Western Hydrogen Limited is developing a new method for producing hydrogen using a bed of molten salts that can gasify carbonaceous materials. The process has been proven in the US Department of Energy's Idaho National Laboratory to generate hydrogen from heavy petroleum residue and glycerol. Depending on operating conditions, the system can produce:
The Molten Salt Gasification process occurs in a single high-pressure reactor — where a carbon-based feedstock and water react with a molten salt bath. The Molten Salt Gasification process can produce either hydrogen, synthesis gas or methane depending on the reactor operating conditions. All of these gases can be produced at pressures up to 2000 psig.
In hydrogen mode, a high-pressure hydrogen stream, separated from the product gas, can be fed directly to an upgrading or refining process with little or no compression. A separate stream of high-pressure carbon dioxide, ready for sequestration or enhanced oil recovery, can be captured at a lower cost due to the higher operating pressures relative to conventional gasification technologies.
In synthesis gas mode, a mixture of hydrogen and carbon monoxide can be fed to a Fischer Tropsch unit to produce synthetic liquid fuels. If required, the hydrogen to carbon monoxide ratio can be adjusted by conducting a water gas shift reaction prior to the Fischer Tropsch reactor. In the process of generating liquid fuels, the Fischer Tropsch process produces water that can, in turn, be recycled as feed water to the Molten Salt Gasification process.
The advantages of integrating the Molten Salt Gasification process with the Fischer Tropsch process are:
a. heat integration (i.e. Molten Salt Gasification is endothermic and Fischer Tropsch is exothermic),
b. the Molten Salt Gasification process supplies the synthesis gas at high pressure — which the Fischer Tropsch process requires and
c. the hydrocarbon contaminated water produced by the Fischer Tropsch reaction can be recycled back into the Molten Salt Gasification process.
The feeds to the process will be water, a carbonaceous fuel (e.g. coal, petroleum coke, pitch, methane or biomass), sodium hydroxide, and sodium carbonate. The process will be initiated with the sodium compounds -- not with sodium. The amounts of sodium present in the process at any given time will be extremely small since the sodium is consumed by the process almost as fast as it is generated. There will be some small amounts of the sodium compounds that will be required for make-up to the process but laboratory results have shown that less than one percent of the compounds are consumed in the process.
The Molten Salt Gasification process uses a wide variety of low value carbon based feedstock. The carbon sources that have been evaluated to date include heavy petroleum residue and glycerol.
Hydrocarbon contamination of the feed water does not affect the Molten Salt Gasification process. Produced water associated with hydrocarbon recovery and water contaminated during refinery operations can be used and actually increases the hydrogen yield from the process. Glycerol (i.e. a waste product from bio-diesel production) can also be blended with water in the sodium water reaction. This increases the quantity of hydrogen produced in the water sodium reaction and provides carbon for the reconstitution of the sodium.