Heavy oil conversion process with in-situ potassium sulfide generation

A process for desulfurizing a heavy oil feedstream with a potassium sulfide reagent and regenerating the potassium sulfide reagent from spent potassium salt reaction products, comprising:

• a) mixing at least a portion of a heavy oil feedstream having an API gravity of about 19 or less with a desulfurization reagent solution comprising potassium sulfide to form a mixed oil/reagent feedstream;
• b) exposing at least a portion of the mixed oil/reagent feedstream to effective desulfurization conditions in a conversion reactor to form a desulfurized reactor outlet stream, thereby removing at least a portion of the sulfur from the heavy oil feedstream components of the mixed oil/reagent stream and converting at least a portion of the potassium sulfide in the mixed reagent stream to spent potassium salts comprising potassium hydrosulfide;
• c) adding a wash water to the desulfurized reactor outlet stream to form a desulfurized oil/water mixture;
• d) separating the desulfurized oil/water mixture into a separate oil phase and a separate water phase in at least one wash water vessel, wherein the water phase contains the majority of the spent potassium salts;
• e) extracting at least a portion of the separate oil phase from the wash water vessel as a desulfurized heavy oil product, and extracting at least a portion of the separate water phase from the wash water vessel as an aqueous spent potassium reagent stream;
• f) splitting the aqueous spent potassium reagent stream into a non-regenerative potassium hydrosulfide stream and a regenerative potassium hydrosulfide stream;
• g) sending the regenerative potassium hydrosulfide stream to a KOH conversion process, converting the majority of the potassium hydrosulfide to potassium hydroxide in the KOH conversion process, and producing an aqueous regenerated KOH stream from the KOH conversion process;
• h) combining at least a portion of the aqueous regenerated KOH stream with at least a portion of the non-regenerative potassium hydrosulfide stream to produce a partially regenerated potassium reagent stream containing potassium hydroxide and potassium hydrosulfide;
• i) sending the partially regenerated potassium reagent stream to a flash regeneration system wherein the partially regenerated potassium reagent stream is subject to a dehydration temperature of at least about 250° C. (482° F.), thereby converting at least a portion of the potassium hydroxide and potassium hydrosulfide in the partially regenerated potassium reagent stream to potassium sulfide;
• j) extracting a regenerated potassium sulfide reagent stream from the flash regeneration system;
• k) utilizing at least a portion of the regenerated potassium sulfide reagent stream in the desulfurization reagent solution of step a).