Certain aspects of natural gas liquid fractionation plant waste heat conversion to simultaneous power and potable water using organic Rankine cycle and modified multi-effect distillation systems can be implemented as a system that includes two heating fluid circuits thermally coupled to two sets of heat sources of a NGL fractionation plant. The system includes a power generation system that comprises an organic Rankine cycle (ORC), which includes (i) a working fluid that is thermally coupled to the first heating fluid circuit to heat the working fluid, and (ii) a first expander configured to generate electrical power from the heated working fluid. The system includes a MED system thermally coupled to the second heating fluid circuit and configured to produce potable water using at least a portion of heat from the second heating fluid circuit. A control system actuates control valves to selectively thermally couple the heating fluid circuit to a portion of the heat sources of the NGL fractionation plant.

The present invention is directed to a method for removing elemental mercury from liquid natural gas comprising changing the stabilizer column operating conditions to beneficially transfer mercury from the stabilized condensate phase to the overhead gas phase, where it may be compressed and recycled with the gas going to the existing feed gas mercury removal units.

Flowing a first buffer fluid and a second buffer fluid through a heat exchanger network thermally coupled to heat sources of a Natural Gas Liquid (NGL) fractionation plant, and transferring heat from the heat sources to the first buffer fluid and the second buffer fluid. Generating power via a first sub-system thermally coupled to the heat exchanger network and generating potable water from brackish water via a second sub-system thermally coupled to the heat exchanger network.

A system and method for producing an NGL product stream in either an ethane retention or rejection mode. Rejection modes include (a) two heat exchange stages between a feed stream and first separator bottoms stream and cooling a side stream withdrawn from a fractionation tower through heat exchange with both the fractionation tower and second separator overhead streams; or (b) warming the first separator bottoms stream and fractionation overhead stream through heat exchange with the side stream prior to heat exchange with the feed stream, to achieve 4-15% ethane recovery and 97%+ propane recovery. In ethane retention mode, a portion of the feed stream and portions of a first separator overhead and bottoms streams are separately cooled through heat exchange with other process streams, including the entireties of a recycled residue gas and fractionation column overhead streams, resulting in around 99% ethane and around 100% propane recovery.

A method of obtaining a liquefied hydrocarbon-rich fraction (product fraction) having a nitrogen content of 1 mol %, wherein the hydrocarbon-rich fraction is liquefied and subcooled with a refrigeration circuit and then subjected to a rectificative removal of nitrogen is disclosed.

A method and apparatus for liquefying a feed gas stream comprising natural gas and carbon dioxide. A method includes compressing an input fluid stream to generate a first intermediary fluid stream; cooling the first intermediary fluid stream with a first heat exchanger to generate a second intermediary fluid stream, wherein a temperature of the second intermediary fluid stream is higher than a carbon dioxide-freezing temperature for the second intermediary fluid stream; expanding the second intermediary fluid stream to generate a third intermediary fluid stream, wherein the third intermediary fluid stream comprises solid carbon dioxide; separating the third intermediary fluid stream into a fourth intermediary fluid stream and an output fluid stream, wherein the output fluid stream comprises a liquefied natural gas (LNG) liquid; and utilizing the fourth intermediary fluid stream as a cooling fluid stream for the first heat exchanger.

Disclosed are simplified and energy-efficient distillation processes and systems for separating a liquefied natural gas stream to obtain a natural gas stream and a national gas liquid stream. Substantial savings in construction costs and operation energy consumption can be achieved by using the processes and systems of this disclosure. Preferably the separation processes are integrated with other industrial processes such as petroleum refining, petrochemical production, chemical production, and the like.

A method for separating nitrogen from an LNG stream with a nitrogen concentration of greater than 1 mol %. A pressurized LNG stream is produced at a liquefaction facility by liquefying natural gas, where the pressurized LNG stream has a nitrogen concentration of greater than 1 mol %. At least one liquid nitrogen (LIN) stream is received from storage tanks, the at least one LIN stream being produced at a different geographic location from the LNG facility. The pressurized LNG stream is separated in a separation vessel into a vapor stream and a liquid stream. The vapor stream has a nitrogen concentration greater than the nitrogen concentration of the pressurized LNG stream. The liquid stream has a nitrogen concentration less than the nitrogen concentration of the pressurized LNG stream. At least one of the one or more LIN streams is directed to the separation vessel.

Certain aspects of natural gas liquid fractionation plant waste heat conversion to simultaneous power and potable water using Kalina Cycle and modified multi-effect-distillation system can be implemented as a system. The system includes a waste heat recovery heat exchanger network coupled to multiple heat sources of a Natural Gas Liquid (NGL) fractionation plant. The heat exchanger network is configured to transfer at least a portion of heat generated at the multiple heat sources to a first buffer fluid and a second buffer fluid flowed through the first heat exchanger network. The system includes a first sub-system configured to generate power. The first sub-system is thermally coupled to the waste heat recovery heat exchanger. The system includes a second sub-system configured to generate potable water from brackish water. The second sub-system is thermally coupled to the waste heat recovery heat exchanger.

Described herein are methods and systems for the liquefaction of natural gas to produce a LNG product. The methods and systems use an apparatus for separating a flash gas from a liquefied natural gas (LNG) stream to produce a LNG product and recovering refrigeration from the flash gas. The apparatus includes a shell casing enclosing a heat exchange zone comprising a coil wound heat exchanger, and a separation zone. The heat exchange zone is located above and in fluid communication with the separation zone. Flash gas is separated from the LNG product in the separation zone and flows upwards from the separation zone into the heat exchange zone where refrigeration is recovered from the separated flash gas.