scholarly journals A comparative evaluation of design factors on bubble column operation in photosynthetic biogas upgrading

2021 ◽  
Vol 8 (2) ◽  
pp. 1351-1373
Author(s):  
Archishman Bose ◽  
Richard O’Shea ◽  
Richen Lin ◽  
Jerry D. Murphy
Keyword(s):  
Removal Efficiency ◽  
Flow Rate ◽  
Bubble Column ◽  
Co2 Removal ◽  
Gas Velocity ◽  
Biogas Upgrading ◽  
Algal Concentration ◽  
Superficial Gas Velocity ◽  
G Ratio ◽  
Design Factors

Studies attempting to optimise photosynthetic biogas upgrading by simultaneous investigation of the bubble column-photobioreactor setup have experienced considerable variability in results and conclusions. To identify the sources of such variation, this work quantitatively compared seven design factors (superficial gas velocity; liquid to gas flow rate (L/G) ratio; empty bed residence time; liquid inlet pH; liquid inlet alkalinity; temperature; and algal concentration) using the L16 Taguchi orthogonal array as a screening design of experiment. Assessments were performed using the signal to noise (S/N) ratio on the performance of CO2 removal (CO­2 removal efficiency, CO2 absorption rate, and overall CO2 mass transfer coefficient) and O2 stripping (O2 concentration in biomethane and O2 flow rate in biomethane). Results showed that pH and L/G ratio were the most critical design factors. Temperature and gas residence times had minimal impact on the biomethane composition. The interactive effect between pH and L/G ratio was the most impactful, followed by the interactive effects between superficial gas velocity and L/G ratio and pH on CO2 removal efficiency. The impact of L/G ratio, algal concentration, and pH (in that order of impact) caused up to a 90% variation in oxygen content in biomethane. However, algal concentration had a diminishing role as the L/G ratio increased. Using only the statistically significant main effects and interactions, the biomethane composition (CO2% and O2%) was predicted with over 95% confidence through regression equations for superficial gas velocity up to 0.2 cm/s.

Separation and Hydrodynamic Performance of Air-Kerosene-Water System by Bubble Column

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Abbas H. Sulaymon ◽  
Ahmed Abed Mohammed
Keyword(s):  
Removal Efficiency ◽  
Flow Rate ◽  
Bubble Column ◽  
Removal Rate ◽  
Air Flow ◽  
Bubble Diameter ◽  
Water Concentration ◽  
Hydrodynamic Performance ◽  
Air Flow Rate ◽  
Flotation Process

The separation of emulsified kerosene in water (concentration 250-750ppm) was investigated in a bubble column15.6 cm diameter and 120 cm height. The effective behaviors of bubble characteristics (bubble diameter, bubble rise velocity and air hold-up) on the removal efficiency were measured by electroresistivity probe. The effects of kerosene concentration, air flow rate,bubble diameter, liquid height, liquid viscosity, NaCl concentration, and alum on the removal rate were found. The experimental results showed that the removal efficiency increased with increasing air flow rate (1.09-2.6cm/s) and decreased with increasing CMC concentration. The results also showed that adding anionic surfactants (SLES and SDBS) leads to increase removal rate. The the flotation process was found to be first order kinetics. New correlations of air holdup and bubble diameter using dimensionless groups were derived.

Influence Parameters in the Ozonation of Clofibric Acid Using a Cascade Bubble Column

2012 ◽  
Vol 573-574 ◽  
pp. 538-541
Author(s):  
Yan Ping Duan ◽  
Sven Geissen ◽  
Ling Chen
Keyword(s):  
Removal Efficiency ◽  
Flow Rate ◽  
Gas Flow ◽  
Liquid Flow Rate ◽  
Bubble Column ◽  
Continuous Operation ◽  
Clofibric Acid ◽  
Gas Flow Rate ◽  
Toc Removal ◽  
Operation Parameters

Ozonation of clofibric acid (CA) in aqueous solution was carried out under continuous operation in a cascade bubble column. The influence of operation parameters including initial CA concentration, gas flow rate, liquid flow rate and pH on the removal of CA and TOC was investigated. The results indicated that ozonation could be used to effectively remove CA from water. Increasing the initial CA concentration resulted in a decrease of the CA and TOC removal efficiency. A comparison of CA removal efficiency and ozone utilization between cascade and conventional bubble column indicated that cascade bubble column was an effective way for increasing the solubility ozone in the reactor.

Mass Transfer Studies in a Novel Perforated Plate Bubble Column

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
S. Dhanasekaran ◽  
T. Karunanithi
Keyword(s):  
Mass Transfer ◽  
Liquid Velocity ◽  
Bubble Column ◽  
Perforated Plate ◽  
Gas Velocity ◽  
Plate Spacing ◽  
Mass Transfer Studies ◽  
Superficial Gas Velocity ◽  
Superficial Liquid Velocity

This investigation reports the experimental and theoretical results carried out to evaluate the volumetric mass transfer coefficient (kLa) in a novel hybrid rotating and reciprocating perforated plate bubble column. Countercurrent condition is performed. kLa is studied by the absorption of oxygen from air into deoxygenated water at room temperature (27 ± 1°C). Effects of agitation level, superficial gas velocity, superficial liquid velocity and plate spacing on kLa were analyzed and found to be significant. With an increase in agitation level at a constant superficial gas and liquid velocities, the breakage process of gas bubbles starts to be more pronounced and intensive oxygen mass transfer occurs. Hence, kLa increases sharply. kLa increases with an increase in superficial gas velocity, due to higher gas holdup and the enhanced breakup of bubbles. Similarly, kLa increases with an increase in superficial liquid velocity and the effect is found to be significant. When plate spacing is decreased (by increasing the number of plates), it is observed that the kLa increases at higher superficial gas velocity and agitation level. Correlation is developed for the determination of kLa and found to concur with experimental results. This correlation can be used for the determination of kLa for this hybrid column with 95% accuracy within the range of variables investigated in this present study.

Hydrodynamic Study of a Gas–liquid–solid Bubble Column Employing CFD–BPBM Method

2017 ◽  
Vol 15 (4) ◽  
Author(s):  
Weiling Li ◽  
Chuanwen Zhao ◽  
Ping Lu
Keyword(s):  
Bubble Size ◽  
Volume Fraction ◽  
Bubble Column ◽  
Particle Density ◽  
Solid Volume Fraction ◽  
Experimental Result ◽  
Bubble Coalescence ◽  
Phase System ◽  
Gas Velocity ◽  
Superficial Gas Velocity

Abstract The computational fluid dynamics – bubble population balance model (CFD–BPBM) was employed to predict the hydrodynamic characteristics of a gas–liquid–solid bubble column. A 3D time dependent numerical study was performed and the bubble size distributions at the conditions of different superficial gas velocity (0.089 m/s–0.22 m/s), solid volume fraction (0.03–0.30) and particle density (2500 kg/m3–4800 kg/m3) in the three–phase system were investigated, and the simulation results were compared with the experimental results. The bubble diameters ranging from 1 mm to 64 mm were divided into ten classes. The predicted pressure changing with the bed height had a good agreemeet with the experimental result. The bubble number density predicted decreased when the bubble size increased at each superficial gas velocity, and the bubble coalescence rate became greater than the breakup rate when Ug shifted from 0.089 m/s to 0.16 m/s. The bubble interaction was similar at 0.16 m/s and 0.22 m/s both at particle size dp = 75 μm and 150 μm. The bubble size corresponding to the maximum of the bubble volume fraction increased as Ug increased. The particles can make the bubble break up and coalesce simultaneously when the solid volume fraction was larger than 0.20, and therefore the particles had a contribution to both of the bubble coalescence and breakup in the bubble coalescence regime (Ug = 0.16 m/s). The effect of the particle density was similar with that of the solid volume fraction. Increasing the particle density can enhance the breakup rate of the large bubbles.

Design and Performance of Slug Damper

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Antonio Reinoso ◽  
Luis E. Gomez ◽  
Shoubo Wang ◽  
Ram S. Mohan ◽  
Ovadia Shoham ◽  
...  
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Liquid Flow Rate ◽  
Liquid Velocity ◽  
Flow Behavior ◽  
Mechanistic Model ◽  
Gas Velocity ◽  
Flow Loop ◽  
Two Phase ◽  
Superficial Gas Velocity

This study investigates theoretically and experimentally the slug damper as a novel flow conditioning device, which can be used upstream of compact separation systems. In the experimental part, a 3 in. ID slug damper facility has been installed in an existing 2 in. diameter two-phase flow loop. This flow loop includes an upstream slug generator, a gas-liquid cylindrical cyclone (GLCC©, ©The University of Tulsa, 1994) attached to the slug damper downstream and a set of conductance probes for measuring the propagation of the dissipated slug along the damper. Over 200 experimental runs were conducted with artificially generated inlet slugs of 50 ft length (Ls/d=300) that were dumped into the loop upstream of the slug damper, varying the superficial liquid velocity between 0.5 ft/s and 2.5 ft/s and superficial gas velocity between 10 ft/s and 40 ft/s (in the 2 in. inlet pipe) and utilizing segmented orifice opening heights of 1 in., 1.5 in., 2 in., and 3 in. For each experimental run, the measured data included propagation of the liquid slug front in the damper, differential pressure across the segmented orifice, GLCC liquid level, GLCC outlet liquid flow, and static pressure in the GLCC. The data show that the slug damper/GLCC system is capable of dissipating long slugs, narrowing the range of liquid flow rate from the downstream GLCC. Also, the damper capacity to process large slugs is a strong function of the superficial gas velocity (and mixture velocity). The theoretical part includes the development of a mechanistic model for the prediction of the hydrodynamic flow behavior in the slug damper. The model enables the predictions of the outlet liquid flow rate and the available damping time, and in turn the prediction of the slug damper capacity. Comparison between the model predictions and the acquired data reveals an accuracy of ±30% with respect to the available damping time and outlet liquid flow rate. The developed model can be used for design of slug damper units.

Bubble Diameter and Effective Interfacial Area in a Novel Hybrid Rotating and Reciprocating Perforated Plate Bubble Column

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Dhanasekaran S ◽  
Karunanithi T
Keyword(s):  
Liquid Velocity ◽  
Bubble Column ◽  
Bubble Diameter ◽  
Perforated Plate ◽  
Interfacial Area ◽  
Gas Velocity ◽  
The Mean ◽  
Superficial Gas Velocity ◽  
Plate Column

This investigation reports on the experimental and theoretical investigation carried out to evaluate the bubble diameter and effective interfacial area in a novel Hybrid Rotating and Reciprocating Perforated Plate Bubble Column. Air-water system is used in this investigation. Countercurrent mode is employed. The effects of agitation level, superficial gas velocity and superficial liquid velocity on the bubble size distribution are studied. The mean bubble diameter is predicted using photographic technique. A simple correlation is developed for the determination of mean bubble diameter. It is found that the mean bubble diameter values for hybrid column are 1.8 to 2.5 times smaller when compared with conventional reciprocating plate column. The interfacial area is calculated based on the experimental results of the gas holdup and bubble diameter. Effects of agitation level, superficial gas velocity, superficial liquid velocity and plate free area on the interfacial area have been investigated. Correlations are developed for the determination of interfacial area for both mixer-settler and emulsion regions. It could be noted that the interfacial area for the hybrid column is 3 to 6 times higher in both mixer-settler region and emulsion region than that of conventional reciprocating plate column which is quite large.

scholarly journals CO2 REMOVAL EFFICIENCY FROM NATURAL GAS AT ELEVATED PRESSURE OF PACKED ABSORPTION COLUMN USING POTASSIUM CARBONATE PROMOTED WITH GLYCINE

2019 ◽  
Vol 1 (2) ◽  
pp. 55-57
Author(s):  
NUR FARHANA AJUA MUSTAFA ◽  
Azmi bin Mohd Shariff ◽  
WeeHorng Tay ◽  
Hairul Nazirah Abdul Halim ◽  
Siti Munirah Mhd Yusof
Keyword(s):  
Removal Efficiency ◽  
Flow Rate ◽  
Co2 Capture ◽  
Potassium Carbonate ◽  
Liquid Flow ◽  
Liquid Flow Rate ◽  
Co2 Removal ◽  
Absorption Column ◽  
Absorption Performance ◽  
Co2 Removal Efficiency

This article reports the absorption removal efficiency for carbon dioxide (CO2) capture from natural gas using an environmental friendly solvent, potassium carbonate promoted with glycine. Recently, CO2 capture using this solvent (with precipitating) was studied by previous researchers. However, the precipitates of the solvent increase the potential of blockage in the packing and piping thus result failure in absorption processes. Therefore, this study focused to assess the CO2 removal efficiency of non-precipitating potassium carbonate promoted with glycine. This green solvent contains aqueous blend of 20 wt% potassium carbonate and 8 wt% glycine. The absorption performance of the solvent was obtained by demonstrated a few experimental works using a bench scale packed absorption column. The packing type was Sulzer metal gauze and the column consisted of six sampling point which located equidistance along the packing The system was running over a range of liquid flow rate 1.81-7.22 m3/m2.h at fixed operating pressure (4 Mpa), CO2 inlet concentration (20%), gas flow rate (33 kmol/m2.h) and solvent temperature (60 . The effect of liquid flow rate was assessed in term of its CO2 removal efficiency and concentration profile along the packing. The study shows the increasing trend of CO2 removal as liquid flow rate increases. Higher liquid/molar flow rate gas (L/G) offers a better absorption performance compared to lower L/G ratio. This study demonstrated the efficient absorption up to 77 % using non-precipitating potassium carbonate promoted with glycine.

Effects of Chemical Reactions on the Local Hydrodynamics in Slurry Bubble Column Reactors Operating under Typical Fischer-Tropsch Process Conditions – Ii

2019 ◽  
Vol 17 (9) ◽  
Author(s):  
Omar M. Basha ◽  
Badie I. Morsi
Keyword(s):  
Chemical Reactions ◽  
Catalyst Concentration ◽  
Bubble Column ◽  
Pilot Scale ◽  
Catalyst Loading ◽  
Cfd Model ◽  
Gas Velocity ◽  
Cfd Simulations ◽  
Bubble Column Reactors ◽  
Superficial Gas Velocity

AbstractOur rigorously validated Computational Fluid Dynamics (CFD) model (Basha et al. 2016) was previously used to predict the effects of gas sparger designs and internals configurations on the local hydrodynamics in a pilot-scale and a conceptual large-scale slurry bubble column reactors (SBCRs) (Basha and Morsi 2018). In this study, the CFD model was used to predict the effect of incorporating the F-T reaction kinetics on the local hydrodynamics in the pilot-scale (0.3-m ID, 3-m height) and the overall performance of the pilot-scale and an industrial-scale (5.8-m ID, 42-m height) SBCRS, both operating under F-T conditions with iron catalyst.In the pilot-scale SBCR, the CFD simulations were carried out with catalyst concentrations of 5, 10 and 15 vol% and three H2/Co ratios of 1, 1.5 and 2, at temperature of 443 K, pressure of 20.5 bar and a superficial gas velocity of 0.24 m/s. The predictions showed that the presence of chemical reactions decreased the gas holdup and the Sauter mean bubble diameters along the reactor height by an average of 15.4 % and 17.63 %, respectively and strengthened the liquid circulations near the reactor wall. The predictions also showed that the CO and H2conversions increased with increasing the catalyst concentration, and the pilot scale SBCR could produce a maximum of 1.87 tons/day of C5+products at a catalyst concentration of 15 vol%.In the commercial-scale SBCR, the CFD simulations were conducted at a catalyst loading of 10 vol% at a temperature of 528 K, pressure of 29 bar and four superficial gas velocities of 0.12, 0.24, 0.3 and 0.4 m/s. The calculations were completed, however, the contours of the local hydrodynamics were not extracted due to computational and memory limitations associated with generating graphics of such a large and complex reactor geometry. The predictions showed that the CO conversions were 48 %, 59 %, 58 % and 55 %; the H2conversions were 36 %, 51 %, 56 % and 54 % and the C5+products yields were are 275, 576, 627 and 654 ton/day at the superficial gas velocities of 0.12, 0.24, 0.3 and 0.4 m/s, respectively. When comparing the CFD model predictions with those of the 1-D empirical model developed by Sehabiague et al. (Sehabiague et al. 2015) at a superficial gas velocity of 0.24 m/s and catalyst loading of 10 %, the CFD model was found to predict lower CO conversion, higher H2conversion and higher C5+yield.

CFD-PBM simulation of hydrodynamics of microbubble column with shear-thinning fluid

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Xi Zhang ◽  
Ping Zhu ◽  
Shuaichao Li ◽  
Wenyuan Fan ◽  
Jingyan Lian
Keyword(s):  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Radial Direction ◽  
Liquid Velocity ◽  
Bubble Column ◽  
Gas Holdup ◽  
Gas Velocity ◽  
Gas Distributor ◽  
Superficial Gas Velocity ◽  
The Right

Abstract A numerical simulation was performed to study the hydrodynamics of micro-bubble swarm in bubble column with polyacrylamide (PAM) aqueous solution by using computational fluid dynamics coupled with population balance models (CFD-PBM). By considering rheological characteristics of fluid, this approach was able to accurately predict the features of bubble swarm, and validated by comparing with the experimental results. The gas holdup, turbulent kinetic energy and liquid velocity of bubble column have been elucidated by considering the influences of superficial gas velocity and gas distributor size respectively. The results show that with the rise of the superficial gas velocity, the gas holdup and its peak width increase significantly. Especially, the curve peak corresponding to high gas velocity tends to drift obviously toward the right side. Except for the occurrence of a smooth holdup peak at the column center under the condition of the moderate distributor size, the gas holdups for the small and large distributor sizes become flat in the radial direction respectively. The distribution of turbulent kinetic energy presents an increasingly asymmetrical feature in the radial direction and also its variation amplitude enhances obviously with the rise of gas velocity. The increase in gas distributor size can enhance markedly turbulent kinetic energy as well as its overall influenced width. At the low and moderate superficial gas velocity, the curves of the liquid velocity in radial direction present the Gaussian distributions, whereas the perfect distribution always is broken in the symmetry for high gas velocity. Both liquid velocities around the bubble column center and the ones near both column walls go up consistently with the gas distributor size, especially near the walls at the large distributor size condition.

EXPERIMENTAL EVALUATION OF THE REMOVAL EFFICIENCY OF SO2 IN A SPRAY TOWER USING DIFFERENT SPRAY NOZZLES

2013 ◽  
Vol 12 (2) ◽  
pp. 23 ◽  
Author(s):  
M. C. Codolo ◽  
W. A. Bizzo
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Removal Efficiency ◽  
Experimental Evaluation ◽  
Gas Velocity ◽  
Spray Tower ◽  
G Ratio

This work presents an experimental evaluation of the removal efficiency of SO2 in a spray tower. The experiments were carried out in different conditions, varying gas velocity and using different sprays nozzles. The influence of the height of tower on the removal efficiency was evaluated through experiments inside spray tower. In this study was used two sets of five nozzles, with diameter of orifice of 2.4 and 3.2 mm, and only one nozzle with diameter of orifice of 5.6 mm. The results showed the influence of the gas velocity and L/G ratio in the removal efficiency, the influence of the gas velocity on the volumetric gas side mass transfer coefficient and the influence of the height of the tower in the removal efficiency.

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