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Pressure swing adsorption (PSA) is a well-established gas separation technique in air separation, gas drying, and hydrogen purification separation. Recently, PSA technology has been applied in other areas like methane purification from natural and biogas and has a tremendous potential to expand its utilization. It is known that the adsorbent material employed in a PSA process is extremely important in defining its properties, but it has also been demonstrated that process engineering can improve the performance of PSA units significantly. This paper aims to provide an overview of the fundamentals of PSA process while focusing specifically on different innovative engineering approaches that contributed to continuous improvement of PSA performance.
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... PSA is a cyclic adsorption technique that separates gas species based on their sorption rates [21,28]. Extensive research has already been conducted to develop PSA technology for gas separation and purification [29,30]. Numerous adsorbents are used in PSA technology to adsorb the target gas molecules, including carbon molecular baskets (CMB), porous carbon, carbon molecular sieves (CMS), carbon nanotubes (CNTs), zeolites, graphene, and metal-organic frameworks (MOFs) for industrial or research applications [31][32][33]. ...
Article
Waste polymer materials offer a lot of promise for recycling or enhancement in terms of the environment. HCPs (hypercrosslinked polymers) are an excellent contender for recycling polymers in environmental applications. We employed waste-expanded polystyrene and waste polycarbonate as precursors to make HCPs adsorbents for O2/N2 adsorption. Characterization analysis were performed to determine the adsorbents' morphology and structure. The fine adsorbent was waste-expended polystyrene which had been synthesized at 45 °C for 12 h and had a surface area of 802.84 (m²/g), an average pore diameter of 2.86 nm, and a micropore volume of roughly 184.46 (cm³/g). The Sips isotherm and Elovich kinetic models provided the best agreement (R² = 0.9994), according to experimental data. At 5 °C and 10 bar, the fine adsorbent had the highest O2 and N2 adsorption, with 12.78 and 7.67 (mmol/g), respectively. Eventually, the kinetic evidence demonstrated that the process physically occurred. Over nine cycles, the sorbent's ability for adsorption decreased by about 5%, indicating a high degree of reusability for air separation. The method described in this study can be considered a promising approach to air separation and purification by eco-friendly hypercrosslinked polymers.
... As such, the PSA performance under cyclic steady state [130] can be equivalent to steady-state. Additionally, the time scale of a PSA cycle (~10 min) [173] is much shorter than the start-up of chemical plants (~days) [174]. Therefore, the overall system can be considered to operate under a steady-state condition. ...
Thesis
Achieving a carbon-neutral, or “net zero” society requires a transition from fossil fuels to low-carbon solutions. However, fossil fuels supply approx. 80% of today’s worldwide energy demand and are projected to play an indispensable role in the immediate future [1]. Carbon capture may be the most effective way to decarbonize the fossil fuel-based energy sector. Carbon capture consists of two major fields: carbon capture and storage (CCS) as well as carbon capture and utilization (CCU). While CCS is more relevant to electricity production, CCU is compatible with the existing downstream processes of the oil and gas industry – the chemicals sector. CCU will be the focus in this thesis. Optimization is applied to explore the maximum performance of CCU. CCU contains multiple process options in both the capture and the utilization sections, eventually resulting in a large multi-process system. Optimizing such a multi-process system can be challenging because of the problem scale and its complexity. The problem scale is significantly larger than a single process and would be challenging to most existing optimization approaches; complexity comes from high-level interactions between sub-systems and the nonlinearity of the individual sub-systems. Optimizing a sub-system before extending it to the whole CCU system can lead to a sub-optimal solution due to the reduced decision space. Using one simulation result to represent a sub-system can neglect the complexity/nonlinearity of the individual processes. In this thesis, I intend to: (1) avoid sub-optimal solutions by simultaneously optimizing the CCU sub-systems, and (2) use surrogates to represent sub-systems to keep a certain complexity/nonlinearity of sub-systems. This thesis is divided into two parts. Part I is methodology development, engaged in identifying suitable surrogate types for CCU sub-systems and how to obtain surrogates in an efficient way. The methodology development lays the foundation for an optimization framework for large multi-process systems. The optimization framework consists of three levels. Level 1 decomposes a large system into several sub-systems, which are digitalized by rigorous process models. Level 2 replaces rigorous process models with machine learning-based surrogates, as to efficiently evaluate mass and energy balances. Level 3 performs surrogate-based optimization. This optimization framework includes the interactions of sub-systems and optimizes sub-systems simultaneously. Part II is concerned with problem-solving, focusing on optimizing a CCU system (by the three-level optimization framework), where no renewables are involved. The result shows that CCU may be worse for greenhouse gas (GHG) emissions than the conventional (unabated gas) process, if operating conditions are not properly set. Single-objective optimization enables CCU to effectively reduce GHG emissions, and electrifying heating can further cut GHG emissions. Additionally, multi-objective optimization enables CCU to balance the competing criteria between environmental and economic aspects. The methodology developed in this thesis can be applied to other multi-process systems. In the long term, net zero needs various low-carbon pathways, which might integrate different sectors and form multi-process systems. While their decarbonization performances are enhanced by optimization, the overall progress of net zero will be accelerated. [1] International Energy Agency, Net Zero by 2050: A roadmap for the global energy sector, 2021.
... The principle is widely used in oxygen concentrators, but is inversely applied in the case of hypoxicators. Instead of oxygen-rich air, the resultant hypoxic gas is administered to the patient [45]. The hypoxicator is connected via medical-grade tubes to two large (> 50L) reservoir air bags that buffer the hypoxic gas mixture, which optimizes stability of the delivered FiO2. ...
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... The process is well-established and has been widely applied for industrial separation processes, such as air separation, drying, and hydrogen purification. Progress in terms of material development and cycle design have led to major improvements as well as new applications, such as the upgrading of biogas and natural gas [13]. The PSA process is commonly used as the final purification step in a helium recovery plant to produce ultrahigh grade (>99.995 ...
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Conference Paper
Biogas is a highly potential renewable fuel source substituting fossil-based natural gas. To commercialize biomethane, biogas purification systems via selective removal of CO2 are a crucial step for the production of biomethane. Technologies based on pressure swing adsorption (PSA) are widely used and achieve promising results, such as water scrubbing, membrane separation, cryogenic processes, chemical absorption, and physical absorption. This review describes the potential of PSA as a technology to separate CO2 from biogas to purify biomethane. PSA is an efficient technology for biogas purification having a low energy penalty, low cost and a safe operation. Nowadays, different biomethane purification technologies are operated, such as cryogenic separation, membrane operations and absorptive separation. The PSA process, as one of the main technology, and its concepts are described. Then, the main process engineering approaches for efficient biogas purification are analyzed. Different adsorbents are compared and key process performance variables are evaluated. Next, the results of different studies on adsorption materials and the yield of real examples as well as the current research trends and improvement potentials are presented and discussed.
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Chapter
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