Multi-stage sulfur removal system and process for an auxiliary fuel system

A process for separating a fuel stream containing a low concentration of sulfur compounds from a primary fuel stream, the process comprising:

• isolating a stage-one permeate stream and a stage-one retentate stream from the primary fuel stream;
• evaporating the stage-one permeate stream at a vacuum;
• and
• isolating a stage-two permeate stream and a stage-two retentate stream from the stage-one permeate stream wherein the stage-one retentate stream and said stage-two permeate stream are mixed and returned to the primary fuel stream, the stage-two retentate stream comprising a fuel stream containing low concentrations of sulfur compounds.

A system for separating a fuel stream containing low concentrations of sulfur compounds from a primary fuel stream, the system comprising:

• a fuel supply providing a primary fuel stream;
• a stage-one separator;
• a first supply line connecting a portion of the primary fuel stream to the stage-one separator, the stage-one separator separating the portion of the primary fuel stream into a stage-one permeate stream and a stage-one retentate stream;
• a stage-two separator;
• a second supply line connecting the stage-one separator permeate stream to the stage-two separator;
• wherein the stage-two separator isolates the stage-one separator permeate stream into a stage-two permeate stream and a stage-two retentate stream, and wherein the stage-two retentate stream contains a low concentration of sulfur compounds, and wherein the stage-one retentate stream and said stage-two permeate stream are mixed and returned to the primary fuel stream.