A nitrogen liquefier configured to be integrated with an argon and nitrogen producing cryogenic air separation unit and method of nitrogen liquefaction are provided. The integrated nitrogen liquefier and associated methods may be operated in at least three distinct modes including: (i) a nil liquid nitrogen mode; (ii) a low liquid nitrogen mode; and (iii) a high liquid nitrogen mode. The present systems and methods are further characterized in an oxygen enriched stream from the lower pressure column of the air separation unit is an oxygen enriched condensing medium used in the argon condenser.

The invention relates to a method for separating air by cryogenic distillation in a column system, comprising a first column operating at a first pressure and a second column operating at a second pressure, in which an argon-enriched flow is sent from an intermediate point of the first column to the tank of the second column and an argon-rich flow is drawn off at the top of the second column, wherein a nitrogen-enriched flow of the first column is compressed in a compressor, the compressed flow is sent to a head condenser of the second column after an expansion step and the vaporized flow is expanded in the condenser in a turbine where it at least partially liquefies.

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.

A method of co-producing liquid hydrogen and ammonia, including a hydrogen generator, a nitrogen generator, and a HLU is presented. The method includes pressurizing a hydrogen stream from the hydrogen generator in a hydrogen compressor, dividing the pressurized hydrogen into at least a first portion and a second portion, wherein the first portion includes at least part of the flow of a first refrigeration cycle in the HLU, and the second part comprises at least part of the feed to an ammonia plant. The method also includes pressurizing a nitrogen stream from the nitrogen generator in a HP nitrogen compressor, dividing the pressurized nitrogen stream into at least a first part and a second part, wherein the first part comprises at least part of the flow of a second refrigeration cycle in the HLU, and the second part comprises at least part of the feed to the ammonia plant.

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 a device for producing an air product based on cryogenic rectification; after being cooled by a main heat exchanger, raw material air and nitrogen compressed by means of a compressor are sent to a rectification system for low temperature separation. In the rectification system, products such as oxygen and nitrogen are obtained by means of low temperature separation, and oxygen-enriched liquid air is obtained at or near the bottom of a rectification tower. The oxygen-enriched liquid air or liquid-state air in the rectification system is sent out after being raised to a target pressure by means of a low temperature liquid air pump; air products of various pressures can be produced by means of selecting low temperature liquid air pumps with different lifts or by connecting in series different amounts of low temperature liquid air pumps. The present method can avoid the need to arrange additional air compressors, entirely changing the method for producing medium and high pressure air products in a nitrogen circulation process, and importantly can reduce production costs significantly whilst having greater flexibility. In addition, the present method can increase the oxygen extraction rate of an apparatus, thereby improving the energy efficiency level.

Certain embodiments of the present invention lies in providing a high-purity oxygen production system which is capable of supplying liquid nitrogen in order to supply the cold required by a high-purity oxygen production apparatus, without the use of a costly conventional liquefaction apparatus.

A high-purity oxygen production system in accordance with an embodiment can include: an air separation apparatus including a main heat exchanger, a medium-pressure column and a low-pressure column; and a high-purity oxygen production apparatus including a nitrogen compressor, a nitrogen heat exchanger and at least one (high-purity) oxygen rectification column, an oxygen-containing stream serving as a starting material for high-purity oxygen is supplied from the low-pressure column to the high-purity oxygen production apparatus, and liquid nitrogen obtained from the medium-pressure column is supplied to the high-purity oxygen production apparatus in order to replenish cold heat required for operation of the high-purity oxygen production apparatus.

A method for producing liquefied natural gas and a stream of liquid nitrogen including step a): producing gaseous nitrogen in an air separation unit; step b): liquefying a stream of natural gas in a natural gas liquefaction unit including a main heat exchanger and a system for producing cold; step c): liquefying the nitrogen stream resulting from step a) in the main exchanger of the natural gas liquefaction unit in parallel with the liquefied natural gas in step b); wherein all the cold necessary for liquefying the stream of nitrogen and for liquefying the natural gas is supplied by the system for producing cold of the natural gas liquefaction unit.

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.

The invention relates to a method for separating air by cryogenic distillation in a column system, comprising a first column operating at a first pressure and a second column operating at a second pressure, in which an argon-enriched flow is sent from an intermediate point of the first column to the tank of the second column and an argon-rich flow is drawn off at the top of the second column, wherein a nitrogen-enriched flow of the first column is compressed in a compressor, the compressed flow is sent to a head condenser of the second column after an expansion step and the vaporized flow is expanded in the condenser in a turbine where it at least partially liquefies.