Computational Dynamic Simulation Of Gas/Solid Two-phase Flow In CFB

Circulating fluidized bed combustion has been accepted worldwide as an advanced technology for the sake of highly effective and clean. In recent years, it has developed rapidly. But for these years, the complex fluid dynamics of the gas-solid flow in the circulating fluidized beds has been the subject of a great deal of academic research throughout the world. For more reliable and improved design and operation, it is necessary to study the hydrodynamics of two-phase flow in the beds. Building a flow model to simulate the flow behavior of the bed is the basis of description on the hydrodynamics of two-phase flow. In this thesis, the mathematical formulation is based on the solute of each phase. The two-fluid model is used to account for the flow state of two phase coexisting in a same volume. Turbulence is represented by means of a modified two-equation k- c -k model. The numerical procedure used is of the finite volume type in which the differential equations are converted into algebraic finite volume equations with the aid of discrete assumptions. The numerical model has been incorporated for general use into the commercial CFD code PHOENICS. The finite volume equations are solved time after time using the SIMPLEST and IPSA algorithms, which are embodied in the PHOENICS code. The theoretical results are been compared with the experimental results and they coincide fairly with each other. The results show that the distribution of particles is un-equal in axes and radial, the velocity of particles increases with increasing of height of tl~ie bed and pressure is influenced by gas velocity.