The present disclosure relates to the technical field of natural gas power generation, and particularly discloses a natural gas combined power generation process with zero carbon emission, the process comprising: introducing the pressurized air into an air separation facility to obtain liquid oxygen and liquid nitrogen, wherein the liquid oxygen is used for gasification and power generation, the liquid nitrogen is applied as the coolant of flue gas, and then used for the gasification and power generation; the liquid nitrogen and a part of liquid oxygen stored during the valley period with low electricity load are provided for use during the peak period with high electricity load; the natural gas, oxygen and the recyclable CO.sub.2 jointly enter a combustion gas turbine for burning to drive an air compressor and a generator to rotate at a high speed, the air compressor compresses the air to a pressure of 0.40.8 MPa, the generator generates electricity; the high-temperature combustion flue gas performs the supercritical CO.sub.2 power generation, its coolant is liquid oxygen; the moderate temperature flue gas then exchanges heat with liquid nitrogen, the liquid nitrogen vaporizes for power generation, the cooled flue gas is dehydrated and subjects to distillation and separation to obtain the recovered CO.sub.2, a part of the CO.sub.2 can be returned for circulation and temperature control, another part of the CO.sub.2 may be used for replenishment of work medium for supercritical CO.sub.2 power generation, and the remaining part of CO.sub.2 may be sold outward as liquid CO.sub.2 product. During the peak period with high electricity load, the liquid nitrogen stored during the valley period with low electricity load and separated during the peak period is pumped and pressurized and then subjects to heat exchange and vaporization for power generation. The power generation process provided by the present disclosure not only solves the difficult problems in the existing natural gas combined power generation technology such as high water consumption, low power generation efficiency and small range of peak load adjustment capacity; but also can compress air with high unit volume for energy storage with a high conversion efficiency, and greatly reduce load of the air compressor, thereby perform CO.sub.2 capture and utilization with low cost, zero NO.sub.x emission and discharging fuel gas at a normal temperature, and significantly improve the power generation efficiency.

The method for producing liquid hydrogen can include the steps of: introducing pressurized natural gas from a high pressure natural gas pipeline to a gas processing unit under conditions effective for producing a purified hydrogen stream; and introducing the purified hydrogen stream to a hydrogen liquefaction unit under conditions effective to produce a liquid hydrogen stream, wherein the hydrogen liquefaction unit provides a warm temperature cooling and a cold temperature cooling to the purified hydrogen stream, wherein the warm temperature cooling is provided by utilizing letdown energy of a pressurized stream selected from the group consisting of a nitrogen stream sourced from a nitrogen pipeline, a natural gas stream sourced from the high pressure natural gas pipeline, an air gas sourced from an air separation unit, and combinations thereof, wherein the cold temperature is provided by utilizing letdown energy of the purified hydrogen stream.

A method for the production of liquefied natural gas (LNG) using a cold fluid provided from a cryogenic unit, such as an air separation unit or nitrogen liquefier, is provided. The method may include the steps of: withdrawing a nitrogen stream from a cryogenic unit, wherein the nitrogen stream is at a temperature between about 155 C. to about 193 C.; and liquefying a natural gas stream in a natural gas liquefaction unit using the nitrogen stream from the cryogenic unit.

A method for compression of an incoming feed air stream using at least two variable speed compressor drive assemblies controlled in tandem is provided. The first variable speed drive assembly drives at least one compression stage in the lower pressure compressor unit driven while the second variable speed drive assembly drives higher pressure compression stage disposed either in the common air compression train or the split functional compression train of the air separation plant. The first and second variable speed drive assemblies are preferably high speed, variable speed electric motor assemblies each having a motor body, a motor housing, and a motor shaft with one or more impellers directly and rigidly coupled to the motor shaft via a sacrificial rigid shaft coupling.

A method for compression of an incoming feed air stream using at least two variable speed compressor drive assemblies controlled in tandem is provided. The first variable speed drive assembly drives at least one compression stage in the lower pressure compressor unit driven while the second variable speed drive assembly drives higher pressure compression stage disposed either in the common air compression train or the split functional compression train of the air separation plant. The first and second variable speed drive assemblies are preferably high speed, variable speed electric motor assemblies each having a motor body, a motor housing, and a motor shaft with one or more impellers directly and rigidly coupled to the motor shaft via a sacrificial rigid shaft coupling.

An apparatus for producing a natural gas using carbon dioxide and water in air that includes an air-compressing member, a water collecting member, a water storing member, a carbon dioxide collecting member, a water electrolysis member, and a methanation reaction member. The water electrolysis member electrolyzes water separated from compressed air. The methanation reaction member generates a natural gas by reacting hydrogen from the electrolysis and carbon dioxide from the carbon dioxide collecting member. A method of producing a natural gas using carbon dioxide and water in air includes supplying hydrogen electrolyzed from water separated from air and carbon dioxide collected from the dry air to a methanation reaction member to generate a natural gas. A natural gas-synthesizing equipment system includes an apparatus for producing a natural gas using carbon dioxide and water in air.

A method for compression of an incoming feed air stream using at least two variable speed compressor drive assemblies controlled in tandem is provided. The first variable speed drive assembly drives at least one compression stage in the lower pressure compressor unit driven while the second variable speed drive assembly drives higher pressure compression stage disposed either in the common air compression train or the split functional compression train of the air separation plant. The first and second variable speed drive assemblies are preferably high speed, variable speed electric motor assemblies each having a motor body, a motor housing, and a motor shaft with one or more impellers directly and rigidly coupled to the motor shaft via a sacrificial rigid shaft coupling.

A process for recovering at least one fluid (e.g. argon gas and/or nitrogen gas, etc.) from a feed gas (e.g. air) can provide an improved recovery of argon and/or nitrogen as well as an improvement in operational efficiency. Some embodiments can be adapted so that at least a portion of a mixed nitrogen-oxygen fluid is at least partially vaporized and fed to a low pressure column.

A supply quantity adjustment device 500 comprises: a total demand quantity calculation unit 502 that calculates a total demand quantity used at a supply destination, based on plant information; an excess/deficit information setting unit 503 that compares the total demand quantity and a flow rate set value and sets a first calculated pressure value; a backup coefficient setting unit that sets a backup coefficient set value based on a reference gasholder pressure, the first calculated pressure value, a reference backup pressure set value, and a measured gasholder pressure value; and a production coefficient setting unit that compares a production pressure set value obtained by adding the reference gasholder pressure and a first pressure output value with the measured gasholder pressure value, and sets a production coefficient so as to modify a variation in the quantity of product gas produced by the air separation apparatus.

The present disclosure relates to systems and methods useful for power production. In particular, a power production cycle utilizing CO.sub.2 as a working fluid may be configured for simultaneous hydrogen production. Beneficially, substantially all carbon arising from combustion in power production and hydrogen production is captured in the form of carbon dioxide. Further, produced hydrogen (optionally mixed with nitrogen received from an air separation unit) can be input as fuel in a gas turbine combined cycle unit for additional power production therein without any atmospheric CO.sub.2 discharge.