On-line particle sizing of pulverized and granular fuels using digital imagingtechniques

Abstract

On-line particle sizing is desirable in many industries, particularly in the powergeneration industry. This paper presents the principle and design of a prototype,digital imaging based, instrumentation system that can measure size distributionof particles that are largely opaque. The system, which is intended as anindustrial rather than a laboratory solution, operates on-line and is non-intrusive.The image processing sequence is discussed in some detail. Experimental resultsobtained using two common types of particulate material demonstrate theviability of the system. The use of static images has allowed the instrumentationsystem to be calibrated. The linearity and repeatability of the system arequantified in addition to direct comparisons between the measurements madeand those from proven, off-line, industrial solutions. The effects of theillumination sub-system on the spatial sensitivity of the viewing field arediscussed along with the turndown ratio. The discrepancies between referenceand static measurements are also identified and discussed. The resultsindicate that the system has good linearity and excellent repeatability andthat practical on-line measurement of particle size distribution can beachieved using this technique. As presented the system can be used withparticles in the range 150µm–25 mm.