Application of fan-beam computed tomography for the analysis of scaling distribution in geothermal pipeline

摘要

A new scanning system approach was applied to analyze scaling distribution in a geothermal pipeline. Computed tomography systems are widely used in medical applications and continue to develop in industrial applications, such as in fertilizer plant, power plant, petrochemical, oil and gas unit process. The scanning system was developing generation by generation, starting from a parallel scanning system as the first generation, until the latest generation, fan-beam tomography system. The design of the fan-beam mechanical scanning system consists of more than one detector and one gamma beam source, which collimated like fan shape in the scanning system. The experiment was set by using a gamma source Cs-137 30 mCi activity, 31 points of scintillator detectors connected with radiation counter, mechanical and electronic system to support the automatic data acquisition. The geothermal pipe with an outer diameter (OD) of 22 cm was put on the center of the scanning system. The projection center of fan rotation was at the source point and measured by 117 projections. This method gets a data set with a regular symmetric pipe shape by averaging the original sinogram along the direction of row (clockwise) and another data set (counter-clockwise) by flipping the averaged data along the direction of the row. Radiation resulted in less than 5% statistical error for three seconds of counting time. The reconstructed image analyzed by 84 × 84 data pixels by using the Matlab software application. The experimental result successfully shows the scaling distribution, distinguish the type of fluids, identification of foreign materials in the geothermal pipe by cross-section viewing which represents the internal condition.