A Multiphase Flow Measurement System Based on Gamma-ray

Min Ma1, Qing-ji Gao1, Hua-xiang Wang2

1 College of Aeronautical Automation, Civil Aviation University of China, Tianjin 300300, China.

E-mail: mm5739@163.com

2 School of Electrical and Automatic Engineering, Tianjin University, Tianjin 300072, China.

ABSTRACT

In this paper, a gamma-ray based on-line detection system has been designed for multiphase-flow measurement, as the complicated fluid property of multiphase flows can be studied by using the principle of ray attenuation. The system is made up of three parts, i.e., the sensing element, the signal conditioning & processing element and the computer imaging element. The sensing element consists of five 241Am sources at a principal energy of 59.5KeV and five sets of CdZnTe semiconductor detectors by using the Geant4 simulating software toolkits. The sources and detectors are mounted equally at the cross section of pipeline to detect different phase medium simultaneously. This functionof the system guarantees the real-time performance of the on-line detection. In order to improve the accuracy of the probe, a low noise probe circuit has been designed, including a low noise charge- sensitive preamplifier, a low noise amplifier, filter circuit and a destructive zero-poles circuit. Some of the emitted gamma-ray photons from the radiation sources are detected by the sensing element, where the photo energy is transferred to electrical energy by using CdZnTe semiconductor detectors. The output of the sensing element is sent to the signal conditioning & processing element, which is amplified and filtered to be a level-discriminated signal. Finally, the output of the signal conditioning & processing element is sent to the computer imaging element, in which the 2D images are reconstructed by using a certain reconstruction algorithm. Under the normal temperature, the system performs the test of energy spectrum and then it has better energy resolution about 4.38% for 241Am 59.5KeV. The result reveals that our system has higher probe accuracy. Using experimental data, the images are reconstructed with Algebraic reconstruction techniques (ART). Images of high quality are

achieved.

Keywords

Multi-phase flow; Gamma-ray Energy spectrum; Low noise Detection circuit; Image reconstruction