Skip over navigation
LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS { or liquefied gaseous} MIXTURES BY PRESSURE AND COLD TREATMENT { or by bringing them into the supercritical state (cryogenic pumps F04B 37/08; gas storage vessels, gas holders F17; filing vessels with, or discharging from vessels, compressed, liquefied or solidified gases F17C; refrigeration machines, plants, or systems F25B) }
Definition statement
This subclass/group covers:

Processes or systems for liquefying or solidifying gases or gaseous mixtures and for separating the constituents of gaseous or liquid mixtures involving the use of liquefaction or solidification by rectification or partial condensation, the processes or systems use internal and/or external refrigeration to reach very low temperatures, i.e. so-called cryogenic temperatures, in general well below -50°C;

Arrangements of cold exchangers or cold accumulators in cryogenic separation or liquefaction plants.

Relationship between large subject matter areas

If the principal aspect of the application concerns the liquefaction or solidification of a gaseous feed stream but comprises also purification aspects of the feed or product stream in general then the main group concerned is F25J 1/00.

Similarly, if the principal aspect of the application concerns the separation of a feed stream but comprises also the withdrawal of a liquid or solid product stream then the main group concerned is F25J 3/00.

If the application, however, concerns details both about liquefaction or solidification techniques as well as separation techniques than both main groups F25J 1/00 and F25J 3/00 are concerned.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Separation processes in general
Production of chemical compounds in general
Filling vessels with, or discharging from vessels, compressed, liquefied or solidified gases
Refrigeration machines, plants, or systems
Heat exchangers in general
Cryogenic pumps
Processes or apparatus for liquefying or solidifying gases or gaseous mixtures { (for ammonia in general C01C 1/00; solidification of carbonic acid C01B 31/22; recovering volatile solvents by condensation B01D 5/00; vapor recovery systems combined with filling nozzles B67D 7/54) (not used) }
Definition statement
This subclass/group covers:

Processes or systems wherein a gaseous feed or feed mixture is liquefied or solidified using internal and/or external refrigeration and withdrawn as liquefied or solidified product or product mixture. The gases or gaseous mixtures comprises so-called "permanent gases", e.g. noble gases, hydrogen and primary air constituents, and gases or main components of gaseous mixtures having boiling points equal to or lower than -78°C, i.e. the boiling point of carbon dioxide, e.g. natural gas, carbon monoxide.

  • Processes or apparatus characterised by the gas or gas mixture to be liquefied or solidified.
  • Processes or apparatus characterised by the kind of cold generation for compensating heat leaks and liquid production.
  • Processes or apparatus characterised by the refrigerant fluid used.
  • Processes or apparatus characterised by details and kind of the refrigeration system used, e.g. by using a single or multi-component vapour compression cycle or a refrigeration cascade; coupling or integration with other units or processes; controlling aspects.
References relevant to classification in this group
This subclass/group does not cover:
Recovering volatile solvents by condensation
Vapour recovery systems combined with filling nozzles
Production of ammonia
Solidification of carbonic acid
Cryogenic pumps
Pipe-line systems

Examples of places where the subject matter of this group is covered when used for a particular purpose, or incorporated in a larger system:

Separation of a feed stream and withdrawal of a liquid product
Informative references
Attention is drawn to the following places, which may be of interest for search:
Floating working-up processes
Refrigerant materials per se
Buildings forming part of cooling plants
Adaptations of expansion engines for refrigeration plants or for driving
Steam engine plants in combination with an industrial process
Gas turbine plants in combination with other processes
Control of compressors in general
Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Refrigeration cascade
The feed stream is cooled by two or more subsequent refrigeration means
Natural gas
Substitute natural gas, gas obtained from a crude oil well, i.e. associated or petroleum gas, or from a gas well, i.e. non-associated gas, gas recovered from a tertiary oil recovery process, mine or coal-bed-seam gas, landfill gas
BOG
Boil-off gases i.e. evaporated gases from cryogenic liquid storage vessels
MCR
Multi-component refrigerant
SCR
Single-component refrigerant
Synonyms and Keywords

In patent documents the following abbreviations are often used:

LNG
Liquefied natural gas
C3MR
Propane pre-cooled mixed refrigerant LNG process (APC)
DMR
Mixed refrigerant pre-cooled mixed refrigerant LNG process (Shell, APC, Liquefin)
MFC®
Three level cascade mixed refrigerant LNG process (Linde)
OCLP
Optimised cascade LNG process (Concoco-Phillips)
Processes or apparatus for separating the constituents of gaseous { or liquefied gaseous} mixtures involving the use of liquefaction or solidification { (not used) }
Definition statement
This subclass/group covers:

Processes or apparatus for separating the constituents of a feed stream at cryogenic temperatures involving the use of liquefaction or solidification by rectification or partial condensation. The feed stream can be a gas, a gaseous mixture, a cryogenic liquid or a cryogenic liquid mixture.

  • Cryogenic separation of gaseous or liquid mixtures, e.g. gaseous or liquefied natural gas, refinery off-gases, gaseous mixtures comprising hydrogen and/or carbon monoxide, carbon dioxide or nitrogen, by rectification in a column or dephlegmator, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream.
  • Cryogenic separation of atmospheric air into its primary components, i.e. nitrogen, oxygen, argon, krypton, xenon, neon and/or helium.
  • Cryogenic separation of gaseous or liquid mixtures, e.g. gaseous or liquefied natural gas, refinery off-gases, gaseous mixtures comprising hydrogen and/or carbon monoxide, carbon dioxide or nitrogen, by partial condensation, i.e. by condensation or anti-sublimation of the high-boiling components and subsequent simple phase separation of the liquefied or solidified components from the remaining low-boiling gaseous components. The high-boiling liquid components can be withdrawn in gaseous or liquid phase.
  • Cryogenic separation of gaseous impurities from an almost pure feed stream (i.e. the concentration of the impurities is in generally less than 5 vol%) wherein the main component of the feed stream and the impurities do have similar volatilities and wherein the product stream has a high or ultra high purity, i.e. with only some ppm or ppb of remaining impurities.
References relevant to classification in this group
This subclass/group does not cover:
Distillation or related processes other than cryogenic processing
Recovering volatile solvents by condensation
Production of hydrogen containing gas not using cryogenic processing
Preparation of oxygen not using cryogenic processing
Production or purification of nitrogen not using cryogenic processing
Purification or separation of noble gases not using cryogenic processing
Production of carbon monoxide containing gas not using cryogenic processing
Production of carbon dioxide
Purification of hydrocarbons
Distillation of hydrocarbon oils
Working-up liquefied petroleum gas
Treating radioactively contaminated gases

Examples of places where the subject matter of this group is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Purification of a gas stream during its liquefaction
Informative references
Attention is drawn to the following places, which may be of interest for search:
Separation of gases or vapours by condensation
Separation of gases or vapours by absorption
Separation of isotopes
Packing elements
Preparation or purification of gas mixtures for synthesis
Separation of hydrogen at low temperatures
Purge gas treatment from ammonia synthesis
Recovery of liquid hydrocarbon mixtures from gases by cooling
Working-up undefined normally gaseous hydrocarbon mixtures
Working-up natural gas
Buildings forming part of cooling plants
Adaptations of expansion engines for refrigeration plants or for driving
Steam engine plants in combination with an industrial process
Steam engine plants in combination with a gasification process and an oxygen producing plant
Gas turbine plants supplying working fluid to a user
Control of compressors in general
Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Cold box
Housing comprising all the cold equipments of the separation/liquefaction process, i.e. working normally under cryogenic temperatures conditions
Natural gas liquids
C2+ hydrocarbons
Liquefied petroleum gas
C3+ hydrocarbons
Synonyms and Keywords

In patent documents the following abbreviations are often used:

ASU
Air separation unit
BAC
Booster air compressor
MAC
Main air compressor
LNG
Liquefied natural gas
NGL
Natural gas liquids
LPG
Liquefied petroleum gas
HYCO
Synthesis gases comprising hydrogen and carbon monoxide as main constituents
Arrangements of cold exchangers or cold accumulators in separation or liquefaction plants (heat exchangers F28C, F28D, F28F)
Definition statement
This subclass/group covers:

Particular configuration and constructional design of cold exchangers and cold accumulators for use in cryogenic separation or liquefaction plants (in contrast to the description of the general functioning of said exchangers and accumulators as found in the flowsheet of the cryogenic process which are to be classified in the corresponding main groups F25J 1/00 and F25J 3/00)

  • Cold regenerators, i.e. cold exchange means cools the feed stream and removes higher boiling impurities by liquefaction/solidification, e.g. H2O, CO2 from the feed gas by alternating purification and regeneration phase, either as reversing heat exchangers or as cold accumulators.
  • Recuperative heat exchangers for continuously recuperating cold from separated components in separation plants or from refrigerant streams in cryogenic liquefaction plants.
  • Reboiler and/or Condensers in a cryogenic separation or liquefaction apparatus.
  • Reflux heat exchangers or dephlegmators, i.e. cold exchangers with continuous interchange of heat and material between a vapour stream and a liquid stream.
Informative references
Attention is drawn to the following places, which may be of interest for search:
Heat exchangers in general
Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Reversing heat exchanger
Recuperative ("counter-current") heat exchanger with continuous heat exchange during the purification phase followed by a regeneration phase; there is no cold accumulation; can be arranged in a single, compact heat exchanger
Cold accumulator
Heat exchange means containing a cold regenerative material for storing and exchanging the cold in a discontinuous manner, i.e. alternating purification and regenerating phase; always at least two heat exchange vessels are necessary
Bath type reboiler
Thermo-siphon reboiler, with natural or forced liquid circulation, or core-in-kettle reboiler with pool boiling
Down-flowing type reboiler
Thin falling liquid film flowing down the heat exchange surface, plate or tube, and is subsequently vaporised
Synonyms and Keywords

In patent documents the following abbreviations are often used:

BA-PFHE
Brazed aluminium - plate fine heat exchanger
MCHE
Main cryogenic heat exchanger
MHE
Main heat exchanger
REVEX
Reversing heat exchanger
SWHE / CWHE
Spiral-/coil wound heat exchanger

In patent documents the following expressions/words "kettle", "bath" and "pool-boiling" are often used as synonyms.

This page is owned by Office of Patent Classification.
Last Modified: 10/11/2013