Optical Mixed Interface Detection System In Pipeline Transportation

The interface detection for refined oil has been an outstanding problem of pipeline detection in the batch transportation. With the development of the oil industry, mixed oil interface detection methods emerged one after another. New technology, new method and new instrument have been applied to the mixed oil interface detection, especially the optical method, and it has become one of new detection methods in the field. Optical mixed interface detection method has several advantages like high sensitivity, safety and environmental protection, and meanwhile it can resolve the density method problem, which is to detect similar density oil difficultly, and make up for the capacitance method's shortcoming, which is not to detect some oil product of dielectric constant similar to their own, and avoid the environmental pollution brought from the fluorescence method and radiation method. This optical method is a new detection means to meet the conditions of our country.This paper has designed a high-precision optical mixed interface detection system in pipeline transportation to detect mixed oil interface and output waveform making use of light intensity. The principle of the system is to detect the reflection and refraction light intensity change which is in proportion to the refractive index of testing oil products when the light from the source goes into the interface. The source provides stable imported light for the system; the photodiode with external circuit changes the reflection light into electrical signals for the following analysis; temperature module controls the system temperature, and prevents the imported light from generating larger shift when the system temperature is too high; DAQ acquires and processes the detection signal which comes from the photoelectric conversion; system computer interface is designed by using the Lab VIEW software.After repeated experiments, I chose suitable materials and structure for the sensor, and received an ideal interface waveform. The design is reasonable, and can achieve the goal of accurate detection, and generally meets the expected requirements. The measurement result is satisfactory.