Integrated and Multi-Period design of Diesel Hydrotreating Process

Hydrotreating processes play a vital role in petroleum refineries to meet theincreasing demand of transportation fuels. The recent trends in processing ofheavier crudes with higher sulphur contents and more stringent productspecifications for cleaner transportation fuels, such as ultra-low sulphur diesel, areresulting in more severe operating conditions and higher hydrogen consumption ofhydrotreating processes. In order to carry out any revamp or design projects forimproving the performance and efficiency of hydrotreating units molecular kineticmodels of hydrotreating reactions may be required to provide detailed and accurateinformation of the composition and properties of hydrotreating products. Theoverall hydrotreating process consisting of the hydrotreater, the separation systemand the associated heat recovery system need to be modelled on a consistent basisof detailed characterisation of petroleum fractions and the interactions of theseindividual subsystems with each other and with the refinery hydrogen networkhandled simultaneously for overall process optimisation.A molecular pathways level model of diesel hydrotreating reactions using themolecular type and homologous series matrix is employed for prediction ofdetailed molecular level information of composition and properties of dieselhydrotreating products. The molecular type and homologous series matrixrepresentation of petroleum fractions is a detailed characterisation approach thatrepresents the composition of a stream in a matrix in terms of the carbon numberrange and compound classes existing in the petroleum fraction. A new strategy isdeveloped for estimation of physical properties of middle distillate and heavypetroleum fractions with molecular type and homologous series matrixrepresentation using group contribution methods.