Patent ID: 8894965

Claim:
A process for the preparation of sulfuric acid comprising: burning sulfur in a dry gas comprising excess oxygen in a combustion zone to produce a sulfur oxide-bearing gas stream comprising a combustion gas comprising sulfur dioxide, oxygen and not more than 0.005 moles water vapor per mole SO 2 ; contacting the sulfur oxide-bearing gas stream comprising said combustion gas with a catalyst for conversion of sulfur dioxide to sulfur trioxide, thereby converting the sulfur oxide-bearing gas stream to a conversion gas containing not more than 0.005 moles water vapor per mole SO 3 ; contacting the conversion gas in a primary heat recovery absorption zone with an absorption liquid comprising sulfuric acid, thereby transferring sulfuric acid from the conversion gas to the absorption liquid; introducing water vapor into the conversion gas into a water vapor injection zone upstream of the primary heat recovery absorption zone with respect to the direction of gas flow in a proportion sufficient to increase the equivalent water vapor content of the gas to at least about 0.55 moles per mole total equivalent sulfur oxide gas content prior to entry of the gas stream into the primary absorption zone; and circulating said absorption liquid between said primary absorption zone and an indirect heat exchanger in which heat generated by reaction of sulfur trioxide and water, condensation of sulfuric acid, and/or absorption of sulfur trioxide into the absorption liquid is transferred to a heat transfer fluid, thereby heating the heat transfer fluid to at least 150° C.