气固流化床气泡发生频率的研究

在单孔二维气固流化床中(292mm×16mm)用高灵敏度电容探针研究气泡发生频率.以频谱分析仪分析气泡频率分布曲线.考察了一系列参数对气泡频率功率分布密度曲线的影响,其中包括颗粒直径(0.105—0.590mm),颗粒重度(590—2990kg/m~3),颗粒最小流化速度(0.0072—0.481m/s),床层初始高度(205—565mm),探针离孔口垂直距离,孔口气体流率(0.5—35×10~(-4)m~3/s)以及床层辅助流化气速(0—3倍最小流化速度)等.对于重度低的小颗粒流化床,单孔气泡发生频率符合Davidson和Harrison早先推导的模型.随着颗粒直径和重度的增大,实验数据与上述模型呈有规律的偏差.本文提出气体从形成中气泡的顶半球以最小流化速度值向乳浊相泄漏的模型,推导了气泡发生频率的基本方程.以本研究的泄漏模型,用数值计算方法在计算机上计算的气泡发生频率与实验数据相吻合.     

化学工业用无泄漏泵的选择

就传统的机械密封泵、磁力驱动泵及屏蔽泵的选择提出了一些重要的看法。     

化学工程的发展和展望

一、化学工程的起源现代化学工业始于十八世纪初的法国,稍后导入英国。十九世纪以煤为基础原料的有机化学工业在德国发展最为迅速。那时的煤化学工业按其规模尚不十分巨大,主要着眼于各种化学产品的开发。因此当时化工过     

BUBBLE FORMATION FREQUENCY STUDY IN A SINGLE-JET GAS-SOLID FLUIDIZED BED

Bubble formation frequencies in a single orifice two-dimensional gas-solid fluidized bed(292mm×16 mm)were measured by means of a high-sensitivity capacitance probe.A spectrum analyzer was used toanalyze the bubble frequency distribution.The effects of a series of parameters,including particle size(0.105—0.590 mm),particle density (590-2990 kg/m~3),minimum fluidization velocity of particles(0.0072-0.481 m/s),initial bed height (205-565 mm),probe vertical location,jet gas flow rate(0.5-35×10~(-4)m~3s)and background fluidizing gas velocity (0-3 times of minimum fluidization velocity),on the bubble frequencypower spectrum density were investigated.For the fluidized bed with small particles of low density,the bubble formation frequency was in goodagreement with Davidson and Harrison model.The data showed a regular deviation from that model asparticle size and density increased.The model is then modified to account for the fact that with largeparticles,gas will leak from the forming bubble into the surrounding emulsion phase.The modifed leakagemodel agrees with the experimental results.