A natural-gas purification apparatus includes: a compressor; a cooling unit that liquefies and separates a part of natural-gas liquid; a heating unit; first to third carbon-dioxide separation units that separate carbon dioxide through carbon-dioxide separation membranes; a detection carbon-dioxide separation unit that further separates carbon dioxide through a carbon-dioxide separation membrane; a carbon-dioxide-flow-rate sensor that detects the amount of carbon dioxide separated by the detection carbon-dioxide separation unit; an arithmetic control device that adjusts and controls at least one of the pressure to be applied by the compressor, the cooling temperature of the cooling unit, and the heating temperature of the heat unit based on information from the carbon-dioxide-flow-rate sensor such that the amount of carbon dioxide to be separated by the detection carbon-dioxide separation unit will be higher than or equal to a prescribed amount.

A method for storage and transport of LPG on LPG carriers, in particular two cargoes of different LPG types on same shipment, having reliquefaction units in which vaporized gases are condensed and then returned into at least one cargo tank for the respective LPG cargo type. The method is further comprising: using the reliquefaction units, at a minimum one running, as to condense vapor from the first cargo type; passing the condensed vapor through a heat exchanger; simultaneously flowing vapor from the second cargo type through the heat exchanger as to condense vapor by means of heat exchanging with the condensed vapor; and returning the condensed vapors leaving the heat exchanger back into the respective cargo types. The present invention is also disclosing a system for storage and transport of LPG on LPG carriers.

A method for storage and transport of LPG on LPG carriers, in particular two cargoes of different LPG types on same shipment, having reliquefaction units (300, 400) in which vaporized gases are condensed and then returned into at least one cargo tank (100) for the respective LPG cargo type. The method is further comprising: using the reliquefaction units (300, 400), at a minimum one running, as to condense vapor from the first cargo type; passing the condensed vapor through a heat exchanger (500); simultaneously flowing vapor from the second cargo type through the heat exchanger (500) as to condense vapor by means of heat exchanging with the condensed vapor; and returning the condensed vapors leaving the heat exchanger back into the respective cargo types. The present invention is also disclosing a system for storage and transport of LPG on LPG carriers.

A system and method for processing natural gas to produce liquefied natural gas is disclosed. The natural gas is cooled in one or more heat exchangers using a first refrigerant from a first refrigerant circuit in which the first refrigerant is compressed in a first compressor driven by a first gas turbine having a first inlet air stream. The natural gas is liquefied using a second refrigerant, the second refrigerant being compressed in a second compressor driven by a second gas turbine having a second inlet air stream. At least one of the inlet air streams is chilled from about the respective dry bulb temperature to a temperature below the respective wet bulb temperature. Water contained in at least one of the chilled first and second air streams is condensed and separated therefrom. At least a portion of the first refrigerant is condensed or sub-cooled using the separated water.

A method and system for cooling a process fluid is disclosed. An inlet air stream of a turbine is cooled with an inlet air cooling system. Moisture contained in the cooled inlet air stream is condensed and separated from the cooled inlet air stream to produce a water stream in an open-loop circuit. The water stream is sprayed into an air cooler air stream. The combined air cooler air stream and sprayed water stream is directed through an air cooler. Heat is exchanged between the process fluid and the combined air cooler air stream and sprayed water stream to thereby condense, chill, or sub-cool the process fluid.

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.

Methods and systems for separating hydrocarbons using one or more dividing wall columns are provided. The method can include introducing a hydrocarbon fluid to a first dividing wall column. A first overhead comprising methane, ethane, or a combination thereof, a first intermediate comprising ethane, a second intermediate comprising ethane, and a first bottoms comprising one or more hydrocarbons having three or more carbon atoms per molecule can be recovered from the first dividing wall column. The first overhead can be introduced to a process for producing a liquefied natural gas. The first bottoms can be introduced to a second dividing wall column. A second overhead comprising propane, a third intermediate comprising butane, and a second bottoms comprising one or more hydrocarbons having five or more carbon atoms per molecule can be recovered from the second dividing wall column. The second overhead can be introduced to the process for producing a liquefied natural gas.

Enhanced low temperature separation (LTS) processes are provided for separating light hydrocarbon components from heavy hydrocarbon components. The enhanced LTS process utilizes an absorber and a de-ethanizer tower to achieve sufficiently pure natural gas liquid (NGL) products and residue gas products. A portion of the de-ethanizer tower overhead is condensed and recycled as reflux for the absorber. The enhanced LTS process requires less refrigeration of the feed gas stream yet still achieves increased recovery of the valuable heavier hydrocarbons from hydrocarbon gas streams. The enhanced LTS process also reduces compression requirements compared to conventional LTS processes.

Methods of butane delivery, methods for reducing VOC emissions resulting from such delivery, and methods for debutanizing nitrogen gas used to expel butane from butane storage tanks.

Contemplated plants for flexible ethane recovery and rejection by allowing to switch the top reflux to the demethanizer from residue gas to the deethanizer overhead product and by controlling the flow ratio of feed gas to two different feed gas exchangers. Moreover, the pressure of the demethanizer is adjusted relative to the deethanizer pressure for control of the ethane recovery and rejection.