5. Results and discussion
5.1. Process synthesis and results analysis
From the base-case HRD process flowsheet in Fig. 3, the flowsheet was designed and simulated in three main steps: hydroprocessing, separating, and product upgrading. The process plant converts 579 g s−1 (50 Mg d−1) of PFAD to 345 g s−1 (29.8 Mg d−1) of HRD products, indicating a 51% mass yield and a 0.761 conversion of PFAD [24]. Simulation results of the hydroprocessing step under the operating conditions of 648.15 K and 4 MPa were compared to the experimental data obtained using Pd/C catalyst as reported by Kiatkittipong [24]. The product distribution from the hydroprocessing step was classified into four groups according to the number of carbon atoms for conventional petroleum liquid fuels: naphtha (C5–C8), kerosene (C9–C14), diesel (C15–C18) and unreacted raw material (un-reacted oil). Fig. 7 shows a comparison of results from process simulation and product distribution from experimental data [24]. It can be seen that the two sets of data were close, with 0.085 RMS, 0.096 MSE and 0.998 R2.