废水液滴在低温烟气中的蒸发特性数值研究
Numerical study on evaporation characteristics of waste water droplet in low temperature flue gas
-
摘要: 建立了液滴在低温低速烟气中运动和蒸发的数学模型,数值研究了液滴在不同的烟气速度和烟气温度环境中的蒸发特性,获得了液滴速度、温度和直径随时间的变化规律,以及烟气速度和温度对液滴蒸发特性的影响。计算结果表明:气相速度越大,液滴初速度对液滴运动速度的影响越小,液滴速度越容易达到烟气速度。对于初始直径和速度一定的液滴,气液初始相对速度越大,液滴达到临界蒸发温度所需的时间越短,完全蒸发时间也越短。在文中研究的烟气速度范围内,整体上气相速度的改变对液滴完全蒸发时间的影响很小。气相温度的改变对液滴达到临界蒸发温度的时间以及完全蒸发时间的影响很大。烟气从较高温度和较低温度分别下降相同幅度的温度时,液滴在烟气中的完全蒸发时间按不同的倍数在增加,烟气温度越低,液滴完全蒸发时间增加的越多。对于文中研究的液滴,无量纲完全蒸发时间随烟气温度变化呈指数递减规律。Abstract: A mathematical model was given to investigate the motion and evaporation characteristics of liquid drop in flue gas with different velocities and temperatures. The velocity, average temperature and diameter of droplet during its evaporation process were analyzed, as well as the influence of the flue gas’ velocity and temperature. The results show that: the bigger the velocity of the flue gas is, the less is the influences of the initial drop velocity on the movement velocity of droplet, and the easier does the droplet reach the flue gas velocity. For the droplet with the same initial diameter and velocity, a bigger initial relative velocity between the flue gas and droplet induces a shorter time for droplet reaches the critical evaporation temperature, also a shorter life time of droplet can be attested. In the range of flue gas velocity considered, the varying of flue gas velocity has a very small influence on the droplet’s life time. In contrast, a much stronger influence of flue gas temperature on the critical evaporation temperature and the life time of droplet can been found. When the temperature drop of flue gas from different initial temperatures are the same, the life time of droplet increases differently. Longer time is needed for the droplet to evaporate at lower flue gas temperature. For the droplet considered, the life time of droplet reveals the index declining rule along the flue gas temperature varying.
-
Key words:
- liquid droplet /
- evaporation characteristics /
- low temperature flue gas
-
-

计量
- 文章访问数: 2120
- HTML全文浏览数: 951
- PDF下载数: 924
- 施引文献: 0