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AssigneeThe United States of America as represented by the United States Department of Energy
InventorsLarry A. Bissett, Larry D. Strickland, John M. Rockey
Estimating the term…
The regeneration of sulfur sorbents having sulfate forming tendencies and used for desulfurizing hot product gas streams such as provided by coal gasification is provided by employing a two-stage regeneration method. Air containing a sub-stoichiometric quantity of oxygen is used in the first stage for substantially fully regenerating the sorbent without sulfate formation and then regeneration of the resulting partially regenerated sorbent is completed in the second stage with air containing a quantity of oxygen slightly greater than the stoichiometric amount adequate to essentially fully regenerate the sorbent. Sulfate formation occurs in only the second stage with the extent of sulfate formation being limited only to the portion of the sulfur species contained by the sorbent after substantially all of the sulfur species have been removed therefrom in the first stage.
A method for regenerating hot-gas desulfurization sorbents with sulfating tendencies to minimize the concentration of sulfates in the regenerated sorbent, comprising the steps of partially regenerating a bed of particulate sorbent containing sulfur species substantially formed of sulfides in a first region of a sorbent regenerator by contacting the bed of particulate sorbent at an elevated temperature with a first stream of oxygen-containing gases at a sufficient volume and velocity for fluidizing the bed of particulate sorbent in said first region and for promoting a first exothermic reaction in said first region between the oxygen and the sulfur species for substantially regenerating the particulate sorbent in said first region to about 56% to substantially 100% of full regeneration without sulfate formation, said first stream having therein a quantity of oxygen corresponding to about 50% to 85% of the stoichiometric amount required for fully regenerating the sorbent by the exothermic reaction between the available oxygen and sulfur species, moving the resulting partially regenerated sorbent from an uppermost portion of the fluidized bed of particulate sorbent in said first region into a second region of the regenerator, and contacting a bed of the partially regenerated sorbent at an elevated temperature in said second region with a second stream of oxygen-containing gases at a sufficient volume and velocity for fluidizing the bed of partially regenerated sorbent in said second region with said second stream containing a quantity of oxygen substantially corresponding to greater than 100% to about 105% of a stoichiometric amount required to regenerate the sorbent to 100% of full regeneration by promoting an exothermic reaction in said second region between the oxygen in said second stream and any sulfur species remaining in the partially regenerated sorbent introduced in said second region of the regenerator, whereby any sulfate formation in the particulate sorbent essentially occurs only during the regeneration of the partially regenerated sorbent in the second region of the regenerator.
Dependencies are inferred from the claim text.