/manager/Index ${session.getAttribute("locale")} 5 A review of the numerical modeling of pulverized coal combustion for high-efficiency, low-emissions (HELE) power generation /manager/Repository/uon:46263 2 emissions per unit energy generation. They represent some of the primary and intermediate solutions to the world’s energy security. Extensive numerical modeling efforts have been undertaken over the past several decades, which have increased our understanding of the technical problems in HELE boilers, including combustion and boiler performance optimization, ash deposition, and material problems at higher operating temperatures and pressures. Overall, the differences in the physical and chemical models, boiler performance, and ash deposition of oxy-fuel combustion in HELE boilers that recirculate CO2 and H2O in the boilers are also discussed in comparison with the combustion of coal in the air. This Review comprehensively summarizes the current research on numerical modeling to offer a better understanding of the technical aspects and provides future research requirements of HELE coal-fired boilers, including boiler performance optimization, ash deposition, and material problems. The effects of changes in the configuration and operating conditions are discussed, focusing on the optimization of boiler performance in aspects such as unburnt carbon and NOx emissions. The paper also reviews the retrofit and optimization of operating conditions and the burner geometry with the low-NOx coal combustion technologies necessary to operate the HELE power plants. In terms of ash deposition, the development of submodels, including particle sticking and impacting behaviors and their effects on the deposit growth predictions under different temperatures, are discussed. Numerical models of the material oxidation and creep in the austenitic and nickel-based alloys generally used in HELE conditions have been developed using the finite element method to predict the availability of advanced alloys and creep life in the actual service time of the boiler parts. The predictions of oxide scale growth and exfoliation on the steam-side and fire-side and the creep strength are analyzed. The review also identifies some further research requirements in numerical modeling to achieve the optimization of coal combustion processes and address the technical problems in advanced HELE power plant operations.]]> Tue 15 Nov 2022 08:05:43 AEDT ]]> Pressurized entrained-flow pyrolysis of lignite for enhanced production of hydrogen-rich gas and chemical raw materials /manager/Repository/uon:37723 2 and polyaromatics during lignite pyrolysis under pressurized entrained-flow conditions. The pyrolysis temperature and pressure ranged between 600-900 ℃ and 0.1-4.0 MPa, respectively, and were found to greatly influence the yield and composition of pyrolysis products. The results showed that the concentration of H2 in the light gas fraction increased drastically with pyrolysis temperature and pressure, reaching 91.69 vol% at 900 ℃ and 4.0 MPa, which corresponded to H2 generation of 0.27 m3/kg coal. The yield of polycyclic aromatic hydrocarbons (PAHs) such as naphthalene, biphenylene, fluorene, phenanthrene, pyrene, and fluoranthene was also promoted at elevated pyrolysis temperatures and pressures. The highest PAHs concentration of 90.4 area% in the pyrolysis oil was obtained at 900 ℃ and 4.0 MPa. It was also found that the changes in the hydrogen distribution under pressurized entrained-flow conditions mainly took place during the secondary pyrolysis reactions. It was postulated that hydrogen was formed via aromatization, condensation, aromatic ring growth mechanism, and direct cleavage reactions. The findings of this study showed that lignite could be efficiently converted to H2-rich gas, PAHs as chemical raw materials, and energy-dense lignite char via a novel poly-generation system based on pressurized entrained-flow pyrolysis.]]> Thu 25 Mar 2021 12:33:52 AEDT ]]> Advances in catalytic hydrogen combustion research: catalysts, mechanism, kinetics, and reactor designs /manager/Repository/uon:40192 Fri 29 Jul 2022 15:46:35 AEST ]]>