Process for the combined production of a mixture of hydrogen and nitrogen, and of carbon monoxide by cryogenic distillation and cryogenic scrubbing, wherein a methane-rich liquid is introduced at a first intermediate level of a scrubbing column as first scrubbing liquid and at least one nitrogen-rich liquid is introduced at a level higher than the first level of the scrubbing column as second scrubbing liquid and a mixture of hydrogen and nitrogen is drawn off as overhead gas from the scrubbing column.

The power required to recover C.sub.3+ hydrocarbons from crude carbon dioxide comprising C.sub.1+ hydrocarbons and hydrogen sulfide may be reduced by distilling the crude carbon dioxide to produce carbon dioxide-enriched overhead vapor and C.sub.3+ hydrocarbon-enriched bottoms liquid such that the hydrogen sulfide is rejected with the overhead vapor. Power consumption reductions may be achieved by incorporating a heat pump cycle using carbon dioxide vapor as working fluid to provide at least a part of the refrigeration duty and using a side reboiler to reduce the bottom reboiler duty. Where the bottoms liquid is further processed to produce lighter and heavier hydrocarbon fractions, the process enables optimization of upgrading crude oil on the basis of API gravity, Reid Vapor pressure and/or viscosity.

A novel method and system for liquefying and distilling raw natural gas into NGL and liquid methane (LNG) product streams, with at least one novel feature including the use of a mixed refrigerant comprising naturally occurring natural gas liquids that were recovered from the inlet gas stream being processed. Heat exchangers and distillation towers are configured to produce high purity liquefied natural gas (LNG) and NGL product streams, utilizing liquid NGL as the process refrigerant for both systems.

A liquefaction system is capable of sequentially or simultaneously liquefying multiple feed streams of hydrocarbons having different normal bubble points with minimal flash. The liquefying heat exchanger has separate circuits for handling multiple feed streams. The feed stream with the lowest normal boiling point is sub-cooled sufficiently to suppress most of the flash. Feed streams with relatively high normal boiling points are cooled to substantially the same temperature, then blended with bypass streams to maintain each product near its normal bubble point. The system can also liquefy one stream at a time by using a dedicated circuit or by allocating the same feed to multiple circuits.

A flare recovery method includes receiving a flare gas inlet stream that has C.sub.1-C.sub.8 hydrocarbons. The flare gas inlet stream is separated in a recovery column to produce a C.sub.1-C.sub.2 hydrocarbon stream and a C.sub.3-C.sub.8 hydrocarbon stream. The C.sub.3-C.sub.8 hydrocarbon stream is separated in a separation column to produce a C.sub.3 hydrocarbon stream and a C.sub.4-C.sub.8 hydrocarbon stream. The C.sub.4-C.sub.8 hydrocarbon stream is transported to a location for blending with crude oil. The C.sub.3 hydrocarbon stream is optionally recovered as a saleable product or is combined with the C.sub.1-C.sub.2 hydrocarbon stream to produce a flare gas stream.

A process for separating the components of a gas mixture comprising methane, nitrogen, and at least one hydrocarbon having at least two carbon atoms, or a mixture of these hydrocarbons, including the following steps: a) demonization of the gas mixture with at least one demethenization column; b) extraction of a liquid comprising at least 85 mol % of the hydrocarbons having at least two carbon atoms, partial condensation of a gas mixture in order to obtain a liquid, at least a portion of which is treated in order to be extracted as denitrogenated natural gas product and a second gas; d) introduction of the second gas and/or the gas mixture into a nitrogen removal column, obtained from which are a gas and a liquid, e) treatment of the gas in a nitrogen removal system in order to produce a gas stream comprising 5 mol % at most of nitrogen.

One or more specific embodiments disclosed herein includes a method for separating hydrogen from an olefin hydrocarbon rich compressed effluent vapor stream, employing a single heat exchanger, multiple gas-liquid separators, multiple expander/compressor sets, and a rectifier attached to a liquid product drum.

Methods and systems for recovering nitrogen and alkenes (e.g. ethylene, propylene) from process gas streams, including multi-step condensing of the process gas stream, are provided herein.

The invention relates to a method and system of preparing a lean methane-containing gas stream (22), comprising: feeding a hydrocarbon feed stream (10) into a separator (100); withdrawing from the separator (100) a liquid bottom stream (12); passing the liquid bottom stream (12) to a stabilizer column (200); withdrawing from the stabilizer column (200) a stabilized condensate stream (13) enriched in pentane, withdrawing from the stabilizer column (200) a stabilizer overhead stream (14) enriched in ethane, propane and butane; splitting the stabilizer overhead stream (14) according to a split ratio into a main stream portion (15) and a slip stream portion (16), passing the slip stream portion (16) to a fractionation unit (300) to obtain an ethane enriched stream (17) and a bottom stream enriched in propane and butane (18).

A system and method for producing acetic acid, including dry reforming methane with carbon dioxide to give syngas, cryogenically separating carbon monoxide from the syngas giving a first stream including primarily carbon monoxide and a second stream including carbon monoxide and hydrogen. The method includes synthesizing methanol from the second stream via hydrogenation of carbon monoxide in the second stream, synthesizing dimethyl ether from the methanol, and generating acetic acid from the dimethyl ether and first-stream carbon monoxide.