Research On Key Technology Of Petroleum Pollution Detection

Currently, Sea water pollution has been increasing concerned around the world. Andoil pollution is one of the key issues among other pollution. Currently, instrumentmeasurements of marine oil pollution that can achieve the precision requirement ofengineering are mostly offline, for example, the Abbe refract meter. But these methodscannot monitoring the oil refractive index in real-time. However, conventional electricalsensors are not applicable for monitoring in poor environment such as the ocean. To solvethis problem, this paper introduces a long period fiber grating based sensing system tomeasure the concentration of oil in seawater. The research I made is as follows.First, a deep study on the coupled mode theory of fiber grating is made. Thus foundlong period fiber grating is very suitable for measuring the external refractive indexamong other fiber gratings. Then a further analysis of its transmission theory is made,and simulated its transmission spectrum. These made a solid theoretical basis for thefollowing experiments.Secondly, after fixing the long period fiber grating by packaging it, someexperiments are made to test the influence of the external temperature on themeasurement results. Through the results can found that temperature change having anon-negligible effect on the measurement results. Thus an oil pollution concentrationdetector system which can remove the influence of temperature is made. Through theactual measurement results using this system, the impact of changes of the experimentalenvironment temperature has been effectively removed.Thirdly, a comparison test on the placement of the long period fiber grating both inangle and placing depth is made. Through a variety of experiments, I found a way toplace the grating that can improve the sensitivity of the measurement most.Finally, in order to be able to be applied in the engineering, I used the F-P filter indesigning the demodulating section. Thereby it can avoid the problems such as high costof the spectrometer, bulky and not suitable for engineering applications. We can simplyobserve data indicators, through data from the serial output of the system, to monitor changes in the concentration of oil pollution in the sea water.