Study Of NIR Measurement Technique For Petroleum Properties

Near infrared (NIR) spectroscopy analytical technique is one of the most important and widely used technique for component analysis, and NIR spectrometer is the device to get the NIR spectroscopy. The demands for portable, compact, good analysis accuracy, low power dissipation, inexpensive, operating easily, in situ or on-line infra-red instrument are increasing nowadays in industry, environment, agriculture and other aspects of society. In this thesis the development situation and development trend of NIR spectroscopy technique are introduced and discussed, a NIR prototype machine based on LED and optical filters is designed and developed which has a lot of advantages, including portable, low cost, low power dissipation and high measurement accuracy. According to design object, such as portable, low cost, low power dissipation and high measurement accuracy for NIR spectrum analysis system, the general function design for optical, mechanical and electronic integration is given, including determination of technical scheme and key technique, selection of the central wavelength and number of NIR filters according to demands for petroleum property measurment, design of optical and circuit based on the general aim and technical route. Secondly, the hardware and software design of the NIR spectroscopy prototype machine is finished, including primary elements selection, lock-in-amplify (LIA) circuit hardware subsystem, MicroController unit monitor system, experiment data acquisition and the man-machine interface system, and so on. Thirdly, this paper developed multiple linear regression (MLR) and partial least squares (PLS) calibration model of ethanol content, and their software module. Lastly, the prototype machine performance test experiments are carried out, including its stability, repeatability, S/N ratio. Study on application is finished, which is relative with petroleum property measurement, including ethanol content prediction in ethanol-water solution and ethanol-gasoline system. Tests and experiments result show that the system is feasible, reliable and effective. This paper also discusses existing problems in the prototype and their reasons, at the same time, this paper also gives out methods as reference to solve the problems in following research and development work.