Artificial Neural Network for Prediction of SO2 Removal and Volumetric Mass Transfer Coefficient in Spray Tower

The gas-liquid volumetric mass transfer coefficient was determined by the dynamic oxygen absorption technique using a polarographic dissolved oxygen probe and the gas-liquid interfacial area was measured using dual-tip conductivity probes in a bubble column slurry reactor. Feed-forward back propagation neural network models were employed to predict the gas-liquid volumetric mass transfer coefficient and liquid-side mass transfer coefficient for Alcohol/Ether fuel direct synthesis system in a commercial-scale bubble column slurry reactor. And the effects of various axial locations, superficial gas velocity and solid concentration on the gas-liquid volumetric mass transfer coefficient kLaL and liquid-side mass transfer coefficient kL were discussed in detail in the range of operating variables investigated.

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Gas–liquid mass transfer characteristics of aviation fuel scrubbing in an aircraft fuel tank

Scientific Reports ◽

10.1038/s41598-021-94786-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Li Chaoyue ◽

Feng Shiyu ◽

Xu Lei ◽

Peng Xiaotian ◽

Yan Yan

Keyword(s):

Mass Transfer ◽

Dissolved Oxygen ◽

Transfer Coefficient ◽

Mass Transfer Coefficient ◽

Oxygen Concentration ◽

Gas Holdup ◽

Aviation Fuel ◽

Volumetric Mass Transfer Coefficient ◽

Dissolved Oxygen Concentration ◽

Liquid Mass Transfer

AbstractDissolved oxygen evolving from aviation fuel leads to an increase in the oxygen concentration in an inert aircraft fuel tank ullage that may increase the flammability of the tank. Aviation fuel scrubbing with nitrogen-enriched air (NEA) can largely reduce the amount of dissolved oxygen and counteract the adverse effect of oxygen evolution. The gas–liquid mass transfer characteristics of aviation fuel scrubbing are investigated using the computational fluid dynamics method, which is verified experimentally. The effects of the NEA bubble diameter, NEA superficial velocity and fuel load on oxygen transfer between NEA and aviation fuel are discussed. Findings from this work indicate that the descent rate of the average dissolved oxygen concentration, gas holdup distribution and volumetric mass transfer coefficient increase with increasing NEA superficial velocity but decrease with increasing bubble diameter and fuel load. When the bubble diameter varies from 1 to 4 mm, the maximum change of descent rate of dissolved oxygen concentration is 18.46%, the gas holdup is 8.73%, the oxygen volumetric mass transfer coefficient is 81.45%. When the NEA superficial velocities varies from 0.04 to 0.10 m/s, the maximum change of descent rate of dissolved oxygen concentration is 146.77%, the gas holdup is 77.14%, the oxygen volumetric mass transfer coefficient is 175.38%. When the fuel load varies from 35 to 80%, the maximum change of descent rate of dissolved oxygen concentration is 21.15%, the gas holdup is 49.54%, the oxygen volumetric mass transfer coefficient is 44.57%. These results provide a better understanding of the gas and liquid mass transfer characteristics of aviation fuel scrubbing in aircraft fuel tanks and can promote the optimal design of fuel scrubbing inerting systems.

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Mass Transfer Coefficients during Steel Decarburization in a RH Degasser

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.273-276.679 ◽

2008 ◽

Vol 273-276 ◽

pp. 679-684

Author(s):

Roberto Parreiras Tavares ◽

André Afonso Nascimento ◽

Henrique Loures Vale Pujatti

Keyword(s):

Mass Transfer ◽

Reynolds Number ◽

Transfer Coefficient ◽

Mass Transfer Coefficient ◽

Gas Flow ◽

Vacuum Chamber ◽

Volumetric Mass Transfer Coefficient ◽

Gas Flow Rate ◽

Rh Process ◽

Kinetics Of

The RH process is a secondary refining process that can simultaneously attain significant levels of removal of interstitial elements, such as carbon, nitrogen and hydrogen, from liquid steel. In the RH process, the decarburization rate plays a very important role in determining the productivity of the equipment. The kinetics of this reaction is controlled by mass transfer in the liquid phase. In the present work, a physical model of a RH degasser has been built and used in the study of the kinetics of decarburization. The effects of the gas flow rate and of the configurations of the nozzles used in the injection of the gas have been analyzed. The decarburization reaction of liquid steel was simulated using a reaction involving CO2 and caustic solutions. The concentration of CO2 in the solution was evaluated using pH measurements. Based on the experimental results, it was possible to estimate the reaction rate constant. A volumetric mass transfer coefficient was then calculated based on these rate constants and on the circulation rate of the liquid. The logarithm of the mass transfer coefficient showed a linear relationship with the logarithm of the gas flow rate. The slope of the line was found to vary according to the relevance of the reaction at the free surface in the vacuum chamber. A linear relationship between the volumetric mass transfer coefficient and the nozzle Reynolds number was also observed. The slopes of the lines changed according to the relative importance of the two reaction sites, gas-liquid interface in the upleg snorkel and in the vacuum. At higher Reynolds number, the reaction in the vacuum chamber tends to be more significant.

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