This paper investigated the effect of oxygen holdup on the current density distribution over the electrode of a vertical/horizontal electrolysis cell with a two-dimensional Eulerian–Eulerian two-phase flow model in the acrylonitrile (AN) electrolytic adiponitrile (ADN) process. The physical models consisted of a vertical/horizontal electrolysis cell 10 mm wide and 600 mm long. The electrical potential difference between the anode and cathode was fixed at 5 V, which corresponded to a uniform current density j = 0.4 A/cm2 without any bubbles released from the electrodes. The effects of different inlet electrolyte velocities (vin = 0.4, 0.6, 1.0 and 1.5 m/s) on the void fraction and the current density distributions were discussed in detail. It is shown that, for a given applied voltage, as the electrolyte velocity is increased, the gas diffusion layer thickness decreased and this resulted in the decrease of the gas void fraction and increase of the corresponding current density; for a given velocity, the current density for a vertical cell was higher than that for a horizontal cell. Furthermore, assuming the release of uniform mass flux for the oxygen results in overestimation of the total gas accumulation mass flow rate by 2.8% and 5.8% and it will also result in underestimation of the current density by 0.3% and 2.4% for a vertical cell and a horizontal cell, respectively. The results of this study can provide useful information for the design of an ADN electrolysis cell.
Three-dimensional thermal-mechanical models for the prediction of heat transfer coefficient distributions with different size beams are investigated. H300 × 300, H250 × 250, and H200 × 200 H-shape steel beams are investigated in a controlled cooling process to obtain the design requirements for maximum uniform temperature distributions and minimal residual stress after controlled cooling. An algorithm developed with the conjugated-gradient method is used to optimize the heat transfer coefficient distribution. In a comparison with the three group results, the numerical results indicate that, with the same model and under the same initial temperature ( = 850 ∘ C) and final temperature ( = 550 ± 10 ∘ C), the heat transfer coefficients obtained with the conjugatedgradient method can produce more uniform temperature distribution and smaller residual web stress, with objective functions of the final average temperature ave ± Δ and maximum temperature difference to minimum min{Δ max ( , )}. The maximum temperature difference is decreased by 57 ∘ C, 74 ∘ C, and 75 ∘ C for Case 1, Case 2, and Case 3, respectively, the surface maximum temperature difference is decreased by 60∼80 ∘ C for three cases, and the residual stress at the web can be reduced by 20∼40 MPa for three cases.
Hot blast stoves are important equipment used in the iron-making process. Its cyclic operating process consists of an on-gas period and an on-blast period. In this study, a 3D thermal and thermomechanical model of a hot blast stove were used to calculate the temperature and stress distribution during the operating process. The thermal analysis simulation results are compared with the in situ data, and the maximum error was found to be lower than 7%. The results indicated that the maximum principal stress mainly occurred outside of the refractory linings, and the minimum principal stress mainly occurred inside of the refractory linings. The maximum deformation occurred inside of the refractory linings in the combustion chamber. The shell is mainly subjected to the maximum principal stress, where the minimum principal stress only occurred at the junction. The maximum deformation of the shell occurred at the top of the combustion dome.
T122 is a competitive heat resistant steel used for the construction of ultra super
critical power stations. The authors experimentally investigated the effect of heat treatment and
variation of influential chemical elements, such as vanadium, copper and nitrogen, on the
microstructure and properties of the steel, in which the optimal heat treatment schedule during
heating was specified and the proper chemical element scope was also decided to achieve the
expected service performance. The application and potential of the steel in China today and
tomorrow were reasonably briefed. On the other hand, the authors also proposed some intrinsic
challenge of the steel, which may undermine the basis of the industrial application of the steel,
comparing to other candidates, i.e. T92 steel. An assessment on T122 steel was carefully made
from the viewpoint of industrial manufacturing and application.
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