Electrolyzer system with steam generation and method of operating same
An electrolyzer system includes a steam generator configured to generate steam, a stack of solid oxide electrolyzer cells configured to generate a hydrogen stream using the steam received from the steam generator, and a water preheater configured to preheat water provided to the steam generator using heat extracted from oxygen exhaust output from the stack.
1. An electrolyzer system, comprising:
a hotbox;
a central column disposed in the hotbox and extending lengthwise in a vertical direction;
stacks of solid oxide electrolyzer cells disposed in the hotbox, surrounding the central column, and configured to convert steam into a hydrogen stream; and
an air heater configured to heat air provided to the stacks, wherein the air heater comprises peripheral heating elements disposed radially around the stacks, between an inner shell and an outer shell of the hotbox.
2. The electrolyzer system of claim 1 , further comprising support elements configured to support the peripheral heating elements and maintain a spacing between the inner shell and the outer shell.
3. The electrolyzer system of claim 2 , wherein the support elements comprise a ceramic material.
4. The electrolyzer system of claim 2 , wherein:
the support elements comprise ceramic tubes that extend in the vertical direction; and
the peripheral heating elements are elements respectively disposed within the ceramic tubes.
5. The electrolyzer system of claim 1 , wherein the peripheral heating elements comprise coiled heating elements or finned heating elements.
6. The electrolyzer system of claim 1 , wherein the peripheral heating elements comprise vertically-stacked annular heating elements or serpentine heating elements.
7. The electrolyzer system of claim 1 , further comprising an insulation layer disposed on the outer shell, surrounding the peripheral heating elements.
8. The electrolyzer system of claim 1 , further comprising guide vanes disposed between the inner shell and the outer shell, the guide vanes configured to radially direct flow of the air through the air heater.
9. The electrolyzer system of claim 1 , wherein the air heater further comprises central heating elements disposed between the central column and the stacks, the central heating elements configured to heat air after the air is heated by the peripheral heating elements.
10. The electrolyzer system of claim 9 , wherein the air heater further comprises bottom heating elements disposed below the stacks, the bottom heating elements configured to heat air flowing from the peripheral heating element to the central heating elements.
11. The electrolyzer system of claim 9 , wherein:
the peripheral heating elements are arranged in at least two groups, and the central heating elements are arranged in at least three groups; and
the air heater further comprises at least one power source configured to independently apply power to each group of the peripheral heating elements and each group of central heating elements.
12. The electrolyzer system of claim 9 , further comprising a steam generator disposed outside of the hotbox and configured to vaporize water into steam and to provide the steam to the central column.
13. The electrolyzer system of claim 9 , further comprising a steam generator disposed inside of the central column, and configured to vaporize water into steam.
14. The electrolyzer system of claim 13 , wherein the steam generator comprises a heating element configured to vaporize water flowing through the steam generator.
15. The electrolyzer system of claim 14 , wherein:
the steam generator comprises a vaporizing manifold configured to receive water provided to the central column; and
the heating element is configured to vaporize water flowing through the vaporizing manifold.
16. The electrolyzer system of claim 13 , wherein the electrolyzer system is configured to evaporate mineralized water output from the steam generator in oxygen exhaust generated by the stacks and output from the hotbox.
17. The electrolyzer system of claim 9 , further comprising an air recuperator disposed in the hotbox and configured to heat air provided to the air heater using oxygen exhaust output from the stacks.
18. An electrolyzer system, comprising:
a hotbox;
a central column disposed in the hotbox and extending lengthwise in a vertical direction;
stacks of solid oxide electrolyzer cells disposed in the hotbox, surrounding the central column, and configured to convert steam into a hydrogen stream;
an air heater configured to heat air provided to the stacks; and
an insulation layer disposed between the inner shell and the outer shell,
wherein the air heater comprises peripheral heating elements that are embedded in the insulation layer and radially surround the stacks.
19. An electrolyzer system, comprising:
a hotbox;
a central column disposed in the hotbox;
stacks of solid oxide electrolyzer cells disposed in the hotbox, surrounding the central column, and configured to receive steam and air and to output a hydrogen exhaust and an oxygen exhaust;
an air recuperator configured to preheat the air provided to the hotbox by extracting heat from the oxygen exhaust output from the stacks;
an air heater configured to heat preheated air output from the air recuperator and provide heated air to the stacks; and
a steam heater disposed in the central column and configured to superheat steam provided to the stacks.
20. The electrolyzer system of claim 19 , wherein the air recuperator surrounds the stacks.
21. The electrolyzer system of claim 20 , wherein oxygen exhaust output from the stacks is configured to flow along the central column, under the stacks, and then through the air recuperator, before exiting the hotbox.
22. The electrolyzer system of claim 21 , wherein air provided to the hotbox is configured to flow into the central column, and through the air recuperator, before entering the stacks.
23. The electrolyzer system of claim 20 , wherein the air heater comprises one or more heating elements disposed between an inner shell and an outer shell of the hotbox.
24. The electrolyzer system of claim 19 , wherein the air recuperator surrounds the central column and is surrounded by the stacks.
25. The electrolyzer system of claim 24 , wherein oxygen exhaust output from the stacks is configured to flow through the air recuperator before exiting the hotbox.
26. The electrolyzer system of claim 25 , wherein air provided to the hotbox is configured to flow into the central column, through the air recuperator, under the stacks, and then through the air heater, before entering the stacks.
27. The electrolyzer system of claim 19 , further comprising a water preheater configured to preheat water provided to the hotbox using heat extracted from oxygen exhaust output from the air recuperator.
28. The electrolyzer system of claim 19 , further comprising a distribution hub disposed below the stacks and the central column, the distribution hub configured to provide superheated steam from the central column to the stacks, and to provide hydrogen output from the stacks to the central column.