New Vision Probe Based on Telecentric Photography and Its Demonstrative Applications in a Multiphase Stirred Reactor

Abstract

A new vision probe based on telecentric photography has been developed for multiphase system measurement. Four outstanding advantages of the probe are as follows: (i) Sharp pictures with little image distortion can be obtained because of the distinctive parallel light paths from the telecentric lens. (ii) The slim probe can be inserted everywhere in large reactors. (iii) Local characteristics such as particle (solid particle or drop or bubble) size, holdup, and interfacial area with one or even more dispersed phases can be measured. (iv) The higher holdup of the dispersed phase is allowed. The robustness of the probe has been tested in a multiphase reactor. Finally, applications in solid−liquid, gas−liquid, and gas−liquid−solid stirred tanks are present respectively to demonstrate the measurements on the particle holdup, bubble size, and particle and bubble size using this vision probe.

Particle Scattering Photography Approach for Poorly Illuminated Multiphase Reactors. I: Theoretical Model and Simulation

“…Especially in the case of the invasive optical photography, a vision probe is directly inserted into the multiphase reactor and then the images of local flow in the measurement volume can be photographed. 1 As such, the various local property distributions can be obtained using image processing software. Meanwhile, noninvasive optical photography that has been applied in dilute suspensions 2,3 and to transparent vessels 4,5 or with viewports installation 6 have been proved successful.…”

“…In our previous work, a novel telecentric vision probe based on photography was developed to obtain images, and one or two dispersed phases can further be measured simultaneously in two-phase or three-phase systems. 1 The success of the photography measurement is heavily dependent on the high-quality images with great brightness contrast between the measured objects (dispersed particles) and the background (continuous phase), thus making the particles distinguished easily by using image processing software. As is known, the brightness difference is sensitive to the reflectivity of the dispersed particles to the incident light.…”

“…As is known, the brightness difference is sensitive to the reflectivity of the dispersed particles to the incident light. 1 In the case of bright particles (e.g., white resin balls), its reflectivity is so great that the interfaces in the images are clearly visible. However, the low-bright particles such as black resin balls and gas bubbles in the ambient fluid lead to a poorly illuminated image.…”

Circulating jet for enhancing the mass transfer in a gas–liquid stirred tank reactor

“…The measurement error mainly comes from the selection of bubble images under stable conditions and the accuracy of image processing technology. The method with boundary extension includes the following steps: (1) gray‐scale image recognition; (2) bubble image segmentation; (3) overlapping bubble contour segmentation; (4) reconstruction of bubble shape with arc grouping; and (5) generation of parameters, such as bubble diameter and area 10,26,27 . The image analysis processing of method with/without boundary extension is shown in Figure 2.…”

Froth Stereo Visual Feature Extraction for the Industrial Flotation Process

“…The need to improve quality and efficiency, coupled with rapid advances in computer technology, has led to the development of machine vision systems for automatic inspection and process control. − Application of machine vision technology in mineral processing has attracted significant research efforts in the mineral engineering community and grown steadily over the last few decades. − Extraction of froth features through machine vision is an essential part of online control systems designed for the flotation process. Froth features yield important information for monitoring flotation parameters such as mineral concentrations and performance improvement. − Previously, research has focused on extraction of froth appearance characteristics, such as color, size, shape, etc.…”