Diesel hydrotreater with closed H2 recycle + amine wash

Diesel (an n-hexadecane carrier with a dibenzothiophene sulfur slice) and hydrogen react over a trickle-bed-equivalent reactor (dibenzothiophene + 3H2 -> biphenyl + H2S, the real HDS desulfurization route) after a fired-heater preheat. Hot and cold high-pressure separators knock the light gas off the treated oil; an amine wash (a fixed-recovery separator — the same simplification the existing carbon-capture example uses, not a full electrolyte amine model) scrubs H2S from the recycle gas before a compressor closes the loop back to the reactor feed, with a small purge controlling buildup. A pressure-letdown valve + stripper finish the treated oil, removing dissolved light ends before the desulfurized diesel leaves the bottoms.