Fuel Gas Clean-Up in a Transport Reactor: Model Development and Analysis

Integrated Gasification Combined Cycle (IGCC) is the leading coal-fired system being developed by the U. S. Department of Energy to produce clean electricity from coal. One of the key components of this IGCC is fuel gas desulfurization (HGD) which is used to remove sulfurous compounds from coal gases with efficient, regenerable, mixed-metal oxide sorbents. Previous commercial desulfurization processes are based on wet scrubbing at or below ambient temperatures, resulting in considerable thermal efficiency loss as well as costly wastewater treatment. This has led to the development of gas-solid processes using transport reactors above the dew point of water. These systems offer the advantages of high throughput, continuous operation, and efficiency gains over low-temperature scrubbing of H₂S. The National Energy Technology Laboratory (NETL) is developing a simplified transport reactor mathematical model to provide a quick estimation of pressure drops and conversions as a function of riser dimensions, sorbent properties and gas velocity. Hydrodynamics and a solid conversion model, together with a transport reactor mass balance, are used to predict the performance of a fuel gas desulfurization reactor. Experimental data collected at NETL’s Gas Process Development Unit (GPDU) are used to provide an initial assessment of the model.