Soot oxidation kinetics under pressurized conditions

The oxidation kinetics, under different pressures, of soot samples obtained from different liquid fuels and two standards (a commercial black carbon sample and a reference diesel soot) was studied. Soot samples were generated in a flat-flame, premixed burner under heavily-sooting conditions and captured on a water-cooled stabilization plate located above the burner surface. The collected soot was oxidized using a high-pressure thermogravimetric analyzer (HTGA). TGA operation was optimized to reduce mass transfer effects by adjusting the oxidizer flow rate and initial sample mass. Further corrections for mass transfer were accomplished by computing the effectiveness factors for intraparticle, interparticle, and external mass transfer. Two pressures were evaluated (1 and 10 atm) and O₂ concentration was varied between 10 and 21%.     

Kinetics of high temperature oxidation of chromium rich HfC reinforced cobalt based alloys

Mostly known to improve the high temperature oxidation resistance of superalloys, hafnium may also form carbides. Several per cents of Hf allow developing a dense carbide network to mechanically strengthen alloys. Here, the high temperature oxidation behaviour of three HfC containing cobalt alloys was characterised at all steps of a thermogravimetry test: heating, isothermal stage and cooling, compared with two Co–Cr–C model alloys. The five alloys were heated in synthetic air, maintained at 1200°C during 50 h and then cooled. The mass gains were plotted versus time or according to (m×dm/dt?=?Kp–m×Kv) to specify the isothermal kinetic constants, or versus temperature to determine how oxidation acts during heating and oxide spallation occurs during cooling. Compared to the ternary alloys, the oxidation of the HfC reinforced alloys starts earlier but leads to lower mass gains during heating, the isothermal oxidation is faster and oxide spallation occurs later.     

Effect of polyelectrolyte size on multilayer conformation and dynamics at different temperatures and salt concentrations

Polyelectrolyte bilayers, which consist of poly-l-lysine (PLL) and hyaluronic acid (HA) were simulated with lipid membranes at different temperatures and ion concentrations. Starting with the sequential deposition of PLL and HA above the membrane surface, PLL and HA become completely mixed, leading to the formation of stable bilayers. PLL/HA bilayers are thicker at higher salt concentration because of weakened electrostatic interactions between PLLs and membrane lipids, in agreement with experiments. This salt effect decreases as PLL size increases. Also, bilayers become thinner at higher temperature because of the increased surface area of membrane. In particular, regardless of temperature and salt concentration, larger PLLs induce thicker bilayers, although larger PLLs have lower diffusivities than do smaller ones. Bilayers with larger PLLs show larger vacancy (more water) inside the bilayer, indicating that larger PLLs are less densely stacked on membrane surface than do smaller ones and thus form the thicker bilayer. These findings show the lower diffusivity of larger polyelectrolytes, which supports the experimental observation regarding the restricted diffusion of large polymers, and also imply the dependence of bilayer thickness on the polymer size.     

烟气脱硫装置改造解析

鉴于烟气脱硫装置没有硫酸铵产出、烟气排放不达标,分析装置存在的问题,采取改变加氨位置,用滴度来控制加氨量,增加氧化空气量等措施后,取得了明显的效果。     

Thermal barrier coating bonded by (Al2O3–Y2O3)/(Y2O3-stabilized ZrO2) laminated composite coating prepared by two-step cyclic spray pyrolysis

Thermal barrier coating bonded by (Al₂O₃–Y₂O₃)/(Y₂O₃-stabilized ZrO₂) (YSZ) laminated coating has been developed on Ni-based superalloy by two-step cyclic pyrolysis. It is demonstrated, from cyclic oxidation tests at 1100 °C, that YSZ top coat and alloy substrate can be bonded together effectively by the (Al₂O₃–Y₂O₃)/YSZ laminated coating, showing good resistance to oxidation, cracking, spallation and buckling. These beneficial effects can be attributed to the sealing effect of the designed multi-sealed compact bond coat with α-Al₂O₃ layers, the decrease of thermal stresses, the increase of fracture toughness in such bond coat and no interdiffusion between the substrate and bond coat.     

Selenium dioxide reaction of substituted diphenacyl sulfides: generation of α -ketoacids

The attempted selenium dioxide oxidation of substituted diphenacyl sulfides in anticipation of further functionalization led to a series of α -ketoacids 3 via oxidation followed by C?S bond cleavage. Two minor products, 5 and 6, have also been isolated and a mechanistic pathway for the formation of 3, 5 and 6 has been proposed.     

Porous Perovskite Fibers – Preparation by Wet Phase Inversion Spinning and Catalytic Activity

Porous perovskite (LaMnO₃) fibers were prepared by means of wet phase inversion spinning. The influence of different spinning procedures, slurry and coagulation bath composition on fiber shape and pore morphology was studied. The catalytic activity of the prepared fibers was tested for carbon monoxide oxidation as a model reaction in a differential recycle reactor. The results revealed that by suitable choice of process conditions porous catalytically active fibers can be prepared. Catalytic measurements confirmed that the catalytic fibers exhibit an open structure that allows full utilization of the catalytically active surface without intraparticle diffusional limitations.     

Fuzzy logic control of a reverse flow reactor for catalytic oxidation of ventilation air methane

Fuzzy logic controllers of type-1 and type-2 were implemented to deal with the high nonlinearities and uncertainties in operation of a reverse flow reactor (RFR) for catalytic oxidation of ventilation air methane (VAM). The results indicated that the fuzzy logic controller is distinctly superior to the traditional logic-based controller and works well under the conditions with high nonlinearities and uncertainties. Owing to the robustness of RFR and particular control aim of regulating bed temperature within a relatively broad range, a fuzzy logic controller of type-1 is sufficient to cope with the uncertainty brought by the extensive variation of VAM concentration.