scholarly journals Numerical study of the dynamics and optimization of the modes of air adsorption separation and oxygen concentration

2019 ◽  
Vol 81 (1) ◽  
pp. 310-317
Author(s):  
E. I. Akulinin ◽  
O. O. Golubyatnikov ◽  
D. S. Dvoretsky ◽  
S. I. Dvoretsky
Keyword(s):  
Oxygen Concentration ◽  
Gas Flow ◽  
Numerical Study ◽  
Air Separation ◽  
Zeolite 13X ◽  
Wide Range ◽  
Cyclic Processes ◽  
Pressure Swing ◽  
Cyclic Adsorption ◽  
Adsorption Desorption

Numerical researches of influence of temperature, composition and pressure changes of the initial gas mixture on the purity, recovery and capacity of the pressure swing adsorption (PSA) unit was made. Air separation dynamics was researches in a wide range of control (pressure at the compressor outlet, the duration of the adsorption – desorption cycle, backflow coefficient, programs of control valves opening degree in time) variables. It was found that the change of regime parameters and the inflow on has a significant impact on the purity and recovery of oxygen. Also was founded that the range of the duration of the adsorption stage and the compressor outlet pressure values should be limited to the intervals of 39-43 s and 2.7–2.8?105 Pa, respectively. The steady-state of the PSA unit mode output time was amount 20-30 cycles of "adsorption-desorption". Formulated and solved the optimization tasks of regime parameters of air separation cyclic processes by criterion of maximum oxygen recovery in 2-bed PSA unit with granular adsorbent zeolite 13X; the optimal values of the control parameters for differential environmental conditions (when the product oxygen concentration not less than 45% vol. and the PSA unit capacity ~2 l/min) are determined. It is shown that the implementation of the optimal of the inlet and discharge valves opening degree changes program in PSA unit allows to provide the set values of the gas flow rate in the "frontal" layer of the adsorbent, in which there is no abrasion of the adsorbent in the cyclic adsorption–desorption processes

scholarly journals The Experimental Study of the Kinetics of the Cyclic Adsorption Process of Air Enrichment with Oxygen

2021 ◽  
Vol 27 (3) ◽  
pp. 387-400
Author(s):  
E. I. Akulinin ◽  
D. S. Dvoretsky ◽  
S. I. Dvoretsky
Keyword(s):  
Mass Transfer ◽  
Adsorption Process ◽  
Numerical Study ◽  
Air Separation ◽  
Diffusion Resistance ◽  
Kinetic Regime ◽  
Atmospheric Air ◽  
Mass Conductivity ◽  
Cyclic Adsorption ◽  
Kinetics Of

For mass transfer cyclic processes in the “adsorptive - porous adsorbent” system when air is enriched with oxygen by the method of short-cycle heatless adsorption, a new method has been implemented for determining the coefficients of mass transfer and mass conductivity of processes in systems with a solid phase from kinetic curves. It has been experimentally proved that during the adsorption separation of atmospheric air, the rate of cyclic “adsorption - desorption” processes can be limited by both internal and external diffusion resistance. The mass conductivity coefficients are determined depending on the mass content of the distributed adsorptive (O2, N2) by a method that does not require the implementation of the intradiffusion kinetic regime. The analysis of the kinetics of the process of air enrichment with oxygen is carried out; the coefficients of mass transfer and mass conductivity, which can be used in kinetic calculations and numerical study of the properties and modes of the cyclic adsorption process of atmospheric air separation and oxygen concentration, are determined.

scholarly journals Problems of analysis, optimization and control in the separation of gas mixtures

2018 ◽  
Vol 80 (2) ◽  
pp. 93-100
Author(s):  
E. I. Akulinin ◽  
O. O. Golubyatnikov ◽  
D. S. Dvoretskii ◽  
S. I. Dvoretskii
Keyword(s):  
Differential Equations ◽  
Mathematical Models ◽  
Relative Error ◽  
Synthesis Gas ◽  
Method Of Lines ◽  
Air Separation ◽  
Gas Mixture ◽  
Wide Range ◽  
Adsorption Desorption ◽  
Kinetics Of

Mathematical models of dynamics of pressure swing adsorption processes for the separation of synthesis gas (into hydrogen, carbon dioxide and carbon monoxide) and air (into oxygen, nitrogen and argon) have been developed. The models allow calculating the profiles of component concentrations and temperature of gas and solid phases, pressure and velocity of gas mixture along the height of adsorbent in relation to time. The models include the following equations: 1) processes of mass and heat transfer during the adsorption (desorption) of a sorptive (H2, CO2, COandO2, N2, Ar) by granulated zeolite adsorbents 5Aand13Х; 2) kinetics of compound diffusion transport of adsorbate and Langmuir-Freundlich isotherm (for the synthesis gas separation), kinetics of external diffusion and Dubinin-Radushkevich isotherm (for the air separation); 3) the Ergun equation for the calculation of pressure and velocity of gas mixture in adsorbent.The system of partial differential equations was solved by method of lines. The system of ordinary differential equations was solved by the fourth-order Runge-Kutta method with automatic step selection.To analyze the accuracy of mathematical models of the adsorption separation of synthesis-gas for recovery hydrogen, the relative error of the mismatch between the calculated values for the model and the experimental values of the concentration of the product (hydrogen, oxygen) in the 'steady state' (after 15-30 operating cycles of the PSA) was calculated. The maximum value of the relative error did not exceed 11.5%.Numerical studies were carried out in a wide range of changes in the time of the cycle "adsorption-desorption" and the pressure at the stage of adsorption to determine the effect of changes in temperature, composition and pressure of the initial gas mixture on the purity, recovery and temperature of production hydrogen and oxygen, as well as the relationship of the PSA unit capacity with the purity of the resulting product (hydrogen, oxygen). The problem of adaptive optimization of the process of adsorption separation of a gas mixture and obtaining hydrogen and oxygen with a maximum concentration was formulated and solved.The algorithmic and software of the automated adaptive control system was developed.

scholarly journals Optimization of Cyclic Adsorption Processes and Gas Mixture Separation Plants

2021 ◽  
Vol 27 (4) ◽  
pp. 599-614
Author(s):  
E. I. Akulinin ◽  
D. S. Dvoretsky ◽  
S. I. Dvoretsky
Keyword(s):  
Gas Flow ◽  
Reverse Flow ◽  
Initial Information ◽  
Mixture Separation ◽  
Product Gas ◽  
Adsorption Processes ◽  
Separation Of Gas Mixtures ◽  
Pressure Swing ◽  
Degree Of Extraction ◽  
Cyclic Adsorption

The analysis of the cyclic adsorption process and the installation of separation of gas mixtures by the method of pressure swing adsorption as an object of optimization have been carried out. The study found operating (control) variables (the duration of the adsorption stage, the pressure at the compressor outlet, the coefficient of reverse flow for the regeneration of the adsorbent, the program of changes in the opening time of the inlet and outlet valves of the installation); undefined parameters (composition, temperature and pressure of the initial gas-air mixture); output variables of the installation (concentration of oxygen, nitrogen in the product gas flow, the productivity of the installation, the degree of extraction and reduced costs for the production of oxygen with a given purity of 40 - 90 and higher vol.%). A one-stage problem of optimization of the regimes of a stationary periodic process of adsorption separation of atmospheric air and oxygen concentration was formulated and solved by the method of short-cycle adsorption under conditions of partial uncertainty of the initial information in the presence of restrictions on the purity of the product gas, the productivity of the installation and the rate of gas flow in the “frontal layer” of the adsorbent. An iterative algorithm for its solution is proposed.

scholarly journals The Study of Cyclic Adsorption Air Separation and Oxygen Concentration Processes

2019 ◽  
pp. 055-072
Author(s):  
V.G. Matveykin ◽  
◽  
E.I. Akulinin ◽  
N.V. Posternak ◽  
S.A. Skvortsov ◽  
...  
Keyword(s):  
Oxygen Concentration ◽  
Air Separation ◽  
Cyclic Adsorption

scholarly journals Simulation study of pressure swing adsorption to purify helium using zeolite 13X

2020 ◽  
Vol 3 (1) ◽  
pp. 1
Author(s):  
Ehsan Javadi Shokroo ◽  
Mehdi Farniaei ◽  
Mehdi Baghbani
Keyword(s):  
Flow Rate ◽  
Pressure Swing Adsorption ◽  
Gaseous Mixture ◽  
Operating Conditions ◽  
Feed Flow Rate ◽  
Zeolite 13X ◽  
Adsorption Step ◽  
Fully Implicit ◽  
Wide Range ◽  
Pressure Swing

A two-bed pressure swing adsorption system on a commercial type of zeolite 13X adsorbent has been studied numerically over a wide range of operating conditions to helium separation from gaseous mixture. The model includes energy, mass and momentum balances. The coupled partial differential equations are solved using fully implicit forth order Rung-Kutta scheme in the simulation. The effects of adsorption step pressure, adsorption step time and feed flow rate on the helium purity and recovery were investigated. Results shown that as the adsorption step pressure increases the helium purity will be increased. In addition, the helium recovery increases, and the helium purity decreases when the feed flow rate increases. Finally, the simulation results indicated a very good agreement with some current literature experimental work.

CO2 Capture onto Zeolite 13X and Zeolite 4A by Pressure Swing Adsorption in a Fixed Bed

2014 ◽  
Vol 592-594 ◽  
pp. 1456-1460 ◽  
Author(s):  
Lalhmingsanga Hauchhum ◽  
P. Mahanta
Keyword(s):  
Adsorption Capacity ◽  
Pressure Swing Adsorption ◽  
Fossil Fuels ◽  
Gas Adsorption ◽  
Fixed Bed ◽  
Fuel Gas ◽  
Zeolite 13X ◽  
Zeolite 4A ◽  
Pressure Swing ◽  
Adsorption Desorption

Combustion of fossil fuels is one of the major sources of greenhouse gas CO2, it is therefore necessary to develop technologies that will allow us to utilize the fossil fuels while reducing the emissions of greenhouse gases. Pressure swing adsorption (PSA) is a potential technique for removing CO2from high-pressure fuel gas streams. Zeolites are suitable candidate sorbents for use in the PSA process. Studies of the gas adsorption of CO2onto zeolite 13X and zeolite 4A were conducted at a temperature of 25 °C, 35 °C, 45 °C and 60 °C up to a pressure of 1 bar. The data fitting is accomplished with the Toth and Sips adsorption models which are generally used for micro-porous adsorbents such as zeolites. Moreover, regeneration studies have been conducted in order to verify the possibility of adsorbents reutilization, to determine its CO2adsorption capacity within consecutive cycles of adsorption–desorption. Zeolite with higher surface area showed higher CO2adsorption capacity. There is no full reversibility for the two zeolites.

scholarly journals Simulation Study of Pressure Swing Adsorption to Purify Helium Using Zeolite 13X

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Ehsan Javadi Shokroo ◽  
Mehdi Farniaei ◽  
Mehdi Baghbani
Keyword(s):  
Flow Rate ◽  
Pressure Swing Adsorption ◽  
Gaseous Mixture ◽  
Operating Conditions ◽  
Feed Flow Rate ◽  
Zeolite 13X ◽  
Adsorption Step ◽  
Fully Implicit ◽  
Wide Range ◽  
Pressure Swing

A two-bed pressure swing adsorption system on a commercial type of zeolite 13X adsorbent has been studied numerically over a wide range of operating conditions to helium separation from gaseous mixture. The model includes energy, mass and momentum balances. The coupled partial differential equations are solved using fully implicit forth order Rung-Kutta scheme in the simulation. The effects of adsorption step pressure, adsorption step time and feed flow rate on the helium purity and recovery were investigated. Results shown that as the adsorption step pressure increases the helium purity will be increased. In addition, the helium recovery increases, and the helium purity decreases when the feed flow rate increases. Finally, the simulation results indicated a very good agreement with some current literature experimentally work.

scholarly journals A single-ligand ultra-microporous MOF for precombustion CO2capture and hydrogen purification

2015 ◽  
Vol 1 (11) ◽  
pp. e1500421 ◽  
Author(s):  
Shyamapada Nandi ◽  
Phil De Luna ◽  
Thomas D. Daff ◽  
Jens Rother ◽  
Ming Liu ◽  
...  
Keyword(s):  
Binding Sites ◽  
Metal Organic Frameworks ◽  
Binding Energies ◽  
Hydrogen Purification ◽  
Zeolite 13X ◽  
Gas Streams ◽  
Surface Areas ◽  
Metal Organic ◽  
Pressure Swing ◽  
Adsorption Desorption

Metal organic frameworks (MOFs) built from a single small ligand typically have high stability, are rigid, and have syntheses that are often simple and easily scalable. However, they are normally ultra-microporous and do not have large surface areas amenable to gas separation applications. We report an ultra-microporous (3.5 and 4.8 Å pores) Ni-(4-pyridylcarboxylate)2with a cubic framework that exhibits exceptionally high CO2/H2selectivities (285 for 20:80 and 230 for 40:60 mixtures at 10 bar, 40°C) and working capacities (3.95 mmol/g), making it suitable for hydrogen purification under typical precombustion CO2capture conditions (1- to 10-bar pressure swing). It exhibits facile CO2adsorption-desorption cycling and has CO2self-diffusivities of ~3 × 10−9m2/s, which is two orders higher than that of zeolite 13X and comparable to other top-performing MOFs for this application. Simulations reveal a high density of binding sites that allow for favorable CO2-CO2interactions and large cooperative binding energies. Ultra-micropores generated by a small ligand ensures hydrolytic, hydrostatic stabilities, shelf life, and stability toward humid gas streams.

Comparative study of zeolite 5A and zeolite 13X in air separation by pressure swing adsorption

2016 ◽  
Vol 33 (4) ◽  
pp. 1391-1401 ◽  
Author(s):  
Ehsan Javadi Shokroo ◽  
Danial Jafari Farsani ◽  
Hadiseh Khalilpour Meymandi ◽  
Nadia Yadollahi
Keyword(s):  
Comparative Study ◽  
Pressure Swing Adsorption ◽  
Air Separation ◽  
Zeolite 13X ◽  
Zeolite 5A ◽  
Pressure Swing

scholarly journals Optimization and analysis of pressure swing adsorption process for oxygen production from air under uncertainty

2020 ◽  
Vol 26 (1) ◽  
pp. 89-104 ◽  
Author(s):  
Evgeny Akulinin ◽  
Oleg Golubyatnikov ◽  
Dmitry Dvoretsky ◽  
Stanislav Dvoretsky
Keyword(s):  
Pressure Swing Adsorption ◽  
Gas Flow ◽  
Optimization Problem ◽  
Air Separation ◽  
Interval Uncertainty ◽  
Problem Solution ◽  
Resource Saving ◽  
Heat And Mass Exchange ◽  
Atmospheric Air ◽  
Pressure Swing

Pressure swing adsorption (PSA) units are widely used for atmospheric air separation and oxygen concentration. However, the efficiency of such installations is reduced due to accidental changes in the characteristics of the atmospheric air to be separated. The article formulates and solves the problem of optimizing the regimes of operation of PSA units with zeolite adsorbent 13X, according to the criterion of oxygen recovery rate in the conditions of interval uncertainty of composition, temperature and pressure of atmospheric air. The optimization problem also takes into account the fulfillment of the requirements on purity of oxygen, productivity of the unit and resource saving of granulated adsorbent from granule abrasion. It is proposed to provide adsorbent saving by limiting the speed of incoming flow in the frontal layer of the adsorbent by means of "soft" stepwise change of the degree of opening of control inlet and outlet valves of the unit. The problem (including the search for time change programs for the degree of opening of control valves) was solved with the use of the developed mathematical model of cyclic heat- and mass exchange processes of adsorption-desorption in a PSA unit and a heuristic iterative algorithm. The comparative analysis of the results of the optimization problem solution, with and without taking into account the constraint on the gas flow velocity in the frontal layer of the adsorbent, is carried out. The influence of the specified requirements for the performance of the PSA unit and the purity of oxygen on the degree of its recovery has been studied.

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