scholarly journals Two-Dimensional Modeling of Pressure Swing Adsorption (PSA) Oxygen Generation with Radial-Flow Adsorber

2019 ◽  
Vol 9 (6) ◽  
pp. 1153 ◽  
Author(s):  
Xiong Yang ◽  
Haoyu Wang ◽  
Jiangwei Chen ◽  
Ziyi Li ◽  
Yingshu Liu ◽  
...  
Keyword(s):  
Pressure Swing Adsorption ◽  
Large Scale ◽  
Radial Flow ◽  
Gas Adsorption ◽  
Flow Direction ◽  
Cfd Modeling ◽  
Generation Process ◽  
Two Dimensional ◽  
Oxygen Generation ◽  
Pressure Swing

Radial flow is an important type of flow direction for large-scale pressure swing adsorption (PSA) oxygen generation systems. In this study, a numerical simulation of a PSA oxygen generation process based on radial-flow adsorbers was performed with two-dimensional CFD modeling. The gas distribution, the maldistribution factor and the pressure difference were comparatively investigated at each flow type of the radial-flow adsorber. Considering the gas adsorption performance, the results indicated that the centripetal π-flow radial adsorber has the best flow characteristics for the PSA process. The oxygen purity distribution within the adsorption bed was studied to compare centripetal and centrifugal π-flows, and the former was shown to perform better on oxygen enrichment and adsorbent desorption. The steady state was achieved after eight cycles for the centripetal-π adsorber and each of the four steps of the PSA process was explored in detail to show the advantageous properties for oxygen generation in terms of adsorption and desorption. The relationships between the product flow rate and the oxygen purity and recovery were further investigated.

Cyclotetrabenzoin Acetate: A Macrocyclic Porous Molecular Crystal for CO2 Separations by Pressure Swing Adsorption

2021 ◽  
Author(s):  
Yao-Ting Wang ◽  
Corie M. McHale ◽  
Xiqu Wang ◽  
Chung-Kai Chang ◽  
Yu-Chun Chuang ◽  
...  
Keyword(s):  
Molecular Crystal ◽  
Pressure Swing Adsorption ◽  
Gas Adsorption ◽  
Close Packing ◽  
Separation Performance ◽  
Mixed Gas ◽  
Water Tolerance ◽  
Pressure Swing ◽  
Breakthrough Experiments ◽  
Group Play

A porous molecular crystal (PMC) assembled by close-packing of macrocyclic cyclotetrabenzoin acetate is an efficient adsorbent for selective CO<sub>2</sub> capture. The 7.1´7.1 Å square pore of PMC and its ester C=O group play important roles in improving its affinity for CO<sub>2</sub> molecules. Thermodynamically, the benzene walls of macrocycle strongly promote CO<sub>2</sub> adsorption via [p···p] interactions at low pressure. In addition, the polar carbonyl groups pointing inward the square channels reduce the size of aperture to a 5.0´5.0 Å square, which offers kinetic selectivity for CO<sub>2</sub> capture. The PMC features water tolerance and high structural stability under vacuum and various gas adsorption conditions, which are rare among intrinsically porous organic molecules. In mixed-gas breakthrough experiments, it exhibits efficient CO<sub>2</sub>/N<sub>2</sub> and CO<sub>2</sub>/CH<sub>4</sub> separations under kinetic flow conditions. Most importantly, the moderate adsorbate–adsorbent interaction allows the PMC to be readily regenerated, and therefore applied to pressure swing adsorption (PSA) processes. The eluted N<sub>2</sub> and CH<sub>4</sub> are obtained with over 99.9% and 99.8% purity, respectively, and the separation performance is stable for 30 cycles. Coupled with its easy synthesis, these properties make cyclotetrabenzoin acetate a promising adsorbent for CO<sub>2</sub> separations from flue and natural gases.

scholarly journals Comparison Between Pressure Swing Adsorption and Liquid Oxygen Enrichment Techniques in the Atacama Large Millimeter/Submillimeter Array Facility at the Chajnantor Plateau (5,050 m)

2021 ◽  
Vol 12 ◽  
Author(s):  
Ivan Lopez ◽  
Reinaldo Aravena ◽  
Daniel Soza ◽  
Alicia Morales ◽  
Silvia Riquelme ◽  
...  
Keyword(s):  
High Altitude ◽  
Pressure Swing Adsorption ◽  
Large Scale ◽  
High Mobility ◽  
Oxygen Enrichment ◽  
Oxygen Availability ◽  
Liquid Oxygen ◽  
High Altitudes ◽  
Pressure Swing ◽  
Very High

The Chilean workforce has over 200,000 people that are intermittently exposed to altitudes over 4,000 m. In 2012, the Ministry of Health provided a technical guide for high-altitude workers that included a series of actions to mitigate the effects of hypoxia. Previous studies have shown the positive effect of oxygen enrichment at high altitudes. The Atacama Large Millimeter/submillimeter Array (ALMA) radiotelescope operates at 5,050 m [Array Operations Site (AOS)] and is the only place in the world where pressure swing adsorption (PSA) and liquid oxygen technologies have been installed at a large scale. These technologies reduce the equivalent altitude by increasing oxygen availability. This study aims to perform a retrospective comparison between the use of both technologies during operation in ALMA at 5,050 m. In each condition, variables such as oxygen (O2), temperature, and humidity were continuously recorded in each AOS rooms, and cardiorespiratory variables were registered. In addition, we compared portable O2 by using continuous or demand flow during outdoor activities at very high altitudes. The outcomes showed no differences between production procedures (PSA or liquid oxygen) in regulating oxygen availability at AOS facilities. As a result, big-scale installations have difficulties reaching the appropriate O2 concentration due to leaks in high mobility areas. In addition, the PSA plant requires adequacy and maintenance to operate at a very high altitude. A continuous flow of 2–3 l/min of portable O2 is recommended at 5,050 m.

scholarly journals Steepened Mach waves near supersonic jets: study of azimuthal structure and generation process using conditional averages

2019 ◽  
Vol 880 ◽  
pp. 594-619 ◽  
Author(s):  
Pierre Pineau ◽  
Christophe Bogey
Keyword(s):  
Acoustic Waves ◽  
Large Scale ◽  
Flow Direction ◽  
Temporal Analysis ◽  
Wave Radiation ◽  
Flow Structures ◽  
Positive Pressure ◽  
Generation Process ◽  
Azimuthal Mode ◽  
Mach Waves

The azimuthal structure and the generation process of steepened acoustic waves are investigated in the near field of temporal round jets at Mach numbers of 2 and 3. Initially, the shear layers of the jets are in a laminar state and display instability waves whose main properties are close to those predicted from linear temporal analysis. Then, they transition to a turbulent state and generate high-intensity Mach waves displaying sharp compressions typical of those recorded for jets producing crackle noise. These waves are first shown to be poorly reproduced when only the axisymmetric mode is considered, but to be well captured with the first five azimuthal modes. Their generation process is investigated by performing conditional averages of the flow and acoustic fields triggered by the detection of intense positive pressure peak close to the jets. No steepened waves are visible in the conditionally averaged pressure profiles when the procedure involves only one azimuthal mode at a time. However, sharp compressions are obtained based on the first five modes taken together. In that case, the steep compressions are correlated over a limited portion of the jet circumference and are steeper as more azimuthal modes are considered. Moreover, a direct link is established between the steepened waves and the supersonic convection of large-scale coherent flow structures located in the supersonic core of the jets. This indicates that these waves constitute an extreme, nonlinear case of Mach wave radiation by these structures. In addition, the capacity of flow structures to generate sharp, steepened waves is related to their shapes. More particularly, flow structures with a large extent in the radial direction are shown to produce stronger and steeper Mach waves than those that are elongated in the flow direction.

Numerical Analysis and Optimization of Oxygen Separation from Air via Pressure Swing Adsorption

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
Seyyed M. Ghoreishi ◽  
Z. Hoseini Dastgerdi ◽  
Ali A Dadkhah
Keyword(s):  
Time Constant ◽  
Pressure Swing Adsorption ◽  
Separation Efficiency ◽  
Optimization Procedure ◽  
Air Separation ◽  
Oxygen Separation ◽  
13X Zeolite ◽  
Oxygen Generation ◽  
Pressure Swing ◽  
Energy And Momentum

A pressure swing adsorption air separation process in a commercial aircraft using 13X zeolite with a more complex cycle than the classic Skarstrom was simulated via a predictive dynamic model to evaluate and optimize oxygen generation system. The coupled mass, energy, and momentum differential equations were discretized using the implicit central finite-difference technique and the obtained equations were solved by Newton-Raphson method. The validated model in conjunction with an optimization procedure (Successive Quadratic Programming) was utilized to investigate the oxygen separation efficiency as a function of β (ratio between the bed time constant and the particle diffusion time constant), Cfp (purge orifice coefficient), θcycle (cycle time), Cff (feed valve), Cfe (exhaust valve) and pH* (high pressure operation). A set of optimum values (β=150, Cfp=0.7, θcycle=1.5, Cff=31, Cfe=52 and pH*=3.8) was obtained and recommended to achieve maximum recovery (0.26) at 98% purity.

Radial flow rapid pressure swing adsorption

Adsorption ◽  
1995 ◽  
Vol 1 (2) ◽  
pp. 153-164 ◽  
Author(s):  
A. S. T. Chiang ◽  
M. C. Hong
Keyword(s):  
Pressure Swing Adsorption ◽  
Radial Flow ◽  
Rapid Pressure Swing Adsorption ◽  
Pressure Swing ◽  
Rapid Pressure

Cyclotetrabenzoin Acetate: A Macrocyclic Porous Molecular Crystal for CO2 Separations by Pressure Swing Adsorption

2021 ◽  
Author(s):  
Yao-Ting Wang ◽  
Corie M. McHale ◽  
Xiqu Wang ◽  
Chung-Kai Chang ◽  
Yu-Chun Chuang ◽  
...  
Keyword(s):  
Molecular Crystal ◽  
Pressure Swing Adsorption ◽  
Gas Adsorption ◽  
Close Packing ◽  
Separation Performance ◽  
Mixed Gas ◽  
Water Tolerance ◽  
Pressure Swing ◽  
Breakthrough Experiments ◽  
Group Play

A porous molecular crystal (PMC) assembled by close-packing of macrocyclic cyclotetrabenzoin acetate is an efficient adsorbent for selective CO<sub>2</sub> capture. The 7.1´7.1 Å square pore of PMC and its ester C=O group play important roles in improving its affinity for CO<sub>2</sub> molecules. Thermodynamically, the benzene walls of macrocycle strongly promote CO<sub>2</sub> adsorption via [p···p] interactions at low pressure. In addition, the polar carbonyl groups pointing inward the square channels reduce the size of aperture to a 5.0´5.0 Å square, which offers kinetic selectivity for CO<sub>2</sub> capture. The PMC features water tolerance and high structural stability under vacuum and various gas adsorption conditions, which are rare among intrinsically porous organic molecules. In mixed-gas breakthrough experiments, it exhibits efficient CO<sub>2</sub>/N<sub>2</sub> and CO<sub>2</sub>/CH<sub>4</sub> separations under kinetic flow conditions. Most importantly, the moderate adsorbate–adsorbent interaction allows the PMC to be readily regenerated, and therefore applied to pressure swing adsorption (PSA) processes. The eluted N<sub>2</sub> and CH<sub>4</sub> are obtained with over 99.9% and 99.8% purity, respectively, and the separation performance is stable for 30 cycles. Coupled with its easy synthesis, these properties make cyclotetrabenzoin acetate a promising adsorbent for CO<sub>2</sub> separations from flue and natural gases.

Oxygen Enrichment through Mini-Scale Rotary Six-Bed Pressure Swing Adsorption

2013 ◽  
Vol 726-731 ◽  
pp. 780-788
Author(s):  
Li Qun Ding ◽  
Peng Cheng Shu
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Pressure Ratio ◽  
Generation Process ◽  
Feed Flow Rate ◽  
Ring Groove ◽  
Remarkable Effect ◽  
Rotating Speed ◽  
Oxygen Generation ◽  
Pressure Swing

This paper presents the structure for a rotary six-bed adsorber that carries out a six-step PSA continuous oxygen generation process with a short cycle time and a low operation pressure ratio. The working principle of a rotary six-bed PSA oxygen generator is introduced and the effects of various operating parameters on PSA performance are experimentally investigated. The results indicate that, the adsorption pressure increases with the reduction of rotating speed and decreases with the lowering of the feed flow rate; with the acceleration of rotating velocity, the oxygen purity of the gas produced first rises and then drops, and it has an optimum rotating velocity; the higher the feed flow rate, the lower the oxygen purity of the product; the ratio of the pressurization angle to the adsorption angle has a remarkable effect on the oxygen purity with the oxygen purity increasing according to the condition of keeping the angle of the feeding ring groove and with the increase in this ratio; and the long-purging time at a low purging-gas flow rate is appropriate for miniature apparatus.

Large-scale optimization strategies for pressure swing adsorption cycle synthesis

AIChE Journal ◽  
2012 ◽  
Vol 58 (12) ◽  
pp. 3777-3791 ◽  
Author(s):  
Alexander W. Dowling ◽  
Sree R. R. Vetukuri ◽  
Lorenz T. Biegler
Keyword(s):  
Pressure Swing Adsorption ◽  
Large Scale ◽  
Large Scale Optimization ◽  
Pressure Swing ◽  
Scale Optimization ◽  
Adsorption Cycle

Automating Model Generation for Image-Based Cardiac Flow Simulation

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Fanwei Kong ◽  
Shawn C. Shadden
Keyword(s):  
Mesh Generation ◽  
Large Scale ◽  
Cfd Simulation ◽  
Cfd Modeling ◽  
Patient Specific ◽  
Model Generation ◽  
Generation Process ◽  
Imaging Data ◽  
Modeling Framework ◽  
Geometry Processing

Abstract Computational fluid dynamics (CFD) modeling of left ventricle (LV) flow combined with patient medical imaging data has shown great potential in obtaining patient-specific hemodynamics information for functional assessment of the heart. A typical model construction pipeline usually starts with segmentation of the LV by manual delineation followed by mesh generation and registration techniques using separate software tools. However, such approaches usually require significant time and human efforts in the model generation process, limiting large-scale analysis. In this study, we propose an approach toward fully automating the model generation process for CFD simulation of LV flow to significantly reduce LV CFD model generation time. Our modeling framework leverages a novel combination of techniques including deep-learning based segmentation, geometry processing, and image registration to reliably reconstruct CFD-suitable LV models with little-to-no user intervention.1 We utilized an ensemble of two-dimensional (2D) convolutional neural networks (CNNs) for automatic segmentation of cardiac structures from three-dimensional (3D) patient images and our segmentation approach outperformed recent state-of-the-art segmentation techniques when evaluated on benchmark data containing both magnetic resonance (MR) and computed tomography(CT) cardiac scans. We demonstrate that through a combination of segmentation and geometry processing, we were able to robustly create CFD-suitable LV meshes from segmentations for 78 out of 80 test cases. Although the focus on this study is on image-to-mesh generation, we demonstrate the feasibility of this framework in supporting LV hemodynamics modeling by performing CFD simulations from two representative time-resolved patient-specific image datasets.

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