A system and method for capturing and separating carbon dioxide from mixed gas streams. The gas stream is processed in a structure including a compression module comprising a plurality of compressors, intercoolers and inter-stage condensate separators. The flow path from the compression module includes a plurality of flow separators, gas stream splitters, heat exchangers and at least a first mixer and a first expander. The gas stream is sequentially compressed and cooled to form process condensate and separate it from the compressed gas stream. The gas stream is further dried and cooled to liquefy carbon dioxide and separate it from the non-condensable portion. Selective expansion of liquid carbon dioxide streams provides cooling for the system, and further energy efficiency is achieved by selective recycling of portions of gas streams, allowing for compact equipment and economical operation, while providing for high purity product streams of carbon dioxide.

Carbon dioxide is recovered from an exhaust gas in the form of liquid carbon dioxide or supercritical carbon dioxide utilizing a rotary separator. Nitrogen gas recovered from the rotary separator can be expanded to provide cooling for carbon dioxide in a closed-loop CO2 power cycle that is used to cool the exhaust gas upstream of the rotary separator. The recovery can power itself and can produce excess electricity from waste heat.

Methods and systems for separating liquid components are disclosed. A vessel is provided containing a solids conveyance device. At least a first portion of the vessel acts as an indirect-contact heat exchanger and a second portion of the vessel contains a filter. A process liquid stream, containing a first component and a second component, is passed into the first portion of the vessel. A portion of the second component is frozen and entrained in the first portion of the vessel into the process liquid stream, resulting in a process slurry stream. The process slurry stream is passed into a second portion of the vessel by the solids conveyance device. The process slurry stream is separated into a solid product stream and a primary liquid product stream by passing the primary liquid product stream through the filter and out of the vessel while separately removing the solid product stream out of the vessel.

A compressing system includes a compression section that compresses a target gas to an intermediate pressure, which is equal to or higher than a critical pressure and lower than a target pressure to generate an intermediate supercritical fluid, a cooling section that cools the intermediate supercritical fluid generated in the compression section to near a critical temperature to generate an intermediate supercritical pressure liquid, and a pumping section that compresses the intermediate supercritical pressure liquid generated in the cooling section to a pressure that is equal to or higher than the target pressure. At least one of the intermediate supercritical pressure liquid compressed in the pumping section, a low-temperature liquid generated by extracting the intermediate supercritical pressure liquid on the upstream side of the pumping section to reduce pressure to near the critical pressure, and an external cooling medium is used as a cooling medium in the cooling section.

A carbon dioxide recovery device provided with a separation device that separates carbon dioxide from to-be-separated gas (for example, combustion exhaust gas) containing carbon dioxide, wherein: in order from the upstream side where the to-be-separated gas is supplied, the separation device and carbon dioxide sublimators, which sublimate (solidify) carbon dioxide that was separated in the separation device, are connected in series, refrigerant circuits in which a fluid having cold heat serves as the refrigerant, are connected to the carbon dioxide sublimators, and the refrigerant is used to sublimate (solidify) the carbon dioxide; and when the carbon dioxide is sublimated (solidified), the carbon dioxide sublimators are depressurized and set to negative pressure so as to draw in the carbon dioxide separated at the separation device.

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.

A method to condense and recover CO.sub.2 from CO.sub.2 containing streams. A first step involve providing at more than one heat exchanger, with each heat exchanger having a first flow path for passage of a first fluid and a second flow path for passage of a second fluid. A second step involves passing a stream of very cold natural gas sequentially along the second flow path of each heat exchanger until it is heated for distribution and concurrently passing a CO.sub.2 containing stream sequentially along the first flow path of each heat exchanger, allowing the water vapor portion of the CO.sub.2 containing stream to condense and precipitate on the condensing heat exchangers. A third step involves passing a water vapor free CO.sub.2 containing stream to a cryogenic heat exchanger to condense, precipitate and recover CO.sub.2. This processes results in the recovery of CO.sub.2 and water vapor from CO.sub.2 containing streams using condensing heat exchangers, chiller, compressor, expander and power generator to recover the low value thermal heat available in CO.sub.2 containing waste streams.

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.

A thermoacoustic refrigerator includes at least one pair of pulse combustion tubes (10), preferably Rijke tubes, each tube (10) having a pair of spaced-apart Stirling engines (12), coupled together but with no separating membrane therebetween.

Systems and methods are provided for recovering helium from a feed comprising helium, carbon dioxide, and at least one intermediate component having a volatility between those of helium and carbon dioxide. In particular, processes of the present invention comprise separating the carbon dioxide and the components of intermediate volatility from the helium at a temperature greater than −82.7° C. to form a helium-rich product stream, wherein the concentration of at least one of the intermediate components in the helium-rich product stream is lower than its concentration in the feed stream, and wherein at least part of the separation is effected by contacting a vapor with a liquid.