Method for producing hydrogen from water by means of a high-temperature electrolyzer

Abstract

Water is heated to a process temperature of an electrolyzer, e.g., more than 500° C. Then, the water is electrolyzed in the electrolyzer to form product gases hydrogen (H 2 ) and oxygen (O 2 ). The product gas hydrogen (H 2 ) is compressed by a compressing apparatus and cooled by a cooling medium that feeds the thermal energy to heat the water.

1 - 12 . (canceled) 
     
     
         13 . A method for producing hydrogen from water using an electrolyzer, comprising:
 heating the water to a process temperature of the electrolyzer of more than 500° C.;   performing electrolysis of the water in the electrolyzer to produce gaseous hydrogen and oxygen;   compressing the gaseous hydrogen by a compressing device to produce compressed hydrogen;   cooling the compressed hydrogen by a coolant,   wherein said heating includes
 supplying heat energy absorbed by the coolant to said heating of the water which is thereby evaporated, and 
 cooling the gaseous hydrogen, after leaving the electrolyzer and before compression, by a heat-exchange process that heats the water fed to the electrolyzer in vapor form and cools the gaseous hydrogen. 
   
     
     
         14 . The method as claimed in  claim 13 , wherein said compressing of the gaseous hydrogen takes place in several compression operations, respectively accompanied by several cooling processes. 
     
     
         15 . The method as claimed in  claim 14 , wherein the compressing device is cooled by the coolant, whereby the heat energy transferred to the coolant is supplied for said heating of the water. 
     
     
         16 . The method as claimed in  claim 15 , wherein the compressing device is insulated at least partially from surroundings. 
     
     
         17 . The method as claimed in  claim 16 , wherein cooling channels pass through the compressing device. 
     
     
         18 . The method as claimed in  claim 17 , wherein the water that is fed to the electrolyzer includes at least part of the coolant. 
     
     
         19 . The method as claimed in  claim 18 , wherein after leaving the electrolyzer, the gaseous hydrogen is cooled by a countercurrent heat exchanger. 
     
     
         20 . The method as claimed in  claim 19 , further comprising, in addition to the gaseous hydrogen, compressing and cooling the oxygen produced by the electrolyzer, with the heat energy thereby extracted being supplied for said heating of the water. 
     
     
         21 . A device for producing hydrogen, comprising:
 a high-temperature electrolyzer converting water to hydrogen;   a compressing device compressing the hydrogen produced by said high-temperature electrolyzer and including a heat exchange device, at least partially surrounding a compression chamber of said compressing device, transferring heat produced by compressing the hydrogen to the water fed to said high-temperature electrolyzer.   
     
     
         22 . The device as claimed in  claim 21 , wherein said compressing device is a compressor. 
     
     
         23 . The device as claimed in  claim 22 , wherein said compressor is at least partially insulated. 
     
     
         24 . The device as claimed in  claim 23 , wherein the heat exchange device includes cooling channels passing through said compressing device.