Numerical modeling of an E-Gas entrained flow gasifier to characterize a high-ash coal gasification

• A 3D numerical simulation for a high-ash coal, with 33% ash, in the E-Gas gasifier.
• Performance parameters of the selected high-ash and a low-ash coals are compared.
• Decreasing in yield syngas and total higher heating value respect to low ash coal.
• Limited economical operating range in high ash-coal gasification.
• Lower syngas temperature, about 600 K, and cold gas efficiency, about 5%, in high-ash coal.

In this paper, a three-dimensional numerical simulation was carried out to characterize a high-ash coal gasification in a pressurized, oxygen-blown, two-stage E-Gas entrained flow gasifier. The Tabas coal was used as a high-ash feedstock, with 32 wt% ash and was compared with the Illinois #6 low-ash coal, with 10 wt% ash. The computational model was conducted in ANSYS FLUENT 14 based on the conservation equations described in the Eulerian–Lagrangian approach. Also, four heterogeneous combined with seven homogeneous reactions were solved via the finite rate and eddy-dissipation/finite rate model, respectively. Two different parametric analyses were conducted to characterize the gasification process in the E-Gas gasifier. These analyses cover the effects of the O2/Coal ratio and coal slurry water content on the gasifier performance characteristics such as the exit temperature, main species mole fractions, carbon conversion, high heating value, yield syngas fraction and cold gas efficiency. It was found that using the higher ash content coal decreases the cold gas efficiency about 5%, limits the gasifier economical operating range, and reduces the exit temperature, yield syngas and total higher heating value.