GOALI: Segregation and Elutriation of a Binary Mixture

目标：二元混合物的分离和淘析

• 批准号: 0650893
• 负责人: Christine Hrenya
• 金额: --
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-05-01 至 2011-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0650893&HistoricalAwards=false
• 关键词: GOALI; Segregation; Elutriation; Binary; Mixture

National Science Foundation - Division of Chemical &Transport Systems Particulate & Multiphase Processes Program (1415)Proposal Number: 0650893Principal Investigators: Hrenya, ChristineAffiliation: University of Colorado at BoulderProposal Title: GOALI: Segregation and Elutriation of a Binary MixtureGas solid flows are ubiquitous, though not well understood. A study of solids processing plants indicates that 80% of the plants experienced solids handling problems such as pipe blockage and that the performance of such operations was typically only 40-50% of design. Furthermore, even "reliable" empirical correlations for fluid catalytic cracking units are often inadequate. The proposed GOALI effort is targeted at advancing the fundamental knowledge associated with a phenomenon that is typically handled empirically, namely elutriation. Elutriation refers to the carryover of fines in a bubbling, gas-fluidized bed. Although more than 50 elutriation correlations have been proposed in the literature over the last two decades, the disagreement between experiments and empirical prediction is typically over 100%, and in some cases may differ by a factor of more than a hundred.Intellectual MeritTo better predict the elutriation phenomenon, a combined modeling and experimental effort is proposed. Research on the bubbling bed (dense) and freeboard (dilute) regions will be pursued in parallel. Two outstanding questions will drive this effort: (i) what physical mechanism(s) lead to the observed segregation (de-mixing) and bubbling patterns in the bubbling bed region, and (ii) what physical mechanisms lead to the counter-intuitive behavior observed in the freeboard region in which the addition of fines to the bed is known to increase the elutriation rate of relatively coarse particles (i.e., particles which have a terminal velocity that is greater than the superficial velocity at which the bed operates)? It is hypothesized that particle particle interactions play a key role in both regions. Similarly, a plausible explanation for the counter-intuitive behavior observed in the freeboard is the expected preferential collision of fine particles with the bottom half of upwardly moving coarse particles (since the fines travel at a higher velocity due to their reduced mass). This additional collisional force on the bottom of the coarse particles is expected to lead to their increased elutriation. The hypotheses will be tested by means of a two-fluid gas-solid model based on a new kinetic theory for mixtures that does not involve any of the assumptions of previous theories (nearly elastic, equipartiton of energy, Maxwellian velocity distribution). Model validation will be carried out with measurements that are both local and species-specific (species velocities and concentrations). A new probe will be developed that is both capable of measuring species velocities and concentrations and is adaptable to an industrial setting. The resulting data will represent the first detailed measurements of segregation and elutriation of two non-cohesive materials, and will be the first to characterize the impact of non-uniform particles on bubbling behavior. Furthermore, the model data comparison will be the first attempt to predict elutriation based on fundamentals (no adjustable parameters).Broader ImpactsThis work is motivated by complementary interests of each partner: the University of Colorado (polydispersity and segregation), Millennium (elutriation modeling), and PSRI (fluidization instrumentation and elutriation). This interdisciplinary team has over 50 years of experience in particle technology. Industry-university interaction will be promoted via industrial internships of PhD students involved in the project, co-advising of PhD students, and regular meetings and telecons. The results will be shared with the public using standard methods (conference presentations, peer-evaluated publications, website, etc.) and via the incorporation of the new model into MFIX (www.mfix.org), an open-source, no-cost CFD code which all of the PI's have extensive experience with. The proposed work will also involve the training student researchers in the area of particle technology, which has been identified as a national need. The PI has a strong record in involving undergraduates in research and promoting a diverse workforce.

国家科学基金会 - 化学与运输系统部颗粒与多相过程计划（1415）提案编号：0650893PRINCIPAL研究人员：Hrenya，Christineafiliation：Colladeafiliation：Colorado at BoulderPropoposal of BoulderPropopolopoposal attropoposal titter：goali：goalii：e gogrigation：e ventegration and derutriation and binary Mixture colduture coliefutigation solde colieft of Biary Mixuture flow as binary Mixturegas solid Follows in理解。对固体加工厂的研究表明，80％的植物经历了固体处理问题，例如管道阻塞，并且此类操作的性能通常仅占设计的40-50％。此外，即使是流体催化破裂单元的“可靠”经验相关性通常不足。拟议的目标努力旨在促进与通常在经验上处理的现象相关的基本知识，即流行。洗脱是指在冒泡的，燃气的床中罚款的结转。尽管在过去的二十年中，文献中已经提出了超过50个理性的相关性，但实验和经验预测之间的分歧通常超过100％，在某些情况下可能会差异超过一百多。提出了干扰现象，合并的建模和实验努力。对冒泡的床（密集）和干舷（稀释）区域的研究将平行进行。两个出色的问题将推动这一努力：（i）哪种物理机制导致观察到的隔离（脱混合）和冒泡的床区域中的气泡模式，以及（ii）哪些物理机制导致了违反直觉行为在自由板区域观察到，在该区域中，已知在床上添加罚款会增加相对较粗的颗粒的洗脱率（即具有末端速度的颗粒大于床的表面速度的末端速度）？假设粒子粒子相互作用在两个区域都起关键作用。同样，在干板上观察到的违反直觉行为的合理解释是预期的优先颗粒的优先碰撞，而向上移动的粗颗粒的下半部分（因为罚款由于质量降低而以较高的速度传播）。预计粗颗粒底部的这种额外的碰撞力有望导致其洗脱力的增加。这些假设将通过基于新的动力学理论的两流体气体固体模型来测试，该模型的混合物不涉及以前理论的任何假设（几乎是弹性的，能量的弹性，麦克斯韦速度分布）。模型验证将通过局部和物种特异性（物种速度和浓度）进行测量。将开发一个新的探针，既能够测量物种速度和浓度，并且适应工业环境。所得的数据将代表两种非粘性材料的隔离和放逐的第一个详细测量，并将是第一个表征不均匀颗粒对冒泡行为的影响的详细测量。此外，模型数据比较将是基于基本面（无可调参数）预测洗脱的首次尝试。Boader的影响是由每个伙伴的互补利益的动机，这是由科罗拉多大学（多分散性和隔离），千年（Elutiriation Modeling）（Elutiriation Modeging）的。 ，以及PSRI（流化仪器和洗脱）。这个跨学科的团队在粒子技术方面拥有超过50年的经验。行业 - 大学的互动将通过参与该项目的博士学位学生的工业实习，博士生的同事以及定期会议和电信来促进。结果将使用标准方法（会议演示，对同行评估的出版物，网站等）与公众共享所有PI都具有丰富经验的CFD代码。拟议的工作还将涉及粒子技术领域的培训学生研究人员，这被认为是国家需求。 PI在参与研究和促进多样化的劳动力方面的大学生方面具有良好的记录。