Clean Energy Technologies through 3-D Imaging
Ohio State University researchers have invented a technique to record three-dimensional scans of the gases and solids that mix inside boilers and other industrial processing reactors. Scientists can use the patented technique, called electrical capacitance volume tomography (ECVT), to observe how the density of materials varies inside a reactor. The end result could be better monitoring of reactor systems, including power plants. Industrial plants need tomography for the same reasons hospitals do, explained L.S. Fan, a Distinguished University Professor and the John C. Easton Professor of Engineering in the Department of Chemical and Biomolecular Engineering at Ohio State. “Hospitals use tomography to view areas of the body that aren’t easily or safely accessible,” Fan said, “and the interiors of boilers and other high temperature reactors in industry are similarly inaccessible.” Fan studies the processes for converting coal to liquid fuels and chemicals, in order to optimize the energy conversion efficiency while reducing power plant emissions. “Right now, the way to convert coal or natural gas to liquid fuels is in high-temperature, high–pressure reactors,” Fan said. “But if we’re going to develop processes to achieve high energy conversion efficiency, we need to be able to see inside those reactors to know how they work. That’s why we developed ECVT.” Fan described the imaging technique at the national meeting of the American Chemical Society on March 27, as he gave the keynote address for the Chinese American Chemical Society 25th Anniversary Symposium. The invention includes a sensor system that measures the capacitance of the materials inside the reactor — their ability to store an electrical charge. Software then converts those measurements to information about the materials’ composition. Materials flow inside these hot reactors in complex ways. So the key to making ECVT work is a visualization system that presents the rapidly changing data accurately in three dimensions, Fan said. Other techniques produce two-dimensional images, or less accurate images. But ECVT is the only method he knows of that gives scientists the accurate three-dimensional images they need to manage these industrial chemical reactors in real time. Fan has already invented two coal-conversion processes, OSCAR (Ohio State Carbonation Ash Reactivation) and CARBONOX (carbon-based NOx reduction technology), both of which remove coal combustion gases from power plant exhaust. He’s optimistic that tools such as ECVT will help scientists think of even more ways to understand and improve reactor operations.