Caracterización de los fenómenos de fluidización en lechos fluidizados empaquetados

Abstract

[ES] El presente proyecto de TFM es un trabajo experimental en el cual se quieren demostrar por primera vez como afectan distintos tipos de empaquetamientos en diversas características de los reactores de lecho fluidizado. Se tienen varios objetivos principales, el primero de ellos es obtener como varía la caída de presión en el reactor al usar distintos empaquetamientos y con diferentes tamaños de partículas en el reactor; con esto podremos determinar cual es la mínima velocidad de fluidización para los casos estudiados. El segundo objetivo consiste en medir los tiempos de residencia de las partículas en la zona de empaquetamiento también con diferentes casos para poder comparar los escenarios en busca de una optimización del flujo de partículas. El proyecto servirá como base para continuar con el estudio de estos empaquetamientos y una futura aplicación a reactores de lecho fluidizado reales.

[EN[ Fluidized bed systems have been widely used in many industrial applications and recently extended its range to a new area called chemical-looping-combustion (CLC) with inherent 𝐶��𝑂��2 capture. Advantages of fluidized bed systems include good mixing, temperature uniformity and high rates of mass and heat transfer. However, at elevated gas velocities achieving high gas-solid mass transfer becomes challenging in the design of fluidized-bed reactors. One solution was the concept of packed-fluidized beds, applying random packings in fluidized beds can prevent bubble growth but few studies have been conducted on this concept. Thus, the present work takes its base to investigate the use of different types of random packing materials, including RMSR and Raschig ring (RR) packings and their effect on the hydrodynamics of fluidized beds compared to spherical packings such as ASB and ECA. Experiments were done in a cylindrical acrylic reactor with an inner diameter of 12 cm and a height of 1 m. Bed material was silica sand particles with mean sizes of 119,181, and 303 𝜇��𝑚��. Different properties of packed-fluidized beds such as minimum fluidization velocity, pressure drop and solids flux inside the beds were investigated for the first time. Two main goals were to be achieved, the first one was to plot the bed pressure drop for each packing mentioned above and compare it with the case without packing, also see the difference between the graphs depending on the diameter of bed particles. Pressure drop increased when spherical packings was used compared to a non-packed bed while non spherical packings have a lower pressure drop. The RMSR packings due to their high void factor have a pressure drop curve very similar to the case without packing. When increasing the size of bed particles, the fluidization bed regime with constant pressure diminishes because the minimum fluidization velocity is higher but the entrainment of bed particles starts at similar velocities regardless of the diameter of the silica sand. The second aim was to investigate the use of packings in a cross-flow reactor, in these experiments only ASB packings have been used to focus on the effect of other parameters. Interesting results regarding the diameter of the bed particles, packing height and size of packings have been achieved.