Presidential Young Investigator Award: Large Particle Fluidization

总统青年研究员奖：大颗粒流态化

• 批准号: 8657548
• 负责人: Richard Turton
• 金额: $ 27.9万
• 依托单位: West Virginia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-07-01 至 1993-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8657548&HistoricalAwards=false
• 关键词: Presidential; Young; Investigator; Award; Large

Narrative: During the 5 years of this Presidential Investigator Award, the following areas wil be investigated: (i) The lubricating effect of small particles on large particle fluidized beds. The addition of a very small amount of fine particle solid lubricant such as graphite or molybdenum sulfide can significantly reduce the amount of attrition that occurs when larger brittle particles are fluidized. Examples of such particles are zeolites with low proportions of binder material. By utilizing greater amounts of binder some zeolite catalysts can be used in moving bed operations, e.g., fluid bed catalytic cracking. However, by using more binder, intraparticle diffusion is affected and this may be undesirable. If the erosion of low binder content zeolite catalysts can be significantly reduced, then a whole family of fixed bed processes could be implemented in fluidized bed reactors. (ii) The characterization of gas-solid heat transfer and particle mixing using changes in magnetic properties of tracer particles. When solids are fed to a fluidized bed, either in batch or continuous operations, it is important to know how quickly these solids mix and obtain thermal equilibrium with the bed. For small particle systems this information is difficult to obtain since the processes occur quickly and the particles are too small for temperature sensing probes to be inserted in them. A technique has been developed to measure these processes by using the change in magnetic properties of a tracer material and this technique will allow detailed information about the heating and mixing of particles to be obtained. (iii) Modeling large particle fluidized systems. The widespread use of fluidized bed waste incinerators and combustors in the last 15 years has given rise to a renewed interest in large particle fluidized systems. Considerable experimental information is available on these systems but as yet there are few reliable flow models to predict the behavior of such systems. There are several similarities between solid-gas turbulent churning fluidization and liquid-gas churning flow. The latter has been modeled quite successfully using a phenomenological approach and it is believed that a similar approach to gas-solid systems could be fruitful.

叙述：在总统研究员奖的 5 年中，将研究以下领域： (i) 小颗粒对大颗粒流化床的润滑作用。 添加极少量的细颗粒固体润滑剂（例如石墨或硫化钼）可以显着减少较大脆性颗粒流化时发生的磨损量。 这种颗粒的例子是具有低比例粘合剂材料的沸石。 通过使用更大量的粘合剂，一些沸石催化剂可用于移动床操作，例如流化床催化裂化。 然而，通过使用更多的粘合剂，颗粒内扩散受到影响并且这可能是不期望的。 如果可以显着减少低粘合剂含量沸石催化剂的侵蚀，则可以在流化床反应器中实施整个固定床工艺系列。 (ii) 利用示踪粒子磁特性的变化来表征气固传热和粒子混合。 当固体被送入流化床时，无论是间歇操作还是连续操作，重要的是要了解这些固体混合的速度以及与床的热平衡。 对于小颗粒系统，此信息很难获得，因为该过程发生得很快，而且颗粒太小，无法在其中插入温度传感探头。 已经开发出一种通过使用示踪材料的磁性变化来测量这些过程的技术，并且该技术将允许获得有关颗粒加热和混合的详细信息。 (iii) 模拟大颗粒流化系统。 过去 15 年中流化床废物焚烧炉和燃烧器的广泛使用引起了人们对大颗粒流化系统的新兴趣。 关于这些系统有大量的实验信息，但迄今为止还没有可靠的流动模型来预测此类系统的行为。 固-气湍流搅拌流化和液-气搅拌流之间有一些相似之处。 后者已经使用现象学方法相当成功地建模，并且相信对气固系统的类似方法可能会取得丰硕成果。