Electrolyzer cell systems and method of operating thereof by water cooling of system exhaust

Abstract

A method of operating an electrolyzer cell system includes providing a steam inlet stream to a stack of electrolyzer cells, generating a main product stream containing hydrogen and steam, and an oxygen exhaust stream in the stack, and providing liquid water into the main product stream to cool the main product stream.

1 . An electrolyzer cell system, comprising:
 a stack of electrolyzer cells located in a hot box and configured to generate a main product stream comprising hydrogen and steam, and an oxygen exhaust stream;   a steam source fluidly connected to the stack and configured to provide the steam inlet stream to the stack;   at least one product conduit fluidly connected to the stack and configured to receive the main product stream; and   a water injector configured to provide liquid water into the main product stream in the at least one product conduit.   
     
     
         2 . The electrolyzer cell system of  claim 1 , further comprising:
 a liquid water source fluidly connected to the water injector;   an air blower fluidly connected to the stack and configured to provide an air inlet stream into the stack;   a product separator fluidly connected to the at least one product conduit and configured to separate the main product stream into a first portion and a second portion; and   a recycle blower fluidly connected to the at least one product conduit and configured to recycle the first portion of the main product stream into the stack.   
     
     
         3 . The electrolyzer cell system of  claim 2 , wherein the at least one product conduit comprises:
 an exhaust conduit fluidly connecting the stack to an inlet of the product separator;   at least one recycle conduit fluidly connecting a first outlet of the product separator to the stack through the recycle blower; and   at least one hydrogen conduit fluidly connecting a second outlet of the product separator to a hydrogen outlet of the electrolyzer cell system.   
     
     
         4 . The electrolyzer cell system of  claim 3 , wherein the water injector is located on the at least one recycle conduit upstream of the recycle blower. 
     
     
         5 . The electrolyzer cell system of  claim 3 , wherein the water injector is located on the exhaust conduit inside the hot box. 
     
     
         6 . The electrolyzer cell system of  claim 3 , further comprising:
 a heat exchanger located on the at least one hydrogen conduit;   a water source conduit fluidly connecting a water source to an inlet of the heat exchanger; and   at least one water inlet conduit fluidly connecting an outlet of the heat exchanger to the water injector, and configured to provide liquid water preheated by the second portion of the main product stream to the water injector.   
     
     
         7 . The electrolyzer cell system of  claim 1 , further comprising:
 at least one water heat exchanger configured to convert liquid water to steam using heat from the oxygen exhaust stream;   at least one water inlet conduit fluidly connected to an inlet of the at least one water heat exchanger;   at least one oxygen exhaust conduit fluidly connecting an outlet of the stack to the at least one water heat exchanger and configured to provide the oxygen exhaust stream to the at least one water heat exchanger; and   at least one steam conduit fluidly connecting an outlet of the at least one water heat exchanger to the stack.   
     
     
         8 . The electrolyzer cell system of  claim 7 , wherein:
 the at least one water heat exchanger comprises first and second water heat exchangers located in the hot box;   the at least one water inlet conduit comprises a first water inlet conduit fluidly connected to an inlet of the first water heat exchanger, and a second water inlet conduit fluidly connected to an inlet of the second water heat exchanger;   the at least one steam conduit comprises a first steam conduit fluidly connecting an outlet of the first water heat exchanger to a first inlet of a steam mixer, a vaporizer conduit fluidly connecting an outlet of the second heat exchanger to an inlet of a water vaporizer, a second steam conduit fluidly connecting an outlet of the water vaporizer to a second inlet of the steam mixer, and a steam inlet conduit fluidly connecting an outlet of the steam mixer to a steam inlet of the stack; and   the steam source comprises at least one of the first water heat exchanger, the water vaporizer or an external steam source.   
     
     
         9 . The electrolyzer cell system of  claim 8 , further comprising:
 a water splitter fluidly connecting a water source to the first and the second water inlet conduits; and   a third water inlet conduit fluidly connecting an outlet of the water splitter to an inlet of the water injector.   
     
     
         10 . The electrolyzer cell system of  claim 1 , wherein the stack comprises a stack of solid oxide electrolyzer cells. 
     
     
         11 . A method of operating an electrolyzer cell system, comprising:
 providing a steam inlet stream to a stack of electrolyzer cells;   generating a main product stream comprising hydrogen and steam, and an oxygen exhaust stream in the stack; and   providing liquid water into the main product stream to cool the main product stream.   
     
     
         12 . The method of  claim 11 , further comprising:
 providing an air inlet stream into the stack;   separating the main product stream into a first portion and a second portion; and   recycling the first portion of the main product stream into the stack.   
     
     
         13 . The method of  claim 12 , further comprising providing a second portion of the main product stream to a hydrogen processor or to a hydrogen storage vessel. 
     
     
         14 . The method of  claim 13 , wherein the liquid water is provided into the first portion of the main product stream upstream of a recycle blower. 
     
     
         15 . The method of  claim 13 , wherein the liquid water is provided into the main product stream prior to the separating the main product stream into the first portion and the second portion. 
     
     
         16 . The method of  claim 13 , further comprising preheating the liquid water using heat from the second portion of the main product stream. 
     
     
         17 . The method of  claim 11 , further comprising converting a first portion of the liquid water to at least a first portion of the steam inlet stream using heat from the oxygen exhaust stream. 
     
     
         18 . The method of  claim 17 , further comprising:
 preheating a second portion of the liquid water using remaining heat from the oxygen exhaust stream after the converting the first portion of the liquid water to at least the first portion of the steam inlet stream; and   vaporizing the preheated second portion of the liquid water in a vaporizer to form a second portion of the steam inlet stream.   
     
     
         19 . The method of  claim 18 , further comprising splitting a water inlet stream into the first portion of the liquid water, the second portion of the liquid water, and a third portion of the liquid water, wherein the third portion of the liquid water is provided into the main product stream to cool the main product stream. 
     
     
         20 . The method of  claim 11 , further comprising cooling the main product stream using air in a cabinet housing the electrolyzer cell system.