An apparatus for separation of air by cryogenic distillation comprising: a system of columns; a first turbine; a warm compressor coupled to the first turbine; a second turbine; a cold compressor coupled to the second turbine; a heat exchanger; means for sending air cooled in the heat exchanger at an intermediate temperature of the heat exchanger to the cold compressor; means for sending expanded air from the second turbine to the system of columns; means for sending air compressed in the cold compressor to an intermediate point of the heat exchanger and then at least in part to the system of columns via a first valve; means for sending air compressed in the cold compressor to the inlet of the first turbine via a second valve without passing through the heat exchanger, wherein the means for sending air compressed in the cold compressor to the inlet of the first turbine via the second valve without passing through the heat exchanger is also connected to the inlet of the first turbine; means for sending a fraction of air cooled in the heat exchanger to an intermediate temperature of the latter to the first turbine; means for sending expanded air from the first turbine to the system of columns; and a bypass line provided with an expansion valve configured to send air from the cold compressor to the system of columns without passing through the heat exchanger.

The present invention provides an air separation system and an air separation method. The air separation system comprises an air separation apparatus and a nitrogen liquefier. In the air separation apparatus, multiple output pipelines are led out from a rectification column system via a main heat exchanger. In the nitrogen liquefier, a gas delivery pipeline delivers a gas flow expanded by an expander. The air separation system further comprises an intermediary pipeline. An inlet end of the intermediary pipeline is connected to the gas delivery pipeline of the nitrogen liquefier, and an outlet end of the intermediary pipeline is connected to at least one of the multiple output pipelines of the air separation apparatus at a position between the rectification column system and the main heat exchanger, such that the intermediary pipeline delivers a gas flow to the at least one output pipeline. The air separation system and air separation method can be started up smoothly without the use of liquid nitrogen stored externally in reserve.

A blow-down method is applied to a reliquefaction system in which boil-off is compressed by a compressor, cooled and reliquefied through a heat exchanger, and returned to the tank after passing through a gas-liquid separator. The reliquefaction system includes a pressure compensation line extending from a downstream side of the compressor to an upside of the gas-liquid separator without passing through the heat exchanger; and a nitrogen blanket line along which nitrogen is supplied to the pressure compensation line. In the event of a trip of the reliquefaction system, nitrogen is supplied to the pressure compensation line along the nitrogen blanket line and is delivered to the downstream side of the compressor to pass through the heat exchanger along the reliquefaction line such that the heat exchanger and the reliquefaction line are blown down to remove compressed gas and reliquefied gas therefrom while being subjected to nitrogen (N.sub.2) purging.

Methods and systems for startup of a natural gas liquids plant without flaring.

Method and system for removing high freeze point components from natural gas. Feed gas is cooled in a heat exchanger and separated into a first vapor portion and a first liquid portion. The first liquid portion is reheated using the heat exchanger and separated into a high freeze point components stream and a non-freezing components stream. A portion of the non-freezing components stream may be at least partially liquefied and received by an absorber tower. The first vapor portion may be cooled and received by the absorber tower. An overhead vapor product which is substantially free of high freeze point freeze components and a bottoms product liquid stream including freeze components and non-freeze components are produced using the absorber tower.

A process is described herein for removing high freeze point hydrocarbons, including benzene compounds, from a mixed feed gas stream. The process involves cooling process streams in one or more heat exchangers and separating condensed compounds in multiple separators to form a methane-rich product gas stream. Select solvent streams from a fractionation train and/or separate solvent streams are employed to lower the freeze point of one or more streams that contain high freeze point hydrocarbons. A corresponding system also is disclosed.

A method and a system for feeding a feed gas including methane (CH.sub.4) and carbon dioxide (CO.sub.2) to a cryogenic distillation column are provided herein. The method includes flowing a freeze zone CO.sub.2 vapor stream into a freezing section of the column to produce an overhead stream that exits the column. The method includes heating the overhead stream via a heating component to reduce or prevent solidification of the CO.sub.2 in the overhead stream.

A unit for producing argon by cryogenic distillation, suitable for connection to a double air separation column consisting of first and second columns interconnected thermally, comprises an argon separation column surmounted with a top condenser and a denitrogenation column, means for withdrawing an argon-rich and nitrogen-depleted product (LAR) at the bottom of the denitrogenation column, means for connecting the top of the argon separation column to the denitrogenation column, means for sending a top gas from the argon separation column to the atmosphere, means for withdrawing a nitrogen-rich fluid from the top of the denitrogenation column, an analyser for measuring the nitrogen content at the top of the argon separation column, and means for opening and closing the means for connecting the top of the argon separation column to the denitrogenation column depending on the nitrogen content detected by the analyser.

A process for separating a gas mixture, a first item of equipment of the process is heated by a first flow of a first heat producer and supplies heat to a first fluid, the first flow of heat producer being heated upstream of the first item of equipment by a heat source, a second item of equipment of the process heats a second fluid while consuming heat, the heat originating from a second flow of the first heat producer heated by the heat source, which heats the second flow of the first heat producer up to an intermediate temperature lower than the second temperature, and by a heater downstream of the source, which heats the second flow of the first heat producer, which has been heated by the heat source, from the intermediate temperature up to a second temperature higher than the first temperature.

The carbon capture process includes, under normal operation: a first stream is compressed, dried, cooled and separated by partial condensation step a phase separator forming a liquid enriched in CO2 and a gas enriched in the at least one component lighter than CO2. And the gas enriched in the component lighter than CO2 is warmed in the heat exchanger and then expanded in a turbine, and then is sent to the atmosphere or to a cooling tower. Under start-up conditions, a phase separator is at a first temperature and a second stream of a gaseous mixture containing CO2 and at least one component lighter than CO2 is expanded in the turbine to produce an expanded gas at a second temperature different from the first temperature, the expanded gas being then warmed in the heat exchanger or sent to be separated in a distillation column of the carbon capture process.