Integrated process for converting sulfur-containing fuels to low sulfur combustible gas

An integrated process for converting a sulfur-containing fuel to a substantially sulfur-free combustible gas in which the fuel is partially combusted within a sulfur-fixing dense-phase fluidized fuel conversion bed operated at a fuel conversion temperature so that the fuel is converted to a substantially sulfur-free combustible gas which is discharged from above the top of the conversion bed and wherein sulfur from the fuel is fixed, by chemical reaction in particles of the conversion bed, and in which particles are transferred from a first region of the conversion bed to a first region of a dense phase fluidized regeneration bed operated at regeneration conditions including a regulated regeneration temperature exceeding the fuel conversion temperature so that at least some of the sulfur which is chemically fixed in the particles is released as gas phase sulfur moieties which are discharged from above the top of the said regeneration bed, and transferring particles from a second region of the regeneration bed, spaced-apart from the first region thereof, to a second region of the fuel conversion bed spaced apart from the first region thereof, wherein the conversion bed is comprised of particles including alkaline earth metal oxide which fixes sulfur from the fuel by forming alkaline earth metal sulfide, and the conversion bed is fluidized by passing into the bottom thereof an oxygen containing gas, and wherein the regeneration bed is fluidized by passing into the bottom thereof an oxygen containing gas whereby at least some alkaline earth metal sulfide from the fuel conversion bed is converted to alkaline earth metal oxide with the evolution of sulfur oxide(s) and the liberation of heat tending to raise the temperature of the regeneration bed towards a deactivating temperature range, regulating the rate of transfer of particles from the fuel conversion bed at the conversion bed temperature to the regeneration bed so as to effect at least partial regulation of the temperature in the regeneration bed in a range not exceeding a predetermined maximum regeneration bed temperature below the said deactivating temperature range, regulating the rate of supply of oxygen-containing gas to the regeneration bed to be such that:

• (a) sulfur is liberated therefrom as sulfur moieties, including sulfur oxide(s) at substantially the same rate as sulfur from the fuel is fixed in the fuel conversion bed;
• but
• (b) insufficient to reduce the temperature of the regeneration bed to that of the
• fuel conversion bed;
• and employing the heat content of the particles transferred from the second region of the regeneration bed to the second region of the fuel conversion bed to provide some of the heat required for maintaining the conversion temperature of the fuel conversion bed whereby a reduced amount of fuel is required to maintain the temperature of the fuel conversion bed and an increased proportion of the fuel is converted to substantially sulfur-free combustible gases.