Gas refining system

A method for refining gas obtained by gasification of coal or oil comprising the steps of:

• providing a reducing gas having sulfur-containing compounds;
• introducing the reducing gas into a fixed-bed desulfurizer packed with an amount of adsorbent;
• adsorbing the sulfur-containing compounds in the form of sulfides onto the adsorbent;
• introducing an oxygen-containing regenerating gas into the desulfurizer to regenerate the adsorbent and form a regeneration reaction gas containing sulfur dioxide;
• introducing the regeneration reaction gas into a reactor having a calcium compound-containing slurry;
• introducing a first oxygen-containing gas into the slurry;
• contacting the regeneration reaction gas and the first oxygen-containing gas with the slurry to absorb the sulfur dioxide and precipitate a gypsum-containing compound within the reactor;
• producing a gas above the surface of the slurry within the reactor;
• withdrawing the gas above the surface of the slurry;
• combining the gas withdrawn from above the surface of the slurry with a second oxygen-containing gas and recycling the combined gases as the oxygen-containing regenerating gas;
• and
• controlling the temperature of the adsorbent by controlling the oxygen concentration of the regenerating gas, said step of controlling the oxygen concentration of the regenerating gas comprising adjusting the first oxygen-containing gas to a flow rate sufficient to provide an amount of oxygen to the reactor greater than that required for complete oxidation of the absorbed sulfur-containing compounds and adjusting the flow rate of the second oxygen-containing gas so as to maintain an oxygen concentration in the recycled regenerating gas that maintains the internal temperature of the desulfurizer during regeneration of the adsorbent within an allowable adsorbent temperature range.