塔式鼓泡流化床内的涌渗流动特性

doi:10.11949/j.issn.0438-1157.20170364

摘要/Abstract

摘要：

为强化气固接触，提出了一种新型塔式鼓泡循环床反应器，采用多个带有风帽的中间分布板、沿床层高度方向将反应器分隔成若干腔室，流化过程中形成一种特殊的涌渗（gushing）现象；依据连续拍照所得图像，基于快速傅里叶变换和小波包变换的方法，对床内压力脉动信号进行分析，研究涌渗产生和消亡条件，频率和能量大小，以期掌握涌渗的形成规律。结果表明，此反应器内流化数为3.47时涌渗产生明显，周期性寿命为1~2 s，频率分布于0.1~0.5 Hz区域；保持流化风速不变，改变反应器结构，加入一层中间分布板构成双腔室、调整下腔室高径比为3：1以及适当增大风帽开孔率时，涌渗主频明显，能量适中，涌渗效果得到优化。因此，塔式鼓泡流化床内的涌渗流动特性取决于流化风速以及塔式鼓泡床的几何结构。

关键词: 鼓泡流化床, 塔式反应器, 涌渗, 频谱分析, 小波分析

Abstract:

In order to enhance the solid-gas contact, a new bubbling fluidized bed with tower reactor is designed. The fuel reactor is divided into several chambers along the bed height direction by internal air distributor with caps. In the period of fluidization, a special phenomenon is caused by slugging, which could be named “gushing”. The forming and disappearing of gushing can be recorded on the basis of image with a digital video camera. By using fast Fourier transform (FFT) and wavelet packet transform methods, the pressure fluctuation signal is analyzed to investigate the characteristics on gushing, including fluidization conditions, dominant frequency and energy mode of gushing. The results showed that gushing fluidization appears under the fluidization number of 3.47 in this reactor. Its cycle period is lasting 1-2 s and dominant frequency is around 0.1-0.5 Hz. Changing of reactor structure, like adding one distributor to reach two chambers, adjusting the aspect ratio of lower chamber to be 3:1 and enlarging the valve opening on caps of distributors, is the better structures for gushing fluidization. Therefore, in order to obtain a satisfactory gushing property in the reactor, the inlet gas velocity and reactor structure must be kept in a suitable condition.

Key words: bubbling fluidized bed, tower reactor, gushing, spectral analysis, wavelet analysis

中图分类号:

TQ053.5

朱晓, 沈来宏. 塔式鼓泡流化床内的涌渗流动特性[J]. 化工学报, 2017, 68(11): 4112-4120.

ZHU Xiao, SHEN Laihong. Characteristics on gushing in tower bubbling fluidized bed[J]. CIESC Journal, 2017, 68(11): 4112-4120.

参考文献 35

[1]	GRACE J R. High-velocity fluidized bed reactors[J]. Chemical Engineering Science, 1990, 45(8):1953-1966.
[2]	KUNⅡ D, LEVENSPIEL O. Circulating fluidized bed reactors[J]. Chemical Engineering Science, 1997, 52(15):2471-2482.
[3]	MARKSTROM P, LYNFELT A. Designing and operating cold-flow model of a 100kW chemical-looping combustor[J]. Powder Technology, 2012, 222(5):182-192.
[4]	薛军鹏, 范海宏, 徐德龙. 大颗粒鼓泡流化床压力脉动信号的小波分析[J]. 化工装备技术, 2006, 27(2):23-27. XUE J P, FAN H H, XU D L. Research on pressure fluctuation signal in coarse bubbling bed based on wavelet analysis[J]. Chemical Equipment Technology, 2006, 27(2):23-27.
[5]	KAGE H, AGARI M, LIU G, et al. Frequency analysis of pressure fluctuation in fluidized bed plenum find its confidence limit for detection of various modes of fluidization[J]. Advanced Powder Technology, 2000, 11(4):459-475.
[6]	WANG H, LU S, LIU G, et al. Modeling of cluster structure-dependent drag with Eulerian approach for circulating fluidized beds[J]. Powder Technology, 2011, 208(1):98-110.
[7]	刘燕, 张少峰, 王琦. 大颗粒循环流化床压力波动信号分析[J]. 化学反应工程与工艺, 2007, 23(4):302-308. LIU Y, ZHANG S F, WANG Q. Analysis on pressure fluctuation signal in coarse circulating fluidized bed[J]. Chemical Reaction Engineering and Technology, 2007, 23(4):302-308.
[8]	YANG T Y, LEU L P. Study of transition velocities from bubbling to turbulent fluidization by statistic and wavelet multi-resolution analysis on absolute pressure fluctuations[J]. Chemical Engineering Science, 2008, 63(7):1950-1970.
[9]	OMMEN J R, SASIC S, SCHAAF J, et al. Time-series analysis of pressure fluctuations in gas-solid fluidized beds-a review[J]. International Journal of Multiphase Flow, 2011, 37(5):403-428.
[10]	BI H T. A critical review of the complex pressure fluctuation phenomenon in gas-solids fluidized bed[J]. Chemical Engineering Science, 2007, 62(13):3473-3493.
[11]	YANG T Y, LEU L P, Multi-resolution analysis of wavelet transform on pressure fluctuations in an L-valve[J]. International Journal of Multiphase Flow, 2008, 34(6):567-579.
[12]	SCHAAF J, SCHOUTEN J C, JOHNSSON F, et al. Non-intrusive determination of bubble and slug length scales in fluidized beds by decomposition of the power spectral density of pressure time series[J]. International Journal of Multiphase Flow, 2002, 28(5):865-880.
[13]	骞伟中, 魏飞, 王壶, 等. 多段流化床技术用于多相催化与纳米材料合成过程[J]. 化工学报, 2010, 61(9):2186-2191. QIAN W Z, WEI F, WANG H, et al. Application of multistage fluidized bed in heterogeneous catalysis and nano-material synthesis[J]. CIESC Journal, 2010, 61(9):2186-2191.
[14]	DIANA C G, TOBIAS P, HERMANN H, et al. Influence of ring-type internals on the solids residence time distribution in the fuel reactor of a dual circulating fluidized bed system for chemical looping combustion[J]. Chemical Engineering Research and Design, 2014, 92:1107-1118.
[15]	DUTTA S, SUCIU G D. An experimental study of the effectiveness of baffles and internals in breaking bubbles in fluid beds[J]. Journal of Chemical Engineering of Japan, 1992, 25(3):345-348.
[16]	GENG C, ZHONG W, SHAO Y, et al. Computational study of solid circulation in chemical-looping combustion reactor model[J]. Powder Technology, 2015, 276:144-155.
[17]	YANG T H, SHI W H, LI S, et al. State of the art and trends of water inrush mechanism of nonlinear flow in fractured rock mass[J]. Journal of China Coal Society, 2016, 41(7):1598-1609.
[18]	李晓光. 煅烧水泥熟料用大颗粒流化床的动力学特性研究[D]. 西安:西安建筑科技大学, 2006. LI X G. Investigation on hydrodynamic properties of the fluidized bed with coarse granules for firing cement[D]. Xi'an:Xi'an University of Architecture and Technology, 2006.
[19]	YANG T Y, LEU L P. Multi-resolution analysis of wavelet transform on pressure fluctuations in an L-valve[J]. International Journal of Multiphase Flow, 2008, 34(6):567-579.
[20]	姜华伟. 基于风帽压力波动的流化床气固流态化特征研究[D]. 北京:华北电力大学, 2013. JIANG H W. Research on gas-solid fluidization characteristics of fluidized beds based on pressure fluctuations in wind caps[D]. Beijing:North China Electric Power University, 2013.
[21]	SVENSSON A, JOHNSSON F, LECKNER B. Fluidization regimes in non-slugging fluidized beds:the influence of pressure drop across the air distributor[J]. Powder Technology, 1996, 86(3):299-312.
[22]	SHEN L H, JOHNSSON F, LECKNER B. Digital image analysis of hydrodynamics two-demensional bubbling fluidized beds[J]. Chemical Engineering Science, 2004, 59(13):2607-2617.
[23]	CAICEDO G R, MARQUES J P, RUIZ M G, et al. A study on the behavior of bubbles of A 2D gas-solid fluidized bed using digital image analysis[J]. Chemical Engineering and Processing, 2003, 42(1):9-14.
[24]	ZI C, LUNGU M, HUANG Z L, et al. Investigation of unstable solids circulation behavior in a circulating fluidized bed with sweeping bend return using pressure frequency analysis[J]. Powder Technology, 2016, 294:159-167.
[25]	WANG Q C, ZHANG K, REN J T, et al. Pressure fluctuation in a gas-solid fluidized bed of Geldart B classification particle[J]. Journal of Fuel Chemistry and Technology, 2009, 37(6):763-768.
[26]	YANG J. Analysis of the relationship of CFBB minimum fluidization air flow in cold and hot positions[J]. Boiler Manufacturing, 2000, 11(4):30-33.
[27]	STEWART P S D, DAVIDSON J F. Slug flow in fluidized beds[J]. Powder Technology, 1967, 29(1):255-265.
[28]	CHEN Z D, CHEN X P, WU Y, et al. Study on minimum fluidization velocity at elevated temperature[J]. Proceeding of the CSEE, 2010, 30(14):21-25.
[29]	李彦华. 基于傅里叶变换的流化床压力波动的实验研究[D]. 天津:天津科技大学, 2011. LI Y H. Experimental study on pressure fluctuations in fluidized bed by Fourier transform[D]. Tianjin:Tianjin University of Science and Technology, 2009.
[30]	BAI D, BI H T, GRACE J R. Chaotic behavior of fluidized beds based on pressure voidage fluctuations[J]. America Institute of Chemical Engineers, 1997, 43(5):1357-1367.
[31]	JOHNSSON F, ZIJERVELD R C, SCHOUTEN J C, et al. Characterization of fluidization regimes by times-series analysis of pressure fluctuations[J]. International Journal of Multiphase Flow, 2000, 26(4):663-715.
[32]	JAIBOON O, CHALERMSINSUWAN B, MEKASUT L, et al. Effect of flow pattern on power spectral density of pressure fluctuation in various fluidization regimes[J]. Powder Technology, 2013, 233(2):215-226.
[33]	ZHEN L, WANG X P, HUANG H, et al. Wavelet analysis of pressure fluctuation signals in a gas-solid fluidized bed[J]. Journal of Zhejiang University Science, 2002, 3(1):52-56.
[34]	兰静. 基于小波变换的鼓泡流化床压力波动特性试验研究[J]. 东北电力技术, 2009, 30(6):1-5. LAN J. Test research on pressure fluctuation characteristics of bubbling fluidized bed based on wavelet transform[J]. Northeast Electrical Power Technology, 2009, 30(6):1-5.
[35]	岑可法, 倪明江, 骆仲泱, 等. 循环流化床锅炉理论设计与运行[M]. 北京:中国电力出版社, 1998:10-22. CEN K F, NI M J, LUO Z Y, et al. Theoretical Design and Operation of Circulating Fluidized Bed Boiler[M]. Beijing:China Electrical Power Press, 1998:10-22.