A method for operating an air separation plant having a distillation column system, a heat exchanger, and an adsorber, wherein, in a first time period, a first operating mode is carried out and, in a second time period following the first time period, a second operating mode is carried out. In a third time period between the second time period and the first time period, a third operating mode is carried out, in which third operating mode compressed air is at least partially freed of water and carbon dioxide in the adsorber and at least part of said compressed air is cooled in the heat exchanger, an air product is removed from the distillation column system and at least part of said air product is heated in the heat exchanger.

A nitrogen producing cryogenic air separation unit with an excess air circuit is provided. The nitrogen producing cryogenic air separation unit is capable of producing high pressure gaseous nitrogen without the use of a nitrogen product compressors and is also capable of producing high rates of liquid nitrogen without adding additional compression stages in the main air compressor and/or without a nitrogen recycle compressor.

Disclosed in the present invention are a pressure equalizing system for air separation purification, and a control method. The system comprises: a first air main pipe; a pressurizing gas pipeline, which is connected to the first air main pipe and used for receiving a pressurizing gas and delivering same to the first air main pipe; and a control valve, located on the pressurizing gas pipeline, and having a degree of opening regulated by the flow regulator, thereby regulating an air intake amount of the pressurizing gas pipeline. The present invention solves the problem of an air separation rectification process being affected when dry nitrogen is used for pressure equalization of an adsorber; in the switching process of entering an adsorption stage from a regeneration stage, pressurizing dry nitrogen used in a pressure equalizing step previously mixes with damp air from a main air compressor before entering the adsorber, such that the gas components flowing towards an air separation cold box remain substantially unchanged, in order to reduce disturbance in conditions of gas entering a rectification column to take part in rectification due to a gas component gradually changing from dry nitrogen to dry air in the prior art, thus stabilizing the process conditions of the air separation cold box.

A method and apparatus for the production of air gases by the cryogenic separation of air with front end purification and air compression can include using an available compressed dry gas such as nitrogen, oxygen, stored purified air, or synthetic air to repressurize the adsorber without diverting any of the purified air just exiting the currently on-line adsorber or changing the flow rate of the main air compressor or air sent to the cold box. This enables the main air compressor (MAC) to operate at a relatively constant flow rate while also sending a relatively constant air flow to the cold box during this repressurization step, thereby reducing the risks of process upsets and minimizing capital expenditures related to the MAC and other warm-end equipments.

An oxygen liquefier system may be configured to defrost an oxygen line included therein. The system may include one or more sieve beds, a liquid oxygen reservoir, an oxygen line, a controller, a heating apparatus, and/or other components. The one or more sieve beds are configured to extract oxygen from air obtained from an ambient environment. The liquid oxygen reservoir is configured to store oxygen extracted at the one or more sieve beds that has been liquefied. The oxygen line is configured to provide fluid communication between the one or more sieve beds and the liquid oxygen reservoir. The controller is configured to detect a blockage caused by frozen liquid within the oxygen line based on a liquid oxygen production rate. The heating apparatus is configured to defrost the oxygen line to melt frozen liquid within the oxygen line responsive to the detection of the blockage.

A method and apparatus for the production of air gases by the cryogenic separation of air with front end purification and air compression can include using an available compressed dry gas such as nitrogen, oxygen, stored purified air, or synthetic air to repressurize the adsorber without diverting any of the purified air just exiting the currently on-line adsorber or changing the flow rate of the main air compressor or air sent to the cold box. This enables the main air compressor (MAC) to operate at a relatively constant flow rate while also sending a relatively constant air flow to the cold box during this repressurization step, thereby reducing the risks of process upsets and minimizing capital expenditures related to the MAC and other warm-end equipments.

The invention relates to a method and a device for generating electrical energy in a combined system consisting of a power plant and an air handling system. The power plant comprises a first gas expansion unit connected to a generator. The air handling system comprises an air compression unit, a heat exchange system, and a fluid tank. In a first operating mode, feed air is compressed in the air compression unit and cooled in the heat exchange system. A storage fluid is generated from the compressed and cooled feed air and is stored as cryogenic fluid in fluid tank. In a second operating mode, cryogenic fluid is removed from fluid tank and is vaporized, or pseudo-vaporized, at superatmospheric pressure. The gaseous high pressure storage fluid generated is expanded in the gas expansion unit. Gaseous natural gas is introduced into the heat exchange system (21) to be liquefied.

A method for operating an air separation unit during an unexpected disturbance is provided. The method can include the steps of: determining that a process disturbance has occurred; starting-up a liquid back-up system that is configured to deliver a product gas at a desired product pressure; and introducing compressed air from an air accumulator into the air separation unit at a location that is downstream a main air compressor and upstream a cold box, wherein the compressed air is introduced in an amount that is effective for maintaining nominal operation of the air separation unit during the process disturbance and until the liquid back-up system is delivering the product gas at the desired product pressure.

A method of efficient cold recovery from a liquid hydrogen stream includes warming a cold liquid hydrogen stream by indirect heat exchange with a cold feed air stream in an ASU sub-cooler, thereby producing a warmed liquid hydrogen stream. Wherein at least a portion of the cool inlet air stream is introduced into a cold booster, thereby producing the compressed cool feed air stream. Wherein at least a first portion of the further cooled feed air stream is introduced into an expander, thereby producing an expanded feed air stream. Wherein a second portion of the further cooled feed air stream is further cooled, thereby producing the cold feed air stream. And, wherein the liquid oxygen stream has a first molar mass flow rate, and the cold liquid hydrogen stream has a second molar flow rate that is between 1.5 and 2.5 times the first molar mass flow rate.

A portion of feed air is expanded and cooled in front of a main heat exchanger, and is used as cold for precooling the remaining unexpanded feed air inside the main heat exchanger. A portion of the feed air precooled inside the main heat exchanger is removed to outside the main heat exchanger, expanded and cooled, and used as cold to cool the remaining unexpanded precooled feed air inside the main heat exchanger.