In Lurgi?Thyssen dedusting system of steelmaking converter, the evaporative cooler represented a crucial operating unit, in which the hot dust-laden flue gas had to be cooled by saturation with water. The cooling process of the gas consisted of gas?liquid two phase flow and interphase heat and mass transfer. In this work, k?? standard equation and Lagrange discrete phase model were employed to describe the gas turbulent flow and the heat/mass transfer with droplet evaporation individually. The computational fluid dynamics (CFD) simulation for practical engineering project showed that the large-flux cooling gas was commonly constructed in a nonuniform flow caused by the sharp turnings at the inlet and outlet channels. The simulation results of the model were in good agreement with the actual working condition parameters of the evaporative cooler. The relative error of flue gas outlet temperature was 3.1%, the simulation results were reliable. The smaller the size of atomized droplet was, the shorter the time was required to reach the critical evaporation temperature and complete evaporation. The droplet with a particle size of less than 300 ?m could evaporate completely within 0.62 s. The main temperature drop of flue gas was within 3.5 m downstream of the nozzle. The heat transfer efficiency of droplet and high temperature flue gas was greatly affected by particle size distribution. The mean temperature of the same section corresponding of droplets with d50=340 ?m and d50=95 ?m can differ by 70 K. Using rosin-rammler distribution function to describe droplet size distribution, the effect of particle size distribution on the cooling efficiency of flue gas was studied. The droplet size should not be too large or too small. The particle size was too small to make a reasonable use of evaporative cooler space. The temperature of flue gas dropped unevenly and the droplet evaporation was incomplete due to the large particle size, resulting in wet bottom or wall hanging of the device.
Haiying LI Dong LIU Chunqi ZHANG Liangxu LIU Xiaobo WANG
. Numerical simulation of heat exchange efficiency of evaporative cooler[J]. The Chinese Journal of Process Engineering, 2019
, 19(3)
: 492
-499
.
DOI: 10.12034/j.issn.1009-606X.218239
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