Simulation of an industrial fixed-bed reactor with cocurrent downflow for hydrogenation of PYGAS

• The simulation results agreement 0.8 AARD with respect to plant data.
• The SRK EoS with mixing rule of PA-RE-SimSci is recommended to get the VLE.
• Thermodynamic model may, or not, improving the results depending on the choice.
• The most of assumptions were confirmed calculating the suitable dimensionless number.
• The solubility of hydrogen in PYGAS depends on both temperature and liquid density.

A fixed-bed Reactor with cocurrent downflow operating in downward bubble flow regime for hydrogenation of pyrolysis gasoline (PYGAS) has been simulated. In order to model the reactor, suitable thermodynamic, hydrodynamic and reaction models were solved simultaneously. A set of ten hydrogenation reaction kinetics was considered, taking into account a cut of hydrocarbons C5–C11. It was demonstrated the importance of how the choice of a specific thermodynamic model may, or not, improve the results obtained, and how this may affect the prediction of the system. The use of Soave–Redlich–Kwong equation of state with the mixing rule of Panagiotopoulo-Reid modified by SimSci is the recommendation made to represent the vapor-liquid-equilibrium, reporting 3.4% AARD (average absolute relative deviation) in the hydrogen solubility in PYGAS. The model predicts the steady state conditions and it is validated by comparing the results with actual plant data under the following operating conditions: Tinlet = 366 K, Pinlet = 5.03 MPa, and (<0.001) molar of styrene in the reactor effluent. From simulation results, it is compared the predictions of the model with actual plant data, finding a good agreement between both, and showing AARD of 0.8% in the temperature profile and 9% in the composition of reactor effluent between ours results and the plant data.

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