A study of hydrodynamic aspects and drying of geldart B materials in circulating fluidized bed

Abstract

A Circulating Fluidised Bed (CFB) system essentially consists of the riser which provides contact between the gas and solids, a gas-solids separator and a solid recycle control system. Gas and solids are fed at controlled rates into the bottom of the riser to flow cocurrently to the top of the riser and into the gas-solids separator. Solid and gas contacting in chemical industries by using CFB has added advantages. The significant among them include effective contact, high amount of material passing per unit cross section, elimination of bubbles, facility to handle cohesive materials, temperature uniformity within the bed, high degree of mixing for solids, high processing capacity.CFB finds successful application for gas-solid reactions such as calcinations, combustion catalytic cracking and drying of solid materials etc, Drying is a significant unit operations broadly utilized in chemical industries, food and pharmaceutical industries to reduce the moisture content and improve the shelf life of various products. Its principle is based on removal of water from material by means of evaporation. The thesis presents a detailed analysis of a CFB with a column height of 1200 mm and diameter of 50 mm was operated under wide range of gas velocity and solids concentration. The materials selected in the present study are Semolina (Rawa), Poppy seeds (Papaversomniferum) and Sand which falls under Geldart B-Type materials. The study consists of the hydrodynamic aspects of all the selected materials and the drying kinetics of Semolina and Poppy seeds. It has been observed from the present investigation, the total pressure drop and aaxial pressure profiles covering wide range in operating conditions newline