|
|
|
|
|
|
|
hyperlink zero |
hyperlink one |
hyperlink two |
hyperlink three |
hyperlink four |
|
|
|
|
|
|
|
|
|
|
Solid Oxide Membrane Electrolyzer for the production of pure hydrogen
and syn-gas from a source of waste and steam |
Prof. Uday B. Pal, Prof. Srikanth Gopalan, Prof. Jillian Goldfarb
and Mr. Abhishek Patnaik |
View a PDF presentation about the
Clean Energy from Waste |
An electrolyzer based on solid-oxygen-ion-conducting membrane
serving as the electrolyte is used for generating high-purity hydrogen
and syn-gas (mixture of CO(g), CO2(g) and H2(g)) from steam and
hydro-carbon waste (such as saw dust, plastics, shredded tires, etc.).
In particular, the device employs one-end-closed
yttria-stabilized zirconia (YSZ) tube at temperatures between 1000-1200
C as an oxygen-ion-conducting solid electrolyte. Liquid metal, with high
solubility and diffusivity for oxygen, is contained inside the YSZ tube
and function as the non-consumable anode. Nickel-yttria stabilized
zirconia (Ni-YSZ) porous cermet is applied on the outer surface of the
YSZ tube and used as cathode. Steam-rich feed (97% steam and 3% H2) is
introduced over the Ni-YSZ cermet cathode. Waste feed containing
compounds of C and H along with other impurities injected using a
molybdenum alloy tube into the liquid metal anode; the molybdenum alloy
tube also serves as an electrical lead for the anode. Similarly, nickel
or its alloys is used as an electrical lead for the Ni-YSZ cermet
cathode. Electrical potential is applied between the cathode and the
anode. The applied electrical potential reduces the steam at the Ni-YSZ
cermet cathode producing pure hydrogen and oxygen ions.
The hydrogen gas is collected and stored after condensing the
residual steam. The oxygen ions produced at the cathode from steam
migrates through the solid YSZ electrolyte tube towards the liquid-metal
anode. At the YSZ/liquid metal anode interface, the oxygen ions oxidize
(lose electrons) and dissolves in the liquid metal as neutral oxygen
atoms ([O]). The dissolved oxygen oxidizes the waste feed (C, N, H,
etc.) injected into the liquid metal to produce syn-gas. It is to be
noted that the hydrogen produced at the cathode does not mix with the
syn-gas produced at the anode. The applied electrical potential between
the electrodes depends on the resistive and polarization losses in the
electrolyzer, the desired rate of hydrogen production and the
corresponding feed rate of waste. It is the objective of this research
to pass 1A/cm2 through the electrolyzer cell.
This translates to producing 67 l/m2-min of hydrogen gas. By
having the waste feed, the electrical energy needed to produce hydrogen
from the steam feed is greatly reduced. Furthermore, the waste feed in
the process also gets converted to useful syn-gas. |
|