For more than a decade, B&W and our university partner have collaborated to develop a fuel direct chemical looping (FDCL) process for steam/power and hydrogen generation with CO2 capture.
Chemical looping is a platform technology which can convert a wide range of fuels, such as natural gas, methane, biomass, coal, petroleum coke (petcoke), and other industrial process off-gases and materials, into multiple products including hydrogen, synthesis gas (syngas), and steam for power, process, and heating. The BrightLoop chemical looping technology inherently isolates a concentrated CO2 stream ready for capture, sequestration or beneficial use. It is also highly scalable with benefits applicable to a wide array of industrial processes.
In the FDCL process, the fuel reacts with the oxygen-carrier particles in a reducer reactor, forming combustion byproducts, predominantly CO2 and H2O, while reducing the iron oxide from Fe2O3 to FeO. The reduced oxygen carrier particles (FeO) then move to a partial oxidizer reactor where they react with steam to partially oxidize the particles to Fe3O4 and generate a stream of hydrogen. The oxygen carrier particles are then transported to a combustor reactor where they are regenerated with air to Fe2O3. The exothermic oxidation reaction of the oxygen carrier particles with air releases heat that both reheats the particles for their return to the reducer reactor and heats the air which can be used to heat water and produce steam for power generation or as a heat source for various other processes. The process can be optimized to produce hydrogen, steam or both products by adjusting the conversion in the partial oxidizer reactor.
Under a DOE-sponsored project, B&W built a 250 kWt coal-based FDCL pilot facility to demonstrate the reducer and combustor operation for application to steam and power generation. On another project, our university partner demonstrated continuous hydrogen generation from the partial oxidizer at their 250 kWt pilot unit constructed and tested at the National Carbon Capture Center.
B&W concluded that given the success of the 250 kWt pilot units for application to hydrogen and steam for power generation, we are ready to demonstrate the technology at a larger scale. B&W is proposing a project to demonstrate steam and hydrogen production and to be rated at a thermal input of between 2.5 and 25 MWt while utilizing the most applicable fuel feedstock.
How It Works
Pilot-scale testing, preliminary process and economic simulations have indicated that the CDCL process is capable of achieving greater than 90 percent carbon capture efficiency while meeting the U.S. DOE’s target of less than a 30 percent increase in the cost of electricity as compared to a base pulverized coal electric generating plant without CO2 capture. Below is an animated diagram to illustrate this proprietary chemical looping process.
The CDCL process consists of a unique moving bed reactor where coal is reacted with oxygen carrier particles, producing an exhaust gas stream of essentially pure CO2.