Supercritical water and ammonia oxidation system and process

A method for upgrading an oil stream, the method comprising:

• combining, in a reactor, the oil stream, an ammonia stream, and a supercritical water stream to form a mixture stream, wherein the supercritical water stream contacts the oil stream in the reactor, thereby upgrading the oil stream, and wherein the ammonia stream reacts with sulfur initially present in the oil stream to produce ammonia-sulfur compounds;
• separating, in a phase separator, non-dissolved components from the mixture stream;
• expanding, in an expansion device, the mixture stream, wherein expansion of the mixture stream reduces the pressure of the mixture stream below a water critical pressure to produce a low-pressure mixture stream;
• cooling, in a cooling unit, the low-pressure mixture stream to create a low-pressure, low-temperature mixture stream;
• separating, in a first separation unit, the low-pressure, low-temperature mixture stream into a hydrocarbon-rich gaseous phase, a water stream containing ammonia-sulfur compounds, and a treated oil stream;
• and
• separating, in a second separation unit, the ammonia-sulfur compounds from the water stream.