Chemistry of inorganic compounds – Sulfur or compound thereof – Oxygen containing
Patent
1976-05-17
1978-07-25
Vertiz, O. R.
Chemistry of inorganic compounds
Sulfur or compound thereof
Oxygen containing
423168, 423171, 423638, 423DIG16, 23277R, C01B 1750, C01B 1314, C04B 1102
Patent
active
041029895
ABSTRACT:
Calcium sulfate is decomposed to CaO and SO.sub.2 by high temperature treatment in a fluidized bed wherein reductive and oxidative conditions are simultaneously maintained. A highly reducing gas is formed in the lower portion of the bed from partial combustion of the fuel in admixture with the primary fluidizing air. The quantity of the primary fluidizing air is limited so that the reducing conditions in the lower zone converts the CaSO.sub.4 to a mixture of CaO and CaS. Secondary air is introduced at a higher level in the bed to create an oxidizing zone in the upper portion of the bed above the reducing zone capable of converting CaS to CaO. The concurrent use of such reducing and oxidizing zones permits reducing conditions to be maintained which favor a high rate of decomposition even though these conditions favor the formation of CaS as well as CaO. The undesirable CaS, which would otherwise be discharged with the CaO product is eliminated by circulation of the fluidized particles through the oxidizing zone. Further, the heat of the exothermic reactions is conserved and utilized for promoting the endothermic reactions, both types of reactions occuring simultaneously while the rapid fluidized circulation of solids maintains a relatively uniform temperature throughout the bed.
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Environmental Protection Technology Series EPA 65012-74-001, Jan. 74 entitled, "A Regenerative Limestone Process for Fluidized Bed Coal Combustion and Resulfurization."
Iowa State University & Research Foundation, Inc.
Straub Gary P.
Vertiz O. R.
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