scholarly journals Dinamika tetes dalam kolom isian

2018 ◽  
Vol 7 (1) ◽  
pp. 710
Author(s):  
Danu Ariono ◽  
Dwiwahju Sasongko ◽  
Priyono Kusumo
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Size Distribution ◽  
Droplet Size ◽  
Droplet Diameter ◽  
Mass Transfer Rate ◽  
Packed Column ◽  
Droplet Size Distribution ◽  
Droplet Dynamics

To date, evaluation of the performance of liquid-liquid extraction in packed columns has not been able to produce satisfactory results, because the correlations used in this evaluation are empirical in nature, with a very limited range of validity. One of the causes of this limitation is the use of the assumption that the dynamics of liquid dispersed in droplets is constant (in terms of shape, dimensions, and numbers), so that the mass transfer interfacial area and mass transfer coefficient in the column are assumed to be constant. In reality, dynamics of droplets in a column is not constant, due to the imbalance between droplet coalescence and disintegration. For a given droplet diameter, there is an increase in numbers of droplets due to coalescence of smaller droplets, and a  decrease in numbers of droplets due to disintegration into smaller droplets. These coalescence and disintegration phenomena may be caused by various factors, including the existence of packings which impede the flow of droplets. These phenomena impact the mass transfer rate from continuous to dispersed phase, and vice versa, due to a variation in the interfacial contact area and mass transfer coefficient. The observation of droplet dynamics from droplet formation until its motion through void spaces between packings is a critical factor in developing a model that can describe the performance of the packed column. The dynamics of droplets is influenced by various operational and physical variables.  A droplet dynamics experiment has been undertaken, aimed at obtaining the droplet size distribution at specific heights along the column. This distribution is to be used to develop mass transfer coefficient correlations in the continuous and dispersed phases.Keywords: droplet size distribution, packed column Abstrak Evaluasi unjuk kerja ekstraksi cair-cair dalam kolom isian (packed column) hingga saat ini belum dapat memberikan hasil yang memuaskan karena korelasi-korelasi yang  digunakan  masih  bersifat  empiris serta daerah keberlakuannya sangat terbatas. Salah satu penyebab keterbatasan berlakunya korelasi tersebut ialah penggunaan anggapan bahwa dinamika cairan yang terdispersi dalam bentuk tetesan bersifat konstan (bentuk, ukuran serta jumlahnya), sehingga harga luas perpindahan massa dan harga koefisien perpindahan massa dalam kolom dianggap tetap. Kenyataannya dinamika tetesan dalam kolom tidak konstan akibat adanya tetesan yang bergabung dan pecah dalam jumlah yang  tidak sama. Pada suatu harga diameter tetesan tertentu, ada penambahan jumlah tetesan akibat penggabungan tetesan­ tetesan yang ukurannya lebih kecil serta adanya pengurangan jumlah tetesan akibat pecahnya tetesan menjadi tetesan-tetesan yang lebih kecil. Peristiwa penggabungan dan pemecahan tetesan dapat disebabkan berbagai faktor temasuk adanya isian yang menghalangi gerakan tetesan. Kejadian tersebut akan mempengaruhi laju proses perpindahan massa dari fasa kontinyu ke fasa  terdispersi  atau sebaliknya, karena adanya variasi luas permukaan kontak serta koefisien perpindahan massanya. Pengamatan dinamika tetesan mulai saat pembentukan tetes hingga pergerakannya saat melewati sela-sela isian merupakan faktor penting dalam  membangun model  yang  dapat menggambarkan unjuk kerja kolom isian. Dinamika tetesan tersebut dipengaruhi oleh berbagai variabel operasi dan variabel fisik. Eksperimen dinamika fetes yang dilakukan diarahkan untuk memperoleh distribusi ukuran tetes pada posisi ketinggian tertentu dan distribusi tersebut akan digunakan untuk pengembangan  korelasi koefisien perpindahan massa difasa  dispersi danfasa kontinyu.Kata kunci: distribusi ukuran tetes, kolom isian.

Mass Transfer Enhancement for CO2 Absorption in Structured Packed Absorption Column

2019 ◽  
Vol 41 (5) ◽  
pp. 820-820
Author(s):  
Pongayi Ponnusamy Selvi and Rajoo Baskar Pongayi Ponnusamy Selvi and Rajoo Baskar
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Gas Flow ◽  
Aqueous Ammonia ◽  
Volume Flow Rate ◽  
Packed Column ◽  
Operating Conditions ◽  
Co2 Absorption ◽  
Absorption Column

The acidic gas, Carbon dioxide (CO2) absorption in aqueous ammonia solvent was carried as an example for industrial gaseous treatment. The packed column was provided with a novel structured BX-DX packing material. The overall mass transfer coefficient was calculated from the absorption efficiency of the various runs. Due to the high solubility of CO2, mass transfer was shown to be mainly controlled by gas side transfer rates. The effects of different operating parameters on KGav including CO2 partial pressure, total gas flow rates, volume flow rate of aqueous ammonia solution, aqueous ammonia concentration, and reaction temperature were investigated. For a particular system and operating conditions structured packing provides higher mass transfer coefficient than that of commercial random packing.

Evaluation of Models for Droplet Shear Effect of Centrifugal Pump

2018 ◽  
Author(s):  
Ramin Dabirian ◽  
Shihao Cui ◽  
Ilias Gavrielatos ◽  
Ram Mohan ◽  
Ovadia Shoham
Keyword(s):  
Experimental Data ◽  
Size Distribution ◽  
Centrifugal Pump ◽  
Droplet Size ◽  
Separation Efficiency ◽  
Droplet Diameter ◽  
Droplet Size Distribution ◽  
Production Equipment ◽  
Transportation Equipment ◽  
Log Normal

During the process of petroleum production and transportation, equipment such as pumps and chokes will cause shear effects which break the dispersed droplets into smaller size. The smaller droplets will influence the separator process significantly and the droplet size distribution has become a critical criterion for separator design. In order to have a better understanding of the separation efficiency, estimation of the dispersed-phase droplet size distribution is very important. The objective of this paper is to qualitatively and quantitatively investigate the effect of shear imparted on oil-water flow by centrifugal pump. This paper presents available published models for the calculation of droplet size distribution caused by different production equipment. Also detailed experimental data for droplet size distribution downstream of a centrifugal pump are presented. Rosin-Rammler and Log-Normal Distributions utilizing dmax Pereyra (2011) model as well as dmin Kouba (2003) model are used in order to evaluate the best fit distribution function to simulate the cumulative droplet size distribution. The results confirm that applying dmax Pereyra (2011) model leads to Rosin-Rammler distribution is much closer to the experimental data for low shear conditions, while the Log-Normal distribution shows better performance for higher shear rates. Furthermore, the predictions of Modified Kouba (2003) dmin model show good results for predicting the droplet distribution in centrifugal pump, and even better predictions under various ranges of experiments are achieved with manipulating cumulative percentage at minimum droplet diameter F(Dmin).

Water droplet condensation and evaporation in turbulent channel flow

2014 ◽  
Vol 749 ◽  
pp. 666-700 ◽  
Author(s):  
E. Russo ◽  
J. G. M. Kuerten ◽  
C. W. M. van der Geld ◽  
B. J. Geurts
Keyword(s):  
Mass Transfer ◽  
Nusselt Number ◽  
Size Distribution ◽  
Water Vapour ◽  
Channel Flow ◽  
Droplet Size ◽  
Droplet Size Distribution ◽  
Turbulent Channel Flow ◽  
Phase Changes ◽  
Cold Wall

AbstractWe propose a point-particle model for two-way coupling of water droplets dispersed in the turbulent flow of a carrier gas consisting of air and water vapour. We adopt an Euler–Lagrangian formulation based on conservation laws for the mass, momentum and energy of the continuous phase and on empirical correlations describing momentum, heat and mass transfer between the droplet phase and the carrier gas phase. An incompressible flow formulation is applied for direct numerical simulation of differentially heated turbulent channel flow. The two-way coupling is investigated in terms of its effects on mass and heat transfer characteristics and the resulting droplet size distribution. Compared to simulations without droplets or those with solid particles with the same size and specific heat as the water droplets, a significant increase in Nusselt number is found, arising from the additional phase changes. The Nusselt number increases with increasing ambient temperature and is almost independent of the heat flux applied to the walls of the channel. The time-averaged droplet size distribution displays a characteristic dependence on position expressing the combined effect of turbophoresis and phase changes in turbulent wall-bounded flow. In the statistically steady state that is reached after a long time, the resulting flow exhibits a mean motion of water vapour from the warm wall to the cold wall, where it condenses on average, followed by a net mean mass transfer of droplets from the cold wall to the warm wall.

ABSORBSI H2S MENGGUNAKAN LARUTAN Fe-EDTA DALAM PACKED COLUMN

EKUILIBIUM ◽  
2011 ◽  
Vol 10 (2) ◽  
Author(s):  
Endang Kwartiningsih ◽  
Arif Jumari
Keyword(s):  
Mass Transfer ◽  
Liquid Phase ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Gas Phase ◽  
Reaction Rate ◽  
Packed Column ◽  
Reaction Rate Constant ◽  
Absorption Process ◽  
Edta Solution

<p><strong><em>Abstract:</em></strong><strong><em> </em></strong><em>Gas purification from the content of H<sub>2</sub>S using  Fe-EDTA (Iron Chelated Solution) gave  several advantages. The advantages were  the absorbent solution can be regenerated that means  a cheap operation cost,  the separated sulfur was a solid that is easy to handle and is save to be disposal to environment. This research was done by simulation and experimental. The simulation step was done by mathematical model arrangement representing the absorption process in packed column through mass transfer arrangement such as mass transfer equations and chemical reaction. The experimental step was done with the making of Fe-EDTA solution from FeCl<sub>2</sub> and EDTA. Then Fe-EDTA solution was flown in counter current packed column that was contacted with H<sub>2</sub>S in the methane gas. By comparing gas composition result of experiment and simulation, the value of mass transfer coefficient in gas phase ( k<sub>Ag</sub>a), mass transfer coefficient in liquid phase (k<sub>Al</sub>a) and the reaction rate constant ( k) were found. The values of mass transfer coefficient in liquid phase (k<sub>Al</sub>a) were lower than values of mass transfer coefficient in gas phase (k<sub>Ag</sub>a) and the reaction rate constant (k). It meant that H<sub>2</sub>S absorption  process using Fe-EDTA absorbent solution was determined by mass transfer process in liquid phase. The higher flow rate of absorbent, the higher value of mass transfer coefficient in liquid phase. </em><em>The smaller packing diameter, the higher value of mass transfer coefficient in liquid phase.From analysis of dimension, the relation of dimensionless number between Sherwood number and flow rate of absorbent, packing diameter was</em><strong></strong></p><p> <strong><em>Keywords:</em></strong><strong><em> </em></strong><em>chemical reaction, Fe-EDTA, H<sub>2</sub>S absorption, mass transfer</em></p>

The effect of microbubbles on gas-liquid mass transfer coefficient and degradation rate of COD in wastewater treatment

2016 ◽  
Vol 73 (8) ◽  
pp. 1969-1977 ◽  
Author(s):  
Kangning Yao ◽  
Yong Chi ◽  
Fei Wang ◽  
Jianhua Yan ◽  
Mingjiang Ni ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Wastewater Treatment ◽  
Activated Sludge ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Degradation Rate ◽  
Mass Transfer Rate ◽  
Cod Removal ◽  
Liquid Mass ◽  
Liquid Mass Transfer

A commonly used aeration device at present has the disadvantages of low mass transfer rate because the generated bubbles are several millimeters in diameter which are much bigger than microbubbles. Therefore, the effect of a microbubble on gas-liquid mass transfer and wastewater treatment process was investigated. To evaluate the effect of each bubble type, the volumetric mass transfer coefficients for microbubbles and conventional bubbles were determined. The volumetric mass transfer coefficient was 0.02905 s−1 and 0.02191 s−1 at a gas flow rate of 0.67 L min−1 in tap water for microbubbles and conventional bubbles, respectively. The degradation rate of simulated municipal wastewater was also investigated, using aerobic activated sludge and ozone. Compared with the conventional bubble generator, the chemical oxygen demand (COD) removal rate was 2.04, 5.9, 3.26 times higher than those of the conventional bubble contactor at the same initial COD concentration of COD 200 mg L−1, 400 mg L−1, and 600 mg L−1, while aerobic activated sludge was used. For the ozonation process, the rate of COD removal using microbubble generator was 2.38, 2.51, 2.89 times of those of the conventional bubble generator. Based on the results, the effect of initial COD concentration on the specific COD degradation rate were discussed in different systems. Thus, the results revealed that microbubbles could enhance mass transfer in wastewater treatment and be an effective method to improve the degradation of wastewater.

Mass transfer coefficient for two-phase countercurrent flow in a packed column with a novel internal

2004 ◽  
Vol 99 (3) ◽  
pp. 273-277 ◽  
Author(s):  
Yanhui Yuan ◽  
Minghan Han ◽  
Lunwei Wang ◽  
Dezheng Wang ◽  
Yong Jin
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Packed Column ◽  
Countercurrent Flow ◽  
Two Phase

Lagrangian Droplet Dynamics in the Subsiding Shell of a Cloud Using Direct Numerical Simulations

2015 ◽  
Vol 72 (10) ◽  
pp. 4015-4028 ◽  
Author(s):  
Vincent E. Perrin ◽  
Harmen J. J. Jonker
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Evaporative Cooling ◽  
Mixing Layer ◽  
Droplet Size Distribution ◽  
Small Scale ◽  
Cumulus Clouds ◽  
Droplet Dynamics ◽  
Turbulent Dissipation ◽  
Environmental Air

Abstract This study investigates the droplet dynamics at the lateral cloud–environment interface in shallow cumulus clouds. A mixing layer is used to study a small part of the cloud edge using direct numerical simulation combined with a Lagrangian particle tracking and collision algorithm. The effect of evaporation, gravity, coalescence, and the initial droplet size distribution on the intensity of the mixing layer and the evolution of the droplet size distribution is studied. Mixing of the droplets with environmental air induces evaporative cooling, which results in a very characteristic subsiding shell. As a consequence, stronger horizontal velocity gradients are found in the mixing layer, which induces more mixing and evaporation. A broadening of the droplet size distribution is observed as a result of evaporation and coalescence. Gravity acting on the droplets allows droplets in cloudy filaments detrained from the cloud to sediment and remain longer in the unsaturated environment. While this effect of gravity did not have a significant impact in this case on the mean evolution of the mixing layer, it does contribute to the broadening of the droplet size distribution and thereby significantly increases the collision rate. Although more but smaller droplets result in more evaporative cooling, more droplets also increase small-scale fluctuations and the production of turbulent dissipation. For the smallest droplets considered with a radius of 10 μm, the authors found that, although a more pronounced buoyancy dip was present, the increase in dissipation rate actually led to a decrease in the turbulent intensity of the mixing layer. Extrapolation of the results to realistic clouds is discussed.

Oil plume simulations: Tracking oil droplet size distribution and fluorescence within high-pressure release jets

2017 ◽  
Vol 2017 (1) ◽  
pp. 1230-1250
Author(s):  
R.N. Conmy ◽  
B. Robinson ◽  
T. King ◽  
M. Boufadel ◽  
S. Ryan ◽  
...  
Keyword(s):  
Water Temperature ◽  
Size Distribution ◽  
Droplet Size ◽  
Oil Spill ◽  
Droplet Diameter ◽  
Performance Testing ◽  
Droplet Size Distribution ◽  
Optical Measurements ◽  
Total Petroleum Hydrocarbons

ABSTRACT Optical measurements have been used during oil spill response for more than three decades to determine oil presence in slicks and plumes. Oil surveillance approaches range from simple (human eyeball) to the sophisticated (sensors on AUVs, aircraft, satellites). In situ fluorometers and particle size analyzers were deployed during the Deepwater Horizon (DWH) Gulf of Mexico oil spill to track shallow and deep subsea plumes. Uncertainties regarding instrument specifications and capabilities during DWH necessitated performance testing of sensors exposed to simulated, dispersed oil plumes. Seventy-two wave tank experiments were conducted at the Bedford Institute of Oceanography. Simulated were oil releases with varying parameters such as oil release rate, oil temperature (reservoir temp ~ 80 °C), water temperature (&lt;8 °C and &gt;15 °C), oil type, dispersant type (Corexit 9500 and Finasol OSR52) and dispersant to oil ratio (DOR). Plumes of Alaskan North Slope Crude (ANS), South Louisiana Crude (SLC) and IFO-120 oils were tracked using in situ fluorescence, droplet size distribution (DSD), total petroleum hydrocarbons (TPH) and benzene-toluene-ethylbenzene-xylene (BTEX). For the lighter SLC, bimodal droplet size with mean diameter &lt; 70 μm was achieved for 1:20 and 1:100 DOR, regardless of water temperature. Similarly, the medium ANS crude exhibited mean droplet diameter &lt;70 μm, but was bimodal only for the 1:20 treatment. Bimodal distribution was not achieved with the heavy IFO, but droplet &lt; 70 μm were observed for 1:20 warm waters, indicating poor dispersibility of the high viscosity oil even for jet releases. Results offer valuable information on the behavior and dispersibility of oils over a range of viscosity, DOR and environmental conditions. Findings have implications for fate and transport models, where DSD, chemistry and fluorescence are all impacted by release variables. This research was supported by the Bureau of Safety and Environmental Enforcement.

Sign in / Sign up

Export Citation Format

Share Document