Fluid-dynamic Analysis of a Fluidized Bed Reactor

In order to take advantage of the solid waste generated by the Colombian agricultural industry, the design of an experimental gasification unit at a laboratory scale using fluidized bed technology is proposed, the unit will allow testing of diverse residues under different operating conditions. In the present work, the methodology used for the basic design of the different components of this unit is presented. The design includes besides the reactor, the solids separation system and solids return system, as well as the biomass and bed material feeding systems and the heating system. In order to carry out the design of all sub-systems, methodologies from different authors have been adapted. The properties of the residual biomasses with the highest energy potential in Colombia were used as input data, thus analyzing the possibilities offered by the design in the use of different residual biomass and the generation of expected thermal energy. The design was delimited by the following requirements: gasification with air, semi-continuous operation, circulating configuration, fluidization regimes from bubbling up to fast, thermal power output of 10 kWth, possibility to gasify different types of residual biomass (of different chemical and physical properties), possibility to test different gasification temperatures. In order to study the fluid dynamics of the design, a cold model of size 1:1 with respect to the size of the pilot plant was constructed. Experimental tests were carried out in the cold model varying the solids inventory, fluidization velocity and solids recirculation rate, and carrying out pressure drop and solids circulation rate measurements. The onset of fluidization is independent of the bed height, nevertheless an influence in the fluid-dynamics of the bed due the weight was observed. At low velocity regimes is recommended not to use deeper beds because there is no adequate fluidization, therefore the contact efficiency might be low. In the cyclone, at high solids load the separation efficiency increases due to the formation of strand of solids which drag both the coarsest and the finest particles. The results allowed the improvement of the initial design and determine the operation window of the unit. The pilot unit is important for the development of thermochemical processes in fluidized beds in Colombia, as it opens the possibility for assessing the energy use of agricultural solid waste in such units.The experimental unit designed allows the use of different residual biomasses operating under different fluidization regimes from bubbling to fast, this is important because the unit will allow to evaluate the conversion efficiency for each biomass under different contact regimes, and in this way to select the most efficient regime to transform the biomass

• Autores: Tibocha Guzmán, Diego Alexander
• Fecha de publicación: 2018
• Institución: Universidad Nacional de Colombia
• Repositorio: Universidad Nacional de Colombia
• Idioma: spa
• OAI Identifier: oai:repositorio.unal.edu.co:unal/68955
• Acceso en línea: https://repositorio.unal.edu.co/handle/unal/68955; http://bdigital.unal.edu.co/70314/
• Palabra clave: 62 Ingeniería y operaciones afines / Engineering; 66 Ingeniería química y Tecnologías relacionadas/ Chemical engineering; Renewable energies circulating fluidized bed, cold flow model; Biomass; Thermochemical transformation; Gasification; Lecho fluidizado circulante; Biomasa; Transformación termoquímica; Gasificación; Energías renovables; Modelo frío
• Rights: openAccess
• License: Atribución-NoComercial 4.0 Internacional