The Experts below are selected from a list of 2106 Experts worldwide ranked by ideXlab platform
Hanna Bengtsson - One of the best experts on this subject based on the ideXlab platform.
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Kinetic modelling of gas-phase reactions of polyethylene-derived pyrolysis Products in steam gasification
2018Co-Authors: Hanna BengtssonAbstract:Today, only 15% of the plastic waste in Europe is recycled. However, the existing recycling processes used, cannot preserve the quality of the material. The main Production of plastic Products is based on fossil resources and to ensure future assets, and to reduced environmental impact, new technology for recycling is demanded. Gasification of plastic has so far been utilized for Production of fuels, and the next step is the possibility of Production of hydrocarbon monomers. Gasification of hydrocarbon polymers includes an initial step of pyrolysis, followed by secondary gas-phase reactions of the volatile pyrolysis Products and the gasifying agent. In this Master’s Thesis, a kinetic model of the secondary gas-phase reactions of polyethylene steam gasification at 700-800°C, is formulated. Based on existing hydrocarbon thermodynamic and kinetic mechanisms, a plug flow model is simulated in ANSYS Chemkin-Pro, with an input of polyethylene-derived pyrolysis Products obtained from earlier published literature. From the simulated results it is concluded, that the provided input temperature profiles and sets of reactant input compositions, have low influence on the obtained results. Instead, the residence time shows the highest influence of the progress of Product Specie concentrations, where the largest increase occurs within 20 ms. Study of reaction pathways for the applied conditions, show that in relation to ethylene, the simulated results are similar to literature of pyrolysis and combustion processes. In relation to existing experimental data of polyethylene steam gasification, from the gasification unit in Chalmers Power Central, the simulated yields are overall higher for the hydrocarbon Species, while the Products of the water-gas shift reaction are underestimated. The formulated model can further be used for explicit examination of specific mechanisms related to the process of steam gasification of hydrocarbon polymers. The model set-up provides the possibility to study different conditions regarding temperature, pressure, residence time and reactant input composition.
Jianmin Chen - One of the best experts on this subject based on the ideXlab platform.
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The influence of temperature on the heterogeneous uptake of SO2 on hematite particles.
Science of The Total Environment, 2018Co-Authors: Tao Wang, Yangyang Liu, Yue Deng, Liwu Zhang, Jianmin ChenAbstract:Abstract Despite the increased awareness of heterogeneous reactions of SO 2 on mineral particles, the knowledge of how temperature influences the Product Species and kinetic parameters remain a crucially important part in atmospheric research. Here, we reported the formation of sulfur-containing Species on hematite particles under various temperature and humidity conditions by mean of in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and ion chromatography (IC). High temperature is helpful in the ionization of H 2 SO 3 , making sulfite compounds occupy a great share among total Products. The whole reaction could be divided into three stages according to the formation rate of hydroxyl groups. High temperature brings about more activated SO 2 and then results in the increased uptake coefficients with increasing temperature in the initial reaction stage. On the contrary, moisture absorption on particles is inhibited by high temperature, leading to the decreased uptake coefficients with increasing temperature in the latter two stages. Observed enthalpy and entropy, as well as activation energy values for relevant reactions were calculated. Overall, the Product Specie and reaction rate vary with temperature and humidity conditions, as well as reaction stages. This work broadens the knowledge of heterogeneous reactions on mineral dust influenced by temperature, and consequently provides important opportunities for atmospheric model improvements.
William G. Houf - One of the best experts on this subject based on the ideXlab platform.
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Radiative fraction and optical thickness in large-scale hydrogen-jet fires
Proceedings of the Combustion Institute, 2007Co-Authors: Alejandro Molina, Robert W. Schefer, William G. HoufAbstract:Abstract The radiative characteristics of large-scale (visible length 1.4–9.1 m) hydrogen jet flames that simulate an accidental leak from a high-pressure hydrogen container were compared with previous experimental and theoretical results for laboratory-scale non-sooting flames. The comparison shows that correlations of radiative heat fraction with global residence time need to account for the differences in thermal emittance of combustion gases for different fuels. This correction was found to be particularly important when hydrogen flames were compared to flames with CO 2 as a Product Specie. Measurements of the radiative heat fraction for CO/H 2 , CH 4 and H 2 flames collapse onto one line when plotted against the logarithm of a characteristic residence time weighted by a factor that accounts for differences in the radiative characteristics of combustion gases. The radiative fraction of large-scale jet flames was found to be smaller than that predicted by the correlation obtained for laboratory-scale flames. This was explained by an increase in optical thickness as the flame size increases.
Jami Mohammed Saedi - One of the best experts on this subject based on the ideXlab platform.
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Aerobic biodegradation potential of proteobacteria mixed- culture consortium on inhibitory refinery effluent
2018Co-Authors: Ahmad Mani Malam, Mohd Azoddein Abd. Aziz, Mohd Zahari Mior Ahmad Khushairi, Abu Seman Mazrul Nizam, Jami Mohammed SaediAbstract:The classical treatment approaches to recalcitrant and offensive petroleum refinery effluents is quite strenuous and defective, thus necessitated the modification of existing protocol for effective and conceivable degradation. The high COD content, presence of toxic substances such as phenol and hydrogen sulfide, coupled with the numerous refractory constituents has made its treatment strenuous using a simple axenic culture. Comparative biodegradation potential of two acclaimed bacteria in pure and mixed-culture form was evaluated. The degree of inhibition casted was assessed based on the effectiveness of each model to remove the targeted compounds within the assigned period. The mutual complementary effect of mixed-culture bacteria was reported to take care of much anticipated constraints by axenic culture and successively offer a perfect option for biodegradation of petroleum refinery wastewater. The performance of bacterial mixed culture (BMC) consortium, Pseudomonas putida (ATCC 49128) and Bacillus cereus (ATCC 14579) was found to agree well with the existing literatures regarding their application for biodegration of racalcitrant wastewaters. The composition of the investigated refinery wastewater was analysed with initial concentration of 8,155 mg/L COD, 100 mg/l phenol, and 500 mg/L sulfide, coupled with other refractory substances, respectively. The experiment was carried out in triplcate batch-wise under defined optimal conditions of 1.0 mg/L O2, temperature of 35 oC, agitation of 170 rpm at 8 hour retention time. To ensure oxidizied sulfide is reduced to economically feasible Product Specie; DO was maitained at low level as explained previously. Aliqouts samples were withdrawn at interval for targeted pollutants estimation and were analysed using respective protocols as described elsewhere. Despite the expected toxicity and inhibitory effect of the medium, an overwhelming biodegradtion was achieved disproportionately in the three tested models, with BMC having the most effective performance trend. This was indicated by a reduction of 99.64% sulfide, 89.54% COD, 80 % phenol, respectively.
Tao Wang - One of the best experts on this subject based on the ideXlab platform.
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The influence of temperature on the heterogeneous uptake of SO2 on hematite particles.
Science of The Total Environment, 2018Co-Authors: Tao Wang, Yangyang Liu, Yue Deng, Liwu Zhang, Jianmin ChenAbstract:Abstract Despite the increased awareness of heterogeneous reactions of SO 2 on mineral particles, the knowledge of how temperature influences the Product Species and kinetic parameters remain a crucially important part in atmospheric research. Here, we reported the formation of sulfur-containing Species on hematite particles under various temperature and humidity conditions by mean of in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and ion chromatography (IC). High temperature is helpful in the ionization of H 2 SO 3 , making sulfite compounds occupy a great share among total Products. The whole reaction could be divided into three stages according to the formation rate of hydroxyl groups. High temperature brings about more activated SO 2 and then results in the increased uptake coefficients with increasing temperature in the initial reaction stage. On the contrary, moisture absorption on particles is inhibited by high temperature, leading to the decreased uptake coefficients with increasing temperature in the latter two stages. Observed enthalpy and entropy, as well as activation energy values for relevant reactions were calculated. Overall, the Product Specie and reaction rate vary with temperature and humidity conditions, as well as reaction stages. This work broadens the knowledge of heterogeneous reactions on mineral dust influenced by temperature, and consequently provides important opportunities for atmospheric model improvements.