Novel adsorbent hollow fibres for oxygen concentration

Abstract

The research examined the development of adsorbent hollow fibres as a low pressure drop structure for the production of oxygen-enriched air. The potential benefits of using a low pressure drop flexible adsorbent structure with molecular sieving properties over a bed packed with pellets include a low attrition resistance which could extend the life of the adsorbent structure. Highly macroporous, highly adsorbent loaded (up to 90 wt%) fibres were produced. By increasing adsorbent density, the separative performance and nitrogen loading were improved. The separative performance of the adsorbent fibre was found to be slightly inferior to that of the bed of smaller 0.4-0.8 mm beads, as the diffusion path length was longer in the fibres and caused increased mass transfer resistances within the macroporous structure. The pressure drop through the fibre was found to be 40 to 70 times lower than that through an equivalent packed bed of 0.4-0.8 mm beads. This experimental feasibility study has demonstrated that the novel zeolite fibre configuration shows good potential for the production of oxygen-enriched air in a low energy, short cycle time, pressure swing process. The challenges of improving the performance of the adsorbent fibres and their operating parameters are described.

Functional Hollow Fiber Adsorbent Materials with a Self-Regulating Composite Outer Layer for Gas Purification with Energy Efficient Electrothermal Regeneration

“…Experimental and theoretical studies have shown that parallel passage adsorbent contactors, such as hollow fibers, are preferable to traditional packed beds for applications where pressure drop is important . Hollow fibers comprising polymers and inorganic porous materials have been prepared by a variety of spinning methods − and are potential alternatives to the use of packed bed adsorbents. ,− Thin fiber walls allow rapid heat transfer, while the hollow fiber structure provides rapid mass transfer and minimizes pressure drop. , Hollow fibers may be spun in multiple layers thereby allowing materials with a wide range of properties to be developed. A hollow fiber adsorption system with rapid heating using a suitable electrically conducting material for regeneration and rapid cooling due to the low thermal mass has major advantages compared to existing packed bed technology.…”

Extruded monoliths for gas separation processes: Height equivalent to a theoretical plate and pressure drop correlations

“…Analytical expressions for w c can be derived from the equation above as a function of the system's characteristic length. For rounded geometries, the corrected thickness has to be calculated from Equation (10), which equates the area of the solid around the channel, A S , to the area of the solid surrounding a hollow cylinder with the same free cross-section:…”

“…In gas separation processes, structured adsorbents can achieve better performance in terms of pressure drop with high gas or liquid velocities and faster cycle times than packed bed adsorption columns 1–3,6 . Some structured adsorbent applications in gas separation processes are carbon capture, 7–9 air separation, 10,11 VOC removal, 12–14 and desiccant cooling 15,16 …”

“…In gas separation processes, structured adsorbents can achieve better performance in terms of pressure drop with high gas or liquid velocities and faster cycle times than packed bed adsorption columns. [1][2][3]6 Some structured adsorbent applications in gas separation processes are carbon capture, [7][8][9] air separation, 10,11 VOC removal, [12][13][14] and desiccant cooling. 15,16 Several types of structured adsorbents have been reported in the literature, such as foams, 17,18 fibers, 7,19 and laminates, 2,20,21 as potential candidates to overcome the limitations of packed beds to handle high flows and good thermal management.…”

Facilitating green ammonia manufacture under milder conditions: what do heterogeneous catalyst formulations have to offer?

“… 19 Consequently, reforming processes with mediocre thermal efficiencies are only economical on a large scale. 25,26 With regards to nitrogen supply for ammonia synthesis, while hollow fibre-based membranes enable efficient air separation on all scales, 27 conventional air separation units (ASU) that provide nitrogen for many ammonia synthesis plants have also been found to benefit from economies of scale. 17,20 Therefore, the conventional ammonia manufacturing process as a whole is ideally suited for large-scale operation.…”