AN APPARATUS FOR DEASHING COAL BY DRY BENEFICATION USING A CIRCULATING FLUIDIZED BED LOOP

摘要

Thus the main object of the present invention is to provide a method of deashing of coal fines (- 1mm) using circulating fluidized bed. Gas-solid fluidization plays a central role in many chemical processes, metallurgical and energy conversion processes. Passing a gas through a bed of solids forms a gas-solid fluidized bed. When this happens, the bed of solids takes on certain fluid-like characteristics. From a chemical processing point of view, the fluidized bed is an excellent way of contacting gaseous reactants with catalyst particles in a heterogeneous gas phase reaction. For the purpose of the present invention, the mixing and segregation pattern in circulating fluidized beds consisting of fine particles and coarse particles having different density, size distributions and terminal settling velocity were investigated using a 0.1016 m ID and 5.62 m height riser of circulating fluidized bed system. Attention is focused on understanding the interaction and mechanism between the particles and the conditions in which complete mixing or segregation is possible in circulating fluidized beds. Effort is made to find out the extent of ash from coal in the circulating fluidized bed at a typical gas velocity and solids circulation rate. Coal comprises lighter organic carbonaceous materials and heavier inorganic inert material leaving behind on ignition what is called commonly as ash. On fluidization heavier inert materials comprising heavier minerals segregates and less lighter material moves up at the top resulting in the benefication process. In the present invention the circulating fluidized bed system uses a blower for blowing air into two air lines, a fast bed column and a slow bed column for keeping the bed respectively in a fluidized condition and a minimum fluidized condition. A cyclone separator is provided at the end of the slow bed column for feeding the solids carried over form the fast bed to be separated by the cyclone separator and collected at its exit end. The heavier separated particles fall back to the slow bed column and transferred to the fast bed column via a solid transfer line for recycling. The present invention thus provides an apparatus for deashing coal by dry benefication, using a circulating fluidized bed loop comprises a fast bed column and a slow bed column, each having a bed of solids and provided with a distributor for blowing in air from a rotary air blower; a cyclone separator provided at the distal end of said slow bed column for receiving and for getting the solid separated from solid fines; and a solid transfer line provided for circulating solids from said slow bed column to said fast bed column for recycling the separated solids.