A Fiber Bragg Grating (FBG)-Based Sensor System for Anaerobic Biodigester Humidity Monitoring

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.

Rapid Response All-Fiber Moisture Sensor

“…Further, the method is intrinsically safe as, being all-optical at the sensor probe, it does not need an external power supply as there are no currents flowing at the sensor probe. In that way it can be used safely in mining applications or in biodigesters or sewers, for example [25], [26] (where explosive gases such as methane are present), taking advantage of the fast measurement speed and probe temperature compensation integrated into the probe design.…”

Review of Fiber Optical Sensors and Its Importance in Sewer Corrosion Factor Analysis

“…IR optical absorption technique is based on dual wavelength absorption techniques [177]. Optical sensors for humidity can be designed using various optical technologies such as optical absorption [178,179], interferometer [180][181][182], resonators [183,184], gratings [185][186][187] and LMR [188][189][190]. In optical absorption method, humidity is measured by tracking variations in the transmitted optical power caused due to the evanescent field interaction with a sensitive coating material such as Tungsten Disulfide (WS 2 ) [178], reduced Graphene oxide (rGO) [179] and Zinc Oxide (ZnO) [191].…”

“…Proper packaging of sensor probe results in a larger working duration without any deterioration in performance. Humidity sensor with two different types of coating has been evaluated for non-degradable performance over an extended period of time in an aggressive sewage environment [186]. To optimize the packaging of sensor probe, two different packaging such as 3D epoxy resin and PEEK material have been used.…”

“…Thin coating provides less response time than a larger one. In 2019, Rente et al [186] extended the work of Alwis et al [7] for humidity sensing in real time sewer system in a Sydney wastewater plant with a large range of temperature variations. The sensor system has been enhanced with 4G technology, data logging and battery equipped power source.…”

Short Circuit and Broken Rotor Faults Severity Discrimination in Induction Machines Using Non-invasive Optical Fiber Technology

“…Engineering: condition monitoring of thermoelectric engines [2], anaerobic bio digester for biomass plants [3], and nuclear fuel cycle facilities [4]; deformation monitoring of subway floating slab [5] • Biomedical engineering: development of a surgical robotic system for less-invasive treatment of osteolysis [6]; force sensor with an ortho-planar spring-based flexure for surgical needle insertion [7,8]; robot-assisted eye surgery [9], and temperature monitoring during thermal ablation procedure [10] • Electrical engineering: temperature monitoring of the lithium-ion batteries crucial for large scale deployment of electric vehicles and their second life power grid support application [11,12]; galloping monitoring of power transmission lines [13]; condition monitoring of an oil-immersed commercial distribution power transformer [14]…”