A method for operating a heat exchanger, in which a first operating mode is carried out in first time periods, and a second operating mode is carried out in second time periods that alternate with the first time periods; in the first operating mode a first fluid flow is formed at a first temperature, is fed into the heat exchanger in a first region at the first temperature, and is partially or completely cooled in the heat exchanger; in the first operating mode a second fluid flow is formed at a second temperature, is fed into the heat exchanger in a second region at the second temperature, and is partially or completely heated in the heat exchanger; and in the second operating mode the feeding of the first fluid flow and of the second fluid flow into the heat exchanger is partially or completely halted.

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.

Method for separating air by cryogenic distillation in an air separation device comprising a system of columns, a first turbine and a second turbine, wherein, in de-icing operation, a common duct bringing air from the two turbines to a column is closed by means of an isolation valve, a purge gas is sent to the turbines at a temperature above 0 C. in order to de-ice them, but purge gas is not sent to the system of columns.

Method for separating air by cryogenic distillation, wherein at least part of the air to be distilled is boosted in an air booster, compressed air is allowed to expand in at least one expansion turbine and, if the pressure drop between two points of the booster passes under a threshold and/or a flow of the booster passes under a minimum flow of the booster, part of the air boosted in the booster is allowed to expand without having been cooled between the booster and the expansion turbine and the boosted expanded air is sent upstream or downstream of the at least one turbine, without having been cooled in the heat exchanger, after having been boosted.

Method for separating air by cryogenic distillation, wherein air is compressed in a compressor and is subsequently sent to a heat exchanger, with the air cooled in the exchanger being sent to a check valve downstream of the heat exchanger and subsequently to a turbine, the valve being positioned so that air from a short-circuiting duct cannot return to the exchanger from the compressor.

A liquefier device which may be a retrofit to an air separation plant or utilized as part of a new design. The flow needed for the liquefier comes from an air separation plant running in a maxim oxygen state, in a stable mode. The three gas flows are low pressure oxygen, low pressure nitrogen, and higher pressure nitrogen. All of the flows are found on the side of the main heat exchanger with a temperature of about 37 degrees Fahrenheit. All of the gasses put into the liquefier come out as a subcooled liquid, for storage or return to the air separation plant. This new liquefier does not include a front end electrical compressor, and will take a self produced liquid nitrogen, pump it up to a runnable 420 psig pressure, and with the use of turbines, condensers, flash pots, and multi pass heat exchangers. The liquefier will make liquid from a planned amount of any pure gas oxygen or nitrogen an air separation plant can produce.

A method and backup system for backing up a supply oxygen in an air separation plant in which during normal operation, a stream of oxygen-rich liquid is pumped through a main flow path, extending from a surge tank to a heat exchanger, to deliver an oxygen product. The surge tank receives the oxygen-rich liquid from a bottom region of the lower pressure column of the plant. Additionally, during normal operations, a stream of the oxygen-rich liquid is also introduced to a reserve storage tank through a backup flow path. During a transient operation, where the air separation plant has ceased operation, the surge tank is isolated and liquid is pumped from the surge tank through an auxiliary flow path to an auxiliary vaporizer to continue the supply of the oxygen product and the surge tank is replenished with oxygen-rich liquid previously stored in the reserve storage tank.

A method and apparatus for separating air in which production of the liquid products can be selectively varied between high and low production rates by varying the pressure ratio across a turboexpander used in imparting refrigeration with the use of a branched flow path. The branched flow path has a system of valves to selectively and gradually introduce a compressed refrigerant air stream into either a booster compressor branch having a booster compressor to increase the pressure ratio during high modes of liquid production or a bypass branch that bypasses the booster compressor to decrease the pressure ratio during low modes of liquid production. A recycle branch is connected to the booster compressor branch to allow compressed air to be independently recycled from the outlet to the inlet of the booster compressor during turndown from the high to the low liquid mode of liquid production to prevent surge.

The invention relates to a control system which comprises: a plurality of flow valves on channels of reaction fluid, which are i) in a closed position or ii) in an open position; a plurality of control pipes connected to a source of control fluid and to a respective control pipe, all or part of the flow valves switching to the closed position when the pressure of the control fluid in the control pipe drops below a predetermined threshold; a discharge pipe connected to the control pipes, in order to discharge the control fluid from the control pipes; a safety device connected i) to each control pipe and ii) to the discharge pipe and configured to have, selectively: i) a service configuration, wherein the control fluid flows to each control pipe, thus opening each flow valve, and ii) a safety configuration, wherein the control fluid is discharged through the discharge pipe, thus closing each flow valve.

A method of liquid air energy storage is provided. This method includes liquefying and storing air to form a stored liquid air during a first period of time; during a second period of time, introducing a compressed air stream into a cryogenic system, wherein the cryogenic system comprises at least one cold compressor, and at least one heat exchanger. The method includes producing a first exhaust stream and a second exhaust stream. The method also includes vaporizing at least part of the stored liquid air stream in the heat exchanger, thereby producing a first high pressure compressed air stream, then combining the first high pressure compressed air stream, the first exhaust stream and the second exhaust stream to form a combined exhaust stream, heating the combined exhaust stream, then expanding the heated combined exhaust stream in an expansion turbine to produce power.