A method for controlling production of high pressure gaseous oxygen in a cryogenic air separation unit that uses a high pressure gaseous oxygen bypass together with adjustments to the split of the incoming compressed and purified air between the boiler air circuit and the turbine air circuit such that the volumetric ratio of the boiler air stream to the turbine air stream is reduced to between about 0.15:1 and 0.35:1.

An apparatus for the separation of air by cryogenic distillation comprises a column system, a heat exchanger, a turbine, means for sending compressed and purified air at a first pressure to be cooled at the first pressure in the heat exchanger, means for sending a first gaseous stream having a nitrogen content at least that of air to be cooled and liquefied or pseudo liquefied in the heat exchanger to form a liquefied stream, means for sending at least part of the liquefied stream to be warmed and vaporized in the heat exchanger to a first intermediate temperature of the heat exchanger to form a vaporized stream, means for removing the vaporized stream from an intermediate section of the heat exchanger, a conduit for sending the vaporized stream to be expanded, in the turbine to form an expanded stream, a conduit for sending at least part of the expanded stream to the column system, a conduit for sending a second gaseous stream having the same nitrogen content as the first stream to be cooled in the heat exchanger, means for removing at least part of the second gaseous stream from an intermediate section of the heat exchanger at a second intermediate temperature and sending the second gaseous stream to the turbine to be expanded with the vaporized stream.

In a method for reheating an atmospheric vaporizer, a cryogenic liquid is vaporized by heat exchange with ambient air in the atmospheric vaporizer and to reheat the vaporizer, a gas is sent thereto at a temperature of at least 0 C., this gas originating from a cryogenic distillation air separation unit.

A method is provided for production of gaseous oxygen at high pressures by splitting a main air feed into at least three separate streams, with the first stream being fed to a heat exchanger and then a column system for rectification; the second stream being further compressed in a warm booster, partially cooled in the heat exchanger, expanded in a turbine coupled to the warm booster and then fed to the column system; the third stream being expanded in a warm expander before being introduced to the heat exchanger and introduced to the column system. In certain embodiments, substantially all of the main air feed is eventually introduced to the column system for rectification, resulting in reduced sizing of a main air compressor and improved product recoveries.

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.

An apparatus for separation of air by cryogenic distillation comprising: a system of columns; a first turbine; a warm compressor coupled to the first turbine; a second turbine; a cold compressor coupled to the second turbine; a heat exchanger; means for sending air cooled in the heat exchanger at an intermediate temperature of the heat exchanger to the cold compressor; means for sending expanded air from the second turbine to the system of columns; means for sending air compressed in the cold compressor to an intermediate point of the heat exchanger and then at least in part to the system of columns via a first valve; means for sending air compressed in the cold compressor to the inlet of the first turbine via a second valve without passing through the heat exchanger, wherein the means for sending air compressed in the cold compressor to the inlet of the first turbine via the second valve without passing through the heat exchanger is also connected to the inlet of the first turbine; means for sending a fraction of air cooled in the heat exchanger to an intermediate temperature of the latter to the first turbine; means for sending expanded air from the first turbine to the system of columns; and a bypass line provided with an expansion valve configured to send air from the cold compressor to the system of columns without passing through the heat exchanger.

A method for producing an air product in an air separation plant. Feed air is cooled at least in a main air compressor and is fed into a distillation column system. A fluid storage unit and a cold accumulator are used. In a first operating mode, fluid is stored in the fluid storage unit and the cold accumulator is heated. In a third operating mode, fluid is released and the cold accumulator is cooled, and in a second operating mode, fluid is neither stored nor released.