NETL’s research, development, and demonstration initiatives are leading to improved operations of coal-based power systems, and future power supplies that are environmentally clean and economically affordable.  One method NETL researchers are using is advanced computational and experimental research, which is helping to develop novel technologies, including transport gasifiers, circulating fluidized-bed combustors, and hot gas desulfurization. Enhanced computational capabilities are leading to major improvements in power plant efficiency, and therefore to reduced emissions.

Transport gasifier and MFIX showing particle trajectories and oxygen concentration. MFIX simulations complement testing and development at the DOE demonstration Power System Development Facility (PSDF) in Wilsonville, Alabama (shown above). Coal and recycled materials feed into the lower mixing zone of the plant’s circulating fluidized-bed. The validated simulation model is currently being used to design a commercial-scale unit.

Computational Research
Computational fluid dynamics (CFD) has become an important tool for achieving scientific and engineering advancements in combustion – and the more efficient the combustion, the cleaner the process becomes, with fewer emissions.  MFIX (Multiphase Flow with Interphase eXchanges) is NETL-developed modeling software that is used to simulate the flow inside combustion reactors, among other useful applications. 

The MFIX tool helps improve researcher and plant designer understandings about how fluid-bed combustion systems work by describing the hydrodynamics, heat transfer, and chemical reactions inherent in these systems.  MFIX calculations allow researchers to visualize the distribution of pressure, velocity, temperature, and behavior of the fuel and its by-products in three-dimensional models. The vast amount of data generated by the detailed models then can be rendered into a readily understandable visual form through NETL’s “virtual reality” environment. This allows scientists to visualize the inner workings of fluidized beds, and allows engineers to make changes to a new plant concept and immediately “see” the impact of these changes on the entire plant.  Using MFIX, NETL researchers now have a tool to provide useful data from pilot to commercial scale, at minimum risk and without turning to traditional, larger-scale, and more expensive testing methods.

MFIX is being used by researchers around the world to model a variety of processes ranging from coal gasification to volcanic eruption flows. Partners include academia, private research and development groups, and other National Laboratories. The MFIX program has been developed as an "open-source" code, distributed through the Web page www.mfix.org. When technology developers contribute to the improvement of MFIX, all modifications are documented using “version control” and tested against a suite of control cases.

For more information contact: Madhava Syamlal

Experimental Research
NETL’s circulating fluidized-bed (CFB) cold flow unit is a flexible, well-equipped, and versatile research facility that is used to validate CFD models, including MFIX. The CFB unit is used to analyze existing plants, optimize plant operation, and evaluate innovative designs and operations. Onsite researchers study solids mixing, and transfer and control issues that are commonly encountered in most advanced power generation systems.

	Laser Doppler velocimeter probe positioned to measure particle velocities and granular temperatures across the diameter of the 12-inch riser in NETL’s cold flow circulating fluidized bed.

The facility has been used to study the hydrodynamics of fluidization for different materials, such as coke, cork, acrylic, polyvinyl particles, char, and glass beads.  It also has studied different non-mechanical valves, such as “J‑valve,” “L‑valve,” and loopseal. A wide range of advanced instrumentation capabilities is employed to track the flow structure in this versatile cold flow unit.

For more information contact: Larry Shadle