Wireless harsh environment SAW array system for power plant application

Power plants operate under harsh environment conditions, with processes subject to diverse environmental conditions and temperatures ranging from 300°C to 1200°C. Monitoring different process characteristics, such as temperature, pressure, strain, corrosion, and vibration in those environments translate into better efficiency, longer term operation before maintenance, reduced pollution, and lower costs. Wireless sensor operation in such environments is a premium, since the lack of wires translates into simpler installation and simpler plant design and maintenance. Surface acoustic wave (SAW) sensors can operate wirelessly in harsh environments and also do without any battery, a significant advantage, since batteries require frequent maintenance, and in most cases they do not operate in the high-temperature harsh-environment conditions at all. This paper reports on the implementation and test of an array of six wireless interrogated SAW temperature sensors mounted in the interior of a power plant chamber. The particular power plant selected burns municipal solid waste (MSW), in an extremely erosive and corrosive environment. Material testing was performed in the MSW boiler prior to the sensor array fabrication, targeting the selection of proper materials for packaging the sensor array. The wireless sensor array was successfully tested for a period of about six weeks and the sensors and packaging yielded reliable quantitative temperature data under the environment. The harsh environment SAW technology has been demonstrated to be appropriate and mature for such demanding commercial applications.