搅拌器内部三相流场特性模拟研究

针对搅拌器内部复杂湍流流场特性研究对提高其工作性能的重要意义,应用标准k-epsilon湍流模型,基于欧拉-欧拉法描述固-液-气三相流,并采用VOF模型捕捉气-液自由液面,离散相零方程模型解算颗粒运动行为,对容积为9L的实验室型搅拌器内部多相流场特性进行了模拟研究。研究结果表明,桶体挡板能有效防止漩涡产生,搅拌器内部流场呈上、下两循环分布,且下循环流速高于中、上部区域;流体运动速度与搅拌强度和正相关性,在较小粒径范围内,颗粒运动速度与其粒径呈正相关性,但其速度差异较小。小粒径颗粒体积分数分布相对较均匀,增大搅拌强度有助于提高颗粒分散性。搅拌器内部流场数值模拟研究可为提高搅拌器工作性能提供理论指导和技术依据。     

筒式搅拌器及其开发

介绍了实用新型专利——筒式搅拌器的结构和设计原理。筒式搅拌器主要有筒体和内弯叶片组成,搅拌时能同时产生强大的径向流和轴向流,具有较大的排液量和循环流量,混合效果极强。筒式搅拌叶轮的各尺寸设计取决于液体性质、混合要求、容器直径和转速等因素。     

Low-water laundering

High-efficiency clothes washers, or front-loading tumbler washers, use much less water and energy for a complete wash cycle than agitator washers. Washing comparably sized loads in less water creates challenges for laundry detergents. This paper reviews federal government efforts to increase washer efficiency, operating dynamics of the tumbler vs. the current agitator washer, the impact on detergent formulation, and the current status of high-efficiency washer adoption by U.S. consumers.     

PTA第一精制结晶搅拌器机械密封失效分析

通过对PTA第一精制结晶器搅拌器机械密封的失效机理进行分析,查找导致机封频繁失效的深层次原因,并制定具体的解决方案。     

凝聚釜搅拌轴断裂原因分析及对策

主要针对凝聚釜搅拌系统中的关键部件——搅拌轴,在较短的时间内,在同一部位连续发生断裂的原因进行详细的分析。找出搅拌轴的断裂主要原因是因轴承磨损后,调节拉杆损坏,造成轴变形,挠度加大,引起附加交变应力,而产生疲劳破坏所致。针对这一原因,采取了变更中间轴承、底轴承材质及改进调节拉杆结构等措施,以提高搅拌轴的运转时间和寿命。     

夹套—蛇管式搅拌釜的传热计算

讨论了夹套－蛇管式搅拌釜的传热过程，提供了各种传热系数的关联式和加热与冷却时间的计算公式。     

Influence of agitator design on powder flow

Design influences the flow within a powder mixer but quantitative guidance is lacking. Here the performance of mixers of different geometry was compared using positron emission particle tracking. One mixer had six long flat blades; the other carried short paddles. With the former, blade angle and number of axial compartments had little effect on agitation in the transaxial plan but axial dispersion was enhanced by longer axial compartments. A loop of circulation was found below the shaft. For the short paddle device, the transaxial agitation was more uniform, with a lower mean angular velocity and narrower ranges of velocities. The mixing elements inhibited the formation of the loop of circulation. In both cases, the axial flow had a cellular structure created by the radial supports for the blades but the short paddles mixer showed more chaotic behaviour, the axial dispersion coefficient being typically five times higher and increasing with fill rather than decreasing as seen with the six-blade device. A rationale for the design of powder mixers is thus emerging.     

污染蜡搅拌釜的研制

介绍了搅拌釜的生产制造过程、主要部件的制造要求及其采取的措施.其中包括釜顶盖、机架、搅拌器、搅拌轴等部件的焊接及热处理要求等.     

Reduced IMRs in a mixing tank via agitation improvement

Mixing of Newtonian fluids in a stirred tank at low Reynolds numbers was investigated experimentally by means of a visual decolourization technique and shaft power measurements. The research was focused on the Isolated Mixing Regions (IMRs), which are “doughnut-shaped” structures in a stirred tank exhibiting little mixing with bulk of the fluids. The effect of Reynolds number on the IMRs was determined. The critical Reynolds numbers beyond which IMRs are destroyed were presented. The study was focused on agitation design which consumes less power input to destroy the IMRs. A pitch-bladed impeller with an alternating pitch was found more energy efficient than other test impellers in eliminating IMRs in both baffled and unbaffled configurations. It was also found that dramatic reduction in the power consumption could be achieved with installation of baffles to eliminate IMRs at typically low Reynolds numbers. The improved energy efficiency was thought related to generation of more chaotic mixing from the disturbance generated by the baffles, or impeller blade asymmetry such as alternating pitch. An energy parameter was introduced to account for the mixing time scale and the power required in regimes above the critical Reynolds number, in order to evaluate the energy efficiency when IMRs are non-existent.     

筒式搅拌器性能试验研究

介绍了获得实用新型专利的筒式搅拌器的结构和工作原理,对筒式搅拌器的搅拌性能进行了试验研究和分析,并与推进式搅拌器和涡轮式搅拌器进行了比较。试验结果表明,3种搅拌器在同等条件下,筒式搅拌器的能耗最小,且其排液量和循环流量最大。