State Key Laboratory of Fine Chemicals, R&D Center of Membrane Science and Technology, School of Chemical Engineering, Dalian University of Technology, 2 Linggong Road, Dalian 116024, China.
Water Res. 2012 May 15;46(8):2535-44. doi: 10.1016/j.watres.2012.02.002. Epub 2012 Feb 9.
The use of turbulence promoter can effectively enhance the permeate flux in crossflow microfiltration (CFMF) of particulate suspensions. Flux enhancement which is generally attributed to the reduction in cake thickness, however, has still not been clearly understood. In this study, the effects of turbulence promoter on cake properties (thickness, porosity and particle size) were investigated during CFMF of calcium carbonate suspension. It indicates that turbulence promoter has important effects on cake properties that directly affect the cake resistance. The significant reduction in thickness and slight increase in porosity are positive to reduce the cake resistance. The remarkable decrease in particle size is the negative effect due to the increased specific resistance of a cake. As a whole, the overall cake resistance is still diminished by turbulence promoter and therefore permeate flux is improved. The theoretical calculation of cake resistance shows a good consistence with the experimental result. The cake properties in both cases (using a turbulence promoter or not) almost exhibit the similar trends under various operating conditions. Differently, the use of turbulence promoter can greatly alleviate the effects of transmembrane pressure or feed concentration on growth of cake layer and intensify the effects of inlet velocity on diminishing the particle deposition.
在颗粒悬浮液的错流微滤（CFMF）中，使用湍流促进剂可以有效地提高渗透通量。通量的增强通常归因于滤饼厚度的减小，但仍未得到清楚的理解。在这项研究中，研究了湍流促进剂在碳酸钙悬浮液的 CFMF 过程中对滤饼性质（厚度、孔隙率和粒径）的影响。结果表明，湍流促进剂对直接影响滤饼阻力的滤饼性质有重要影响。厚度的显著减小和孔隙率的轻微增加有利于降低滤饼阻力。粒径的显著减小是由于滤饼的比阻力增加而产生的负面影响。总的来说，由于湍流促进剂的存在，整体滤饼阻力仍然降低，因此渗透通量得到提高。滤饼阻力的理论计算与实验结果具有很好的一致性。在各种操作条件下，无论是使用湍流促进剂还是不使用，滤饼性质几乎都呈现出相似的趋势。不同的是，使用湍流促进剂可以大大减轻跨膜压力或进料浓度对滤饼层生长的影响，并增强入口速度对减少颗粒沉积的影响。
