洗涤冷却管内垂直降膜流动特性

Flow characteristics of vertical falling film in scrubbing-cooling pipe

采用双平行电导探针对多喷嘴煤气化过程中洗涤冷却管内垂直降膜的液膜厚度分布进行了实验研究,研究发现,经洗涤冷却水分布环分配后在洗涤冷却管内形成的液膜在进口段200～400mm处呈明显的不均匀分布,液膜厚度差值高达3mm。流动方向上的液膜波动变化与平均液膜厚度变化相似,但具有滞后性。研究还表明,在2.4～14m3.h-1的进水流量范围内,整体液膜厚度随着流量的增大而增大,由此对洗涤冷却管内液膜充分发展区的平均液膜厚度建立了经验关联式。实验还发现,洗涤冷却水分布环的槽缝宽度对液膜分布影响显著,在本文研究条件下,最佳槽缝宽度为3mm,槽缝宽度继续增大,液膜的均匀性下降。另外,随着气相表观速度的增大,整体液膜厚度减小,但一定程度上改善了液膜分布的均匀性。

The liquid film thickness inside the scrubbing-cooling pipe in the process of coal gasification with multi-burners was investigated by parallel conductivity probe. The results showed that the liquid film was not uniform, especially in the entrance region of 200--400 mm, with the difference up to 3 mm. The unsteady fluctuation of liquid film was related to the film thickness. For a thicker liquid film, the fluctuation range was larger, but the change of fluctuation lagged. It was also found that the film thickness increased with increasing liquid flow rate. On the basis of the experimental data, an empirical equation was proposed for the mean film thickness in the fully developed zone. The slot width of quench ring had a significant influence on the thickness of liquid film. In this study, the best slot width was 3 mm, and larger slot width would make the film thickness more non-uniform. In addition, the film thickness became thinner under the effect of gas phase. In some way, the film thickness was more uniform because the drag force increased with increasing superficial gas velocity.