Pilot scale experience on IGCC hot gas cleanup

Enviropower Inc. is developing and commercializing a simplified IGCC process which applies pressurized air-blown gasification technology and hot gas cleanup. Hot gas cleanup consists of a sulfur removal system using regenerable sorbent and a filter unit having ceramic candle filter elements. During coal gasification test runs the major emphasis in development of hot gas cleanup was focused on testing of the sulfur removal system. The ceramic filter unit testing was already in the category of routine operation. The filter cleaning strategy was mainly based on a constant cycle time using on-line pulsing with pressurized nitrogen. The filter unit is completely integrated with the control system of the pilot plant. Dust loadings below 5 ppmw in product gas and vapor-phase alkali (Na+K) concentrations below 0.05 ppmw were measured after filtration. These values are below the levels generally required by gas turbine manufacturers and well below the environmental standards. As part of the CRADA, two different types of regenerable zinc titanate sorbents (1.5ZnO{center_dot}TiO{sub 2}) were used in the test runs in the new sulfur removal system. As a result, steady-state operation of the sulfider and regenerator fluidized bed reactors linked together was obtained at design pressures and temperatures. Very high sulfur removalmore » efficiency in the sulfider with both sorbents was achieved, as well as continuous production of SO{sub 2}-containing off-gas from the regenerator.« less