the slurry to generate liquid CO.sub.2

Embodiments described herein provide methods and systems for separating a mixed ethane and CO.sub.2. A method described includes generating a liquid stream including ethane and CO.sub.2. The liquid stream is flashed to form an ethane vapor stream and solid CO.sub.2. The solid CO.sub.2 is accumulated in an accumulation vessel and the gas is removed from the top of the accumulation vessel.

Exhaust gas from which impurities have been removed through pressurization and cooling by a compressor-based impurity separation mechanism is further cooled by a refrigerator-type heat exchanger. Drain produced from the cooling by the refrigerator-type heat exchanger is discharged and supplied as an alkalinity control agent to at least upstream of an aftercooler in a first impurity separator.

In an example aspect, a system for subcooling liquid carbon dioxide to be used for dry ice production comprises a refrigeration unit that includes cooling fluid within a cooling fluid circuit and a condenser to cool the cooling fluid. The system further comprises a heat exchanger connectable along a first fluid path between a liquid carbon dioxide source and dry ice production equipment via a liquid carbon dioxide supply line, the heat exchanger having a second fluid path connectable to the refrigeration unit via the cooling fluid circuit; wherein the heat exchanger maintains the first fluid path and the second fluid path adjacent to one another to facilitate heat exchange therebetween, and an outlet that outputs the liquid carbon dioxide to the dry ice production equipment and is in fluid communication with the heat exchanger through the liquid carbon dioxide supply line.

A system and method for power generation and CO.sub.2 sequestration include a fuel cell system configured to generate power using natural gas (NG), a container configured to store liquid natural gas (LNG), and a fluid processor configured to convert LNG received from the container into NG and to convert exhaust output from the fuel cell system to dry ice by transferring heat between and the LNG and the exhaust.