High-Temperature Embedded Sensors for In-situ Material Condition and Temperature Monitoring

The utilization of America¿s substantial coal reserves for energy production has become a national priority. Gasification technologies such as Integrated Gasification Combined Cycle (IGCC) offer an environmentally friendly means to achieve that goal. IGCC power plants can provide very high thermal efficiency along with greatly reduced emissions of greenhouse gases and other pollutants. The life cycle costs of these plants can be reduced by replacing scheduled maintenance and time-based retirement of key plant components with Condition Based Maintenance (CBM) and retirement-for-cause. However, the implementation of CBM is severely hindered by: (1) uncertainties in the material condition at the level of individual components, and (2) the inability to accurately predict remaining life, consistent with these uncertainties. Networks of embedded sensors ¿ which could provide component-by-component information about material condition, as well as a temperature monitoring function ¿ could be combined with adaptive remaining-life-prediction tools to permit the effective implementation of CBM. This project addresses this need by developing a high-temperature version of the Meandering Winding Magnetometer (MWM). MWM-Arrays are used to produce digital images of material properties that can reveal fatigue cracking, internal damage, wall thickness loss, corrosion damage, and, in some materials, pre-crack fatigue damage and applied and residual stresses. These patented sensors, coupled with multi-variate inverse methods, will provide superior performance for flaw detection, material property characterization, and noncontact or through-wall temperature monitoring. Commercial Applications and other Benefits as described by the awardee: An embedded high-temperature MWM would provide in situ material condition monitoring and through-wall temperature measurements in advanced fossil power plants, enabling remaining-life prediction and decision support. Scanning MWM arrays are currently being used by the US Navy to inspect critical rotating engine components, where they have proven capable of detecting fatigue cracks that cannot be detected by other nondestructive testing methods. Also, MWM arrays and networks of MWM arrays are also being used as embedded sensors in programs sponsored by the Air Force, Navy, DARPA, and NASA.