DEVELOPMENT OF ENHANCED ENERGY-EFFICIENT FLUIDIZED BED DRYING PROCESSES

前言：沸腾床在制药工业中被广泛用于干燥过程。需要对干燥过程进行监控，以确定合适的操作条件和最佳终点，以防止损失和产品质量下降。然而，在线测量沸腾干燥器中的水分含量是具有挑战性的。这项研究计划将开发一种新的在线监测技术，基于药物粉末在干燥过程中的摩擦电学行为。药粉在干燥过程中，由于与壁面和其他颗粒的碰撞和滑动接触，极易产生静电，这种行为的变化可以作为水分含量的指标。**目的：对药物颗粒在沸腾床干燥器中的摩擦荷电行为缺乏全面的了解。因此，需要对沸腾床干燥器中的摩擦荷电行为有更深入的了解，以开发对干燥过程的在线监测。此外，需要更好地了解摩擦充电行为对流体力学现象的影响，以改进沸腾床干燥的设计，这是一个能量密集型过程。这项研究的具体短期目标是：1)提高对药物颗粒在沸腾床干燥器中的荷电行为的了解；2)开发用于沸腾床干燥过程的新的在线监测技术；以及3)在考虑静电力的情况下进行沸腾床干燥的数值模拟。**方法：目标1将采用非原位和原位两种实验方法进行。在非原位方法中，将使用自由落体装置来模拟流化床中颗粒与壁面的接触和颗粒之间的碰撞。这种方法的灵活性允许在更大的范围内描述操作参数对静电充电行为的影响。在现场方法中，将在实验室和中试规模以及与制药行业相关的操作条件下，在沸腾床干燥器中探索摩擦荷电行为。基于对沸腾干燥器中摩擦带电行为的深入了解，将随后开发新的摩擦带电探头(目标2)。开发的技术的验证将在商业规模的沸腾床干燥器中实施。同时，将进行数值模拟，以补充实验工作。数值模拟将在任何所需的尺度下产生丰富的沸腾床内的详细信息，包括温度分布、速度分布、水分含量和电荷分布。模拟结果将进一步促进优化工艺和改进干燥工艺的设计(目标3)。**影响：拟议中的研究将产生与流态化干燥器中静电充电相关的动力学的全面知识，并将开发可靠和准确的在线监测技术，以优化干燥过程的设计。开发的技术将优化操作条件，提供更好的产品质量控制，从而将能耗和产品损失降至最低。更好地了解摩擦带电行为也将提供考虑到操作员安全的主动措施。我的长期目标是开发创新的流态化技术，应用于可再生能源、制药、食品加工、化肥和农业行业。我的目标是在流态化和颗粒技术方面建立一个世界级的研究计划，并将其应用于绿色工艺、可再生能源和可持续发展。

INTRODUCTION: Fluidized beds are widely used for drying processes in the pharmaceutical industry. Monitoring of the drying process to determine suitable operation conditions and an optimal endpoint is required to prevent losses and poor product quality. However, online measurement of moisture content in a fluidized-bed dryer is challenging. This research program will develop a new online monitoring technique based on the triboelectric behaviour of pharmaceutical powders in the drying process. Pharmaceutical powders are very prone to electrostatic charging by colliding and sliding contacts with walls and other particles during the drying process, and the change in this behavior can be utilized as an indicator of moisture content. * *OBJECTIVES: A comprehensive understanding of tribocharging behavior of pharmaceutical granules in fluidized-bed dryers is lacking. Therefore, an advanced understanding of tribocharging behavior in fluidized bed dryers is required to develop online monitoring for the drying process. Moreover, a better understanding of hydrodynamic phenomena influenced by tribocharging behavior is required for improved design of fluidized bed drying, which is an energy intensive process. The specific short-term objectives of this research are to 1) Advance understanding of pharmaceutical particle charging behaviour in a fluidized bed dryer; 2) Develop novel online monitoring techniques for fluidized bed drying processes; and 3) Conduct a numerical simulation of fluidized bed drying taking electrostatic force into account. **METHODS: Objective 1 will be conducted employing by both ex situ and in situ experimental approaches. In the ex situ approach, a free-dropping device will be employed to simulate contacts between particles and the wall and collisions among particles occurring in the fluidized bed. The flexibility of this approach allows for delineating effects of operating parameters within a broader range on electrostatic charging behaviors. In the in situ approach, tribocharging behavior will be explored in fluidized bed dryers at both the lab and pilot scale and under operatingconditions of relevance to the pharmaceutical industry. New triboelectric probes will subsequently be developed based on the advanced understanding of tribocharging behavior in fluidized bed dryers (Objective 2). Validation of the developed techniques will then be implemented in a commercial scale fluidized bed dryer. In parallel, numerical simulations will be carried out to complement experiment work. The numerical simulations will produce a wealth of detailed information within the fluidized bed at any desired scale, including temperature distribution, velocity distribution, moisture content, and charge distribution. The simulated results will further facilitate designs to optimize the process and improve the drying process (Objective 3). **IMPACT: The proposed research will produce comprehensive knowledge of the dynamics associated with electrostatic charging in fluidized bed dryers and will develop reliable and accurate online monitoring techniques for the optimal design of drying processes. The techniques developed will optimize operating conditions and provide better product quality control, thus minimizing both energy consumption and product loss. A better understanding of tribocharging behavior will also provide proactive measures in consideration of operator safety. My long-term goal is to develop innovative fluidization technologies with applications in renewable energy, pharmaceutical, food processing, fertilizer, and agriculture industries. I aim to build a world-class research program in fluidization and particle technologies with applications geared towards green processes, renewable energy, and sustainable development.