Secagem de suspensão de carbonato de cálcio em leito fluidizado utilizando análise espectral gaussiana

Abstract

The phenomenon of partial or total defluidization of a fluidized bed is not desirable in industrial applications, as it may result in the interruption of the process. On the other hand, rapid detection of fluid dynamics changes from the bed can cause the bed to return to desired conditions with increasing fluidization air flow and / or suspension feed reduction. In this context, the present work aims to identify the transition of fluidodynamic regime in the drying process of calcium carbonate suspension, using Gaussian spectral analysis, which is a technique based on measures of pressure fluctuation in the bed. The tests were carried out in a laboratory scale fluid bed dryer, which consists of an acrylic column of 0.11 m internal diameter and 1 m high. The inert material used was glass sphere as the mean Sauter diameter of 0.334 mm, and aqueous calcium carbonate suspension at 15% concentration by mass. It suspension flow rate was maintained at 6 mL / min and two drying temperatures were used: 90 and 1000C. To the experimental equipment were pressure transducers coupled, of quick answer together a signals acquisition and processing system consisting of a data acquisition board, microcomputer and LabView software version 10.0. Through the results it was observed that the transition between the bubbling regime and the defluidization was identified using the Gaussian spectral analysis. Additionally, it was found that at both temperatures used, the bed temperature tended to approach the wet bulb temperature, indicating bed saturation, and, consequently, compromising the drying process.