Flow visualisation for gas solid measurement using optical tomography fan beam projection

Abstract

In granules manufacturing industry, a real time monitoring is vital to observe the distribution of solid and gas mixture in pipelines. For solid and gas mixture such as pharmaceutical and grain production, the tiny pills and grains are poured through industrial chutes and silos in mass quantities. Nevertheless, the uncontrolled large scale flow can cause blockage in the pipeline and consequently can cause severe limited production efficiency. To determine the blockage area as well as its size, various flow meters are available in the market. However, most of the flow meters are intrusive and invasive; therefore can disrupt material flow. The optical tomography system technique is one of the methods to be adopted because of the ability of the system to observe material flow non-intrusively, hence determine the affected blockage area. In this research, alternate arrangements of 16 pairs of optical sensors which consist of transmitters and receivers have been mounted on a 10cm acrylic pipeline. Since the fan beam projection technique has been used, infrared Light Emitting Diode (LED) and photodiode with greater angle of projection and response were chosen. A specially designed jig has been developed for sensor positioning to ensure they are exactly on the periphery of the pipeline. Most previous researchers utilised digital timing and Data Acquisition System (DAS) units to control the projection and receiving unit of the optical tomography system. In this research, a circuit integrated with a dsPIC30F6014A microcontroller has been designed for controlling the projection of light by transmitters and the receiving signal of receivers. To operate the dsPIC30F6014A microcontroller together with the designed circuit, C programming language via MicroC compiler is applied. For image reconstruction, Linear Back Projection (LBP) has been applied via Visual Basic 6. Different flow regimes have been tested and analysed thoroughly to observe the overall performance of the system. The results obtained show that the optical tomography system developed is capable of observing multiple flows with different flow regimes; hence successfully determine blockage area of the solid gas flow. Apparently, the proposed single dsPIC30F6014A microcontroller usage indicates its ability to control acquisition process effectively with 480 µs sampling time rate.