A Fiber Bragg Grating (FBG)-Based Sensor System for Anaerobic Biodigester Humidity Monitoring
Bruno Rente, Matthias Fabian, Miodrag Vidakovic, Jerry Sunarho, Heriberto Bustamante, Tong Sun, K. T. V. Grattan
Abstract
An operational, Fiber Bragg Grating (FBG)-based sensing system, specifically designed to monitor conditions in a harsh industrial environment is reported. The sensors used were placed inside tanks with high levels of methane (CH4), carbon dioxide (CO2) and hydrogen sulphide (H2S) gases and high relative humidity in the North Head sewage treatment plant in Sydney, Australia. The sensor system was developed primarily to monitor the effect of >98% relative humidity and temperature changes on the corrosion rates of various materials inside the tanks. Data have been obtained from the use of the system for eight months: these have been correlated with key climate data including the changing weather conditions experienced during the continued monitoring activity. The sensor system specifically developed has been shown to be sufficiently robust to work well, and safely, in such a harsh environment (due to the gaseous H2S and CH4 present) with no signs of deterioration of the sensors or of the signals obtained from the system. The remote operation through flexible data transmission has allowed continuous and up-to-date monitoring of the conditions inside the tanks.