Using dynamic tests to study the continuous mixing of xanthan gum solutions
Using dynamic tests to study the continuous mixing of xanthan gum solutions
复制标题
使用动态测试研究黄原胶溶液的连续混合
DOI：
10.1002/jctb.1833
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发表时间：
2008
影响因子：
3.4
通讯作者：
F. Ein‐Mozaffari
中科院分区：
文献类型：
--
作者：
S. Saeed;F. Ein‐Mozaffari
背景技术背景：目前对非牛顿流体的连续混合的理解和实施不足以确保在许多情况下的良好混合。在这项研究中，连续混合的黄原胶溶液，这是一个假塑性流体与屈服应力的动态响应，量化使用的动态模型，将非理想的流动内的混合容器。该模型允许通过罐的两个平行流动路径：（1）沟道区和（2）混合区。
研究结果：动态测试使用频率调制的随机二进制输入的盐水溶液与饲料，以确定非理想流量的大小。从动态试验中确定了绕过混合区的流动程度和有效混合体积，并将其用作混合质量标准。我们探讨了叶轮速度，叶轮类型，通过混合罐的进料流速，流体流变学，进料和出口位置对沟流程度和完全混合体积分数的影响。试验表明，当叶轮形成的空腔表面接近罐壁、罐底和混合容器内流体表面时，非理想流动的百分比接近于零。
结论：本研究确定了提高混合效率的连续混合容器的重要标准。通过应用这些发现，可以实现非理想流动的程度的减小，这将改善连续混合过程的质量和控制，例如连续高粘度反应器、连续发酵罐和连续固液混合。版权所有© 2008化学工业协会
BACKGROUND: The current understanding and implementation of continuous mixing of non-Newtonian fluids is insufficient to ensure good mixing in many cases. In this study, the dynamic response of the continuous mixing of xanthan gum solution, which is a pseudoplastic fluid with yield stress, was quantified using a dynamic model that incorporated non-ideal flows within the mixing vessel. The model allowed for two parallel flow paths through the tank: (1) a channeling zone and (2) a mixing zone.
RESULTS: Dynamic tests were made using the frequency-modulated random binary input of a brine solution with the feed to determine the magnitude of non-ideal flows. The extent of flow bypassing the mixing zone and the effective mixed volume were determined from dynamic tests and used as mixing quality criteria. We explored the effect of impeller speed, impeller type, feed flow rate through the mixing tank, fluid rheology, and feed and exit location on the degree of channeling and the fraction of fully mixed volume. Tests show that when the surface of the cavern created by impeller approaches the tank wall, the bottom of the tank, and the surface of the fluid within the mixing vessel, the percentage of non-ideal flow approached zero.
CONCLUSION: This study identifies important criteria for continuous mixing vessels that will improve mixing efficiency. By applying these findings, a reduction in the extent of non-ideal flow can be achieved, which will improve the quality and control of the continuous mixing processes such as continuous high-viscosity reactor, continuous fermenter, and continuous solid–liquid mixing. Copyright © 2008 Society of Chemical Industry