Numerical simulation of a new two-stage dry feed gasifier for double-high coal

In order to study the characteristics of a new two-stage dry feed gasifier with multi underneath nozzles jetting tangentially, numerical simulation and analysis of the gasifier for high ash melting point pulverized coal was conducted based on Fluent. A comprehensive mathematical model for simulation of pulverized coal gasifier has been developed in this paper, chemical process was described with presumed PDF mode, a gasification look-up table was built to describe the relationship between mixture fraction and the scalars of temperature, species, et al. Body fitted hexahedron mesh was adopted and k-epsiv RNG turbulent model was used to make a closure for turbulence equations. Dispersed phase model (DPM) were employed to describe the coupling effect between gas phase and discrete phase, and stochastic tracking method (STM) were used to track turbulent dispersion of char particles and to consider the turbulent disturbance effects on particle motion on gasification process. In addition, user defined functions (UDF) was used to mend heterogeneous gasification reactions model, including carbon with O₂, H₂O, CO₂ and H₂. The numerical simulation and analysis of the inner velocity, temperature and species concentrations of the two-stage entrained flow coal gasifier for high ash melting point pulverized coal shown that spatial gasification reactions can be achieved in the gasifier, inner temperature grads reduce remarkably and temperature field become more even, and the key gasification parameters, such as [O]/[C] atom ratio, steam/coal ratio, were optimized through simulation, will offer reference for the further research on the gasifier for high ash melting point pulverized coal.