OPTIMISATION OF THE MEXICAN REFINING SYSTEM FOR LOW SULPHUR DIESEL PRODUCTION

摘要

The Mexican refining industry is facing the challenge of producing ultra-clean fuels, while processing increasingly proportions of heavy and sour crude oil. Of particular relevance in the strategies devised for optimising the overall domestic petroleum industry, are the actions for assuring the supply of low sulphur diesel within a schedule that considers different stages for achieving reductions from 500 to 300 ppm in the near future, to 50 ppm for the year 2006. Other specifications considered are cetane, aromatics, density and distillation points. The Mexican Refining System includes 6 refineries with a total processing of 8,140.6 m~3/h. Diesel feedstock is mainly constituted by atmospheric gasoil; all streams are hydrotreated in 14 units operating in average at 52.6 x 105 N/m~2 g. that produce diesel fuel with less than 500 ppm sulphur. Future streams to be incorporated, resulting from ongoing projects, include cracked products from coking and FCC plants. Additionally the refinery reconfiguration in progress will permit the processing of a higher proportion of heavy crude oil, representing a movement from 2.2% to 2.6% sulphur in the crude blend. The reported strategies in this paper are based on a formal mathematical model and an optimisation exercise, considering operating condition adjustments, catalyst replacement, revamp and new installations. Technology projects for process and catalyst development were considered as scenarios for the decision taking process.