Effect of hydrocarbon vaporization and gases solubility on performance and cycle length of gas-phase – Trickle bed reactors system used for deep diesel hydrotreatment

Abstract

The use of high-pressure, high-temperature diesel stripper ahead of the reactors boosts low-sulfur diesel production on existing HDT units. The new hydrotreating process scheme use a combination gas phase and liquid phase reactors to treat Diesel. The gas and liquid properties of the stream were determined in dynamic conditions and hydrocarbon vaporization and gases solubility simulated based on Peng-Robinson state equation with modified pseudo-species properties, interaction coefficients and mixing rules. The gas-liquid pseudo-equilibrium simulation allows calculation of concentration of pseudo-species present in gas-liquid separators and in reactors along the cycle length. The new experimental vapor-liquid equilibria data were developed for synthetic feed, diesel, diesel plus hydrotreated product and product of reaction at high-temperature and high-pressure. This data was used to developed new sets of Akl, Bkl, E and F parameters for interaction coefficients and blending values. The results of simulation using Peng Robinson EOS state equation with new interaction coefficients and rules for blending show an improvement in the prediction of pseudo-species vaporization and solubility of hydrogen, methane, ethane, and hydrogen sulfide on liquid phase (diesel). Prediction of gas-liquid pseudo species concentration and phase properties along the cycle length have significant impact on the economy of the new HDT process. Experimental dynamic VLPE data is included.