Experimental techniques are crucial for determining real-world system behavior, as well as for model validation. In SPI, we have state-of-the-art chemical and physical laboratory facilities at our disposal, and we continue to develop novel techniques to chart undiscovered territory.
Optical measurements of bubbles rising in a swarm are performed to statistically determine their behavior (e.g. rise velocity, size distribution, clustering, etc). For this purpose, commonly Digital Image Analysis (DIA) techniques are used, often based on long decision trees; we have recently developed a technique based on artificial intelligence to recognize the bubbles on a video. A convolutional neural network is trained to recognize bubbles and is able to determine the bubble positions very quickly and very accurately, with minimal arbitrary parameters.
Due to the large heat losses of a transparent pseudo-2D bed, virtually all research using optical measurements takes place under cold-flow conditions. In our labs, we have developed a unique high-temperature fluidization setup with optical access using endoscopes. The setup can reach temperatures up to 800 °C, and has already shown significant differences between cold-flow fluidization and fluidization at elevated temperature.
Whole-field gas concentration measurements in fluidized beds
For a better understanding and description of the mass transport phenomena in dense multiphase gas-solids systems such as fluidized bed reactors, detailed and quantitative experimental data on the concentration profiles is required, which demands for advanced non-invasive concentration monitoring techniques with a high spatial and temporal resolution. A novel technique based on the selective detection of a gas component in a gas mixture using infra-red properties has been developed within SPI. Thorough optimization and calibration of the technique has been done and the technique can be applied for whole-field measurements with high temporal resolution. The developed technique allows the use of a relatively inexpensive configuration for the measurement of detailed concentration fields and can be applied to a large variety of important chemical engineering topics.
Due to our large involvement with granular flows and particle-based systems, we have a large inventory of particle characterization techniques, such as particle size distributions, BET and chemisorption, TGA, XRD, Hg porosimetry, density analysis, etc.