On-Line Real-Time Measurement and Control of Aggregate Gradation in AsphaltPlants

摘要

Current practice in the asphalt industry is to use sieve analysis to determinethe gradation of each stockpile. Samples are taken regularly at the entrance of the mixer and sieved, and adjustments to PFs are made, if necessary. Sieving is the classical standard for industry. It is a time-and effort-consuming technique and is not suitable for on-line real-time measurement and control because, in many cases, by the time the plant manager identifies the source of the problem, the job is complete and out of specifications. The IDEA product developed during this contract measures, on-line and in real-time every 5 minutes, the size distribution of the aggregates coming out of each belt feeder. Based on these measurements and the JMF, the optimal PFs for all bins are calculated to dynamically adjust the speed of their belt feeders. This novel aggregate gradation control technology (AGCT) is based on the principles of machine vision, image processing, stereology, and deconvolution mathematics. Figure 1 shows the measurement and control concept, which starts with a lamp and a high-resolution line-scan video camera at each belt feeder associated with each cold bin.