2-Point Optical Fiber Probes for Gas-Solid System
New 2-point optical probes for gas-solid systems have been developed and implemented. This technique can measure simultaneously at the same point, the solids concentration and velocity and their time series fluctuations. These probes are equipped with quartz window to overcome the dead zones. The technique has been manufactured by Chinese Academy of Science. A new reliable and simple calibration method has been developed to convert the solids concentration related signals into solids holdups which eliminates the use of traditional calibration devices like downer, riser etc. The technique and the probes are characterized with fast response, relatively inexpensive, reliable accuracy and nearly free of interference by temperature, humidity, electrostatics and electromagnetic fields. Depending on the size of solid particles to monitor, 4 different sizes of optical probes are available Optical probes work on the principle of back reflection of light. The multi-fiber probes contain alternatively arranged layers of optical fibers, one emits light and the other receives reflected light by the particulate material. The reflected light intensity from the measuring volume of the probe is converted into electrical impulses and integrated over time, so that a quantitative measure of local solids volume fraction is achieved with prior calibration. The optical probe technique also measures velocity of particulate materials by employing the principle of cross-correlative signal analysis from the two channel tips The Optical probe electronic system consists of photoelectric converter and amplifying circuits, signal pre-processing circuits, high-speed A/D interface card and its software PV6
