A method for liquefying a feed gas stream. A refrigerant stream is cooled and expanded to produce an expanded, cooled refrigerant stream. Part or all of the expanded, cooled refrigerant stream is mixed with a make-up refrigerant stream in a separator, thereby condensing heavy hydrocarbon components from the make-up refrigerant stream and forming a gaseous expanded, cooled refrigerant stream. The gaseous expanded, cooled refrigerant stream passes through a heat exchanger zone to form a warm refrigerant stream. The feed gas stream is passed through the heat exchanger zone to cool at least part of the feed gas stream by indirect heat exchange with the expanded, cooled refrigerant stream, thereby forming a liquefied gas stream. The warm refrigerant stream is compressed to produce the compressed refrigerant stream.

A method for the liquefaction of hydrogen is provided. The can include the steps of: precooling a hydrogen feed stream in a precooling cold box having a heat exchanger disposed therein to form a cooled hydrogen stream, wherein the heat exchanger is configured to cool down the feed stream within the precooling cold box by indirect heat exchange between the hydrogen feed stream and a precooling refrigerant; and withdrawing the cooled hydrogen stream from the precooling cold box; introducing the cooled hydrogen stream to a plurality of liquefaction cold boxes, wherein the cooled hydrogen stream liquefies within the plurality of liquefaction cold boxes by indirect heat exchange against a liquefaction refrigerant to form a product hydrogen stream in each of the plurality of liquefaction cold boxes, wherein the product hydrogen stream is in liquid form or pseudo-liquid form wherein there are M total precooling cold boxes and N total liquefaction cold boxes, wherein M is less than N.

A system for liquefying a gas includes a liquefaction heat exchanger having a feed gas inlet adapted to receive a feed gas and a liquefied gas outlet through which the liquefied gas exits after the gas is liquefied in the liquefying passage of the heat exchanger by heat exchange with a primary refrigeration passage. A mixed refrigerant compressor system is configured to provide refrigerant to the primary refrigeration passage. An expander separator is in communication with the liquefied gas outlet of the liquefaction heat exchanger, and a cold gas line is in fluid communication with the expander separator. A cold recovery heat exchanger receives cold vapor from the cold gas line and liquid refrigerant from the mixed refrigerant compressor system so that the refrigerant is cooled using the cold vapor.

A system and method for producing an LNG product stream to provide fuel to generators, as an alternative to diesel, to power drilling and other equipment. Using sales gas from a natural gas/NGL plant containing less than 95% methane as a feed stream, production of LNG having 95% or more methane in quantities of 100,000 GPD or more LNG product are achievable with the system and method. The system and method preferably combine use of strategic heat exchange between the feed and a nitrogen-methane flash vapor stream and other streams within the LNG processing system without requiring heat exchange with process streams in the natural gas/NGL plant and a rectifier column that uses an internal knockback condenser and does not require a reboiler to remove heavier components from the sales gas feed.

A system for natural gas cooling using nitrogen. The system can include a nitrogen liquefier and a natural gas cooler. The nitrogen liquefier can provide liquid nitrogen to the natural gas cooler. One or more heat exchangers of the natural gas cooler can include a gaseous nitrogen output that is in fluid communication with the nitrogen liquefier. In response to receiving gaseous nitrogen at the nitrogen liquefier, from the one or more heat exchangers, a production rate of the the nitrogen liquefier is adjusted.

A method for recovering boil-off gas from a system including one or more liquefaction trains including transport trucks or loading bays, a gaseous hydrogen feed stream, a lower-temperature cold box, and a low-pressure hydrogen compressor. The method including collecting a boil-off gas stream from the transport trucks or loading bays, determining the pressure of the boil-off gas stream, and depending on the pressure, recycling the boo-off gas stream to predetermined destinations. Wherein the boil-off gas stream has either a low-pressure, having a pressure of less than 2 bara, or a medium-pressure, having a pressure equal to or greater than 2 bara.

A liquefaction system is capable of sequentially or simultaneously liquefying multiple feed streams of hydrocarbons having different normal bubble points with minimal flash. The liquefying heat exchanger has separate circuits for handling multiple feed streams. The feed stream with the lowest normal boiling point is sub-cooled sufficiently to suppress most of the flash. Feed streams with relatively high normal boiling points are cooled to substantially the same temperature, then blended with bypass streams to maintain each product near its normal bubble point. The system can also liquefy one stream at a time by using a dedicated circuit or by allocating the same feed to multiple circuits.

A plant and process are used to liquefy and purify a high pressure ethane feed stream. The plant includes a cascaded refrigeration system that refrigerates the ethane feed stream. The refrigeration system includes a propylene circuit, an ethylene circuit and a mixed refrigerant circuit. The mixed refrigerant circuit includes a refrigerant that includes ethane and methane. The plant includes a demethanizer that is configured to remove methane and other natural gas liquids from the refrigerated ethane stream.

A method is disclosed for start-up of a system for liquefying a feed gas stream comprising natural gas. The system has a feed gas compression and expansion loop, and a refrigerant system comprising a primary cooling loop and a sub-cooling loop. The feed gas compression and expansion loop is started up. The refrigerant system is pressurized. Circulation in the primary cooling loop is started and established. Circulation in the sub-cooling loop is started and established. A flow rate of the feed gas stream and circulation rates of the primary cooling loop and the sub-cooling loop are ramped up.

A liquid natural gas (LNG) reforming system of the present invention may include a reformer provided to receive LNG from an LNG tank; a C02 PSA unit connected to the reformer and configured to extract carbon dioxide from off-gas generated from the reformer; a cooler connected to the C02 PSA unit and configured to cool and liquefy the carbon dioxide extracted by the C0.sub.2 PSA unit using the LNG supplied from the LNG tank to the reformer; a storage tank connected to the cooler and provided to store liquid carbon dioxide of the cooler therein; and a circulation pump provided to pump the liquid carbon dioxide from the cooler into the storage tank and circulate a part of the liquid carbon oxide into the cooler.