Cryogenic process for recovering valuable components from a hydrogen-rich feed gas

Abstract

The invention relates to a cryogenic process for recovering valuable components, in particular hydrogen, from a hydrogen-rich feed gas, in particular a hydrogen-rich natural gas, comprising the following steps: in a first separation column (T 1 ), hydrocarbons having two or more carbon atoms are separated off, in a second separation column (T 2 ), methane is separated off, and in a third separation column (T 3 ) nitrogen is separated off, the hydrogen-rich feed gas, after optional precleaning R, being fed to the separation columns T 1 to T 3 according to steps a) to c) and being separated in the separation columns into a liquid fraction, the bottom product, and a gas fraction, the overhead product. In the cryogenic process according to the invention, the cold supply preferably takes place at least partially through one or more refrigeration cycles.

1 . A cryogenic process for recovering valuable components, in particular hydrogen, from a hydrogen-rich natural gas, comprising the following steps:
 a) separating hydrocarbons containing two or more carbon atoms in a first rectification column (T 1 ),   b) separating methane in a second rectification column (T 2 ), and   c) separating nitrogen in a third rectification column (T 3 ), wherein the hydrogen-rich natural gas is fed to the rectification columns T 1  to T 3  according to steps a) to c) and is separated in the rectification columns into a liquid fraction, a bottom product, a gas fraction, and an overhead product.   
     
     
         2 . The process according to  claim 1 , wherein cooling and at least partial liquefaction of the hydrogen-rich natural gas in the rectification columns against a refrigerant or refrigerant mixture takes place in at least one heat exchanger. 
     
     
         3 . The process according to  claim 1 , wherein the natural gas has a hydrogen content of between 50 and 99.9% by volume, a methane content of between 0.02 and 40% by volume and a nitrogen content of between 0.02 and 30% by volume. 
     
     
         4 . The process according to  claim 1 , wherein the bottom product of rectification column T 2  is either recovered as methane product or is further cooled by means of the heat exchanger and is recovered as liquified natural gas. 
     
     
         5 . The process according to  claim 1 , wherein the bottom product from rectification column T 3  is expanded and fed into a refrigeration cycle as refrigerant, or as a component of the refrigerant. 
     
     
         6 . The process according to  claim 1 , wherein a partial stream of the hydrogen-rich natural gas is fed into a lower part of rectification column T 1  and/or a partial stream of the overhead product of rectification column T 1  is fed into a lower part of rectification column T 2 , and/or a partial stream of the overhead product of rectification column T 2  is fed into a lower part of rectification column T 3 . 
     
     
         7 . The process according to  claim 1 , wherein the overhead product of rectification column T 3 , after further cooling in a hydrogen rectification column (T 5 ), is split into helium and hydrogen by rectification or via at least one-stage depressurization, freed separately from residual impurities in cryogenic standard liquefaction plants, then at least the helium is liquefied and then helium and hydrogen are stored separately. 
     
     
         8 . The process according to  claim 1 , wherein the overhead product from rectification column T 3  is heated in a heat exchanger and freed from residual impurities in a standard hydrogen liquefaction plant, then liquefied and stored. 
     
     
         9 . The process according to  claim 1 , wherein the overhead product of rectification column T 3 , either
 a) is heated and compressed and fed into a pipeline, including any inert gas components that may be present, or   b) is purified in a special unit by means of adsorption, then liquefied and stored.   
     
     
         10 . The process according to  claim 1 , wherein carbon monoxide enriched in the bottom product of rectification column T 3  is removed in a further process unit or converted to carbon dioxide. 
     
     
         11 . The process according to  claim 1 , wherein the bottom product of rectification column T 2 , the overhead product and bottom product of rectification column T 3 , and the overhead product of rectification column T 4  are adjusted in purity as a liquified petroleum gas product ethane product methane product, or nitrogen product, or hydrogen product. 
     
     
         12 . The process according to  claim 1 , wherein condensers of the rectification columns T 1  to T 4  and reboilers of the rectification columns T 1  to T 3  are connected to at least one heat exchanger or integrated in the at least one heat exchanger. 
     
     
         13 . The process according to  claim 1 , wherein the heat exchanger comprises at least one multi-flow plate heat exchanger and/or at least one spiral wound heat exchanger. 
     
     
         14 . The process according to  claim 1 , wherein cold supplied to the separation processes of the rectification columns T 1  to T 4  is supplied
 a) via a nitrogen expander cycle with at least one expander compressor (Xi-Ci), the compressors Ci serving as final stages of cycle compression, 
 b) via an expander refrigeration cycle with nitrogen and methane as components, 
 c) via a mixed refrigerant cycle consisting of at least two components selected from the group consisting of nitrogen, methane, ethane, propane, i-butane, n-butane, i-pentane, n-pentane, hexane and heptane, or 
 d) via a serial arrangement of selected refrigeration cycles of selected refrigeration cycles a) to c).