Method and apparatus for cooling hydrogen

Abstract

The invention relates to a method for cooling hydrogen, in which method liquefied natural gas is heated by indirect heat exchange in a first heat exchanger with an intermediate fluid flow, the intermediate fluid flow is cooled, a hydrogen gas flow is cooled in a second heat exchanger without being condensed, and a gas flow derived from the cooled intermediate fluid is heated in a second heat exchanger to a temperature of between −150° C. and −90° C., which gas flow is withdrawn from the second heat exchanger at said temperature and compressed in a compressor with an inlet temperature of between −150° C. and −90° C.

1 - 15 . (canceled) 
     
     
         16 . A method for cooling hydrogen, wherein
 i) heating either a liquefied natural gas or a vaporized natural gas, the vaporized natural gas being at a temperature lower than −50° C., to a temperature higher than 0° C. by indirect heat exchange in a first heat exchanger with a flow of intermediate fluid at a pressure of between 3 and 70 bar abs if the intermediate fluid is not nitrogen and between 3 and 25 bar if the intermediate fluid is nitrogen which is cooled down to a temperature higher than or equal to −145° C.;   ii) cooling the flow of intermediate fluid at a first temperature higher than or equal to −145° C.:
 a) by introducing the flow of intermediate fluid at said first temperature into a second heat exchanger where the flow of intermediate fluid is cooled by indirect heat exchange, and/or 
 b) by expansion in a turbine optionally driving a compressor of the method, or a valve; 
   iii) cooling a flow of gaseous hydrogen in the second heat exchanger without condensing,   iv) heating a gaseous flow derived from the intermediate fluid cooled in step a) and/or b) in the second heat exchanger to a second temperature of between −150° C. and −90° C., and then withdrawing the gaseous flow from the second heat exchanger at said second temperature and then compressing the gaseous flow in a compressor to form a compressed intermediate fluid, wherein the compressor has an inlet temperature of between −150° C. and −90° C., wherein at least one part of the compressed intermediate fluid is cooled first in the first heat exchanger and then heated from a temperature of at most −110° C.; and   v) at least one part of the heated intermediate fluid constitutes the flow of intermediate fluid of step i),   wherein the at least one part of the compressed intermediate fluid, cooled first in the first heat exchanger, is then heated in the second heat exchanger from the temperature of at most-110° C. so as to constitute the flow of intermediate fluid of step i).   
     
     
         17 . The method as claimed in  claim 16 , wherein the maximum temperature difference between countercurrent fluids in the first exchanger is lower than 25° C., preferably lower than 20° C., or even lower than 15° C. 
     
     
         18 . The method as claimed in  claim 16 , wherein the intermediate fluid contains more than 50 mol % nitrogen, preferably at least 90 mol % nitrogen or even at least 99 mol % nitrogen. 
     
     
         19 . The method as claimed in  claim 16 , wherein liquefied natural gas is vaporized in the first heat exchanger and heated there up to a temperature higher than 0° C. 
     
     
         20 . The method as claimed in  claim 16 , wherein the flow of gaseous hydrogen cooled in the second heat exchanger condenses in another heat exchanger following cooling down to its liquefaction temperature. 
     
     
         21 . The method as claimed in  claim 16 , wherein vaporized liquefied natural gas or natural gas heated in the first heat exchanger is sent to a conversion unit to be converted into hydrogen. 
     
     
         22 . The method as claimed in  claim 16 , wherein for start-up the liquefied natural gas is vaporized in a heat exchanger by heat exchange with water, for example seawater. 
     
     
         23 . The method as claimed in  claim 16 , wherein a part of the compressed intermediate fluid is cooled first in the first heat exchanger down to an intermediate temperature of the first heat exchanger, for example between −40° C. and −90° C., preferably between 45° C. and −70° C., and is sent to cool an auxiliary heat exchanger and then is sent after being heated in the auxiliary heat exchanger to be cooled in the first heat exchanger. 
     
     
         24 . The method as claimed in  claim 23 , wherein the auxiliary heat exchanger serves to cool a flow of gas containing carbon dioxide and at least one other component in an apparatus for separating and/or liquefying carbon dioxide. 
     
     
         25 . The method as claimed in  claim 23 , wherein the part of the compressed intermediate fluid is heated with heating means connected in parallel with the auxiliary heat exchanger. 
     
     
         26 . The method as claimed in  claim 16 , wherein a part of the cold generated by liquefied natural gas or vaporized natural gas serves to cool cooling water of a compressor of the method and/or to cool the flow of gaseous hydrogen upstream of a drying step and/or of the second heat exchanger. 
     
     
         27 . The method as claimed in  claim 16 , wherein the flow of gaseous hydrogen cooled in step iii) is then liquefied by heat exchange with a refrigeration cycle. 
     
     
         28 . An apparatus for cooling hydrogen, the apparatus comprising:
 a source of natural gas in either liquid or gaseous form, wherein the gaseous natural gas is at a temperature lower than −50° C.;   a first heat exchanger in fluid communication with the source of natural gas, wherein the first heat exchanger is configured to heat the natural gas to a temperature higher than 0° C. by indirect heat exchange;   a second heat exchanger configured to cool a flow of gaseous hydrogen without condensing;   a compressor;   means for sending a flow of intermediate fluid at a pressure of between 3 and 70 bar abs if the intermediate fluid is not nitrogen and between 3 and 25 bar if the intermediate fluid is nitrogen to be cooled in the first heat exchanger down to a temperature higher than or equal to −145° C.;   means for sending the flow of intermediate fluid at a first temperature higher than or equal to −145° C. to be cooled:
 a) by introducing the flow of intermediate fluid at said first temperature into the second heat exchanger where the flow of intermediate fluid is cooled by indirect heat exchange, and/or 
 b) by expanding the flow of intermediate fluid in valve or a turbine, wherein the turbine is optionally configured to drive the compressor; 
   means for sending a gaseous flow derived from the intermediate fluid cooled in step a) and/or b) to be heated in the second heat exchanger up to a second temperature of between −150° C. and −90° C.;   means for withdrawing the gaseous flow from the second heat exchanger at said second temperature;   means for sending the withdrawn gaseous flow to the compressor with an inlet temperature of between −150° C. and −90° C. to be compressed;   means for sending at least one part of the compressed intermediate fluid to be cooled first in the first heat exchanger; and   means for sending the at least one part of the cooled intermediate fluid into the first exchanger, to be heated from a temperature of at most −110° C., at least one part of the heated intermediate fluid constituting the flow of intermediate fluid,   wherein the means for sending the at least one part of the intermediate fluid to be heated are connected so that the at least one part is heated in the second heat exchanger from the temperature of at most −110° C. so as to constitute the flow of intermediate fluid.   
     
     
         29 . The apparatus as claimed in  claim 28 , further comprising the turbine and a phase separator configured to separate a fluid coming from the turbine, the gaseous flow being the overhead gas and/or the vaporized liquid from the separator. 
     
     
         30 . The apparatus as claimed in  claim 28 , further means for liquefying the hydrogen cooled in the cooling apparatus.