Abstract: 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.

Abstract: Natural gas liquids (NGLs) are recovered by cooling and partial condensation of a purified natural gas feed wherein a portion of the necessary feed cooling and condensation duty is provided by expansion and vaporization of condensed feed liquid after methane stripping, thereby yielding a vaporized NGL product. Additional refrigeration for feed cooling is provided by vaporizing methane-stripped liquid, which in turn provides vapor boilup for the stripping step. Recompression and cooling of the vaporized NGL product can be utilized if a liquid product is required.

Abstract: A cryogenic distillative separation of air to recover nitrogen in large quantities and at relatively high pressure wherein a portion of the nitrogen reflux for the distillation is achieved by heat exchanging nitrogen gas in a side reboiler against waste oxygen at reduced pressure.