101 100
Conversion wt%
93 92 91 95 94 97 96 99 98
Mix 1 Pred. (VGO 80% + WCO 20%)
Mix 3 Pred. (VGO 80% + WLO 10% + WCO 10%) Mix 1 act. (VGO 80% + WCO 20%) Mix 3 act. (VGO 80% + WLO 10% + WCO 10%) Mix 2 Pred. (VGO 80% + WLO 20%) Mix 4 Pred. (VGO 70% + WLO 20% + WCO 10%) Mix 2 act. (VGO 80% + WLO 20%) Mix 4 act. (VGO 70% + WLO 20% + WCO 10%)
370
380
390
400
410
420
430
440
450
Temp. (˚C)
Figure 1 Predicted and actual reaction conversion
the co-hydroprocessing mixture blended with petroleum feedstock. Axens has recently introduced a new proprietary technology called Revivoil, developed jointly with Itelyum (formerly Viscolube Italiana SpA). This technology is a signif- icant step forward in waste lube oil re-refining and has the potential to accelerate its success. UOP has also developed with ENI a proprietary technol- ogy called Ecofining for hydroprocessing plant-derived oil. Feedstocks include plant-derived oils like soybean, rape- seed and palm. The co-processing of waste oils is not only of interest to process technology developers, but also to refineries. For example, Petrobras has developed the H-BIO hydrogenation process to produce renewable diesel using a mixture of waste vegetable oil and mineral oil in existing oil refineries through hydrotreating units. The co-processing of waste frying oils in a gasoil hydrodesulphurisation unit (HDS-I) at CEPSA’s refinery in Tenerife has been successful. CanmetENERGY’s research centre supports and funds such research activities. It has been observed that most refiners choose to inject WCO (on a large scale) or WLO (on a small scale) with VGO for co-hy - droprocessing units, rather than installing a separate unit to hydroprocess pure WCO or WLO, taking into consideration the high degree of similarity between technologies and cata- lysts used in these units. The novelty of this work is to study the co-hydroprocessing of VGO, WCO, and WLO blend over commercial industrial hydrocracking catalyst. This will be fol- lowed by an economic study of the produced model in the recent market changes caused by COVID-19.5 , 6 , 7 The aim of this study is to simulate a conceptual design of an industrial hydrocracking unit that utilises the same cat- alyst as our previous experimental work. 1 This conceptual design has been performed using Aspen Hysys V.11, which comes with a built-in hydrocracker model (HCR). This model simulates the hydroprocessing of light and heavy petroleum fractions based on a built-in reaction network and kinetic lumps. This simulation can be used to evaluate technically and economically co-hydroprocessing normal unit feedstock of VGO vs blends of unconventional feedstocks of WCO and WLO with VGO. Process simulation case The industrial hydrocracking unit licensed by UOP
(commercially called Unicracking unit) was simulated using Aspen Hysys V.11. This unit was selected because it utilises the experimentally used catalyst (TK-711 and DHC-8) and a similar reactor bed configuration. The reaction section of the unit consists of two reactors. The first reactor has three beds, with one for hydrotreating and the other two for hydrocrack- ing. The second reactor has two beds, both for hydrocrack- ing. All five beds are roughly equal in weight. The unit is designed to process 33,500 barrels per stream day (BPSD) of combined feed consisting mainly of vacuum gasoil (VGO) from the vacuum distillation unit and heavy cocker gasoil (HCGO) from the delayed cocker unit. The unit is targeted to produce light fuel products from heavy petroleum distillates while removing the majority of impurities such as sulphur, nitrogen, and oxygen. Performance evaluation of simulation model The hydrocracking unit represented in the simulation case includes two main sections: the reaction section and frac- tionation section. The performance of the reaction section can be evaluated by comparing the predicted feed with the actual feed conversion. Figure 1 shows both the actual and predicted feed conversion wt%, represented by solid and dash lines respectively. A clear positive gap can be observed between the actual and predicted values of conversion. This gap widens as the WCO content in the feed mixture increases and reaches its minimum value or disappears completely when WCO is not present in the mixture. This observation aligns with the results of our previous work, which clearly states that increasing the WCO content in the feed mixture increases catalyst acidity and activity, leading to a higher reaction conversion at the same reaction temperature. The model provides accurate pre- dictions of the relationship between reaction temperature and conversion profile in the hydrocracking reactor. This is impor - tant for estimating product yields and hydrogen consumption (see Figure 2 ). This prediction tool helps in anticipating the operating cost of each case and determining its feasibility. There are seven different products in the simulated hydro- cracking unit, namely: purge gas, fuel gas, LPG, hydrocracked naphtha (represented as gasoline in this study), kerosene (generally known as jet fuel or dual-purpose kerosene [DPK]), diesel (ultra-low sulphur diesel according to Euro
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