流化床中气固均匀分布的失稳现象

doi:10.16085/j.issn.1000-6613.2018-1227

摘要/Abstract

摘要：

流化床因其均匀且剧烈的气固相互作用保证了其优异的流动和传递性能，因而广泛应用于化学工业中。因此，构建定量计算气固均匀分布的失稳临界点既是重要的学术问题又具有工程意义。本文分别使用气相和固体颗粒相的质量分数表示气固分布状态；引入颗粒床层压力载荷（Φ _T）描述分布器输入的规则负熵和固体颗粒床层自身混沌熵产生之间相互作用；由于密相颗粒床层远离平衡态且具有强非线性耗散项，因此需基于普利高津最小超量熵增原理给出气固密相流在并联系统均布状态的失稳临界点（Φ _Tc）：分布器和固体颗粒床层总熵增在气固均布和气固非均布情况下相等；由于并联系统的对称性，可将N单元路径并联系统气固均布稳定性分析简化为判断单元路径压降二阶导数正负；在此基础上讨论了操作参数、固体颗粒性质和分布器结构参数对气固密相床层均布稳定性的影响。此外，通过气体示踪和压力脉动频谱分析在直径为300mm冷模实验验证了颗粒床层压力载荷（Φ _T）对密相气固均布稳定性的影响；同时应用该方法论计算了工业流化床反应器临界床层高度、临界表观气速以及分布器临界阻力系数，指导了操作工况的调整和分布器结构设计，对比分析了改造前后的反应情况。

关键词: 气固流态化, 稳定性分析, 均匀分布, 分布器

Abstract:

The highly chaotic entropy dissipation across solids bed will trigger non-uniform fluidization, although distributor plays an important role in obtaining homogenous gas stream. For dense gas solids flow, total solids pressure loading (Φ _T), the pressure drop ratio between solids bed and distributor, were introduced here to present the gas solids interaction. The boundary between uniform and non-uniform fluidization can be detected by stability analysis based on Prigogine’s minimum of extra entropy production principle since the dense solids bed is far from equilibrium state and contains inelastic dissipation. Based on the framework of stability analysis of uniform distribution for dense gas solids flow, a phase diagram, illustrating the effects from operational parameter (Φ _T), geometrical characteristics of distributor (C _d) and property of solids (Ga) on instability of uniformity, were attained to draw some useful conclusions of robust uniform fluidization. Besides, the gas tracer method and pressure analysis have been provided to verify the effect of total solids pressure loading on the stability of uniform distribution in cold flow fluidized bed (ID 300mm). The framework has been also applied to calculate the critical point and provides guideline to find better operational conditions and design principle for various industrial fluidized bed reactors.

Key words: fluidization, stability analysis, uniform distribution, distributor

中图分类号:

TQ051

张晨曦, 蔡达理, 贾瞾, 崔宇, 王垚, 罗国华, 骞伟中, 魏飞. 流化床中气固均匀分布的失稳现象[J]. 化工进展, 2019, 38(01): 155-170.

Chenxi ZHANG, Dali CAI, Zhao JIA, Yu CUI, Yao WANG, Guohua LUO, Weizhong QIAN, Fei WEI. Non-uniform gas solids distribution in fluidized beds[J]. Chemical Industry and Engineering Progress, 2019, 38(01): 155-170.

图/表 26

图1 规则负熵输入与混沌熵产生对气固均匀分布稳定性的影响

图 2 分布器上方气固分布不均匀的现象[30,31]

图3 密相气固流态化并联系统建模

表1 气固稀相流过N并联路径的自由度分析

N=路径数目	2N+1=未知量	N+1=约束方程	N=自由度
2	5	3	2
3	7	4	3
4	9	5	4
6	13	7	6
8	17	9	8
12	25	13	12

表2 稳定性分析的计算参数[13,34] （20oC和101.3kPa）

参数	数值
气体
类型	空气
密度/kg·m^-3	1.225
黏度/kg·ms^-1	1.79×10^-5
固体颗粒
类型	B类颗粒
密度/kg·m^-3	2600
平均粒径/μm	300
颗粒装填量/kg	10

图4 全局总压降曲面及投影（其中颗粒床层压力载荷（Φ T）的取值范围2～30；气体质量分数γ 1的取值范围0.3～0.7）

图5 单元路径总压降以及各部分压降对颗粒床层压力载荷(Φ T)的二阶导数

图6 密相气固均匀分布的稳定性与颗粒床层压力载荷(Φ T)、分布器阻力系数(C d)和固体颗粒特性(Ga)之间关系的稳定相图

图7 固体颗粒床层高度对气固均布稳定性的影响

图8 冷态实验和分析

图9 径向示踪浓度分布及压力脉动平均振幅

图10 对氯甲苯(PCT)氨氧化制备对氯苯甲腈(PCBN)工艺流程示意图[54]

表3 氨氧化流化床反应器案例A和案例B的操作参数

操作参数	案例A	案例B
原料组成	PCT∶NH₃∶Air	PCT∶NH₃∶Air
反应器直径D/m	1.2	1.2
催化剂装填量/kg	7000	4650
静床高H/m	7.29	4.84
高径比H/D	约6	约4
反应温度/K	483	483
操作压力/kPa	101.3	101.3
表观气速U _g/m·s^-1	0.3	0.3

图11 随固体颗粒床层(H/D)升高流化床状态的变化

图13 工业对氯甲苯氨氧化反应流化床反应器中高径比对反应性能的影响

图12 固体颗粒床层中的压力波动和轴向温度分布（其中操作参数列于表3）

图14 邻硝基甲苯加氢反应流程示意图[57]

表4 邻硝基甲苯（ONT）加氢流化床反应器的操作条件

操作参数	数值
进料	ONT∶H₂
操作温度/K	523
操作压力/kPa	121.3
反应器直径D/m	2.2
催化剂装填量/kg	8500
静床高H/m	约3
催化剂平均粒径d _p/μm	120
催化剂堆密度/kg·m^-3	750
表观气速U _g/m·s^-1	0.10，0.15，0.20，0.25

图15 表观气速(U g)与单元路径总压降(ΔP t)对颗粒床层压力载荷(Φ T)二阶导数的关系

图16 ANT收率及AN、ONT含量

图17 气固流化状态随表观气速(U g)增大的改变

图18 工业间苯二甲腈(IPN)氯化制备工艺示意图[58]

表5 间苯二甲腈（IPN）氯化流化床反应器操作参数

操作参数	数值
进料	IPN∶Cl₂∶N₂
操作温度/K	573
操作压力/kPa	101.3
催化剂装填量/kg	2400
催化剂平均粒径d _p/μm	120
催化剂平均堆密度/kg·m^－3	500
表观气速U _g /m·s^－1	0.1
分布器阻力系数/C _d	25000，55000，75000

图19 表观气速(U g)和分布器阻力系数(C d)对气固均匀性稳定性的影响

图20 HCB收率及催化剂单耗

图21 双通道火灾逃生系统人流不均现象[62]

参考文献 63

1	KUNII D , LEVENSPIEL O . Fluidization engineering[M]. New York: Wiley, 1969.
2	BI H T , ELLIS N , GRACE J R . A state-of-art review of gas-solid turbulent fluidization[J]. Chem. Eng. Sci., 2000, 55: 4789-4825.
3	ZHOU Z Y , YU A B , ZULLI P . Particle scale study of heat transfer in packed and bubbling fluidized beds[J]. AIChE J., 2009, 55: 868-884.
4	SOBRINO C , ELLIS N , VEGA M . Distributor effects near the bottom region of turbulent fluidized beds[J]. Powder Tech., 2009, 189: 25-33.
5	AGARWAL G , LATTIMER B , EKKAD S , et al . Experimental study on solid circulation in a multiple jet fluidized bed[J]. AIChE J., 2012, 58: 3003-3015.
6	ARGENTINA M , CLERC M G , SOTO R . Van der Waals–like transition in fluidized granular matter[J]. Phys. Rev. Lett., 2002, 89: 044301.
7	GLASSER B J , SUNDARESAN S , KEVREKIDIS I G . From bubbles to clusters in fluidized beds[J]. Phys. Rev. Lett., 1998, 81: 1849-1852.
8	NAMARA S M , YOUNG W R . Inelastic collapse in two dimensions[J]. Phys. Rev. E, 1994, 50: 50-67.
9	ZHANG C X , QIAN W Z , WEI F . Uniform bubble growth in fluidized bed and its stability analysis[C]// The 12th International Conference on Fluidized Bed Technology, Kraków, Poland, 2017.
10	QURESHI A E , CREASY D E . Fluidised bed gas distributors[J]. Powder Tech., 1979, 22: 113-119.
11	GELDART D , BAYERNS J . The design of distributors for gas fluidized beds[J]. Powder Tech., 1985, 42: 67-78.
12	SATHIYAMOORTHY D , HORIO M . On the influence of aspect ratio and distributor in gas fluidized beds[J]. Chem. Eng. J., 2003, 93: 151-161.
13	THORPE R B , DAVIDSON J F , POLLITT M , et al . Maldistribution in fluidized beds[J]. Ind. Eng. Chem. Res., 2002, 41: 5878-5889.
14	DU B , WARSITO W , FAN L S . Bed nonhomogeneity in turbulent gas-solid fluidization[J]. AIChE J., 2003, 49: 1109-1126.
15	DEPYPERE F , PIETERS J G , DEWETTINCK K . CFD analysis of air distribution in fluidized bed equipment[J]. Powder Tech., 2004, 145: 176-189.
16	COCCO R , ISSANGYA A , KARRI S B R , et al . Understanding streaming flow in deep fluidized beds[C]// AIChE Annual Meeting: Particle Technology Forum. Reno, USA, 2001.
17	DONG S Q , CAO C Q , SHI C D , et al . Effect of perforated ratios of distributor on the fluidization characteristics in a gas-solid fluidized bed[J]. Ind. Eng. Chem. Res., 2009, 48: 517- 527.
18	SÁNCHEZ-PRIETO J , SORIA-VERDUGO A , GÓMEZ-HERNÁNDEZ J , et al . Maldistribution detection in bubbling fluidized beds[J]. Chem. Eng. J., 2015, 270: 272-281.
19	SÁNCHEZ-PRIETO J , SORIA-VERDUGO A , GÓMEZ-HERNÁNDEZ J , et al . Stagnant regions estimation in fluidized beds from bed surface observation[J]. Chem. Eng. J., 2015, 281: 109-118.
20	GUO Q J , WERTHER J , AUE-KLETT C , et al . Flow maldistribution at bubble cap distributor in a plant-scale circulating fluidized bed riser[J]. AIChE J., 2005, 51: 1359-1366.
21	SIEGEL R . Effect of distributor plate-to-bed resistance ratio on onset of fluidized-bed channeling[J]. AIChE J., 1976, 22: 590-592.
22	ELNASHAIE S S E H , GRACE J R . Complexity, bifurcation and chaos in natural and man-made lumped and distributed systems[J]. Chem. Eng. Sci., 2007, 62(13): 3295-3325.
23	GRACE J R , CUI H , ELNASHAIE S S E H . Non-uniform distribution of two-phase flows through parallel identical paths[J]. Can.J. Chem. Eng., 2007, 85: 662-668.
24	MASNADI M S , GRACE J R , BI X , et al . Distribution of multi-phase gas-solid flow across identical parallel cyclones[J]. Sep. Purif. Technol., 2010, 72: 48-55.
25	MASNADI M S , ELYASI S , GRACE J R , et al . Gas-solid flow distribution through identical vertical passages: modeling and stability analysis[J]. AIChE J., 2010, 56: 2039 -2051.
26	DING Y L , ANDERSON R , ZHANG L F , et al . Simulations of two-phase flow distribution in communicating parallel channels for a PEM fuel cell[J]. Int. J. Multiphase Flow, 2013, 52: 35-45.
27	ZHANG C X , QIAN W Z , WEI F . Direct Lyapunov method to analysis mal-distribution of gas solids flow through parallines[C]// The 8th Sino-US Joint Conference of Chemical Engineering, Shanghai, China, 2015.
28	ZHANG C X , WANG Q Z , JIA Z , et al . Design of parallel cyclones based on stability analysis[J]. AIChE J. 2016, 62: 4251-4258.
29	GELDART D . Expansion of gas fluidized beds[J]. Int. Eng. Chem. Res., 2004, 43: 5802-5809.
30	RICHARDSON J F , ZAKI W N . Sedimentation and fluidization[J]. Trans. Inst. Chem. Eng., 1954, 32: 35-45.
31	FINNEMORE E J , FRANZINI J B . Fluid mechanics with engineering applications[M]. Boston: McGraw-Hill Companies Inc., 2002.
32	GLANSDORFF P , PRIGOGINE I . Thermodynamic theory of structure, stability and fluctuations[M]. London: Wiley, 1971.
33	PRIGOGINE I . Introduction to thermodynamics of irreversible processes[M]. 3rd ed. New York: Interscience, a Division of John Wiley & Sons, 1967.
34	ZHANG C X , QIAN W Z , WEI F . Instability analysis of uniform fluidization[J]. Chem. Eng. Sci., 2017, 173: 187-195.
35	THOMAS G B , WEIR M D , HASS J R . Thomas' calculus[M]. Boston: Addison-Wesley, 2003.
36	MERKIN D R . Introduction to the theory of stability[M]. New York: Springer, 1997: 25-75.
37	KARIMIPOUR S , PUGSLEY T . Study of gas streaming in a deep fluidized bed containing Geldart’s Group A particles[J]. Chem. Eng. Sci., 2010, 65: 3508-3517.
38	SATHIYAMOORTHY D , HORIO M . On the influence of aspect ratio and distributor in gas fluidized beds[J]. Chem. Eng. J., 2003, 93: 151-161.
39	SIERRA C , BONNIOL F , OCCELLI R , et al . Practical scaling considerations for dense gas fluidized beds interacting with the air-supply system[J]. Chem. Eng. Sci., 2009, 64: 3717-3720.
40	BONNIOL F , SIERRA C , OCCELLI R , et al . Similarity in dense gas-solid fluidized bed, influence of the distributor and the air-plenum[J]. Powder. Tech., 2009, 189: 14-24.
41	RAMIREZ E , FINNEY C E A , PANNALA S , et al . Computatinal study of the bubbling-to-slugging transition in a laboratory-scale fluidized bed[J]. Chem. Eng. J., 2017, 308: 544-556.
42	WANG JW , VAN DER HOEF M A , KUIPERS J A M . Coexistence of solidlike and fluidlike states in a deep gas-fluidized bed[J]. Ind. Eng. Chem. Res., 2010, 49: 5279-5287.
43	WELLS J . Streaming flow in large scale fluidization[C]//AIChE Annual Meeting Particle Technology Forum, Reno, USA, 2001.
44	KARIMIPOUR S , PUGSLEY T . Experimental study of the nature of gas streaming in deep fluidized beds of Geldart A particles[J]. Chem.Eng.J. 2010, 162: 388-395.
45	GAO Y J , MUZZIO F J , IERAPETRITOU M G . A review of the residence time distribution (RTD) application in solid unit operations[J]. Powder Tech. 2012, 228: 416-423.
46	LEE G S , KIM D S . Gas mixing in slugging and turbulent fluidized beds[J]. Chem. Eng. Comm., 1989, 86: 91.
47	DU B , FAN LS , WEI F , et al . Gas and solids mixing in a turbulent fluidized bed[J]. AIChE J., 2002, 48: 1896-1909.
48	LIU Y J , LAN X Y , XU C M , et al . CFD simulation of gas and solids mixing in FCC strippers[J]. AIChE J. 2012; 58: 1119-1132.
49	LI T W , ZHANG Y M , GRACE J R , et al . Numerical investigation of gas mixing in gas-solid fluidized beds[J]. AIChE J. 2010, 56:2280-2296.
50	FAN L T , HO T C , HIRAOKA S , et al . Pressure fluctuations in a fluidized bed[J]. AIChE J., 1981, 27: 388-396.
51	ZHAO G B , YANG Y R . Multiscale resolution of fluidized bed pressure fluctuation[J]. AIChE J., 2003, 49: 869-882.
52	BI H T . A critical review of the complex pressure fluctuation phenomenon in gas-solids fluidized beds[J]. Chem. Eng. Sci., 2007, 62: 3473-3493.
53	LUNGU M , WANG H T , WANG J D , et al . Two-fluid model simulations of the national energy technology laboratory bubbling fluidized bed challenge problem[J]. Ind. Eng. Chem. Res., 2016, 55: 5063-5077.
54	ZHANG C X , LI P L , LEI C , et al . Experimental study of non-uniform bubble growth in deep fluidized beds[J]. Chem. Eng. Sci., 2017. .
55	JIA Z , ZHANG C X , QIAN W Z , et al . Research and simulation of fast, strong exothermic reaction in gas-solid fluidized bed about temperature distribution[C]// Fluidization XV, Quebec, Canada, 2016.
56	ZHANG C X , QIAN W Z , WEI F . Non-uniform gas solids distribution and its effect on performance of fluidized bed reactors[C]// The 253th ACS national Meeting, San Francisco, USA, 2017.
57	LI J , KUIPERS J A M . On the origin of heterogeneous structure in dense gas-solid flows[J]. Chem. Eng. Sci., 2015, 60: 1251-1265.
58	ZHANG C X , QIAN W Z , WEI F . Phase separation of gas solids fluidization[C]// The 7th Asian Particle Technology, TaiBei, China, 2017.
59	PAIK K . Search for the optimality signature of river network development[J]. Phys. Rev. E, 2012, 86: 046110.
60	MURAMATSU M , IRIE T . Jamming transition in pedestrian conter flow[J]. Physica. A, 1999, 267: 487-498.
61	HELBING D . Traffic and related self-driven many-particle systems[J]. Rev. Mod. Phy., 2001, 73: 1067-1141.
62	HELBING D , FARKAS I J , VICSEK T . Simulating dynamical features of escape panic[J]. Nature, 2000, 407: 487-490.
63	HELBING D , FARKAS I J , VICSEK T . Freezing by heating in a driven mesoscopic system[J]. Phys. Rev. Lett., 2000, 84(6): 1240-1243.

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