Bulk density estimation using a 3-dimensional image acquisition and analysis system

The paper presents a concept of dynamic bulk density estimation of a particulate matter stream using a 3-d image analysis system and a conveyor belt scale. A method of image acquisition should be adjusted to the type of scale. The paper presents some laboratory results of static bulk density measurements using the MS Kinect time-of-flight camera and OpenCV/Matlab software. Measurements were made for several different size classes. 1 Importance and range of bulk density measurements Bulk density, also called an apparent density, is defined as the mass per unit volume of loosely piled granular material (eg. coal or coke). The coal bulk density depending on its particle size, impurities, moisture may be in the range of 700 to 1100 kg/m. The bulk density varies depending on the way in which this material is stored. Under gravity load or under external pressure, spaces between the particles can be reduced, so the bulk density may increase over time. The bulk density, like the material volume, is particularly important for aggregates used in civil engineering [1, 2] since they act as volume fillers to concrete mixes. However, this parameter is important also for coal [3], especially in the case of measuring the stored coal amount in the landfill. This was sanctioned in national regulation, according to which "the mass of stored coal is determined by weight or calculated as the product of volume and bulk density." This is connected with coal excise taxation and with trading CO2 emission rights. However it should be noticed that, in accordance with [3] the regulation method of calculating the weight of the stored coal on the basis of the volume and bulk density, is only valid for coarse size classes. Therfore, the analysis performed in this paper was restricted to the coarse size classes. 2 Static and dynamic measurements of bulk density National standards and regulations define the density measurement in a static manner [3] by using the box the with size dependent on the coal particle size (the larger the particle size the greater the box dimensions). The mass of the coal sample is simply defined as a difference of the full box mass and empty box mass. This rule of a discrete measurement is presented demonstratively in Fig. 1. However, a Corresponding author: [email protected] , 010 (2016) DOI: 10.1051/ E S Web of Conferences e sconf /2016 3 3 0 010 8 8