Mass Transfer Coefficients during Steel Decarburization in a RH Degasser

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.

scholarly journals TOTAL VOLUMETRIC MASS TRANSFER COEFFICIENT AT CO2 GAS ABSORPTION USING K2CO3 BY MSG PROMOTER

Konversi ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 6
Author(s):  
Erlinda Ningsih ◽  
Abas Sato ◽  
Mochammad Alfan Nafiuddin ◽  
Wisnu Setyo Putranto
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Liquid Flow ◽  
Total Mass ◽  
Gas Flow ◽  
Liquid Flow Rate ◽  
Gas Flow Rate ◽  
Co2 Gas

Abstract- One of the most widely used processes for CO2 gas removal is Absorption. Carbon dioxide is the result of the fuel combustion process which of the hazardous gases. The aim of this research is to determine the total mass transfer coefficient and analyze the effect of the absorbent flow rate of the absorbent solution with the promoter and the gas flow rate to the total mass transfer coefficient value. The variables consisted of liquid flow rate: 1, 2, 3, 4, 5 liter/min, gas flow rate: 15, 25, 30, 40, 50 liter/min and MSG concentration: 0%, 1%, 3% and 5% by weight. The solution of Pottasium Carbonate as absorbent with MSG promoter is flowed through top column and CO2 gas flowed from bottom packed column. Liquids were analyzed by titration and the gas output was analyzed by GC. From this research, it is found that the flow rate of gas and the liquid flow rate is directly proportional to the value of KGa. The liquid flow rate variable 5 liters / minute, gas flow rate 15 l / min obtained value of KGa 11,1102 at concentration of MSG 5%. Keywords:  Absorption, CO2,  K2CO3, MSG. 

scholarly journals NO Separation Characteristics in Integrated Electromigration Membrane Reactor

2020 ◽  
Vol 10 (15) ◽  
pp. 5071
Author(s):  
Zuwu Wang ◽  
Guifen Shen
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Total Mass ◽  
Membrane Reactor ◽  
Gas Flow ◽  
Separation Efficiency ◽  
Discharge Voltage ◽  
Gas Flow Rate

An integrated electromigration membrane absorption method has been proposed for the separation of NO from simulated mixed gas. The experiments were conducted to investigate the effect of discharge voltage, gas flow rate, inlet concentrations, and absorbents on the NO separation efficiency and total mass transfer coefficient in the integrated electromigration membrane reactor. The experimental results demonstrated that the NO separation efficiency and total mass transfer coefficient increased with the increase in the applied discharge voltage of the integrated electromigration membrane reactor. Regardless of discharge or not, the separation efficiency of NO continuously decreased with the increase in the gas flow rate and inlet concentration of NO in the experimental process. The total mass transfer coefficient of NO increased first and then decreased with an increase in the gas flow rate, while it decreased with an increase in NO inlet concentration. Compared with the membrane absorption without discharge voltage under the condition tested, at a discharge voltage of 18kV, the NO separation efficiency and the total mass transfer coefficient increased by 48.7% and 9.7 times, respectively.

Experimental Investigation on Ozone Mass Transfer Coefficient Enhanced by Electric Field in Liquid Phase

2013 ◽  
Vol 864-867 ◽  
pp. 2139-2144 ◽  
Author(s):  
Yang Lin Li
Keyword(s):  
Mass Transfer ◽  
Liquid Phase ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Ozone Concentration ◽  
Total Mass ◽  
Gas Flow ◽  
Electrode Spacing ◽  
Gas Flow Rate

In order to improve the efficiency of ozone mass transfer in liquid phase, the method enhanced by electric field was put forward. The effect on ozone mass transfer was investigated from voltage, electrode spacing and gas flow rate. The result showed that ozone concentration in water and the total mass transfer coefficient increased correspondingly with the increase of the voltage, and ozone concentration in water and the total mass transfer coefficient increased correspondingly with increase of the electrode spacing in the range from 1 to 3 cm, and ozone concentration in water increased correspondingly with increase of the gas flow rate, but the total mass transfer coefficient reduced correspondingly.

Influence of suspended solid particles on gas-liquid mass transfer coefficient in a system stirred by double impellers

2009 ◽  
Vol 63 (2) ◽  
Author(s):  
Anna Kiełbus-Rąpała ◽  
Joanna Karcz
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
High Speed ◽  
Gas Flow ◽  
Research Work ◽  
Experimental Studies ◽  
Solid Particles ◽  
Solid Concentration ◽  
Volumetric Mass Transfer Coefficient

AbstractThe aim of the research work was to investigate the effect of the presence and concentration of solid particles on the gas-liquid volumetric mass transfer coefficient in a mechanically stirred gas-solid-liquid system. Experimental studies were conducted in a tall vessel of the diameter of 0.288 m, equipped with two designs of double stirrers. Three high-speed stirrers were used: A 315, Smith turbine, and Rushton turbine. The following operating parameters were changed: gas flow rate, stirrer speed, and solid concentration. The volumetric mass transfer coefficient was determined using the dynamic gassing-out method. In the range of the measurements conducted, this coefficient was strongly affected by both the presence and the concentration of particles in the system. Generally, a low concentration of particles in the system, equal to 0.5 mass %, caused an increase of the volumetric mass transfer coefficient values for both stirrer configurations compared to a system without solids whilst more particles (2.5 mass %) caused a decrease of this coefficient. It could be supposed that an increase of slurry viscosity affected the decrease of the volumetric mass transfer coefficient at higher solid concentration. An empirical correlation was proposed for volumetric mass transfer coefficient prediction. Its parameters were fitted using experimental data.

scholarly journals Mass Transfer Coefficient of Ozone in a Bubble Column

2018 ◽  
Vol 156 ◽  
pp. 02015 ◽  
Author(s):  
Ratnawati Ratnawati ◽  
Dyah Arum Kusumaningtyas ◽  
Purbo Suseno ◽  
Aji Prasetyaningrum
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Gas Flow ◽  
Bubble Column ◽  
Bubble Column Reactor ◽  
Ozone Generator ◽  
Gas Flow Rate ◽  
State Concentration

The effect of flow rate of ozone-containing gas and pH on the mass transfer coefficient of ozone through water in a bubble column reactor has been studied. Ozone was generated from air using a corona discharge ozone generator. The flow rate of air was varied from 2 to 5 L min-1, while pH was varied from 4 to 10. The gas containing ozone was bubbled to the reactor containing 1.5 L of 2% KI solution. The temperature was set at 28±1ºC. The concentration of ozone was determined using titrimetric method every 5 minutes. The results show that the concentration of ozone increases with time, and it reaches a steady-state concentration after 30 minutes of ozonation. The gas flow rate and pH apparently affect both the concentration and the kLa. The highest kLa of 2.1 X 10-2 s-1 is obtained at pH 4 with a gas flow rate of 4 L min-1.

Characteristics of Heat and Mass Transfer in Condesation Process of Gas-Liquid Cross Flow

2014 ◽  
Vol 1070-1072 ◽  
pp. 1718-1721
Author(s):  
Feng Zhen Zhang ◽  
Xie Ma ◽  
Hu Yang ◽  
Xing Yong Liu ◽  
Huai Ming Du
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Heat And Mass Transfer ◽  
Gas Flow ◽  
Cross Flow ◽  
Condensation Process ◽  
Gas Flow Rate ◽  
Staggered Arrangement ◽  
Main Factors

The condensation process of liquid-gas cross flow was mathematically modeled, and the expressions of heat and mass transfer coefficient were obtained. The characteristics of high temperature and humidity gas that flowed across an array of liquid columns were experimentally studied in various working conditions to get the heat and mass transfer coefficient. The results showed that: the heat and mass transfer coefficient of the staggered arrangement is 20~40% higher than that of the aligned arrangement; the gas turbulence near the gas-liquid interface caused by the flow of the liquid columns and that caused by the gas flow around liquid columns are the main factors that intensify the heat and mass transfer in low and high gas flow rate respectively.

scholarly journals Effects of geometric parameters on volumetric mass transfer coefficient of non-Newtonian fluids in stirred tanks

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Haider Ali ◽  
Sofia Zhu ◽  
Jannike Solsvik
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Gas Flow ◽  
Scale Up ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Volumetric Mass Transfer Coefficient ◽  
Transfer Coefficients ◽  
Stirred Tanks

Abstract Scaling up stirred tanks is a significant challenge because of the research gaps between laboratory and industrial-scale setups. It is necessary to understand the effects of scale-up on the mass transfer in stirred tanks, and this requires meticulous experimental analysis. The present study investigates the effects of tank size and aspect ratio ( H L T ${H}_{L}}{T}$ ) on the volumetric mass transfer coefficients of shear-thinning fluids. The experiments were conducted in three stirred tanks of different sizes (laboratory and pilot scale) and geometries (standard and nonstandard). H L T ${H}_{L}}{T}$ was 1 for the standard tanks and 3.5 for the nonstandard stirred tanks. Three sizes of stirred tanks were used: 11 L with H L T ${H}_{L}}{T}$ of 1, 40 L with H L T ${H}_{L}}{T}$ of 3.5, and 47 L with H L T ${H}_{L}}{T}$ of 1. Impeller stirring speeds and gas flow rates were in the range of 800–900 rev min−1 and 8–10 L min−1, respectively. The volumetric mass transfer coefficient was estimated based on the dissolved oxygen concentration in the fluids, and the effects of rheology and operating conditions on the volumetric mass transfer coefficient were observed. The volumetric mass transfer coefficient decreased as tank size increased and increased with an increase in operating conditions, but these effects were also clearly influenced by fluid rheology. The impacts of scale-up and operating conditions on the volumetric mass transfer coefficient decreased as liquid viscosity increased.

scholarly journals Effect of pH and Gas Flow Rate on Ozone Mass Transfer of Κ-Carrageenan Solution in Bubble Column Reactor

REAKTOR ◽  
2019 ◽  
Vol 18 (04) ◽  
pp. 177 ◽  
Author(s):  
Aji Prasetyaningrum ◽  
Dyah Arum Kusumaningtyas ◽  
Purbo Suseno ◽  
Ratnawati Ratnawati
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Gas Flow ◽  
Bubble Column ◽  
Operating Conditions ◽  
Bubble Column Reactor ◽  
Gas Flow Rate ◽  
Column Reactor

This research was conducted to calculate the mass transfer coefficient value for ozonation reaction of κ-carrageenan solution in the bubble column reactor. Ozone gas was produced using ozone generator type corona discharge. In this study, operating conditions were regulated at ozone gas flow rate 2- 5 L min-1, pH 4-10, and temperature 29 ± 1 oC. Samples were tested every 5 minutes to determine the dissolved ozone concentration. The results showed that dissolved ozone concentrations increased with increasing ozonation time and ozone gas flow rate. However, a very high gas flow rate can increase turbulence so that the mass transfer coefficient (kLa) value decreased. In alkaline conditions, the formation of free radicals (HO*) increases so that the amount of dissolved ozone decreases. The kLa value of ozone gas in κ-carrageenan solution is slightly lower than the kLa value of the ozone gas in the water. The results of this study indicate that (kLa) ozone gas in water is 0.131 / minute while the value (kLa) in κ-carrageenan solution is 0.128 / minute.

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