Direct Desulfurization System and Method

Abstract

Embodiments of a desulfurization system of the present invention generally include a mixing vessel and one or more desulfurization zones, each desulfurization zone including, in sequence, a reheater, a reactor and a condenser, wherein the desulfurization system is operable to react sulfur dioxide with a hydrocarbon gas stream containing hydrogen sulfide to remove the hydrogen sulfide therefrom. In certain embodiments the desulfurization system also includes a back-end system that includes equipment designed to further process the purified hydrocarbon gas stream. Methods of using embodiments of the desulfurization system of the present invention are also provided.

I claim: 
     
         1 . A desulfurization system, comprising:
 a mixing vessel; and   one or more desulfurization zones;   wherein:
 said mixing vessel is configured and adapted to proving a mixing function for a hydrocarbon fluid stream containing hydrogen sulfide and a fluid sulfur dioxide stream; 
 each said desulfurization zone comprises, in sequence:
 a reheater; 
 reactor; and 
 a condenser; 
 
 each said desulfurization zone is operable such that a fluid stream comprising said hydrocarbon fluid stream and said fluid sulfur dioxide stream that exits said mixing vessel and flows through said desulfurization system provides for reaction of at least a portion of hydrogen sulfide contained in said hydrocarbon gas stream with said sulfur dioxide to produce molecular sulfur; and 
 said molecular sulfur is separable from said hydrocarbon gas stream. 
   
     
     
         2 . The desulfurization system of  claim 1 , wherein at least one said reheater is configured and adapted to heat said mixed fluid stream to about 550° F. 
     
     
         3 . The desulfurization system of  claim 1 , wherein at least one said reactor contains a catalyst that facilitates the formation of molecular sulfur. 
     
     
         4 . The desulfurization system of  claim 1 , wherein at least one said reactor is configured and adapted to maintain said mixed fluid stream at a temperature of at least about 30° F. above the sulfur dew point. 
     
     
         5 . The desulfurization system of  claim 4 , wherein at least one said reactor is configured and adapted to maintain said mixed fluid stream at a temperature of about 600° F. 
     
     
         6 . The desulfurization system of  claim 1 , wherein at least one said condenser is configured and adapted to cool said mixed fluid stream to a temperature of about 300° F. to about 310° F. 
     
     
         7 . The desulfurization system of  claim 1 , comprising a back-end system that is configured and adapted to process the mixed fluid stream exiting at least on said condenser such that residual molecular sulfur is removed from said mixed fluid stream. 
     
     
         8 . The desulfurization system of  claim 7 , wherein said back-end system comprises:
 one or more pre-heaters; and/or   one or more hydrogenation reactors; and/or   one or more coolers; and/or   one or more contacters.   
     
     
         9 . The desulfurization system of  claim 7 , wherein said back-end system comprises:
 one or more cold bed absorbers; and/or   one or more condensers; and/or   one or more crystallizers; and/or   one or more quench towers.   
     
     
         10 . A method of operating the desulfurization system of  claim 1 , comprising:
 providing said desulfurization system;   mixing said fluid hydrocarbon stream containing hydrogen sulfide with said fluid sulfur dioxide stream in said mixing vessel;   flowing said mixed stream from said mixing vessel through one or more series of vessels, each series comprising, sequentially, a reheater, a reactor and a condenser;   operating said desulfurization system such that at least a portion of said hydrogen sulfide is reacted with said sulfur dioxide to produce molecular sulfur; and   separating said molecular sulfur from said gaseous hydrocarbon stream.   
     
     
         11 . The method of operating the desulfurization system of  claim 10 , wherein at least one said reheater heats said mixed fluid stream to about 550° F. 
     
     
         12 . The method of operating the desulfurization system of  claim 10 , wherein one said reactor contains a catalyst that facilitates the formation of molecular sulfur. 
     
     
         13 . The method of operating the desulfurization system of  claim 10 , wherein at least one said reactor maintains said mixed fluid stream at a temperature of at least about 30° F. above the sulfur dew point. 
     
     
         14 . The method of operating the desulfurization system of  claim 13 , wherein at least one said reactor maintains said mixed fluid stream at a temperature of at least about 600° F. 
     
     
         15 . The method of operating the desulfurization system of  claim 10 , wherein at least one said condenser cools said mixed fluid stream to a temperature of about 300° F. to about 310° F. 
     
     
         16 . The method of operating the desulfurization system of  claim 10 , wherein said desulfurization system comprises a back-end system, said back-end system comprising:
 one or more pre-heaters; and/or   one or more hydrogenation reactors; and/or   one or more coolers; and/or   one or more contacters;   wherein, said back-end system is operated such that residual molecular sulfur is removed from a fluid stream flowed thereto.   
     
     
         17 . The method of operating the desulfurization system of  claim 16 , wherein:
 at least one said pre-heater heats a fluid stream provided thereto to about 450° F.; and/or   at least one said hydrogenation reactor is operated such that a fluid stream exiting therefrom has a temperature of about 400° F. 500° F.; and/or   at one said cooler cools a fluid stream provided thereto to about 300° F.   
     
     
         18 . The method of operating the desulfurization system of  claim 10 , wherein said desulfurization system comprises a back-end system, said back-end system comprising:
 one or more cold bed absorbers; and/or   one or more condensers; and/or   one or more crystallizers; and/or   one or more quench towers;   wherein, said back-end system is operated such that residual molecular sulfur is removed from a fluid stream flowed thereto.   
     
     
         19 . The method of operating the desulfurization system of  claim 18 , wherein:
 at least one said cold bed absorber is operated in a first mode, wherein from a stream provided thereto molecular sulfur is solidified, and a second mode; wherein said solidified molecular sulfur is vaporized; and/or   at least one said crystallizer is operated in a first mode, wherein from a stream provided thereto molecular sulfur is solidified, and a second mode; wherein said solidified molecular sulfur is liquified; and/or   at least one said quench tower is operated such that from a stream provided thereto residual sulfur dioxide is removed.   
     
     
         20 . The method of operating the desulfurization system of  claim 19 , wherein:
 at least one said cold bed absorber is operated in said first mode at about 250° F. to about 300° F., and in said second mode at about 600° F.; and/or   at least one said crystallizer in said first mode at about 200° F. to about 230° F., and in said second mode at about 275° F. to about 300° F.