基于EMMS曳力模型的提升管进料混合段模拟

提升管进料混合段是催化裂化提升管反应器最关键的区域。为找到一种合理的方法以改善提升管进料段内油剂两相流动及混合状况，采用了 EMMS 曳力模型，对提升管进料混合段气固两相流混合及流动进行三维计算流体力学（CFD）模拟，并与实验数据进行了对比；分析了气固两相流动及混合特性，还模拟分析了不同进料角度对提升管进料混合段内二次流的影响以及两相流动、混合状况。结果表明，EMMS/Matrix曳力模型能够较为准确地模拟进料混合段内气固两相流动、混合过程；当喷嘴斜向上喷射进料时，射流影响区颗粒流混合不均匀，颗粒流恢复稳定流型所需时间长，且边壁受二次流影响，出现“高浓度、高返混”区域，工业过程中易引起结焦。由此提出了一种新型提升管进料段结构的改进方案，能合理利用二次流，实现颗粒流均匀混合和流动

基于EMMS曳力模型的提升管进料混合段模拟

提升管进料混合段是催化裂化提升管反应器最关键的区域。为找到一种合理的方法以改善提升管进料段内油剂两相流动及混合状况，采用了 EMMS 曳力模型，对提升管进料混合段气固两相流混合及流动进行三维计算流体力学（CFD）模拟，并与实验数据进行了对比；分析了气固两相流动及混合特性，还模拟分析了不同进料角度对提升管进料混合段内二次流的影响以及两相流动、混合状况。结果表明，EMMS/Matrix曳力模型能够较为准确地模拟进料混合段内气固两相流动、混合过程；当喷嘴斜向上喷射进料时，射流影响区颗粒流混合不均匀，颗粒流恢复稳定流型所需时间长，且边壁受二次流影响，出现“高浓度、高返混”区域，工业过程中易引起结焦。由此提出了一种新型提升管进料段结构的改进方案，能合理利用二次流，实现颗粒流均匀混合和流动

提升管进料射流对气固两相流动混合的影响

为改善提升管进料区气固两相不均匀混合状况,针对一套大型冷模实验装置的提升管,结合实验和三维数值模拟,研究了提升管进料区催化剂和进料相不均匀混合的形成机理,考察了操作参数的影响,基于不均匀混合形成机理提出了一种新进料方式.结果表明,传统斜向上进料方式导致进料区催化剂和进料相不均匀混合,合适的操作参数[颗粒循环速率Gs=80 kg/(m~2?s),表观气速Ug=3.28 m/s,进料速度Ujet=62.5 m/s]可改善不均匀分布,将不均匀混合高度范围缩短约一半,但不均匀混合仍存在;新进料方式可实现快速均匀混合,尤其是向下30o进料方式.</p

催化裂化提升管进料区新型助流剂技术的CFD模拟

为改善提升管进料区气固两相混合状况、消除二次流对近壁面处返混的影响,提出了一种新型助流剂技术。该技术在边壁处形成一层助流剂&quot;保护层&quot;,可阻止进料射流与催化剂在边壁处过长接触。通过三维CFD模拟对比了3种助流方式(逆流式、顺流式、交叉式)对传统进料区催化剂与进料混合和边壁返混的改进效果,并对最佳方式下助流剂量做进一步的优化。结果表明,逆流式助流方式最理想,交叉式助流方式最差。合适的逆流式助流方式(如助流剂注入量为进料相总流率的15%时)可改善进料区催化剂与进料相混合,抑制二次流扩张,明显减弱近边壁处(|r/R|&gt;0.9)返混强度。</p

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies