Water. Desalination + reuse
Issue link: https://fhpublishing.uberflip.com/i/670678
outlined challenges. In a first step, basic feed spacer geometries were evaluated, using 3D printed samples. Next, detailed CFD (computational fluid dynamics) calculations towards decreasing pressure drop and minimized low flow areas were made. Low velocity areas, seen as the starting point for biofouling for example, were calculated, making use of feed spacers with equal strands, alternating strands and bottleneck type strands (Figure 3). The basic results of these calculations are summarized in Figure 4, and show that the system of alternating strand type feed spacers are well balanced with regard to pressure drop while minimizing areas of low feed water velocity. To prove the performance of alternating strand design feed spacers, a number of different feed spacer types, produced using large scale netting production technology, were tested in a flow cell measurement program. The pressure drop performance was evaluated. The feed spacer samples were installed in a special flow cell and tested using different conditions ( e.g. feed flow, time or fouling conditions). A selection of tested feed spacer materials is shown in Figure 5 along with corresponding pressure drop results in Figure 6 at a given flow rate of 20 l/h. This research confirmed the enhanced pressure drop performance of feed spacer material based TECHNOLOGY Figure 3 Figure 4 Figure 6 | 20 | Desalination & Water Reuse | May-June 2016 Co-research project leads to optimized feed spacer geometry called Alternating Strand Design (ASD) Based on the above knowledge, a co-research project was initiated to develop a novel feed spacer technology addressing the Figure 5 on the new alternating strand design (ASD) technology. The RO elements constructed with such an innovative spacer geometry achieve a lower pressure drop than commercially available feed spacers based on equal strands. This leads to savings in energy consumption. In addition, the new ASD type spacer shows a finely tuned flow pattern resulting in reduced low flow areas, thought to reduce biofouling tendency. This reduced biofouling tendency can be seen as an improvement towards increased membrane life, and lower cleaning frequency, of such RO membrane elements.