吸附脱汞中活性炭输送管路的设计与模拟

Design and Numerical Simulation of Activated Carbon Transport Pipeline for Adsorption Mercury Removal

燃煤源汞是造成大气汞污染的重要原因。利用活性炭进行吸附脱汞是目前重点研究的汞污染控制技术。在通过管路将活性炭送入烟道的过程中,必须保证活性炭的量严格按照要求进行分配。文中通过理论分析与CFD数值模拟,考察了二叉树型管路、多叉树型管路和线型管路在活性炭均匀分配上的效果,并讨论了其应用的条件。研究认为,线型管路无论对连续相还是离散相都难以做到均匀分配;多叉树型管路(典型的如三叉树、四叉树)可以做到均匀分配,并且有一定的灵活性,最适宜在实际工业中应用;二叉树型管路只有在确保管路对称性的情况下才能得到较好的均分活性炭效果,且灵活性较差。此外研究还发现,活性炭颗粒在流场中的运动较为复杂,受包括时间在内的诸多参数影响,且管路非对称性对颗粒分布的影响大于其对流场分布的影响。如对均分的要求较为严格,须加装颗粒浓度实时监测装置与控制装置。

coal combustion is the major reason for mercury pollution of atmosphere. Adsorption technology is a main mercury control technologies under study. To ensure the exact mass distribution of activated carbon particles in different inlets, the transport pipeline must be carefully designed. Based on theoretical analysis and numerical simulation of computational fluid dynamics （CFD）, this paper investigated the pipeline allocation efficiency of binary tree type, multi tree type and linear type, and discussed their application conditions. Studies indicate that linear pipeline is hard to allocate uniformly for neither discrete phase nor continuous phase; multi tree type （i.e. triple type, quad type etc.） has advantages of uniform allocation and flexibility, and is suitable for industrial application; binary type pipeline has good uniformity of activated carbon for only symmetrical pipeline arrangement, and lacks of flexibility. In addition, studies show that activated carbon particles are of complex motion in flow field, and influenced by multiple parameters including time; moreover, pipeline asymmetry has more influence on particle distribution than flow field distribution. Real-time monitoring devices and control devices are required with the strict need for uniformity.