Numerical Investigation Of Gas-solid Hydrodynamic Characteristics In A 660MW Supercritical CFB Boiler

Supercritical circulating fluidized bed technology is an efficient and low pollution clean combustion technology. It has been more and more get the attention of the countries all over the world. For large circulating fluidized bed boiler, a mathematical model of flow process to establish effective of internal, to simulate the complex process of gas-solid flow and accurately predict the performance of CFB boiler, they can provide reliable technical guidance with boiler design and operation.So promoting the development of large-scale circulating fluidized bed boiler is very necessary.Euler-euler model has been introduced in this paper and basic control equation and constitutive equation are derived by particle kinetics theory. Analyzing the double fluid model of the drag force of the model is very important. Gidapow drag model, the Syamlal-O'brien drag model and the EMMS are discussed. Finally UDF can keep material of circulating fluidized bed boiler. Secondly, in view of the circulating fluidized bed riser pipe, this paper compare simulation results with the experimental data analysis and found that accord well with those dates. You can verify the accuracy of the calculation model. We should adopt different drag model, turbulence model and particle collision recovery coefficient to analyze class B particle flow simulation accuracy in a circulating fluidized bed and study different operating parameters on gas-solid flow characteristics of circulating fluidized bed riser. Conclusion:when only consider riser dilute phase zone particle concentration and velocity or particle, when reunion effect is not important, Gidaspow simulated calculation model can be used as a drag. Using discrete turbulence model can predict riser gas-solid two phase flow characteristics, when the particle collision when the recovery coefficient is 0.9 particle diffusion effect is best, the highest concentration distribution results coincide with the experimental results. The smaller the particle size, the axial velocity along the radial distribution is uneven, the bigger the particle diameter, the axial of the concentration distribution more uniform; With the increase of operating gas velocity, bed section average rate decreased in the solid particles, particles of solid holdup radial distribution tends to be relatively uniform, Bed layer stack height increases, the grain circulation flow rate, the greater the granular solid content rate in the whole cross section.Finally, this paper studies the 660 MW supercritical CFB boiler furnace gas solid flow characteristics, analyzed the gas-solid two-phase pressure in hearth, concentration and velocity distribution, and studies a wind velocity and particle size influence on gas-solid flow characteristics in furnace, the results showed that the concentration of particle axial overall presents the distribution trend of thin under thick, roughly in the index distribution curve; Particle radial concentration distribution showed a typical flow structure, furnace bed pressure changing with furnace is to present an exponential function. Particle velocity distribution center area is high, low side wall area distribution, furnace dense-phase zone "M" type distribution of particle velocity distribution. With the increase of wind speed, pressure drop dense-phase zone change more intense; In dilute phase zone near the furnace top area, boiler furnace pressure increases with wind speed change more smoothly; Dilute phase zone of particle concentration increasing, the dense-phase area of particle concentration change very gently; Dense-phase zone of particle velocity increases gradually, while in dilute phase particle velocity decreases. With the increase of particle diameter, furnace pressure dense-phase zone change smaller, dilute phase zone of a stove or furnace pressure gradually reduce; Dense-phase zone of particle concentration increases gradually, and dilute phase zone particle concentration changes smaller; Center of particle velocity increases significantly better than the gradient of the side wall.