A New Type of Non-Mechanical Valves for Recirculation of Fine Particles

Gas-solid systems are applied in various industries such as pharmaceutical, food industry and chemical processes like catalytic cracking, combustion and gasification.One of the leading technologies to deal with such processes is the fluidized bed technology. Considering the increasing demands on production, process and application of solid particles, investigation, characterization and optimization of the whole or a part of a fluidized bed system is getting vital. Nowadays, fine particles are utilized in lots of number of applications and dueto present challenges in fluidization of these type of particles, assistive methods are applied to make it possible. One the major points where these challenges impacts is the loop-seals. Conventional loop-seal are operated around minimum fluidization condition and definitely fine particles has difficulties to be operated under this regime. The goal of the thesis is to design a new version of a non-mechanical valve for transportation of the particles and closing the loop in circulating or interconnected fluidized bed systems. As the primary proposal, combination of three assistive methods (tapered fluidized bed, mixture of coarse and fine particles and high velocity gas jet) in a single device was examined to check feasibility of handling the fine particles. A draft tube spouted bed is considered to be operated with coarse particles and the standpipe which is filled with fine particles represents the downcomer of acyclone. This set-up was somewhat capable of transporting the fine particles but introducing the particles through an inclined tube was not possible. After performing some supportive experiments, new version of the experimental set-up, namely four draft tubes pneumatic transport (4-DTPT), was design, constructed and examined. Successful introduction and transportation of fine particles are observed for this device. For the purpose of characterization of the 4-DTPT test rig, different type of experiments were performed considering changes in operating conditions and geometric parameters as well as the particles size. Although, more investigations are needed to be carried out to thoroughly characterize and optimize the new device. Further analysis, modifications, corrections and systematic investigation of the4-DTPT will provide the knowledge about scale-up of this device to be utilized for industrial applications.