搅拌槽内高粘度流体混合性能实验研究及数值模拟
发布时间：2018-12-17 14:50
【摘要】：在工业生产中,经常出现某种工艺流程在不同的反应阶段物料粘度变化范围很宽的情况,传统高粘度流体混合搅拌桨,如螺带式桨、锚式桨、最大叶片式桨,在过渡域及湍流域内的混合效率较低；而湍流域常用搅拌桨,如直叶桨、斜叶桨、涡轮桨等在高粘度流体中作用区范围有限,无法达到全槽循环流动。目前,多层较大桨径的开式桨组合操作方式被提出应用于上述工况。本文以FCC催化剂生产工艺为背景,采用较大桨径的三叶后掠式桨与CBY桨的组合桨搅拌型式,对不同参数的三叶后掠桨及其与CBY桨组合操作的功率及混合特性进行实验研究和数值模拟。实验采用内径为476 mm的椭圆封头搅拌槽,选取不同粘度的糖浆水溶液作为模拟物料,液位H/T=1.0。改变三叶后掠式桨的叶轮直径D,‘曲率半径厂,叶根角θ,叶片宽度w等参数,研究几何参数改变对三叶后掠式桨及组合桨搅拌功率及混合特性的影响；此外利用CFX数值模拟软件,对层流域及湍流域内,不同几何参数的三叶后掠桨流型、速度分布及不同直径三叶后掠桨的作用范围进行研究。实验结果表明：层流域内,D/T=0.7的三叶后掠式桨沿径向的作用范围可以达到槽壁,轴向作用范围可达H有效/D=0.8；三叶后掠桨的曲率半径和叶轮宽度的增加,均会使搅拌桨的功率准数增加,而叶根角的增大使得功率准数减小；通过功率及混合性能测试,叶根角为200的三叶后掠式桨混合效率最高。推荐采用三叶后掠式桨(D/T=0.7, r/D=0.333,θ=20°)与CBYW桨的双层组合桨形式应用于FCC催化剂生产等类似工业过程生产中。利用CFX软件进行的数值模拟发现：对于层流域的流场而言,单层三叶后掠搅拌桨沿径向的作用范围约为1.4倍的搅拌桨直径。层流域内,D/T小于0.7时,在槽壁附近将存在流动死区。另外,增加三叶后掠桨的曲率半径r对流场的影响不大,但叶根角的增大,可以提高三叶后掠搅拌桨的轴向循环能力,较高速流体(V0.2VTS)区域的轴向高度可增加10%。
[Abstract]:In industrial production, there is often a situation in which the viscosity of materials varies widely in different reaction stages. Traditional high viscosity fluid mixing propellers, such as propellers, anchor propellers, maximum vane propellers, are often used in industrial production. The mixing efficiency in transition region and turbulent basin is low. However, in the turbulent domain, the impeller, such as the straight blade propeller, the oblique blade propeller, the turbine impeller and so on, have a limited range of action zones in the high viscosity fluid, so they can not reach the circulating flow in the whole tank. At present, the open propeller combined operation mode with multi-layer and large diameter has been proposed to be applied to the above working conditions. In this paper, based on the production process of FCC catalyst, the combined propeller type with large impeller diameter is adopted, which is composed of three blade backswept propeller and CBY propeller. The experimental study and numerical simulation of the power and mixing characteristics of the three-leaf swept back propeller with different parameters and its combined operation with CBY propeller are carried out. In the experiment, an elliptical head stirring tank with an inner diameter of 476 mm was used, and syrup aqueous solution with different viscosity was selected as the simulation material, and the liquid level was 1.0. The influence of geometric parameters on the stirring power and mixing characteristics of the three-leaf swept impeller and combined impeller was studied by changing the parameters such as the diameter of the impeller D 'curvature radius factory, the angle 胃 of the blade root and the width w of the blade. In addition, the flow pattern, velocity distribution and the action range of trifoliate impeller with different geometric parameters in the layer basin and turbulent region are studied by using CFX software. The experimental results show that the radial range of D/T=0.7 three-leaf swept propeller can reach the groove wall, and the axial action range can reach H effective / D0. 8; The increase of the radius of curvature and the width of impeller will increase the power number of the impeller, but the increase of the blade root angle will decrease the power criterion. According to the test of power and mixing performance, the mixing efficiency is the highest when the blade root angle is 200. It is recommended that the double-layer combined propeller with CBYW propeller (D / T _ (0.7), r / D _ (0.333), 胃 = 20 掳) should be used in the production of FCC catalyst and other similar industrial processes. The numerical simulation with CFX software shows that for the flow field of the watershed, the radial action range of the single-layer three-leaf swept impeller is about 1.4 times of the diameter of the impeller. When D / T is less than 0.7, there will be a dead zone near the trough wall. In addition, increasing the curvature radius r of the impeller has little effect on the flow field, but the axial circulation ability of the impeller can be improved by increasing the blade root angle, and the axial height of the impeller can be increased by 10% than that of the high speed fluid (V0.2VTS) region.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ027.2
本文编号：2384347
[Abstract]:In industrial production, there is often a situation in which the viscosity of materials varies widely in different reaction stages. Traditional high viscosity fluid mixing propellers, such as propellers, anchor propellers, maximum vane propellers, are often used in industrial production. The mixing efficiency in transition region and turbulent basin is low. However, in the turbulent domain, the impeller, such as the straight blade propeller, the oblique blade propeller, the turbine impeller and so on, have a limited range of action zones in the high viscosity fluid, so they can not reach the circulating flow in the whole tank. At present, the open propeller combined operation mode with multi-layer and large diameter has been proposed to be applied to the above working conditions. In this paper, based on the production process of FCC catalyst, the combined propeller type with large impeller diameter is adopted, which is composed of three blade backswept propeller and CBY propeller. The experimental study and numerical simulation of the power and mixing characteristics of the three-leaf swept back propeller with different parameters and its combined operation with CBY propeller are carried out. In the experiment, an elliptical head stirring tank with an inner diameter of 476 mm was used, and syrup aqueous solution with different viscosity was selected as the simulation material, and the liquid level was 1.0. The influence of geometric parameters on the stirring power and mixing characteristics of the three-leaf swept impeller and combined impeller was studied by changing the parameters such as the diameter of the impeller D 'curvature radius factory, the angle 胃 of the blade root and the width w of the blade. In addition, the flow pattern, velocity distribution and the action range of trifoliate impeller with different geometric parameters in the layer basin and turbulent region are studied by using CFX software. The experimental results show that the radial range of D/T=0.7 three-leaf swept propeller can reach the groove wall, and the axial action range can reach H effective / D0. 8; The increase of the radius of curvature and the width of impeller will increase the power number of the impeller, but the increase of the blade root angle will decrease the power criterion. According to the test of power and mixing performance, the mixing efficiency is the highest when the blade root angle is 200. It is recommended that the double-layer combined propeller with CBYW propeller (D / T _ (0.7), r / D _ (0.333), 胃 = 20 掳) should be used in the production of FCC catalyst and other similar industrial processes. The numerical simulation with CFX software shows that for the flow field of the watershed, the radial action range of the single-layer three-leaf swept impeller is about 1.4 times of the diameter of the impeller. When D / T is less than 0.7, there will be a dead zone near the trough wall. In addition, increasing the curvature radius r of the impeller has little effect on the flow field, but the axial circulation ability of the impeller can be improved by increasing the blade root angle, and the axial height of the impeller can be increased by 10% than that of the high speed fluid (V0.2VTS) region.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ027.2
【引证文献】
相关硕士学位论文 前1条
1 吴雨唐;基于普鲁兰多糖发酵的搅拌桨参数优化及搅拌性能分析[D];西南大学;2017年
，本文编号：2384347
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