Hydrodynamics of Fluidization of Mixtures

混合物流态化的流体动力学

• 批准号: 9610053
• 负责人: Dimitri Gidaspow
• 金额: $ 20万
• 依托单位: Illinois Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-06-01 至 2001-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9610053&HistoricalAwards=false
• 关键词: Hydrodynamics; Fluidization; Mixtures

Abstract CTS-9610053 Quantitative understanding of the hydrodynamics of fluidization is needed for the design and scale-up of efficient new reactors in the oil, chemical, and electric power industries. The objective of this research is to extend the development of the hydrodynamic theory of fluidization and multiphase flow. This theory uses the principles of conservation of mass, momentum and energy for each phase and particle size. While the conservation laws are well known and accepted, relatively little has been done theoretically and experimentally to determine the constitutive equations for a mixture of different particle sizes that are needed as an input into various computational fluid dynamics (CFD) codes. The recently developed theory of granular flow, as reviewed by Gidaspow in Multiphase Flow and Fluidization, Academic Press, 1994, gave us a different perspective on the subject. During the last three years much experimental evidence was gathered that shows that indeed the particles in a fluid behave as another phase with their own pressure, granular temperature, viscosity, etc. In the dilute limit the particles obey an ideal "gas" equation of state. For denser flow of 75 micron fluidized catalytic cracking catalyst particles, the standard hard sphere model for a cohesive pressure was corrected. Cohesion was independently determined using radial distribution functions measured using a charge coupled device (CCD) camera. These experiments will be repeated for larger particles with negligible cohesion. Then this theory will be extended to a mixture of binary sizes, where the principle of equi-partition does not apply. Measurements will be made of particle velocities, concentrations and radial distribution functions using the newly developed CCD camera method and more conventional techniques, such as X-ray densitometers, in a two-story circulating fluidized bed (CFB) in a liquid-solid loop and in a gas-liquid-solid rectangular fluidized bed. These measurements will give th e viscosities of the mixtures. The measured velocity, particle concentration and turbulence (granular temperature) profiles will be compared to the CFD computations using the computer code.

摘要CTS-9610053 在石油、化工和电力工业中，设计和放大高效的新型反应器需要对流化流体动力学有定量的了解。 本研究的目的是推广流化和多相流流体力学理论的发展。该理论使用质量守恒、动量守恒和能量守恒的原理，适用于每个相和颗粒尺寸。虽然守恒定律是众所周知的和公认的，相对较少的理论和实验已经做了，以确定本构方程的不同颗粒大小的混合物，需要作为输入到各种计算流体动力学（CFD）代码。最近发展起来的颗粒流理论，如Gidaspow在Multiphase Flow and Fluidization，Academic Press，1994中所述，给了我们关于该主题的不同观点。在过去的三年里，大量的实验证据被收集起来，表明流体中的粒子确实表现为另一种状态，具有自己的压力、颗粒温度、粘度等。 对于75微米流化催化裂化催化剂颗粒的更密集的流，校正用于内聚压力的标准硬球模型。 使用电荷耦合器件（CCD）相机测量的径向分布函数独立地确定内聚性。 这些实验将对具有可忽略的凝聚力的较大颗粒重复进行。 然后，这个理论将扩展到二进制大小的混合，其中均分原则不适用。 将使用新开发的CCD照相机方法和更传统的技术，如X射线密度计，在液-固回路中的两层循环流化床和气-液-固矩形流化床中测量颗粒速度、浓度和径向分布函数。这些测量将给出混合物的粘度。 将测量的速度、颗粒浓度和湍流（颗粒温度）分布与使用计算机代码的CFD计算进行比较。