SwRI to Design Flameless, Low-Emission Coal Combustion Pilot

San Antonio-based Southwest Research Institute (SwRI) said on Aug. 12 it will get $3 million from the U.S. Department of Energy (DOE), and another $760,658 from an assortment of industry giants to design a large-scale flameless pressurized oxy-fuel combustion pilot plant.

The announcement is a major boost for the promising, but yet unproven technology, that industry observers herald as a groundbreaking new approach to utility-scale power generation. As SwRI explained, "the process uses air that is stripped of other elements like argon and nitrogen until it is pure oxygen. It is then combined with a fuel, usually either coal or natural gas, into a stream of carbon dioxide (CO₂) and water inside a combustor. The fuel and oxygen chemically react, and the hot gas can be used to boil steam, which pushes a turbine that generates power."

Among the benefits of pressurized oxy-fuel combustion is that it has the potential to substantially improve overall cycle efficiency. Because it uses oxygen-rich combustion, it could also generate pure CO₂ that can be easily captured and stored, or reused.

SwRI said that it chose coal for the proposed pilot over natural gas. "Both fuels primarily produce water and CO₂ during the combustion process, but when coal is used the incombustible ash is trapped by a mechanism in the novel combustor design, emerging as small, manageable pellets," it explained. "Other undesirable elements, such as sulfur and mercury, are removed prior to CO₂ purification in a standard emission control process."

The project, which is one of six recently selected by the DOE, to improve coal economics and efficiency, will be led by SwRI research engineer Joshua Schmitt. "This will be a completely new type of power plant," Schmitt said. "Oxy-fuel combustion plants generally don't exist on this scale because the technology is so new."

Entities other than the DOE that are invested in the pilot include: Itea, Sargent & Lundy, Electric Power Research Institute, General Electric Global Research and the University of Wyoming.

SwRI researchers now plan to proceed with a front-end engineering study that will involve basic engineering, full design, cost analysis and schedule metrics for building the large-scale pilot plant. After August 2020, the DOE is expected to select the pilot plant projects that show the most promise to move forward with construction and operation.

-Sonal Patel is a POWER senior associate editor.

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