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  • ISSN 1006-3080
  • CN 31-1691/TQ

扭曲片强化裂解炉管多尺度混合特性分析

柏德鸿 宗原 赵玲

柏德鸿, 宗原, 赵玲. 扭曲片强化裂解炉管多尺度混合特性分析[J]. 华东理工大学学报(自然科学版), 2020, 46(3): 301-309. doi: 10.14135/j.cnki.1006-3080.20190315003
引用本文: 柏德鸿, 宗原, 赵玲. 扭曲片强化裂解炉管多尺度混合特性分析[J]. 华东理工大学学报(自然科学版), 2020, 46(3): 301-309. doi: 10.14135/j.cnki.1006-3080.20190315003
BAI Dehong, ZONG Yuan, ZHAO Ling. Analysis of Multi-scale Mixing Character of Enhanced Cracking Coil with Twisted Tape[J]. Journal of East China University of Science and Technology, 2020, 46(3): 301-309. doi: 10.14135/j.cnki.1006-3080.20190315003
Citation: BAI Dehong, ZONG Yuan, ZHAO Ling. Analysis of Multi-scale Mixing Character of Enhanced Cracking Coil with Twisted Tape[J]. Journal of East China University of Science and Technology, 2020, 46(3): 301-309. doi: 10.14135/j.cnki.1006-3080.20190315003

扭曲片强化裂解炉管多尺度混合特性分析

doi: 10.14135/j.cnki.1006-3080.20190315003
基金项目: 国家自然科学基金(2012CB720501)
详细信息
    作者简介:

    柏德鸿(1990-),男,江苏扬州人,博士生,主要研究方向为反应过程计算与优化、反应器设计开发。E-mail:Dehongbaiecust@163.com

    通讯作者:

    赵 玲,E-mail:zhaoling@ecust.edu.cn

  • 中图分类号: TQ021.4

Analysis of Multi-scale Mixing Character of Enhanced Cracking Coil with Twisted Tape

  • 摘要: 通过耦合丙烷裂解自由基动力学,对装有扭曲片的裂解炉管中的反应流体进行模拟计算,深入分析了流体多尺度混合特性与结焦速率及产物分布之间的相互关系。计算结果表明,相比于空炉管,扭曲片强化炉管虽然压力损失增加5.31%,但在扭曲片下游轴向长度与炉管总长度之比为0.228截面处湍动能提高39.6%,全管特征微观混合时间仅为空炉管时对应值的1.72%,表明扭曲片对裂解过程有较好的介观和微观混合强化作用,该作用提高了管内场分布协同性,使得努赛尔准数(Nu)和史伍德准数(Sh)分别提高7.50%和2.34%,烯烃收率提高5.88%,管壁平均温度下降24.01 K。旋流产生的径向分速度提高了近壁区湍动程度,使得扭曲片强化炉管径向距离(r)与炉管半径(R)之比(r/R)为0.993处的流体停留时间比空管时的对应值降低53.01%,缓解了近壁高温区流体的过度裂解结焦。此外,扭曲片强化炉管微观尺度上的混合强化促使管内达到均匀分子尺度的反应区域比空炉管增大了5.29%,解释了烯烃收率提高的原因。

     

  • 图  1  扭曲片几何结构示意图

    Figure  1.  Schematic diagram of geometry structure of twisted tape

    图  2  空炉管(a)和扭曲片强化炉管(b)示意图

    Figure  2.  Schematic diagram of bare coil (a) and coil with twisted tape (b)

    图  3  (a)裂解混合流体经过扭曲片后流线分布图;(b)扭曲片下游Z/L=0.228截面处速度云图

    Figure  3.  (a) Flow pattern of cracking mixture fluid after passing through the twisted tape; (b) Velocity contour in the downstream of twisted tape at Z/L=0.228

    图  4  两种炉管Z/L=0.228处径向速度分布

    Figure  4.  Radial velocity distribution for two coils at Z/L=0.228

    图  5  扭曲片下游Z/L=0.228截面处湍动能分布图

    Figure  5.  Turbulent kinetic energy distribution in the downstream of twisted tape at Z/L=0.228

    图  6  r/R=0.993处空炉管和扭曲片强化炉管的离集系数沿轴向分布趋势图

    Figure  6.  Xs variation trend along the flowing direction for bare coil and coil with twisted tape at r/R=0.993

    图  7  空炉管和扭曲片强化炉管在Z/L=0.228处温度梯度沿径向分布

    Figure  7.  Temperature gradient along the radial for bare coil and coil with twisted tape at Z/L=0.228

    图  8  空炉管和扭曲片强化炉管在扭曲片下游Z/L=0.228处传热协同角(a)和传质协同角(b)余弦值沿径向分布趋势

    Figure  8.  Cosine value of heat transfer synergy angle (a) and mass transfer angle (b) along the radial for the bare and coil with twisted tape at Z/L=0.228

    表  1  空炉管和扭曲片强化炉管观测精度和网格收敛指数

    Table  1.   Observed precision and grid convergence index of bare coil and coil with twisted tape

    TypeGrid level1)PobsIGC/%
    PressureVelocityPressureVelocity
    Bare coilI (305 088)1.921.724.823.31
    II (487 740)1.921.723.172.66
    III (885 388)1.921.722.341.69
    IV (1 279 744)1.921.721.821.48
    Coil with twisted tapeI (874 336)1.831.617.127.19
    II (1 163 261)1.831.615.293.70
    III (1 401 079)1.831.612.111.33
    IV (1 818 209)1.831.611.491.18
    1) Numbers in brackets represent the number of grids
    下载: 导出CSV

    表  2  空炉管和扭曲片强化炉管传递过程强化评价指标

    Table  2.   Transfer enhancement evaluation for bare coil and coil with twisted tape

    Type$\Delta p$NuShNu/fSh/fFPECY/f
    Bare coil28 845.5664.51139.782 734.635 925.391.0020.54
    Coil with twisted tape30 375.8769.35143.052 772.455 718.731.0520.62
    下载: 导出CSV

    表  3  相同转化率下空炉管和扭曲片强化炉管烯烃收率和选择性对比

    Table  3.   Y and S of olefin for bare coil and coil with twisted tape under the same conversion rate

    TypeY/%S/%
    C2H4C3H6C2H4C3H6
    Bare coil31.7516.7141.8222.00
    Coil with twisted tape32.1319.1842.3325.27
    下载: 导出CSV
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出版历程
  • 收稿日期:  2019-03-15
  • 网络出版日期:  2019-07-09
  • 刊出日期:  2020-06-01

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