Search Results (4)

This study aimed to determine the effect of the supplied pyrolysis oils (oils obtained from the pyrolysis of used tyres and the depolymerisation of plastics) on the activity of the hydrodesulphurisation catalyst. Each pyrolysis oil was added at 20% weight to a standard feedstock and processed on pilot plant reactors under the set conditions of a commercial unit, including an activated catalyst. Following the catalyst stabilisation, the standard material was changed to the mixture with the pyrolysis oils. The reaction conditions, particularly the reaction temperature, were controlled. The results of the product analyses were compared with the EN 590 standard for evaluating diesel fuel; the hydrogenated mixed fuel meets most requirements. Only the density, flash point, distillation curve and lubricity have minor deviations, which could be adjusted by treating the sample before or after hydrogenation. The properties of the products, in terms of the low-temperature properties, were also investigated. The tyre-derived pyrolysis oils showed improved low-temperature properties, possibly due to the higher levels of the aromatic hydrocarbons. The pyrolysis oil obtained from the depolymerisation of the plastics was found to be more suitable for use in refineries without substantially impacting the existing technologies. For the tyre-derived pyrolysis oils, higher reaction temperatures were required for processing, which could affect the catalyst operation. Full article

A techno-economic analysis has been used to evaluate three processes for hydrogen production from advanced steam reforming (SR) of bio-oil, as an alternative route to hydrogen with BECCS: conventional steam reforming (C-SR), C-SR with CO₂ capture (C-SR-CCS), and sorption-enhanced chemical looping (SE-CLSR). The impacts of feed molar steam to carbon ratio (S/C), temperature, pressure, the use of hydrodesulphurisation pretreatment, and plant production capacity were examined in an economic evaluation and direct CO₂ emissions analysis. Bio-oil C-SR-CC or SE-CLSR may be feasible routes to hydrogen production, with potential to provide negative emissions. SE-CLSR can improve process thermal efficiency compared to C-SR-CCS. At the feed molar steam to carbon ratio (S/C) of 2, the levelised cost of hydrogen (USD 3.8 to 4.6 per kg) and cost of carbon avoided are less than those of a C-SR process with amine-based CCS. However, at higher S/C ratios, SE-CLSR does not have a strong economic advantage, and there is a need to better understand the viability of operating SE-CLSR of bio-oil at high temperatures (>850 °C) with a low S/C ratio (e.g., 2), and whether the SE-CLSR cycle can sustain low carbon deposition levels over a long operating period. Full article

Over the years, the hydrotreating process has been considerably improved in order to facilitate the production of environmentally friendly diesel fuels by reducing sulphur and aromatics concentrations, as mandated by contemporary emissions regulations. In this study, different kinetic models for the hydrodearomatisation reaction and the influence of reaction rate on performance of the industrial trickle bed reactor for hydrotreating of gas oil and light cycle oil fractions were analysed. The impact on reactor temperature, catalyst wetting efficiency, and conversion of sulphur and aromatics were determined. The results of simulations were compared with experimental data from an industrial test run and the best model for the observed process is proposed. Reactor performance and overall efficiency of the process is strongly dependent on the kinetics of hydrodearomatisaton with respect to aromatics conversion but even more so with respect to the temperature increase in the reactor, which affects all key catalytic reaction parameters, catalyst wetting efficiency, and thus the sulphur conversion. Based on the obtained simulation results, it could be concluded that reactor performance is strongly dependent on the hydrodearomatisation reaction. The best predictions of outlet temperature as well as sulphur and aromatic conversion (deviation from the experimental value 0.87 K, 0.01% and 2.57%, respectively) are achieved with the Langmuir–Hinshelwood kinetic model proposed by Owusu-Boakye. Full article

An intensified three-step reaction-separation process for the production of bio-jet diesel from tryglycerides and petro-diesel mixtures is proposed. The intensified reaction-separation process considers three sequentially connected sections: (1) a triglyceride hydrolysis section with a catalytic heterogeneous reactor, which is used to convert the triglycerides of the vegetable oils into the resultant fatty acids. The separation of the pure fatty acid from glycerol and water is performed by a three-phase flash drum and two conventional distillation columns; (2) a co-hydrotreating section with a reactive distillation column used to perform simultaneously the deep hydrodesulphurisation (HDS) of petro-diesel and the hydrodeoxigenation (HDO), decarbonylation and decarboxylation of the fatty acids; and (3) an isomerization-cracking section with a hydrogenation catalytic reactor coupled with a two-phase flash drum is used to produce bio-jet diesel with the suitable fuel features required by the international standards. Intensive simulations were carried out and the effect of several operating variables of the three sections (triglyceride-water feed ratio, oleic acid-petro-diesel feed ratio, hydrogen consumption) on the global intensified process was studied and the optimal operating conditions of the intensified process for the production of bio-jet diesel were achieved. Full article