Investigation of the oxy-fuel combustion process in the full-loop circulating fluidized bed
Yuyang Chen, Shiliang Yang, Jianhang Hu, Hua Wang
Abstract
Oxy-fuel combustion of fossil fuels in circulating fluidized bed (CFB) reactors has been widely implemented in various industries. However, the knowledge of complex gas thermal characteristics (e.g., gas temperature, viscosity , density, conductivity and specific heat capacity) is still in lack. Understanding the distribution of these gas thermal properties within the oxy-fuel combustion CFB reactor is crucial for predicting particle behavior, optimizing operating conditions, and performing design optimizations. In this study, the hydrodynamics and thermochemical characteristics of dense reactive flow in a 0.1 MW th pilot-scale CFB are simulated via a developed multi-phase particle-in-cell (MP-PIC) reactive model. The impacts of some key operating parameters on the gas thermal properties, gas species distribution and gas-solid flux are studied. The results show that the dynamics and thermochemical variables of gas-solid flow show non-uniform distributions in the riser due to the segregation mechanism and lateral injection of solid fuels. Combustible gases (e.g., CH 4 , CO , H 2 , and H 2 S) mainly concentrate in the left area of the riser. Enlarging the oxygen concentration increases gas viscosity while decreases gas density. The density of gas phase ranges from 0.35 kg/m 3 to 0.50 kg/m 3 while gas turbulent viscosity ranges from 4.2 × 10 −5 m 2 /s to 4.8 × 10 −5 m 2 /s.