Apparatus and process for hydrogen recycling to avoid liquefier shutdown due to insufficient feed of hydrogen

Abstract

An apparatus and process for recycling hydrogen can be provided so that hydrogen is recycled during hydrogen liquefaction processing to account for an unexpected loss of feed of hydrogen so the recycled hydrogen can be provided to avoid liquefier operations having to be shut down. Embodiments can utilize a parahydrogen to ortho-hydrogen conversion unit to facilitate such recycling of hydrogen to avoid liquefaction processing problems in liquefaction of the recycled hydrogen included into the feed to account for the loss of fee hydrogen.

What is claimed is: 
     
         1 . A process for recycling hydrogen, comprising:
 feeding a feed of hydrogen to a liquefaction unit;   the liquefaction unit liquefying the hydrogen to output liquid hydrogen, the liquid hydrogen having a parahydrogen content of between 80 mole percent (mol %) parahydrogen and 100 mol % parahydrogen;   in response to determining that the feed of hydrogen has decreased to at or below a pre-selected threshold, recycling the liquid hydrogen to a feed of the liquefaction unit such that the liquid hydrogen is vaporized into a gaseous state and undergoes a parahydrogen to orthohydrogen conversion so that the parahydrogen content of the recycled hydrogen recycled to the feed of the liquefaction unit has a parahydrogen content of between 20 mol % parahydrogen and 30 mol % parahydrogen.   
     
     
         2 . The process of  claim 1 , wherein the feed of hydrogen has a parahydrogen content within a pre-selected parahydrogen content range of between 20 mole percent parahydrogen and 30 mole percent parahydrogen. 
     
     
         3 . The process of  claim 1 , comprising:
 in response to determining that the feed of hydrogen has increased to at or above the pre-selected threshold, ceasing the recycling of the liquid hydrogen.   
     
     
         4 . The process of  claim 1 , wherein the recycling of the liquid hydrogen comprises:
 feeding hydrogen having a parahydrogen content of between 80 mol % and 100 mol % stored in at least one storage tank towards a conversion unit positioned to convert the parahydrogen to orthohydrogen so that the parahydrogen content of the recycled hydrogen recycled to the feed of the liquefaction unit has the parahydrogen content of between 20 mol % parahydrogen and 30 mol % parahydrogen; and/or   feeding liquid hydrogen output from the liquefaction unit to a heater of a recycle loop to vaporize the liquid hydrogen and subsequently pass the vaporized hydrogen to the conversion unit positioned to convert the parahydrogen to orthohydrogen so that the parahydrogen content of the recycled hydrogen recycled to the feed of the liquefaction unit has the parahydrogen content of between 20 mol % parahydrogen and 30 mol % parahydrogen.   
     
     
         5 . The process of  claim 1 , comprising:
 feeding the liquid hydrogen having the parahydrogen content of between 80 mole percent (mol %) parahydrogen and 100 mol % parahydrogen output from the liquefier to at least one storage tank of hydrogen storage in fluid communication with the liquefaction unit; and   wherein the recycling of the liquid hydrogen comprises:
 adjusting at least one valve so that the liquid hydrogen output from the liquefaction unit is not passable to the at least one storage tank; and 
 feeding liquid hydrogen output from the liquefaction unit to a heater of a recycle loop to vaporize the liquid hydrogen and subsequently pass the vaporized hydrogen to the conversion unit positioned to convert the parahydrogen to orthohydrogen so that the parahydrogen content of the recycled hydrogen recycled to the feed of the liquefaction unit has the parahydrogen content of between 20 mol % parahydrogen and 30 mol % parahydrogen. 
   
     
     
         6 . The process of  claim 5 , comprising:
 feeding hydrogen stored in at least one storage tank towards a conversion unit positioned to convert the parahydrogen to orthohydrogen so that the parahydrogen content of the recycled hydrogen recycled to the feed of the liquefaction unit has the parahydrogen content of between 20 mol % parahydrogen and 30 mol % parahydrogen;   after determining that sufficient hydrogen has been recycled to the liquefaction unit to account for the decrease of the feed of hydrogen, ceasing the feeding of the hydrogen stored in the at least one storage tank towards the conversion unit.   
     
     
         7 . The process of  claim 1 , wherein the recycling of the liquid hydrogen comprises:
 compressing the hydrogen before the hydrogen is fed to a conversion unit positioned to convert the parahydrogen to orthohydrogen so that the parahydrogen content of the recycled hydrogen recycled to the feed of the liquefaction unit has the parahydrogen content of between  20  mol % parahydrogen and 30 mol % parahydrogen.   
     
     
         8 . The process of  claim 1 , wherein the recycling of the liquid hydrogen comprises:
 feeding hydrogen having a parahydrogen content of between 80 mol % and 100 mol % stored in at least one storage tank towards a conversion unit positioned to convert the parahydrogen to orthohydrogen so that the parahydrogen content of the recycled hydrogen recycled to the feed of the liquefaction unit has the parahydrogen content of between 20 mol % parahydrogen and 30 mol % parahydrogen; and/or   feeding liquid hydrogen output from the liquefaction unit to a heater of a recycle loop to vaporize the liquid hydrogen and subsequently pass the vaporized hydrogen to the conversion unit positioned to convert the parahydrogen to orthohydrogen so that the parahydrogen content of the recycled hydrogen recycled to the feed of the liquefaction unit has the parahydrogen content of between 20 mol % parahydrogen and 30 mol % parahydrogen;   and the process also comprises:   in response to a start-up of the liquefaction unit when the liquefaction unit is at an ambient temperature, feeding liquid hydrogen stored in at least one storage tank to the liquefaction unit to facilitate operation of the liquefaction unit and cooling of the liquefaction unit to a cryogenic operational temperature and recycling the hydrogen output form the liquefaction unit during the start-up via the recycle loop.   
     
     
         9 . The process of  claim 8 , wherein a controller having a processor connected to a non-transitory memory is positioned and configured to determine whether the feed of hydrogen has decreased to at or below the pre-selected threshold. 
     
     
         10 . An apparatus for hydrogen recycling, comprising:
 a liquefaction unit configured to liquify a feed of hydrogen to output a first stream of liquid hydrogen to feed the liquid hydrogen to at least one storage tank, the liquid hydrogen having a parahydrogen content of between 80 mole percent (mol %) and 100 mol %); and   a conversion unit positioned to convert parahydrogen of hydrogen output by the liquefaction unit to orthohydrogen so hydrogen output from the liquefaction unit is recyclable to a feed inlet of the liquefaction unit with a parahydrogen content that is between 20 mol % and 30 mol %.   
     
     
         11 . The apparatus of  claim 10 , comprising:
 a recycle loop conduit heater feed conduit connected between the liquefaction unit and a recycle loop conduit heater, the recycle loop conduit heater positioned to heat liquid hydrogen output from the liquefaction unit to vaporize the liquid hydrogen to gaseous hydrogen;   the recycle loop conduit heater positioned to feed the gaseous hydrogen to the conversion unit.   
     
     
         12 . The apparatus of  claim 10 , wherein the conversion unit includes at least one parahydrogen to orthohydrogen converter. 
     
     
         13 . The apparatus of  claim 10 , comprising:
 the at least one storage tank, the at least one storage tank being positioned to output hydrogen stored therein to feed the hydrogen to the conversion unit.   
     
     
         14 . The apparatus of  claim 13 , comprising:
 a recycle loop heater positioned to receive hydrogen from the at least one storage tank and heat the hydrogen so the hydrogen output from the at least one storage tank to be fed to the conversion unit is fed to the conversion unit as gaseous hydrogen.   
     
     
         15 . The apparatus of  claim 10 , comprising:
 a recycle loop conduit heater feed conduit connected between the liquefaction unit and a recycle loop conduit heater, the recycle loop conduit heater positioned to heat liquid hydrogen output from the liquefaction unit to vaporize the liquid hydrogen to gaseous hydrogen, and the recycle loop conduit heater positioned to feed the gaseous hydrogen to the conversion unit; and/or   a recycle loop heater positioned to receive hydrogen from the at least one storage tank and heat the hydrogen so the hydrogen output from the at least one storage tank to be fed to the conversion unit is fed to the conversion unit as gaseous hydrogen.   
     
     
         16 . The apparatus of  claim 10 , comprising:
 a recycle loop conduit heater feed conduit connected between the liquefaction unit and a first recycle loop conduit heater, the first recycle loop conduit heater positioned to heat liquid hydrogen output from the liquefaction unit to vaporize the liquid hydrogen to gaseous hydrogen, and the first recycle loop conduit heater positioned to feed the gaseous hydrogen to the conversion unit; and   a second recycle loop heater positioned to receive hydrogen from the at least one storage tank and heat the hydrogen so the hydrogen output from the at least one storage tank to be fed to the conversion unit is fed to the conversion unit as gaseous hydrogen.   
     
     
         17 . The apparatus of  claim 10 , comprising:
 a compression system positioned upstream of the conversion unit to compress the hydrogen for feeding the hydrogen to the conversion unit.   
     
     
         18 . An apparatus for hydrogen recycling, comprising:
 a liquefaction unit configured to liquify a feed of hydrogen to output a first stream of liquid hydrogen to feed the liquid hydrogen to at least one storage tank, the liquid hydrogen having a parahydrogen content of between 80 mole percent (mol %) and 100 mol %);   a conversion unit positioned to convert parahydrogen of hydrogen output by the liquefaction unit to orthohydrogen so hydrogen output from the liquefaction unit is recyclable to a feed inlet of the liquefaction unit with a parahydrogen content that is between 20 mol % and 30 mol %, the conversion unit including at least one parahydrogen to orthohydrogen converter;   the at least one storage tank, the at least one storage tank being positioned to output hydrogen stored therein to feed the hydrogen to the conversion unit in response to the feed of hydrogen being at or below a pre-selected threshold;   a recycle loop conduit heater feed conduit connected between the liquefaction unit and a first recycle loop conduit heater, the first recycle loop conduit heater positioned to heat liquid hydrogen output from the liquefaction unit to vaporize the liquid hydrogen to gaseous hydrogen, and the first recycle loop conduit heater positioned to feed the gaseous hydrogen to the conversion unit; and   a second recycle loop heater positioned to receive hydrogen from the at least one storage tank and heat the hydrogen so the hydrogen output from the at least one storage tank to be fed to the conversion unit is feedable to the conversion unit as gaseous hydrogen.   
     
     
         19 . The apparatus of  claim 18 , comprising:
 a compression system positioned upstream of the conversion unit to compress hydrogen for feeding the hydrogen to the conversion unit.   
     
     
         20 . The apparatus of  claim 18 , wherein the liquefaction unit has a closed loop refrigeration system or an open loop refrigeration system.