Hydrogen is liquefied through a process utilizing refrigeration from hydrogen at one, two, or three different pressures as well as a nitrogen refrigeration cycle. One or more stages of catalyst are used to convert ortho-hydrogen to para-hydrogen as the hydrogen is cooled and liquefied. Subcooled liquid hydrogen feeds the final stage of ortho-hydrogen to para-hydrogen conversion to reduce or eliminate vaporization of the hydrogen during the exothermic ortho-hydrogen to para-hydrogen conversion.

A system and method for integrated heavy hydrocarbon removal in a liquefaction system having a lean natural gas source. An economizer located between a main cryogenic heat exchanger and a reflux drum is provided to cool an overhead vapor stream against a partially condensed stream. In addition, pressure of the natural gas feed stream is maintained into a scrub column. A pressure drop is provided by a valve located between the economizer and the reflux drum on a partially condensed stream withdrawn from the cold end of the warm section of the main cryogenic heat exchanger.

Systems, devices, and methods for recovering mixed refrigerant and/or nitrogen within liquefaction systems are provided. The systems, devices, and methods facilitate recovering mixed refrigerant (MR) and/or nitrogen vapor that can leak from a compressor, separating the MR from the nitrogen, and reusing the MR and/or the nitrogen within the liquefaction system. Recovering and reusing MR and/or nitrogen can minimize loss of MR and nitrogen which can lower the total operating cost of a liquefaction system. Additionally, recovering the MR, rather than burning it, can reduce environmental emissions by reducing the amount of MR that is burned.

A system for preparing subcooled liquid oxygen based on mixing of liquid oxygen and liquid nitrogen and then vacuum-pumping, including atmospheric-pressure saturated liquid nitrogen and oxygen tanks. An inlet of the liquid nitrogen tank communicates with pressurized gas, and an outlet is connected to an inlet a of a secondary subcooler. An inlet of the liquid oxygen tank communicates with the pressurized gas, and a first outlet is connected to an inlet b of the secondary subcooler. An outlet c of the secondary subcooler is connected to an inlet d of a primary subcooler. An outlet e of the primary subcooler is connected to a pumping-out device through a rewarming device. A second outlet of the liquid oxygen tank is connected to an inlet n of the primary subcooler. An outlet o of the primary subcooler is connected to an inlet r of the secondary subcooler.

The invention relates to an integrated process and apparatus for liquefaction of natural gas and recovery of natural gas liquids. In particular, the improved process and apparatus reduces the energy consumption of a Liquefied Natural Gas (LNG) unit by using a portion of the already cooled overhead vapor from a fractionation column from an NGL (natural gas liquefaction) unit to, depending upon composition, provide, for example, reflux for fractionation in the NGL unit and/or a cold feed for the LNG unit, or by cooling, within the NGL unit, a residue gas originating from a fractionation column of the NGL unit and using the resultant cooled residue gas to, depending upon composition, provide, for example, reflux/feed for fractionation in the NGL and/or a cold feed for the LNG unit, thereby reducing the energy consumption of the LNG unit and rendering the process more energy-efficient.

The disclosure relates to a method and apparatus for cooling, preferably liquefying a boil off gas (BOG) stream from a liquefied cargo in a floating transportation vessel, said liquefied cargo having a boiling point of greater than −110° C. at 1 atmosphere and comprising a plurality of components, said method comprising at least the steps of: compressing a boil off gas stream (01) from said liquefied cargo in two or more stages of compression comprising at least a first stage (65) and a final stage (75) to provide a compressed BOG discharge stream (06), wherein said first stage (65) of compression has a first stage discharge pressure and said final stage (75) of compression has a final stage suction pressure and one or more intermediate, optionally cooled, compressed BOG streams (02, 03, 04) are provided between consecutive stages of compression; cooling the compressed BOG discharge stream (06) to provide a cooled vent stream (51) and a cooled compressed BOG stream (08); expanding, optionally after further cooling, a portion of the cooled compressed BOG stream (08) to a pressure between that of the first stage discharge pressure and the final stage suction pressure to provide an expanded cooled BOG stream (33); heat exchanging the expanded cooled BOG stream (33) against the cooled vent stream (51) to provide a further cooled vent stream (53).

A system for reliquefying a boil off gas generated in a storage tank includes a first compressor compressing a partial amount (hereinafter, referred to as ‘fluid a’) of boil off gas discharged from the storage tank, a second compressor compressing another partial amount (hereinafter, referred to as ‘fluid b’) of boil off gas discharged from the storage tank, a second expanding unit expanding a partial amount (hereinafter, referred to as ‘fluid c’) of a flow formed as the fluid a and the fluid b join, a heat-exchanger cooling another partial amount (hereinafter, referred to as ‘fluid d’) of the flow formed as the fluid a and the fluid b join, and a first expanding unit expanding the fluid d cooled by the heat-exchanger, wherein the heat-exchanger heat-exchanges the fluid d with the fluid c as a coolant expanded by the second expanding unit to cool the fluid d.

A liquefaction system that is configured to use a single methane expander to provide primary refrigeration duty. The liquefaction system can include a first or main heat exchanger and a fluid circuit coupled with the heat exchanger, the fluid circuit configured to circulate a process stream derived from an incoming feedstock of natural gas. The fluid circuit can comprise a compression circuit, methane expander coupled with the compression circuit and the main heat exchanger, a sub-cooling unit coupled with the methane expander, the sub-cooling unit configured to form a liquid natural gas (LNG) product from the process stream, and a first throttling device interposed between the main heat exchanger and the sub-cooling unit. The first throttling device can be configured to expand the process stream to a process pressure that corresponds with the suction pressure internal to the compression circuit.

The present invention relates to a method of liquefying a hydrocarbon stream such as a natural gas stream, the method at least comprising the steps of: supplying a partly condensed hydrocarbon feed stream (10) to a first gas/liquid separator (2); separating the feed stream (10) in the first gas/liquid separator (2) into a gaseous stream (20) and a liquid stream (30); expanding the gaseous stream (20) thereby obtaining an expanded stream (40) and feeding it (40) into a second gas/liquid separator (3); feeding the liquid stream (30) into the second gas/liquid separator (3); removing from the bottom of the second gas/liquid separator a liquid stream (60) and feeding it into a fractionation column (5); removing from the top of the second gas/liquid separator (3) a gaseous stream (50) and passing it to a compressor (6) thereby obtaining a compressed stream (70); cooling the compressed stream (70) thereby obtaining a cooled compressed stream (80); heat exchanging the cooled compressed stream (80) against a stream being downstream of the first gas/liquid separator (2) and upstream of the fractionation column (5).

A process for co-producing a liquid oxygen and a liquefied hydrocarbon stream, including introducing a gaseous hydrocarbon stream and a gaseous nitrogen stream into a liquefier, thereby producing a liquefied hydrocarbon stream and a liquid nitrogen stream, liquefying a gaseous oxygen stream, wherein at least a portion of the required refrigeration is obtained from the liquid nitrogen stream. Wherein the liquefied hydrocarbon stream and the liquefied gaseous oxygen stream have mass flow rates. The liquid oxygen stream may be produced in an aft separation unit, wherein at least a portion of the required refrigeration is obtained from the liquid nitrogen stream.