摘要
在直径150 mm、静床层高280 mm的柱锥形喷动床中,采用平均粒径为1 mm、密度为2 770 kg/m^3的刚玉球为实验固相,采集不同气速下无导流管和带开孔导流管喷动床中的压力信号,通过小波分析与功率谱相结合的方法表征柱锥形喷动床的流型转变。首先利用平均压力法测得本实验条件下无导流管和带开孔导流管喷动床的最小喷动速度分别为0.57,0.50 m/s,然后采用Daubechies2小波对压力信号进行7层小波分解得出能反映喷动床流动特性的主频信号,再对主频信号进行功率谱分析。结果表明:无导流管和带开孔导流管喷动床的主频分别出现在D3(6.25—12.5 Hz)和D2(12.5—25 Hz)频段,且主频信号的功率谱图可以表征喷动床的3种流型:固定床、稳定喷动和不稳定喷动;开孔导流管喷动床的操作弹性(1<u_g/u_(ms)<1.23)明显比无导流管喷动床的操作弹性(1<u_g/u_(ms)<1.12)大。
Pressure signals were collected in conventional spouted bed and spouted bed with spotting punch draft tube respectively with the diameter of 150 mm and the static bed height of 280 mm under different gas flow velocities. Spherical particles were used as experimental solid, with an average diameter about 1 mm, and a particle density of 2 770 kg/m3. A method combining wavelet analysis and power spectral analysis was applied to predict the transition of flow patterns for spouted bed. The minimum spouting velocities of conventional spouted bed and spouted bed with spotting punch draft tube were 0.57 m/s and 0.50 m/s respectively, which were obtained by the average pressure under the experimental conditions, then the dominant frequency which reflect the fluid characteristics of spouted bed were acquired by Daubechies 2 wavelet for 7 scales, finally the dominant frequency signals were analyzed by power spectrum. The results show that the dominant frequency appears in D3 （ 6.25-12.5 Hz） and D2 （ 12.5-25 Hz ） band in conventional spouted bed and spouted bed with spotting punch draft tube respectively. According to the characteristics of the dominant frequency signals power spectrum, the gas-solid flow can be identified into three regimes： fixed bed, stable spouting and unstable spouting. And the operational flexibility for spouted bed with spotting punch draft tube （ 1 〈 Ug//Ums 〈 l. 23 ） is larger than that for conventional spouted bed （ 1 〈 Ug/Ums 〈 1.12）.
出处
《化学工程》
CAS
CSCD
北大核心
2017年第8期37-41,59,共6页
Chemical Engineering(China)
基金
河北省科技支撑计划(14273105D)
河北省自然基金资助项目(D2014202074)
河北省高等学校青年拔尖人才计划项目(BJ2016016)
关键词
喷动床
压力信号
小波分析
功率谱
流型
spouted bed
pressure signals
wavelet analysis
power spectral density
flow pattern
