A method for obtaining one or more air products, wherein an air separation system having a rectification column system is used, in which pressurized air is processed in an adjustable total air volume, wherein the total air volume is set to a first value during a first operating period and set to a second value that is different from the first value during a second operating period, and wherein the setting of the total air volume is changed from the first value to the second value in a third operating period from a first time to a second time. The second operating period is after the first operating period, the third operating period is between the first operating period and the second operating period. In the third operating period, a setting of a volume of a fluid, is changed from a third time up to a fourth time.

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 liquefaction of an industrial gas by integration of a methanol plant and an air separation unit (ASU) is provided. The method can include the steps of: (a) providing a pressurized natural gas stream, a pressurized purge gas stream originating from a methanol plant, and a pressurized air gas stream comprising an air gas originating from the ASU; (b) expanding three different pressurized gases to produce three cooled streams, wherein the three different pressurized gases are the pressurized natural gas stream, the pressurized purge gas stream, and the pressurized air gas stream; and (c) liquefying the industrial gas in a liquefaction unit against the three cooled streams to produce a liquefied industrial gas stream. The industrial gas to be liquefied is selected from the group consisting of a first portion of the pressurized natural gas stream, a nitrogen gas stream, hydrogen and combinations thereof.

A method for the liquefaction of an industrial gas by integration of a methanol plant and an air separation unit (ASU) is provided. The method can include the steps of: (a) providing a pressurized natural gas stream, a pressurized purge gas stream composed predominately of hydrogen and originating from a methanol plant, and a pressurized air gas stream comprising an air gas from the ASU; (b) expanding three different pressurized gases to produce three cooled streams, wherein the three different pressurized gases consist of the pressurized natural gas stream, the pressurized purge gas stream, and the pressurized air gas stream; and (c) liquefying the industrial gas in a liquefaction unit against the three cooled streams to produce a liquefied industrial gas stream, wherein the industrial gas to be liquefied is selected from the group consisting of a first portion of the pressurized natural gas stream, a nitrogen gas stream, hydrogen and combinations thereof

It is proposed to integrate a gas processing unit with a liquefaction unit. The industrial gas stream may be but is not limited to air gases of oxygen, nitrogen argon, hydrocarbon, LNG, syngas or its components, CO.sub.2, or any other molecule or combination of molecules. It is proposed to integrate the underutilized process inefficiencies of a gas processing unit into the liquefaction unit to produce a liquid at a reduced operating cost. The gas processing unit may be any system or apparatus which alters the composition of a feed gas. Examples could be, but are not limited to, a methanol plant, steam methane reformer, cogeneration plant, and partial oxidation unit.

A method and apparatus to obtain a compressed nitrogen product by low-temperature fractionation of air in a distillation column system. The system has a high-pressure column, a low-pressure column, a main condenser, and a low-pressure column top condenser. Bottoms liquid from the low-pressure column is evaporated in the top condenser and the gas formed is decompressed to perform work that drives a cold compressor. A gaseous first compressed nitrogen product stream from the high-pressure column is warmed in the main heat exchanger. A further gaseous nitrogen stream from the low-pressure column is compressed in the cold compressor and warmed as a second compressed nitrogen product stream in the main heat exchanger. The cold compressor overcomes a pressure differential which is at least equal to two thirds of the pressure differential between the top of the high-pressure column and the top of the low-pressure column.

The present invention provides methods and system for power generation using a high efficiency combustor in combination with a CO.sub.2 circulating fluid. The methods and systems advantageously can make use of a low pressure ratio power turbine and an economizer heat exchanger in specific embodiments. Additional low grade heat from an external source can be used to provide part of an amount of heat needed for heating the recycle CO.sub.2 circulating fluid. Fuel derived CO.sub.2 can be captured and delivered at pipeline pressure. Other impurities can be captured.

The invention relates to a unit and method for melting in a furnace comprising a combustion-heated melting chamber, in which the air is heated by means of heat exchange with the fumes generated by combustion. The heated air is used in a gas turbine in order to generate electrical and/or mechanical energy. In addition, the effluent from the gas turbine is used to pre-heat the combustion oxygen and/or gaseous fuel upstream of the melting chamber.

The present invention provides methods and system for power generation using a high efficiency combustor in combination with a CO.sub.2 circulating fluid. The methods and systems advantageously can make use of a low pressure ratio power turbine and an economizer heat exchanger in specific embodiments. Additional low grade heat from an external source can be used to provide part of an amount of heat needed for heating the recycle CO.sub.2 circulating fluid. Fuel derived CO.sub.2 can be captured and delivered at pipeline pressure. Other impurities can be captured.

A cooling arrangement for an at least two-stage compressed air generator comprises an intercooler arranged between a first and a second compressor stage, an aftercooler arranged after the second compressor stage, and a subassembly cooler, which absorbs heat from further subassemblies of the compressed air generator. A coolant circuit comprises a main cooler, the cold side supplying a cooled coolant parallel to the respective coolant inlet of the intercooler, of the aftercooler and of the subassembly cooler, and the hot side receiving the heated coolant exiting in parallel at the respective coolant outlet of the intercooler and of the aftercooler. The coolant outlet of the subassembly cooler is connected to a feed inlet of the intercooler and/or of the aftercooler.