DEVELOPMENT OF ENHANCED ENERGY-EFFICIENT FLUIDIZED BED DRYING PROCESSES

简介：流化床广泛用于制药行业的干燥过程。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差。然而，在线测量流化床干燥机中的水分含量是具有挑战性的。本研究计划将开发一种新的在线监测技术，该技术基于药物粉末在干燥过程中的摩擦电行为。药用粉末在干燥过程中很容易通过与壁和其他颗粒的碰撞和滑动接触而产生静电电荷，这种行为的变化可以作为水分含量的指标。* *目的：对药物颗粒在流化床干燥器中的摩擦充电行为缺乏全面的了解。因此，需要深入了解流化床干燥器中的摩擦充电行为，以开发干燥过程的在线监测。此外，需要更好地理解受摩擦充电行为影响的流体动力现象，以改进流化床干燥的设计，这是一个能源密集型过程。本研究的具体短期目标是：1)提高对流化床干燥器中药物颗粒充电行为的理解；2)开发新型流化床干燥过程在线监测技术；3)对考虑静电力的流化床干燥过程进行数值模拟。**方法：目的1将采用离体和原位实验方法进行。在非原位方法中，将采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广泛的范围内描述操作参数对静电充电行为的影响。在原位方法中，将在实验室和中试规模以及与制药工业相关的操作条件下探索流化床干燥器的摩擦充电行为。基于对流化床干燥器中摩擦充电行为的深入了解，新的摩擦电探针将随后被开发出来（目标2）。所开发技术的验证将在商业规模的流化床干燥机中实施。同时，将进行数值模拟以补充实验工作。数值模拟将在任何期望的尺度下产生流化床内丰富的详细信息，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设计优化过程和改进干燥过程（目标3）。**影响：拟议的研究将产生与流化床干燥器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，用于干燥过程的优化设计。所开发的技术将优化操作条件，提供更好的产品质量控制，从而最大限度地减少能源消耗和产品损失。更好地了解摩擦充电行为也将为考虑操作人员的安全提供主动措施。我的长期目标是开发创新的流化技术，应用于可再生能源，制药，食品加工，化肥和农业行业。我的目标是在流化和颗粒技术方面建立一个世界级的研究项目，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.