Studies on Solids Flow in a Cold Model of a Dual Fluidized Bed Reactor for Chemical Looping Combustion of Solid Fuels

Abstract

Abstract The results of investigations on solids flow in a cold model of the dual fluidized bed reactor designed for chemical looping combustion of solid fuels (DFB-CLC-SF) are presented in this paper. The constructed unit consists of two interconnected reactors. The first one, so-called fuel reactor (FR), is operated under bubbling fluidized bed (BFB) conditions, whereas the second one, so-called air reactor (AR), is structurally divided into two sections. The bottom part of AR works under BFB while the upper part, i.e., the riser, is operated in the fast fluidized bed (FFB) regime. In these studies, the air was used for fluidization process in all parts of the DFB-CLC-SF reactor. The glass beads with similar parameters to oxygen carriers (OCs) used in the CLC process were utilized as an inventory. The fluidization conditions are controlled by using the sets of pressure sensors installed around the circulation loop. The experimental data acquired in the tests are further employed to the analysis of solids behavior in a cold model of the DFB-CLC-SF reactor. The main goal of these studies was to establish the conditions for smooth fluidization, which concurrently provide the required residence time of solids in both reactors that is one of the most crucial factors in the CLC process. It was found that the fluidizing gas velocity in reactors has a significant impact on solids behavior and the investigated parameters. However, what is the most important, it was confirmed that the operation condition of the DFB-CLC-SF reactor can be adjusted to meet the requirements resulting from the properties of OCs.