EFFECT OF OPERATING PARAMETERS OF VERTICAL PNEUMATIC TRANSPORT OF CRUSHED PEAT ON RELATIVE SLIDING OF AIR AND SOLID PHASES

The actual operating parameters of the vertical pneumatic conveying of milled peat are determined by numerical methods on the grounds of the pressure differential in the pneumatic conveying pipeline section and flow rates known from experience. The assessment of the influence of the main operating parameters on the coefficient of relative slip of the air and solid phases is carried out.

Detection and Modeling of the Core-Annulus Transition in Industrial and Pilot Plant Risers

The core-annulus structure is essential to the modeling and optimization of riser reactors such as used in Fluid Catalytic Cracking. This paper presents results of measurements taken with various probes in a pilot plant and in an industrial riser. The instantaneous probe signals were analyzed with sophisticated signal analysis methods based on the detection of cycles and the determination of the correlation dimension.In a pilot plant riser, a core-annulus structure was identified with optical and momentum probe measurements. Cycle analysis of the optical probe measurements showed that the annulus was unstable: its thickness fluctuated with an average cycle time of 0.3 s. There were waves at the core-annulus boundary. In an industrial riser, a similar core-annulus structure could be identified with temperature and momentum probe measurements. Local temperature measurements are much easier to perform in an industrial riser than momentum probe measurements but can provide, with cycle analysis, the location of the core-annulus transition. Analysis of the momentum probe and temperature signals showed that the thickness of the wavy transition layer between core and annulus was about the same in the pilot plant and the industrial riser, meaning that the relative range of fluctuations in annulus thickness was much smaller in the larger industrial riser.A model was developed to predict the time-averaged transition between core and annulus. This model, which had been successfully used to predict the annulus thickness in dilute-phase vertical pneumatic transport lines, assumes that the annulus thickness is such that the riser pressure drop is minimized. Measurements and model predictions were in good agreement.