scholarly journals AIR SEPARATION BY PRESSURE SWING ADSORPTION USING SUPERIOR ADSORBENTS

2001 ◽  
Author(s):  
Ralph T Yang
Keyword(s):  
Pressure Swing Adsorption ◽  
Air Separation ◽  
Pressure Swing

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.

scholarly journals An Improved Method to Calculate the Conservation of Mass in the Simulation of Rapid Pressurization Depressurization in a Packed Bed

2008 ◽  
Vol 2 (1) ◽  
pp. 30
Author(s):  
Thomas S.Y Chong ◽  
William R. Paterson ◽  
David M. Scott
Keyword(s):  
Differential Equations ◽  
Pressure Swing Adsorption ◽  
Packed Bed ◽  
Air Separation ◽  
Simple Problem ◽  
Improved Method ◽  
Conservation Of Mass ◽  
Rapid Pressure Swing Adsorption ◽  
Pressure Swing ◽  
Rapid Pressure

The work described here forms part of a project to model rapid pressure swing adsorption (RPSA), which is a single-bed process used for air separation. We have earlier identified a form of model and boundary conditions for an axially dispersed plug flow model that conserves mass. We solve the RPSA models numerically by spatially discretizing the partial differential equations to a system of ordinary differential equations (ODEs), which are then integrated over time. Although the formulation of our models conserves mass, our numerical simulations, however, do not perfectly conserve mass because of discretization error and rounding error. The discrepancy in the conservation of mass is computed as a guide to the numerical accuracy of the calculations. The computation of the conservation error requires the evaluation of time integrals of molar flowrates in and out of the bed. Since the velocity at the feed end of the bed changes rapidly with time, the application of quadrature to evaluate the time integrals does not provide the accuracy required. In this paper, the inadequacy is demonstrated using a simple problem, i.e. pressurization and depressurization into a non-adsorptive bed. An improved method is proposed. By transforming equations involving time integrals into ODEs, excellent accuracy is obtained. Further, this transformation minimizes the number of decision parameters that need to be specified by the users of the computer programs. Keywords: rapid pressure swing adsorption, modelling and simulation, packed bed.

Analysis and Optimization of a Pressure-Swing Adsorption Process for Air Separation

2005 ◽  
Vol 31 (6) ◽  
pp. 441-449 ◽  
Author(s):  
Masatoshi Yoshida ◽  
Pathiphon Koompai ◽  
Yoshiyuki Yamashita ◽  
Shigeru Matsumoto
Keyword(s):  
Pressure Swing Adsorption ◽  
Adsorption Process ◽  
Air Separation ◽  
Pressure Swing

scholarly journals Air Separation Characteristics of Pressure Swing Adsorption Apparatus using Molecular Sieving Carbon.

1993 ◽  
Vol 19 (2) ◽  
pp. 162-168
Author(s):  
Chisato Marumo ◽  
Eiji Hayata ◽  
Niro Shiomi ◽  
Kenji Kojima ◽  
Fujio Watanabe ◽  
...  
Keyword(s):  
Pressure Swing Adsorption ◽  
Air Separation ◽  
Pressure Swing ◽  
Molecular Sieving

On the Numerical Simulation of Rapid Pressure Swing Adsorption for Air Separation

2012 ◽  
Author(s):  
Thomas S. Y. Choong ◽  
William R. Paterson ◽  
David M. Scott
Keyword(s):  
Numerical Simulation ◽  
Differential Equations ◽  
Pressure Swing Adsorption ◽  
Air Separation ◽  
Orthogonal Collocation ◽  
Conservation Of Mass ◽  
Rapid Pressure Swing Adsorption ◽  
Spatial Discretisation ◽  
Pressure Swing ◽  
Rapid Pressure

Model penjerapan buai tekanan deras yang konsisten (RPSA) secara fizikal telah dibangunkan oleh Choong (2000). Model ini boleh diselesaikan secara berangka dengan menjelmakan persamaan kebezaan biasa (ODE). Seterusnya, sistem ODE dikamirkan terhadap masa. Dua kaedah pendiskretan ruang dipertimbangkan, iaitu kaedah penempatan bersama ortogon (OC) dan penempatan bersama ortogon terhadap unsur terhingga (OCFE). Program penyelakuan RPSA disahkan menggunakan model proses supaya dapat dibandingkan keputusan berangka dengan penyelesaian keserupaan yang diperoleh oleh Scott (1991), bagi penekanan dan penyahtekanan udara terhadap lapisan penjerapan separuh tak terhingga. Ralat keabadian jisim digunakan sebagai pengukur kepada kejituan pengiraan berangka. Bagi menjamin hasil pengiraan keabadian jisim yang jitu, semua kamiran masa dijelmakan kepada ODE. Dengan jelmaan ini, kejituan pengiraan berangka hanya bergantung kepada pendiskretan ruang dan had terima yang digunakan dalam algoritma pengamiran ODE. Kesan pendiskretan ruang dan nilai had terima yang digunakan dalam penyelesaian ODE (TOL) terhadap ketepatan keputusan berangka dan masa pemprosesan komputer dikaji. Suatu sekaitan untuk mengganggar TOL dicadangkan. Walaupun kaedah OC memerlukan masa pengkomputeran yang lebih panjang, tetapi keputusan yang dihasilkan lebih jitu berbanding kaedah OCFE. Kaedah OC sesuai digunakan untuk projek masa depan kami seperti membangunkan ciri algoritma bagi proses berkitar. Kata kunci: Penjerapan buai tekanan deras; pemodelan; penyelakuan berangka; pemisahan udara The physically consistent rapid pressure swing adsorption (RPSA) models developed by Choong are solved numerically by spatially discretisating the partial differential equations (PDEs) to a system of ordinary differential equations (ODEs), which are then integrated over time. Two spatial discretisation methods are considered, i.e. the methods of orthogonal collocation (OC) and orthogonal collocation on finite elements (OCFE). The RPSA simulation programs are validated by simplifying the process models to compare the numerical results with similarity solutions obtained by Scott for air pressurisation and depressurisation into a semi–infinite adsorbing bed. The error in conservation of mass is computed as a guide to the numerical accuracy of the calculations. To ensure good accuracy in the calculation of conservation of mass, we transform all the time integrals into ODEs. With the transformation, the accuracy of the numerical calculations depends only on the spatial discretisation and the tolerance used in the ODE integration algorithm. The effect of the spatial discretisation and the value of TOL on the accuracy of the numerical results and the computer processing time is studied. A rule of thumb to estimate the value of TOL is proposed. The method of OC is found to give accuracy comparable to that of the method of OCFE, albeit requiring more computing time. We consider the method of OC sufficient for the purpose of our future work, i.e. to develop novel algorithm features for cyclic processes. Key words: Rapid pressure swing adsorption; modelling; numerical simulation; air separation

Design of a Moderate Speed-High Capacity Centrifugal Compressor With Application to PSA and VPSA Air Separation Processes

2005 ◽  
Author(s):  
Ahmed Abdelwahab
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Swing Adsorption ◽  
Low Cost ◽  
High Capacity ◽  
Operating Conditions ◽  
Air Separation ◽  
Guide Vanes ◽  
Inlet Guide Vanes ◽  
Process Machinery ◽  
Pressure Swing

The performance of the PSA (Pressure Swing Adsorption) or VPSA (Vacuum Pressure Swing Adsorption) cycle in an oxygen air separation process is significantly dependent upon the working capacity and working selectivity afforded by the adsorbent. These parameters in turn are dependent on the adsorption pressures employed in the VPSA cycle. Despite the increasing demand for increased capacity and pressure in VPSA air separation plants, they have conventionally used rotary-type positive displacement blowers as the process machinery. These blowers, while most adapted to the oscillating nature of the pressure swing cycles, have increasing high cost per capacity at higher capacities and become very inefficient as the cycle pressures are increased. A new low cost and more efficient process machinery solution is introduced through the use of a moderate speed direct coupled integrated feed and vacuum centrifugal compressor with inlet guide vanes to achieve high efficiencies during the varying operating conditions of the VPSA cycle. In this paper the fundamentals of a VPSA cycle as it applies to a centrifugal compressor operation is presented. A model of the design and predicted performance of a feed and vacuum VPSA centrifugal compressor is presented. A discussion of the proposed design in comparison to a conventional blower is presented. The model and predictions indeed show the superiority of the new design concept to the conventional process machinery equipment in terms of power savings and capacity increase. This new design however requires a feedback control system for the inlet guide vanes.

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