System for acquiring an image of a multi-phase fluid by measuring backscattered light

摘要

The present invention describes an optical technique for analyzing undiluted, multi-phase fluid flows as typically encountered inside reactor vessels or flow lines in the chemical industries. In particular the technique uses a pulsed, coherent light source and measures the back-scattered light collected over a wide scattering angle. A light beam is relayed via a set of lenses down a long probe tube, through a window at a probe tip to illuminate the material that is passing past the window. The light beam is pulsed to "freeze" the motion of the particles streaming past the window. The backscattered light is collected by the same set of optics and is focused on the front surface of a CCD chip. The lens closest to the front window has a short focal length with a large numerical aperture to collect the back-scattered light over a wide range of backward angles, thereby increasing the detection sensitivity to larger particles, which lie behind and are partially obscured by the myriad of smaller particles closest to the window. The probe tube is inserted through an insertion assembly so that the front viewing window is in direct contact with the material flow, and can be positioned so that the flow will provide a continuous and representative stream of material past the window. Best measuring conditions are obtained by placing the probe window at a modest angle of 30 DEG -45 DEG into the flow. The preferred embodiment combines imaging technology with a specific probe configuration, which is optimized for use in the chemical process industries.