查看更多>>摘要：To increase the product value out of a crude barrel, some refineries produce Group III Lube Base Oil (LBO) through catalytic hydroprocessing, in addition to the conventional fuels slate, such as gasoline, diesel, kerosene etc. This study proposes an overall optimization methodology for complex oil refineries with a lube base oil processing capability. The optimization problem of a refinery with fuels and lubes portfolios is considered a challenge, since there are several tradeoffs in terms of crude selection and operational conditions. These tradeoffs are addressed by employing a crude classification model based on the Viscosity Index (VI) of the Hydrocracking Unit (HCU) feed, and by taking into account the change in VI and yields besides the other conventional bulk properties through the refinery units, to select the optimal crude types that maximize the products value and hence overall refinery margin. Using the VI model was found critical to ensure that the LBO VI is within the specification and can save the refinery up to US$1 million per day. When the hydrocracking conversion decreases from 80% to 75%, the volume of paraffinic crudes increases by 3% and 16% for VI specification at 120 and 125, respectively.
查看更多>>摘要：Activated carbon (AC) and char derived from coconut shell were modified using urea and KOH to achieve N-doped AC. The effect of activated temperature and gas agent was studied. The series of adsorbents was characterized and it was found that the pore size and surface functional group were developed thoroughly. Paracetamol (PC) removal from aqueous solution was accomplished by adsorption in a batch system at 298 K. The in-traparticle diffusion model was suitable to describe the kinetic PC removal from water rather than other models because of a complicated adsorption process in the pore connection of actual materials. The maximum capacity of these adsorbents was in a range of 39.9-357.1 mg/g, promoting them as an alternative adsorbent. Among them, the N-doped AC had the highest surface area (538 m~2/g) and the highest PC adsorption capacity. The PC equilibrium uptakes in these samples were not pH-dependent, indicating that the pore size is the most dominant factor than the electrostatic charge of functional group on the solid surface for adsorption, which is evidenced in our simulation results. Furthermore, a Grand Canonical Monte Carlo simulation was used to study equilibrium adsorption. The effect of pore size and functional group type (carboxylic, hydroxyl, carbonyl, quaternary-N, pyrrolic-N, and pyridinic-N) were investigated on PC-water mixtures at 298 K. The heat contributions including fluid-fluid, fluid-solid, and fluid-functional group interactions of each adsorbate were investigated. The maximum capacity was found in the pore size of 0.70 nm, which was the best fit for complete monolayer coverage of PC molecules. The simulation confirmed that N-group types, especially pyridinic-N were more attractive than O-group types for enhanced PC removal. This work provided a new strategy to develop the optimal pore size and functional group type of ACs for high capacity of PC removal from aqueous solution. The estimated costs of production for char, AC, and N-doped AC were about 0.73, 2.63, and 3.83 U.S.$/kg respectively, indicating a highly competitive cost in the market. However, the N-doped AC was the cheapest price in order to remove the same amount of PC from aqueous solution.
查看更多>>摘要：The aim of the paper was to analyze the separation process of solid-liquid systems in designed and constructed modified swirl sedimentation tanks. The analysis process included a series of experimental tests performed using model research materials, such as water and quartz grains with different diameter. An attempt was made to determine the correlation between the process parameters, structural elements, and the obtained efficiency of the separation process. The obtained data allowed for the broadening of knowledge concerning the phenomenon of sedimentation and swirling, as well as the principle of operation of rainwater separators. The aim of the research was to enable a more precise selection of separators according to the conditions in which they are meant to fulfill their function. The achieved results are a motivation for, and justify, further research concerning the design and operation of such devices.
查看更多>>摘要：Green alga Neochloris oleoabundans cultivated in medium of varied phosphate (K2HPO4) concentration was investigated as the biosorbent for Cu(II) removal from aqueous solutions. The highest biosorption capacity of 180.19 mg-Cu/g-biomass was achieved with biomass grown in medium containing 300 mg/L K2HPO4) which was 2.4 and 2.3 times of that of the biomasses grown in media containing 100 and 500 mg/L K2HPO4, respectively. The Cu(II) biosorption was fast with equilibrium established within 10 min of contact time and the kinetics was characterized as pseudo-second order. A modified Langmuir isotherm model is proposed to account for the inhibition of Cu(II) biosorption by the cell aggregation induced by Cu(II). Furthermore, it was shown that the Cu(II)-induced cell aggregation could be explored to enhance the sedimentation of biomasses to facilitate biomass recovery after Cu(II) adsorption.
查看更多>>摘要：The atomized droplet size distribution (DSD) produced by a nozzle is a fundamental information to define the performance of application systems. In this paper a new model to represent the atomization of a pre-orifice nozzle is presented. It is based on the Maximum Entropy Principle (MEP), the Linearized Instability Sheet Atomization (LISA) model and Computational Fluid Dynamics (CFD) simulations. Different atomization liquids with varied physical properties were sprayed at different pressures and their droplet size distributions were measured for model calibration and validation. The LISA model correctly predicts the effect of the pressure and physical properties of the mixtures on the most probable droplet diameter. The CFD studies allow to predict the influence of the flowrate on the energy source term of the MEP energy balance, which is not negligible. On the other hand, based on the LISA model, the calculated momentum source term does not impact on the DSD prediction significantly. The developed model, which just includes two adjustable parameters, is able to well represent experimental DSDs from a pre-orifice nozzle operating at different pressures.
查看更多>>摘要：The key group of research methods used for the analysis of formation and flow of gas bubbles in liquids are those involving digital imaging and shadowgraphy. Despite their frequent use, there is no comprehensive analysis of the compliance of different procedures to determine bubble size based on experimental data. In this work, fifteen different approaches for shape recognition were used to determine the equivalent diameter of a bubble and then the results obtained were compared with bubble equivalent diameters determined experimentally. The experiments concerned bubbles of equivalent diameters in the range of 2.4-5.4 mm which correspond to the size of the bubbles most commonly encountered in industrial practice. Particularly, three algorithms for bubble shape detection were evaluated and then three sets of parameters to express the size of the bubble and two types of bubble equivalent diameter were derived. It was found that the most accurate results are obtained by using image binarization and Canny edge detection for the determination of the bubble shape, combined with the Feret diameter employed to express its size and with the volumetric equivalent diameter instead of the superficial one. As the binarization method is not versatile, we recommend using the Canny edge detector.
Carolina de Araujo GusmaoLeonardo Almeida DinizBruno Ramos
16页
查看更多>>摘要：An investigation on TiO2/SiO2 catalysts was performed, covering a wide range of TiO2 contents (0-100 % wt%) and calcination temperatures (150-1000 °C), which were applied to a continuous gas-solid photocatalytic reactor, irradiated by UV-LED for n-hexane degradation. A series of characterization analyses were conducted and the effects of the operational parameters and the catalyst stability over time were investigated. The TEM images confirmed the results of XRD crystallography, showing the preferential (101) anatase plane, in the form of 4-5 nm nanocrystals. Silica gel delayed the phase transformation from anatase to rutile even after calcination at 750 °C, while the band gap energy decreased from 3.21 to 3.06 eV with increasing calcination temperature from 150 to 1000 °C. The 20 %-TiO2 material calcined at 450 °G exhibited the best performance among 14 different materials, reaching a conversion rate of 2.7 × 10~(-7) mol g~(-1) min~(-1), n-hexane degradation of 40 %, maintaining its stability even after 20 h of continuous photoreaction, with resistance to TiO2 leaching and particle breakage. Therefore, the presence of silica significantly enhanced the properties of the catalyst, and contributed to improving its photocatalytic activity, making the use of these materials in gas-solid photoreactors a viable alternative for removing volatile organic compounds.
E.E. Merodio-MoralesD.I. Mendoza-CastilloA. Bonilla-Petriciolet
14页
查看更多>>摘要：A novel activation route for the preparation of carbon-based adsorbents functionalized with lanthanum and their application for arsenic adsorption was proposed. This procedure is based on carbon dioxide activation at room temperature, which could allow to reduce the energy consumption and adsorbent cost. A comparison of this novel activation approach with respect to the conventional thermal activation at 800 °C under N2 atmosphere was performed on biochar from avocado seeds and functionalized with lanthanum. Results showed that the arsenic adsorption properties of the lanthanum-functionalized adsorbent activated with CO2 at room temperature were higher up to 179% than those activated with N2 at 800 °C. The carbonation of lanthanum oxygenated functionalities on the adsorbent surface favored the ligand exchange and surface complexa-tion interactions during the arsenic adsorption. Arsenic adsorption using this engineered lanthanum-based adsorbent was endothermic and transited from a multi-molecular process at 25 °C to a multi-anchorage process at 30 °C. The estimated arsenic adsorption capacities at saturation for these novel adsorbents were 15 - 20 mg/g at 25 - 40 °C, respectively.
查看更多>>摘要：The presence of sulfur components in diesel fuel can produce SOx gases, which emit from the combustion of diesel fuel and cause serious environmental problems. In this study, four various adsorbents biochar/CuFe2O4 (BC/CuFe2O4)i oxidized biochar/CuFe2O4 (0-BC/ CuFe2O4), ethylene diamine-functionalized biochar/CuFe2O4 (Et-BC/CuFe2O4) and mela-mine-functionalized biochar/CuFe2O4 (Me-BC/CuFe2O4) were prepared for application in the total sulfur (all sulfur compounds) adsorption from diesel fuel. The prepared samples were characterized by XRD, TGA, VSM, FT-IR, FE-SEM, TEM and Raman techniques. Also, the Response Surface Methodology-Box-Behnken design was used in order to optimize adsorption key parameters included contact time, amount of adsorbent and percentage of Cu. Because of the presence of CuFe2O4 nanoparticles, all of the prepared adsorbents can be regenerated and reused for consecutive adsorption tests. The π-complexation can be formed between Cu in adsorbents and aromatic sulfur compounds. Also Cu~(+2) can be a proper cation for adsorption of mercaptan components from diesel fuel. Formation of oxygenated group in O-BC sample and presence of -NH2 functions in Et-BC and Me-BC samples can form hydrogen bonding with sulfur atom in sulfur compounds and create a very high adsorption capacity. Kinetic as well as isotherm studies showed that total sulfur adsorption by the prepared adsorbents followed second order and Langmuir adsorption model. For the sample of Me-BC/CuFe2O4, the adsorption capacity was obtained 1666.7 mg/g, while this value was 192.3 mg/gin the presence of BC adsorbent. It was found that 98.6% of total sulfur was removed by Me-BC/CuFe2O4. Thermodynamic data demonstrated that total sulfur adsorption was spontaneous and followed an endothermic path. Regeneration of the prepared adsorbents employing NaOH solution showed that the adsorbents have suitable reusabilities after five sorption and desorption runs.
查看更多>>摘要：With the deterioration of global climate and environment, the carbon emission of the oil and gas industry has been an important issue of global concern. At present, there is a lack of systematic research on carbon emission calculation of natural gas pipeline from construction to disposal. We propose a life cycle assessment method for natural gas pipeline in order to quantify the carbon emissions from construction to disposal. The carbon emissions of natural gas pipeline are divided into four parts in this model: manufacturing, construction, operation, and recycling. For each of the four stages, carbon emissions from material production and construction, facility construction and equipment operation are all detailedly calculated. In addition, methane, the main component of natural gas, has a non-negligible impact on the atmosphere. Therefore, gas leakage from the pipeline system is also considered in this paper. And data from actual pipelines are utilized in the case study. The results show that the carbon emissions of these pipelines are in the range of 26.58-67.14t CO2 / (km×10~8 m~3 / a) and 11.41-30.27t CH4 / (km×10~8 m~3 / a). Among them, the production process of pipelines contributes the most to carbon emissions, accounting for about 80 % of the total CO2 emissions. Through sensitivity analysis, we found that pipeline parameter, power emission factor, and compressor operation status turn out to be the main factors affecting carbon emission. With the establishment of this model, potential carbon emission of planned pipelines can be estimated, which has guiding significance for future pipeline construction.
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