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US 8,894,965 B2Granted
Energy recovery in manufacture of sulfuric acid
AssigneeMECS, Inc.
InventorErnesto Vera-Castaneda
Life of this patent
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Abstract
This invention relates to the recovery of energy in the manufacture of sulfuric acid, and more particularly to enhanced recovery of energy from the absorption of wet SO3 in sulfuric acid. The invention is further directed to control of mist formation during SO3 absorption, and of the sulfuric acid mist content of the gas stream leaving the SO3 absorption step in a process wherein SO3 absorption energy is recovered from absorption acid in useful form.
Claims51
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 SO2;
- 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 SO3;
- 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.
3 more elements
A process for the preparation of sulfuric acid comprising:
- burning a sulfur source in a gas comprising excess oxygen to produce a sulfur oxide-bearing gas stream comprising a combustion gas comprising sulfur dioxide and oxygen;
- 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 SO3;
- contacting the conversion gas in a heat recovery absorption zone with an absorption liquid comprising sulfuric acid, thereby transferring sulfur trioxide from the conversion gas to the absorption liquid;
- circulating said absorption liquid between said absorption zone and a principal indirect heat exchanger in which heat is transferred to a principal heat transfer fluid, thereby heating said principal heat transfer fluid to at least 150° C.;
- dividing the absorption liquid stream exiting said principal heat exchanger to provide a principal absorption liquid stream that is recirculated to said heat recovery absorption zone and an auxiliary absorption liquid stream;
- passing said auxiliary liquid stream through an indirect heat exchanger auxiliary to a boiler feed water deaerator, heat being transferred in said deaerator auxiliary heat exchanger from said auxiliary liquid to a water stream for generation of deaerating steam;
- directing the deaerating steam to said deaerator wherein boiler feed water is contacted with the deaerating steam for stripping non-condensables from the boiler feed water;
- removing a deaerator exhaust stream from said deaerator, said deaerator exhaust stream comprising water vapor and non-condensable gases;
- and
- introducing water vapor contained in said deaerator exhaust stream into the sulfur oxide bearing stream upstream of the absorption zone with respect to the direction of gas flow.
7 more elements
Dependencies are inferred from the claim text.