双切向环流式气体分布器结构优化数值模拟

Numerical Simulation of Structure Optimization of Double Tangential Circulating Gas Distributor

双切向环流式气体分布器因压力损失小、气体分布效果好、液沫夹带量小、综合性能优良而被广泛应用于填料塔内,但双切向环流式气体分布器存在局部气体流速小、回流现象明显的问题。因此,应该通过结构改进提高气体分布器的综合性能。利用FLUENT软件模拟双切向环流式分布器内的流场分布,分析产生不均性的原因。模型中塔段内壁直径为6000mm,入口直径为1220mm,内筒高1500mm,环形顶板宽度为500mm,距离分流板最近的导流叶片高450mm,其余导流叶片高度按照150mm等差递增;分布器内筒、环形顶板和导流叶片厚度均为10mm;导流叶片和分流板宽度与环形通道宽度一致,分流板高度与内筒高度一致。以分布器上端面为基准,分布器上下两段塔段均高2500mm。将此模型称为基准模型。在基准模型基础上,分别在分布器顶板上增加出气孔,调整分布器顶板宽度,调整分布器顶板位置,模拟调整后的内部流场分布,为分布器的结构优化设计提供方向。调整分布器顶板宽度能够有效降低分布器压力损失,提高气体均布性。当分布器环形顶板完全摘除时,分布器压力损失以及气体分布不均匀度相对于未做调整时分别下降29.24%与15.90%,分布器综合性能得到明显提升,因此可将摘除分布器顶板作为分布器结构改进的重要方向。在分布器环形顶板开孔能够在一定程度上降低分布器压力损失,提高气体均布性。顶板开孔后相比未开孔时压力损失最大降低18.04%,气体分布不均匀度最大降低9.10%。故环形顶板开孔可作为分布器结构改进的一个参考方向。调整分布器顶板位置对于降低分布器压力损失有一定积极作用,但对气体分布效果的提升作用有限,分布器压力损失以及气体分布不均匀度相对于未做调整时分别下降13.27%与4.62%,此种结构改进方法效果并不理想。

Double tangential circulating gas distributor is widely used in packed tower because of its low pressure loss,good gas distribution effect,small entrainment of liquid foam and excellent comprehensive performance.However,there are some problems in double tangential circulating gas distributor,such as low local gas flow rate and obvious reflux phenomenon.Therefore,the comprehensive performance of gas distributor should be improved by structural improvement.The Fluent software is used to simulate the flow field distribution of the double tangential circulating distributor,and the reasons of the unevenness are analyzed.In the model,the inner diameter of the tower section is 6 000 mm,the inlet diameter is 1 220 mm,the height of inner cylinder is 1 500 mm,the width of annular roof is 500 mm,the height of the nearest guide vane from the flow distribution plate is 450 mm,and the height of other guide vanes is increased by 150 mm.The thickness of the inner cylinder,annular roof and guide vanes of the distributor is 10 mm,the width of the guide vanes and the flow distribution plate is the same as the width of the annular passage,and the height of the flow distribution plate is consistent with the height of the inner cylinder.Based on the upper end face of the distributor,the length of upper tower and lower tower is 2 500 mm,and this model is called the benchmark model.Based on the benchmark model,the air holes on the distributor roof are added,the width of the distributor roof is adjusted and the position of the distributor roof is adjusted,and the optimized internal flow field distribution is simulated to provide the direction for the structural optimization design of the distributor.Adjusting the width of the distributor roof can effectively reduce pressure loss of the distributor and improve gas uniformity.When the annular roof of the distributor is completely removed,the pressure loss and gas distribution unevenness of the distributor decrease by 29.24%and 15.90%respectively compared with the unadjusted,and the comprehensive performance of the distributor is obviously improved.Therefore,the removal of the distributor roof can be taken as an important direction for the structural improvement of the distributor.Opening holes in distributor annular roof can reduce pressure loss of the distributor to a certain extent and improve gas uniformity.The pressure loss of the roof and the gas distribution unevenness after opening holes reduce by 18.04%and 9.10%compared with no opening holes.Therefore,the opening holes in annular roof can be used as a reference direction for the structural improvement of the distributor.Adjusting the position of the distributor roof has a positive effect on reducing pressure loss of the distributor,but it has a limited effect on improving the effect of gas distribution.The pressure loss of the distributor and the gas distribution unevenness decrease by 13.27%and 4.62%respectively compared with the unadjusted,and the effect of this structural improvement method is not ideal.