Sensoriamento ótico distribuído e quase-distribuído para o setor de energia

Abstract

In this thesis, it is presented the development of three photonic sensors for the energy sector, specifically to the electricity generation as well oil and gas production. The first transducer uses Fiber Bragg Grating (FBG) for simultaneous temperature and vibration measurement in electric power generators stator bars. The transducers present 10 pm/ºC sensitivity and maximum error of 3 ºC within the range of 50 ºC in comparison to the reference PT 100. The vibration characterization used an instrumented hammer determining the resonant frequency of the transducer being of about 560 Hz. With a shaker the average sensitivity of the transducer is determined to be 7.2 pm/g ranging from 5 Hz to 1 kHz. Six transducers calibrated and characterized are installed at the Salto Santiago power plant. The installation generated temperature and vibration results with two tests lasting 23 and 45 hours. All the FBGs used to monitor vibration were able to monitor the frequencies of mechanical vibration (2 Hz) with its resonances as well as the electromagnetic vibration (120 Hz) of the generator. The second optical sensor developed is a Distributed Acoustic Sensing (DAS) using optical fiber to future application in the oil and gas production. For vibration monitoring, a phi-OTDR system based on the detection of Rayleigh coherent backscatter is used. Results of human voice detection are presented using a 10 m long optical microphone excited by a loudspeaker. The results indicate the possibility of the system, with 10 m spatial resolution, to detect voice emitted from a speaker localized 5 cm from the microphone. Results are also presented regarding the detection of intruders in the laboratory using a tube-loose optical cable. Results of field tests using an optical cable buried at 15 cm depth in the soil are analyzed. The first and second tests are related to successive and single impacts over the buried cable. With these tests it is possible to determine the velocity propagation of surface mechanical waves as well as the location of the disturbance source with the DAS system. The third result is the measurement of a sound wave propagating through the air causing measurable deformation in the buried cable. The sound wave velocity travelling through the air is measured with success. The third energy sector sensors results are related to the comparison of two types of Lossy Mode Resonance (LMR) sensors without and with thermal treatment at 500 ºC during 5 h. Thermal stability is verified during temperature cycles between 24 ºC and 140 ºC, showing the sensor with annealing better stability and repeatability than the sensor without annealing. Finally, tests were carried out with different types of gases, being the sensor without thermal treatment sensitive to the gases NH3 , CO2 , O2 e N2O.