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.

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.

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.

The invention relates to a method and apparatus for removing CO.sub.2 gas emissions from a coal combustion power plant, comprising a means for physically removing the CO.sub.2 gas from the coal, and then using a turbo compressor and turbo expander device to produce super chilled air, which can then be mixed with the CO.sub.2 gas to form frozen CO.sub.2 crystals which can agglomerate together to form dry ice blocks, wherein the ice blocks can be easily transported and stored, and/or used for commercial purposes (such as for the beverage industry). The heating (compression) and cooling (expansion) processes preferably generate additional energy which can then be used to offset the substantial costs associated with separating the CO.sub.2 gas from the coal.

A method and a plant for producing liquid CO.sub.2 from flue gas as described with reduced energy consumption and a stable behavior.

A cryogenic method for capturing carbon dioxide in the gaseous emissions produced from the fossil-energy combustion of solid, liquid, or gaseous fossil fuels in a power generation installation employing an OxyFuel mode of combustion. The method includes: producing essentially pure carbon dioxide under elevated pressure and at near ambient temperatures in a Carbon-Dioxide Capture Component from the carbon-dioxide content of at least a part of the gaseous emissions produced from fossil-energy fueled combustion in the Oxyfuel mode of combustion; separating atmospheric air in an Air Separation Component into a stream of liquid nitrogen and a stream of high-purity oxygen; supplying low temperature, compressed purified air to a cryogenic air separation unit (cold box) within the Air Separation Component; collecting low temperature thermal energy from coolers employed within the Carbon-Dioxide Capture Component and the Air Separation Component; and converting the collected thermal energy to electricity within a Thermal-Energy Conversion Component.

A process for separating carbon dioxide from a fluid containing carbon dioxide, NO.sub.2, and at least one of oxygen, argon, and nitrogen comprises the steps of separating at least part of the fluid into a carbon dioxide enriched stream, a carbon dioxide depleted stream comprising CO.sub.2 and at least one of oxygen, argon, and nitrogen and a NO.sub.2 enriched stream and recycling said NO.sub.2 enriched stream upstream of the separation step.

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.

A method for liquefying ammonia can include the steps of: providing a pressurized carbon dioxide stream from a power generating facility; expanding the pressurized carbon dioxide stream to a lower pressure that is sufficient to produce a dual phase carbon dioxide fluid; introducing the dual phase carbon dioxide fluid to a gas-liquid separator; withdrawing a liquid stream from the gas-liquid separator; and liquefying an ammonia gas stream in an ammonia liquefier by indirect contact with the liquid stream from the gas-liquid separator, thereby forming a liquid ammonia stream and a gaseous carbon dioxide stream.