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 level, is fed into the heat exchanger in a first region at the first temperature level, 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 level, is fed into the heat exchanger in a second region at the second temperature level, and is partially or completely heated in the heat exchanger. A corresponding arrangement and a system with such an arrangement are also covered by the present invention.

A method for starting up an air separation plant having a higher-pressure column, a lower-pressure column, and a falling film vaporizer disposed within a lower section of the lower-pressure column is provided. The method can include the steps of: introducing a cooled and compressed air stream into the higher pressure column; withdrawing an oxygen-enriched liquid stream from a bottom section of the higher-pressure column and introducing said oxygen-enriched liquid stream to an upper section of the lower-pressure column; and exchanging heat between nitrogen gas coming from a top section of the higher-pressure column and liquid oxygen from the lower-pressure column within the falling film vaporizer. During a start-up period, flow of liquid oxygen is at least reduced to the closed core. This reduces the available heat exchange area during start up, which increases ΔT and ΔP in the condenser/reboiler.

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 for starting up an air separation plant having a higher-pressure column, a lower-pressure column, and a falling film vaporizer disposed within a lower section of the lower-pressure column is provided. The method can include the steps of: introducing a cooled and compressed air stream into the higher pressure column; withdrawing an oxygen-enriched liquid stream from a bottom section of the higher-pressure column and introducing said oxygen-enriched liquid stream to an upper section of the lower-pressure column; and exchanging heat between nitrogen gas coming from a top section of the higher-pressure column and liquid oxygen from the lower-pressure column within the falling film vaporizer. During a start-up period, flow of liquid oxygen is at least reduced to the closed core. This reduces the available heat exchange area during start up, which increases ΔT and ΔP in the condenser/reboiler.

An air separation device according to the present invention is an air separation device in which air is distilled at a low temperature, and includes a high-pressure column which separates high-pressure raw material air into high-pressure nitrogen gas and high-pressure oxygen-enriched liquefied air; a low-pressure column which separates the high-pressure oxygen-enriched liquefied air into low-pressure nitrogen gas, low-pressure liquefied oxygen, and argon-enriched liquefied oxygen; an argon column which separates the argon-enriched liquefied oxygen having a pressure higher than the pressure into argon gas and medium-pressure liquefied oxygen; a first indirect heat-exchanger which heat-exchanges between the argon gas and the low-pressure liquefied oxygen; a second indirect heat-exchanger which heat-exchanges between the high-pressure nitrogen gas and the medium-pressure liquefied oxygen; a first gas-liquid separation chamber which separates the low-pressure oxygen gas which has been vaporized by the first indirect heat-exchanger and the low-pressure liquefied oxygen which has not been vaporized; a second gas-liquid separation chamber which separates the medium-pressure oxygen gas which has been vaporized by the second indirect heat-exchanger and the medium-pressure liquefied oxygen which has not been vaporized; a first passage which communicates the gas phase of the low-pressure column and the gas phase of the second gas-liquid separation chamber; a second passage which communicates the liquid phase of the low-pressure column and the second gas-liquid separation chamber; a first opening/closing mechanism located on the first passage; and a second opening/closing mechanism located on the second passage.

The present invention relates to a process and a system for supplying a backup gas at a higher pressure from a source gas at a lower pressure. The backup gas at the lower pressure is at least partially condensed against a backup liquid at a higher pressure in a reprocessing heat exchanger and as a result, the backup liquid is at least partially vaporized. The backup liquid at the higher pressure is formed from boosting liquefied backup gas at the lower pressure. A backup vaporizer is disposed downstream of the reprocessing heat exchanger to completely vaporize the backup liquid at a higher pressure before it was delivered to the customer. The present invention eliminates the use of costly gas compressor and mitigates associated safety risks, in particular when the backup gas is oxygen.

A method for temperature-controlled delivery of the gaseous product at temperatures at or below ambient in the event of an air separation unit failure. In one embodiment, a first portion of a stored cryogenic liquid product is sent to the back-up vaporizer and heated to ambient conditions, and a second portion of stored cryogenic liquid product, which is at the cryogenic storage temperature, bypasses the back-up vaporizer using a bypass line controlled by a bypass valve and is mixed with the vaporized gas. This mixed stream will then preferably go through a static mixer in order to get to an homogenous temperature that is below the ambient temperature. A temperature control loop can be used to adjust the opening of the by-pass valve in order to reach the desired product temperature.

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 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 system and method for supplying a backup product in an air separation device, as well as a system and method for supplying a lower-pressure product to a user by means of pressurization of a cryogenic liquid pump during normal operation of an air separation device, i.e., when the cryogenic liquid pump is in the cold standby state. By means of the system and method, a cryogenic liquid product taken from a storage tank is pressurized by the cryogenic liquid pump to produce a lower-pressure product by taking full advantage of the low-speed operation of the cryogenic liquid pump in the cold standby state, and the lower-pressure product is transmitted to product supply lines of a user, to achieve the function of supplying the lower-pressure product to the user. The system and method not only reduce the energy loss of the cryogenic liquid pump in the cold standby state for a long time, but also avoid the bleeding rate of the cryogenic liquid product generated by sending a part of the cryogenic liquid product back to the storage tank, so that the advantage of quickly starting the cryogenic liquid pump from the cold standby state is ensured, and the requirements of the user to the higher-pressure product and the lower-pressure product can be satisfied.