Coal conversion to SNG: Thermochemical insights through kinetic-free modeling in entrained flow gasifier

Abstract

In this study, a kinetic-free thermodynamic equilibrium model consisting of five units was developed to predict SNG production via coal gasification, using two distinct feeding technologies (SFT and DFT) and two coal ranks (BT and BL) in an entrained flow gasifier using Aspen Plus (V10), and comparing results with empirical data. The alignment between simulation outcomes and experimental observations is verified, and analysis of various parameters' impacts on product gas composition and yield is conducted. Sensitivity analysis reveals consistent trends across different coal ranks. The O2/coal ratio emerged as a key factor, demonstrating notable effects on syngas composition and yield. Specifically, increasing the O2/coal ratio from 0.3 to 1.0 enhanced H2 and CO2 proportions in the syngas which are beneficial for SNG production, as hydrogen is a key component for SNG. Elevating the O2/Coal ratio from 0.2 to 0.6 (optimal) favors CGE, facilitating high-quality syngas production. Additionally, increasing the CO2 flow rate up to 3 ton/hr improves the HHV of syngas, beyond which HHV declines. Raising the W/C ratio from 0.3 to 1.0 leads to decreased HHV for BL and BT coal. Additionally, increasing the W/C ratio from 0.3 to 1.0 decreases HHV. Therefore, it is crucial to undergo the production of SNG within the optimal ranges, and these findings provide crucial insights into optimizing gasification parameters for enhanced syngas production across various feed technologies and coal types to produce desired syngas results.

Keywords

• Coal to SNG
• O2/coal ratio
• Carbon conversion efficiency
• Thermochemical processes
• Water gas shift reaction