Monitoring Power Plant Efficiency Using the Microwave-Excited Photoacoustic Effect to Measure Unburned Carbon

Abstract

Three test instruments are being evaluated to determine the feasibility of using photoacoustic technology for measuring unburned carbon in fly ash. The first test instrument is a single microwave frequency system previously constructed to measure photoacoustic signals in an off-line configuration. A second off-line instrument was constructed based in part on lessons learned with the first instrument, but which also expands the capabilities of the first instrument. Improvements include a control loop to allow more constant microwave power output and an ability to operate over a range of microwave frequencies. The third instrument, the on-line version of the fly ash monitor, has been designed, constructed, and initial efficiency tests have been conducted on the monitor's electrical components. Design and construction of the on-line fly ash monitor has been completed, as well as supporting apparatus that includes the independent support stands for the fly ash feeders and customized bottom hopper and feeder system. Modifications were made to the original design of the on-line monitor to improve the flow of fly ash through the monitor, and improvements were made to the diaphragm assembly where the accelerometer is to be mounted. The electrical components that provide and regulate the microwave source has been completed. Microwave leakage tests have also been completed to determine the robustness of the on-line monitor