Competing Rates in Mixing Sensitive Processes: design fundamentals for meso-scale and transient effects

在化学过程工程中有两个有趣的全球趋势值得关注。在欧洲，土地稀缺，人们强烈致力于工艺集约化。这导致了微型反应器的发展，微型反应器非常小（体积为微升数量级）。在全球商品化学品市场上，规模经济驱动工艺设计和“创纪录的能力”工厂定期投产。这些反应器体积通常为1兆升。加拿大的两个重要行业，油砂开采和矿物加工，需要一些世界上最大的船舶。这两个行业还面临着多相和部分互溶的多组分混合的难题。纳米技术告诉我们，规模的巨大变化需要思维的转变：物理学保持不变，但主导变量发生变化。在从升到微升的尺度上，粒子质量变得可以忽略不计，微小的表面电荷变得极其重要。在从1L移动到1ML规模时，混合时间相对于关键过程时间尺度变得如此之长，以至于它基本上是无限的。在超大规模生产中，局部混合条件变得极其重要，通常会主导工艺性能。为了成功设计和操作1ML工艺容器，需要明确的混合规格。这需要了解局部湍流、局部偏析（注入浓度）和混合时间如何与过程中的时间尺度、长度尺度和浓度尺度相互作用。我们有两个测试容器，可以有效地测量这些变量。第一个已被应用到规模缩小的纳米颗粒沉淀在非常高的湍流水平，第二个使我们能够提高破乳剂的性能在兆规模。通过更好地了解当地混合条件的重要性，这两个项目都为我们的工业合作伙伴提供了巨大的成功。在这项建议中，我们扩大从实际的设计和应用的混合原则，发展的理论，这将允许建模和预测的混合从微升到兆升规模。

There are two interesting global trends to watch in chemical process engineering. In Europe, land is scarce and there is a strong commitment to process intensification. This has led to the development of micro-reactors which are extremely small (volumes of the order of micro-litres). In the global commodity chemicals market, economies of scale drive process design and "record capacity" plants are regularly commissioned. These reactor volumes are typically 1 Mega-litre. Two important industries in Canada, oil sands extraction and mineral processing, require some of the largest vessels in the world. These two industries also face difficult problems in multi-phase and partially-miscible multi-component mixing.Nano-technology has taught us that dramatic changes of scale require a shift in thinking: the physics stays the same but the dominant variables change. On moving from the litre to the micro-litre scale, the particle mass becomes negligible and tiny surface charges become extremely important. On moving from the 1L to the 1 ML scale, the blend time becomes so long relative to the key process time-scales that it is essentially infinite. At the Mega-Scale, local mixing conditions become extremely important and often dominate process performance.To successfully design and operate 1ML process vessels, clear mixing specifications are needed. This requires an understanding of how local turbulence, local segregation (injection concentration), and mixing time interact with the time scales, length scales, and concentration scales in the process. We have two test vessels which allow efficient measurement of these variables. The first has been applied to scale-down of nano-particle precipitation at very high turbulence levels; the second has allowed us to improve demulsifier performance at the Mega-Scale. Both have provided dramatic successes for our industrial partners through a better understanding of the importance of local mixing conditions. In this proposal we expand from the practical design and application of mixing principles to developing the theory which will allow modelling and prediction of mixing from the micro-litre to the Mega-Litre scale.