Liquid Circulation Velocity Measurements in a Semi-Batch Ebullated-Bed Reactor
-
摘要: 采用内径286 mm、高7.2 m的气-液-固三相沸腾床反应器进行了液相间歇、气相连续的操作研究，以水、空气、Al2O3球形颗粒构成三相体系，在固含率（体积分数）12% ~ 30%和表观气速0.086 ~ 0.216 m/s下对宏观液相循环速度进行了测定。采用示踪剂法测定反应器进出口的多组示踪剂浓度曲线，使用MATLAB软件对液相轴向扩散系数进行求解，再代入爱因斯坦扩散系数定义式得到液相循环速度。实验结果表明，随着表观气速增大，液相循环速度相应增大；在固含率低于30%时，随着固含率增加，液相循环速度相应增加；但随着固含率进一步增大，液相循环速度的增幅越来越小。Abstract: A gas-liquid-solid three-phase ebullated-bed reactor with an inner diameter of 286 mm and a height of 7.2 m was used to conduct intermittent liquid phase and continuous gas phase operations. The three-phase system was composed of water, air and Al2O3 spherical particles. The macroscopic liquid circulation velocity was measured at a solid holdup of 12% ~ 30% with a superficial gas velocity of 0.086 ~ 0.216 m/s. In this study, the tracer method was used to determine the concentration curves of multiple tracers at the inlet and outlet of the reactor. The axial dispersion coefficient of the liquid phase was solved by MATLAB software. Substituting it into the definition of Einstein's diffusion coefficient produced the liquid circulation velocity. The experimental results show that at a certain solid holdup, as the superficial gas velocity increases, small bubbles gradually gather into large bubbles. The rising velocity of the bubbles continues to increase, and the liquid circulation velocity also increases accordingly. Increasing the superficial gas velocity significantly increases the liquid circulation velocity. At a constant superficial gas velocity, as the solid holdup increases, both the large bubble holdup and the bubble rise velocity increase. This subsequently causes the liquid circulation velocity to increase. However, because the increase of solid holdup hinders the circulation of liquid to a certain extent, as the solid holdup increases, the increase rate of the liquid circulation velocity continues to decline. It is suggested that an optimal value for the solid holdup exists.
-
Key words:
- ebullated-bed reactor /
- liquid circulation velocity /
- axial dispersion /
- solid holdup /
- tracer method
-
图 1 沸腾床实验装置
Figure 1. Ebullated bed experimental device
1—Water tank; 2—Pump; 3—Liquid flow meter; 4—Nitrogen cylinder; 5 —Tracer storage tank; 6 —Bubble sparger; 7—Ebullated-bed; 8—Expansion section; 9—Sampling port; 10—Conductivity detection and acquisition system; 11—Gas flow meter; 12—Air storage tank; 13—Air compressor
图 2 不同固含率和表观气速下沸腾床1.8 m和4.8 m处示踪剂响应曲线图
Figure 2. Response curves of tracer at 1.8 m and 4.8 m of the ebullated-bed under different solid holdups and different superfical gas velocities
图 3 不同固含率下液体循环速度与表观气速的关系
Figure 3. Relationship between the liquid circulation velocity and superfical gas velocity under different solid holdups
图 4 不同表观气速下液体循环速度与固含率的关系
Figure 4. Relationship between liquid circulation velocity and solid holdup under different superficial gas velocities
-
[1] AL-DALAMA K, STANISLAUS A. Comparison between deactivation pattern of catalysts in fixed-bed and ebullating-bed residue hydroprocessing units[J]. Chemical Engineering Journal, 2006, 120(1/2): 33-42. doi: 10.1016/j.cej.2006.03.013 [2] MARTINEZ J, SANCHEZ J L, ANCHEYTA J, et al. A review of process aspects and modeling of ebullated bed reactors for hydrocracking of heavy oils[J]. Catalysis Reviews-Science and Engineering, 2010, 52(1): 60-105. doi: 10.1080/01614940903238858 [3] 姜来. 渣油沸腾床加氢技术现状及操作难点[J]. 炼油技术与工程, 2014, 44(12): 8-12. [4] 刘信瑀, 张海涛, 马宏方, 等. 工业聚乙烯流化床的气固流动特性数值模拟[J]. 华东理工大学学报(自然科学版), 2021, 48(6): 736-743. [5] SERIZAWA A, KATAOKA I, MICHIYOSHI I. Turbulence structure of air-water bubbly flow: I. Measuring techniques[J]. International Journal of Multiphase Flow, 1975, 2(3): 221-233. doi: 10.1016/0301-9322(75)90011-7 [6] 任欧旭, 张少峰, 闫文军, 等. 气(汽)-液-固三相流化床中的气(汽)泡行为研究进展[J]. 河北工业大学学报, 2002, 31(5): 44-48. doi: 10.3969/j.issn.1007-2373.2002.05.011 [7] BEGOVICH J M, WATSON J S. An electroconductivity technique for the measurement of axial variation of holdups in three-phase fluidized beds[J]. American Institute of Chemical Engineers Journal, 1978, 24(2): 351-354. doi: 10.1002/aic.690240228 [8] MACCHI A, GRACE J R, BI H. Use of ultrasound for phase holdup measurements in multiphase systems[J]. Canadian Journal of Chemical Engineering, 2001, 79(4): 570-578. doi: 10.1002/cjce.5450790415 [9] BRENN G, BRAESKE H, DURST F. Investigation of the unsteady two-phase flow with small bubbles in a model bubble column using phase-Doppler anemometry[J]. Chemical Engineering Science, 2002, 57(24): 5143-5159. doi: 10.1016/S0009-2509(02)00423-2 [10] 贾翔飞, 钱嘉澍, 吴幼青, 等. 鼓泡塔反应器中两相流动CFD-PBM耦合数值模拟[J]. 华东理工大学学报 (自然科学版), 2021, 47(1): 1-10. [11] MATOUšEK V. Solids transport formula in predictive model for pipe flow of slurry above deposit[J]. Particulate Science and Technology, 2011, 29(1): 89-106. doi: 10.1080/02726351.2010.510549 [12] PäRSSINEN J H, ZHU J X. Particle velocity and flow development in a long and high-flux circulating fluidized bed riser[J]. Chemical Engineering Science, 2001, 56(18): 5295-5303. doi: 10.1016/S0009-2509(01)00200-7 [13] DAYAN A, ZALMANOVICH S. Axial dispersion and enterainment of particles in wakes of bubbles[J]. Chemical Engineering Science, 1982, 37(8): 1253-1257. doi: 10.1016/0009-2509(82)85068-9 [14] ADEKOMAYA O, OLAFUYI O. An experimental study of the effect of contaminants on the flow properties of oil based drilling mud[J]. Petroleum & Coal, 2011, 53(4): 315-319. [15] ADEKOMAYA O A. Modelling of solid flow effect on pressure drop in a vertical gas well[J]. Petroleum Exploration and Development, 2012, 39(2): 245-249. doi: 10.1016/S1876-3804(12)60038-X [16] 赵学明, 王一平, 胡宗定, 等. 三相流化床液相径向和轴向扩散的研究[J]. 化工学报, 1990, 41(6): 718-722. [17] LEVENSPIEL O. Chemical Reaction Engineering[M]. New Jersey, USA: John Wiley & Sons, 1998. [18] LEVENSPIEL O, BISCHOFF K B. Patterns of flow in chemical process vessels[J]. Advances in Chemical Engineering, 1964, 4: 95-198. [19] HSU J T, DRANOFF J S. On initial condition problems for reactor dispersion model[J]. Chemical Engineering Science, 1986, 41(7): 1930-1934. doi: 10.1016/0009-2509(86)87076-2 [20] STANDART G. The thermodynamic significance of the Danckwerts’ boundary conditions[J]. Chemical Engineering Science, 1968, 23(6): 645-655. doi: 10.1016/0009-2509(68)89009-8 [21] 宋晓晖, 戴猷元, 沈忠耀, 等. 分散-聚合型脉冲萃取柱中分散相轴向混合的研究[J]. 高校化学工程学报, 1986(1): 55-64. [22] 杨基础, 费维扬, 沈忠耀, 等. 用时间域最小二乘拟合法研究萃取柱中的轴向混合[J]. 化工学报, 1982, 33(2): 103-116. [23] LEVENSPIEL O, SMITH W K. Notes on the diffusion-type model for the longitudinal mixing of fluids in flow[J]. Chemical Engineering Science, 1957, 6(4/5): 227-235. doi: 10.1016/0009-2509(57)85021-0 [24] 程振民, 朱开宏, 袁渭康. 高等反应工程[M]. 北京: 化学工业出版社, 2020. [25] 杨涛, 方向晨, 蒋立敬, 等. STRONG沸腾床渣油加氢工艺研究[J]. 石油学报(石油加工), 2010(S1): 33-36. [26] ZEHNER P. Momentum, mass and heat transfer in bubble columns: Part 1. Flow model of the bubble column and liquid velocities[J]. International Chemical Engineering, 1986, 26: 22-28. [27] UEYAMA K, MIYAUCHI T. Properties of recirculating turbulent two phase flow in gas bubble columns[J]. American Institute of Chemical Engineers Journal, 1979, 25(2): 258-266. doi: 10.1002/aic.690250207 [28] RIQUARTS H. A physical model for axial mixing of the liquid phase for heterogeneous flow regime in bubble columns[J]. German Chemical Engineering, 1981, 4: 18-23. [29] ULBRECHT J J, KAWASE Y, AUYEUNG K F. More on mixing of viscous liquids in bubble columns[J]. Chemical Engineering Communications, 1985, 35(1/6): 175-191. doi: 10.1080/00986448508911225 [30] KAWASE Y, MOO-YOUNG M. Liquid phase mixing in bubble columns with Newtonian and non-Newtonian fluids[J]. Chemical Engineering Science, 1986, 41(8): 1969-1977. doi: 10.1016/0009-2509(86)87113-5 [31] MATSUMOTO T, HIDAKA N, KAMIMURA H, et al. Turbulent mixing-length model for axial turbulent diffusion of liquid in three-phase fluidized bed[J]. Journal of Chemical Engineering of Japan, 1988, 21(3): 256-261. doi: 10.1252/jcej.21.256 [32] CHENG Z M, HUANG Z B, YANG T, et al. Modeling on scale-up of an ebullated-bed reactor for the hydroprocessing of vacuum residuum[J]. Catalysis Today, 2014, 220: 228-236. [33] KRISHNA R, VAN BATEN J M, URSEANU M I, et al. Design and scale up of a bubble column slurry reactor for Fischer–Tropsch synthesis[J]. Chemical Engineering Science, 2001, 56(2): 537-545. doi: 10.1016/S0009-2509(00)00258-X [34] RIQUARTS H P. Strömungsprofile, impulsaustausch und durchmischung der flüssigen phase in blasensäulen[J]. Chemie Ingenieur Technik, 1981, 53(1): 60-61. doi: 10.1002/cite.330530118 [35] 朱闯杰, 岳志, 黄子宾, 等. 固含率对沸腾床反应器气泡行为的影响[J]. 化工学报, 2018, 69(11): 4763-4769. [36] SMITH D N, RUETHER J A. Dispersed solid dynamics in a slurry bubble column[J]. Chemical Engineering Science, 1985, 40(5): 741-753. doi: 10.1016/0009-2509(85)85027-2 [37] LI H, PRAKASH A. Influence of slurry concentrations on bubble population and their rise velocities in a three-phase slurry bubble column[J]. Powder Technology, 2000, 113(1/2): 158-167. doi: 10.1016/S0032-5910(00)00228-X -
下载:
点击查看大图
图(5)
计量
- 文章访问数: 161
- HTML全文浏览量: 80
- PDF下载量: 87
- 被引次数: 0
