Systems and methods for liquefying a gaseous hydrogen that include a first refrigeration stage and a second refrigeration stage. The first refrigeration stage includes a first heat exchanger configured to flow a first refrigerant to pre-cool the gaseous hydrogen. The second refrigeration stage includes a second heat exchanger configured to flow a second refrigerant to liquefy and sub-cool the hydrogen. The second refrigerant is split into two streams that flow through two compressor-expanders and multiple passes through the second heat exchanger before being recombined to repeat the second refrigeration stage circuit.

Natural gas liquefaction unit including at least one cryogenic cold box having at least one heat exchanger; a fixed assembly zone on its outer wall; at least one closed loop nitrogen refrigeration cycle; at least one device for equipment required for implementing the liquefaction of a natural gas stream from a hydrocarbon supply stream; at least one interconnection module comprising a pipe holder means and a set of pipes and valves, designed to connect said at least one cold box to at least one equipment device for the cycle for refrigerating and/or separating C6+ type hydrocarbon elements contained in the natural gas, wherein the interconnection module rests on a frame allowing it to be handled and is connected to the cold box and to the other method or equipment sub-assemblies located around said fixed assembly zone.

Plant and process for the production of liquid methane from a feed gas stream comprising at least methane and carbon dioxide. A feed gas stream is injected into a CO.sub.2 crystallizer in countercurrent fashion against a stream of predominantly liquid methane, thereby crystallizing amounts of carbon dioxide from the feed gas stream. Gaseous methane recovered from the CO.sub.2 crystallizer is liquefied at a liquefaction exchanger.

Systems and methods are described for increasing capacity and efficiency of a nitrogen refrigerant boil-off gas recovery system for a natural gas storage tank. Boil-off gas is condensed against two-phase nitrogen in a condensing heat exchanger having an inner vessel through which the boil-off gas flows and an outer vessel through which the two phase nitrogen flows. Logic controls maintain storage tank pressure and power consumption within preferred levels by adjusting the pressure of the two-phase nitrogen in the heat exchanger. Additional logic controls maintain the temperature difference between the nitrogen streams entering into and returning from the cold end of a second heat exchanger by controlling the position of an expansion valve on the return circuit.

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 gas processing system according to an embodiment of the present invention controls inflow fuel pressure of a low pressure demand source according to an operation or a non-operation of a high pressure demand source and the low pressure demand source.

In an aspect, a system comprises a water stream in fluid communication with an electrolyzer; the electrolyzer comprising an anode and a cathode side chamber; a deep space oxygen radiator in fluid communication with the anode side chamber of the electrolyzer; a cryogenic heat exchanger comprising an oxygen storage tank in fluid communication with the deep space oxygen radiator; an electrochemical hydrogen compressor in fluid communication with the cathode side chamber; a hydrogen storage tank in fluid communication with the electrochemical hydrogen compressor via a cooled hydrogen stream; wherein at least a portion of the cooled hydrogen stream is in a first fluid communication with an expansion valve and the cryogenic heat exchanger; wherein the hydrogen storage tank is in a second fluid communication with the electrochemical hydrogen compressor via a warmed hydrogen stream; and wherein the cryogenic heat exchanger is in fluid communication with the warmed hydrogen stream.

A liquefier device which may be a retrofit to an air separation plant or utilized as part of a new design. The flow needed for the liquefier comes from an air separation plant running in a maxim oxygen state, in a stable mode. The three gas flows are low pressure oxygen, low pressure nitrogen, and higher pressure nitrogen. All of the flows are found on the side of the main heat exchanger with a temperature of about 37 degrees Fahrenheit. All of the gasses put into the liquefier come out as a subcooled liquid, for storage or return to the air separation plant. This new liquefier does not include a front end electrical compressor, and will take a self produced liquid nitrogen, pump it up to a runnable 420 psig pressure, and with the use of turbines, condensers, flash pots, and multi pass heat exchangers. The liquefier will make liquid from a planned amount of any pure gas oxygen or nitrogen an air separation plant can produce.

Plant and method for producing hydrogen at cryogenic temperature, in particular liquefied hydrogen, comprising: an electrolyzer having an oxygen outlet and a hydrogen outlet; a hydrogen circuit to be cooled, comprising an upstream end connected to the hydrogen outlet and a downstream end to be connected to a member for collecting cooled and/or liquefied hydrogen, the plant also comprising a set of heat exchanger(s) in heat exchange with the hydrogen circuit to be cooled, the plant further comprising at least one cooling device in heat exchange with at least a portion of the set of heat exchanger(s), the hydrogen circuit to be cooled comprising a system for expanding the hydrogen stream and at least one hydrogen compressor upstream of the hydrogen stream expansion system, the hydrogen stream expansion system comprising at least one expansion turbine, wherein said at least one expansion turbine and said at least one compressor are coupled to the same rotating shaft to transfer expansion work from the pressurized hydrogen stream to the compressor in order to compress the hydrogen stream upstream of the turbine.

A method and apparatus for producing liquefied natural gas. A portion of a natural gas stream is cooled in a heat exchanger and combined with the natural gas stream. Heavy hydrocarbons are removed from the combined natural gas stream, and the resulting separated natural gas stream is partially condensed in the first heat exchanger, with a liquid stream separated therefrom. The natural gas stream is warmed in the first heat exchanger and then is compressed and cooled. The resultant cooled compressed natural gas stream is expanded, thereby forming a chilled natural gas stream that is separated into a refrigerant stream and a non-refrigerant stream. The refrigerant stream recycled to the heat exchanger to be warmed through heat exchange with one or more process streams associated with pretreating the natural gas stream, thereby generating a warmed refrigerant stream. The warmed refrigerant stream and the non-refrigerant stream are liquefied.