鼓泡塔列管传热系数的测量与估算

Measurement and Correlation for Heat Transfer Coefficient in Bubble Column with Vertical Pipe Bundles

在φ500 mm×5000 mm的冷模实验装置中,使用自制传热探头,对无内构件的空塔和安装31根竖直换热列管的鼓泡塔内列管传热系数进行了测量。实验表明,列管传热系数随表观气速的增加而增大,传热系数沿径向呈抛物型分布,垂直列管内构件的加入使得传热系数的径向分布变得更为陡峭。基于表面更新理论,结合鼓泡塔内气含率和液速分布的测量及计算结果,提出了计算传热系数的数学模型,该模型既可以用于空塔的局部传热系数与平均传热系数计算,也可以用于安装列管束的局部传热系数与平均传热系数计算。模型计算值与实验数据符合良好,最大相对误差为5.62%。

The radial distributions of heat transfer coefficient h were measured with heat transfer probes in a φ500 mm×5000 mm bubble column without and with internals of 31 vertical pipe bundles in it, respectively. The experiments show that the heat transfer coefficient h increases with the increase of the superficial gas velocity, and the h distributions exhibit parabolic profiles along the radial direction. It was found that the vertical internals in the column increase the gradient of h distribution profiles. Based on the surface renewal model and combined with the computation on radial distribution of gas holdup and liquid velocity, a novel heat transfer model was developed to correlate the radial distributions of h under conditions of with and without vertical pipe bundles. The model developed is a unified one which can be used to calculate both the average and local heat transfer coefficients for all the situations of with and without vertical pipes. The values of h predicted by the developed model were compared with the experimental values, and the results show that the predicted h values agree well with the experimental data with a difference of less than 5.62%. This indicates that the proposed model has a strong prediction capability.