Patent ID: 8715380

Claim:
A method for deep desulfurization of synthesis gas, the method comprising: producing a flue gas and a gasifier product synthesis gas in a dual fluidized bed loop by: introducing a carbonaceous material and optionally steam into a fluid bed gasifier comprising a heat transfer media; extracting a first heat transfer stream comprising heat transfer media and optionally unconverted carbonaceous material from the fluid bed gasifier, and introducing at least a portion of the first heat transfer stream into a fluid bed combustor, wherein the first heat transfer stream has a first temperature; introducing oxidant and optionally a fuel into the fluid bed combustor, whereby unconverted carbonaceous material in the first heat transfer stream, fuel, or both is combusted and the temperature of the heat transfer media is raised; extracting a second heat transfer stream comprising heat transfer media and having a second temperature from the fluid bed combustor, and introducing at least a portion of the second heat transfer stream into the fluid bed gasifier, wherein the second temperature is greater than the first temperature; introducing a compound capable of reacting with sulfur to produce sulfate, sulfide or both into the dual fluidized bed loop; extracting a purge stream comprising ash, sulfate, halide, or a combination thereof from the second heat transfer stream; extracting the flue gas from the fluid bed combustor; and extracting the gasifier product synthesis gas stream comprising less than 1000 ppm sulfur from the fluid bed gasifier of the dual fluidized bed loop; introducing the gasifier product synthesis gas into a fluid bed conditioner, the fluid bed conditioner one fluidized bed reactor of a second dual fluidized bed loop; introducing the flue gas from the fluid bed combustor into a second fluid bed combustor, wherein the second fluid bed combustor is the second fluidized bed reactor of the second dual fluidized bed loop; extracting a first catalytic heat transfer stream comprising a catalytic heat transfer material and having a third temperature from the fluid bed conditioner, and introducing at least a portion of the first catalytic heat transfer stream into the second fluid bed combustor; extracting a second catalytic heat transfer stream comprising catalytic heat transfer material and having a fourth temperature greater than the third temperature from the second fluid bed combustor, and introducing at least a portion of the second catalytic heat transfer stream into the fluid bed conditioner; and extracting, from the fluid bed conditioner, a high quality synthesis gas comprising less sulfur than the gasifier product synthesis gas.