In a process of the separation of a mixture of carbon monoxide, hydrogen and methane, the mixture is sent to a scrubbing column, a bottom liquid withdrawn at the bottom of the scrubbing column is depleted in hydrogen with respect to the mixture and is sent to a stripping column, a bottom liquid from the stripping column is sent to a separation column and a liquid enriched in methane withdrawn from the bottom of the separation column is vaporized in order to form a final product.

A system and method for removing nitrogen and producing a high pressure methane product stream and an NGL product stream from natural gas feed streams where at least 90%, and preferably at least 95%, of the ethane in the feed stream is recovered in the NGL product stream. The system and method of the invention are particularly suitable for use with feed streams in excess of 5 MMSCFD and up to 300 MMSCFD and containing around 5% to 80% nitrogen. The system and method preferably combine use of strategic heat exchange between various process streams with a high pressure rectifier tower and the ability to divert all or a portion of a nitrogen rejection unit feed stream to optionally bypass a nitrogen fractionation column to reduce capital costs and operating expenses.

Processes and systems for recovery of a dilute ethylene stream are illustrated and described. More specifically, embodiments disclosed herein relate to processes and systems for separation of a dilute ethylene stream from an offgas or other vapor streams, where the ultra-low temperature refrigeration for the desired separations is provided by the offgas itself, and only moderately-low temperature externally supplied propylene refrigerants (for example, at 40 C. to 15 C.) are necessary.

In a process of the separation of a mixture of carbon monoxide, hydrogen and methane, the mixture is sent to a scrubbing column, a bottom liquid withdrawn at the bottom of the scrubbing column is depleted in hydrogen with respect to the mixture and is sent to a stripping column, a bottom liquid from the stripping column is sent to a separation column and a liquid enriched in methane withdrawn from the bottom of the separation column is vaporized in order to form a final product.

Described herein are methods and systems for removing natural gas liquids from a natural gas feed stream and for liquefying the natural gas feed stream so as to produce a liquefied natural gas (LNG) stream and a natural gas liquids (NGL) stream

Processes and systems for recovery of a dilute ethylene stream are illustrated and described. More specifically, embodiments disclosed herein relate to processes and systems for separation of a dilute ethylene stream from an offgas or other vapor streams, where the ultra-low temperature refrigeration for the desired separations is provided by the offgas itself, and only moderately-low temperature externally supplied propylene refrigerants (for example, at 40 C. to 15 C.) are necessary.

A method is proposed for compressing a gas in stages in a compressor arrangement (100, 200, 300, 400) having a plurality of compression stages (I-VI) which are connected together sequentially by a main line (1) and in which the gas, guided through the main line (1), is respectively compressed from a suction-side pressure level to a pressure-side pressure level and is heated by this compression from a suction-side temperature level to a pressure-side temperature level, wherein a feedback amount of the gas, guided through the main line (1), is at least temporarily removed from the main line (1) downstream of one of the compression stages (V), is fed to an expansion process, and is fed back into the main line (1) upstream of the same compression stage (V). It is provided that the pressure-side pressure level of the compression stage (V) downstream of which the feedback amount is removed from the main line (1) is a supercritical pressure level, that the feedback amount is expanded to a subcritical pressure level, that the feedback amount is fed to the expansion process at the pressure-side temperature level of the compression stage (V) downstream of which it is removed from the main line (1), and that the feedback amount is cooled only after being expanded and before and/or after being fed back into the main line (1). The invention also relates to a compressor arrangement (100, 200, 300, 400).

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.

In a process for separating at least one heavy impurity such as hydrogen sulfide from crude carbon dioxide comprising significant quantities of at least one light impurity such as non-condensable gases, involving at least one heat pump cycle using carbon dioxide-containing fluid from the process as the working fluid, the light impurity is removed from the crude carbon dioxide and carbon dioxide is subsequently recovered from the removed light impurity, thereby improving overall carbon dioxide recovery and efficiency in terms of energy consumption.

A method to pre-treat an inlet natural gas stream at gas pressure reduction stations to produce LNG removes water and carbon dioxide from a natural gas stream. The energy required for the process is provided by recovering pressure energy in the inlet gas stream. The process eliminates the conventional gas pre-heating process at pressure reductions stations employing gas combustion heaters. The process provides a method to produce LNG at natural gas pressure reduction that meets product specifications.