关键词: 炼化企业, 含盐污水, 降膜蒸发管, 数值模拟

Abstract: Evaporation treatment is one of methods for treatment of salt-containing waste water in refineries. However, there is a problem that the heat transfer effect is not good due to the difference of flow conditions in the evaporation process. Taking the salt-bearing wastewater of falling film evaporation as the object, the effects of different parameters on heat and mass transfer in evaporating tubes were analyzed by numerical simulation. The results showed that the effect of different liquid inlet velocities on the heating effect of the evaporative tube was complicated. The increase of inlet velocity leads to the increase of axial velocity. Although the heating time of the liquid thus became shorter, the heating effect was better. The increase of film gap had a positive effect on the temperature distribution near the wall, but the gas-phase turbulence intensity was slightly lower within 13.5-18.0 mm away from the center of the pipe. The temperature drop when the film gap was 1.25 mm was larger than that when the film gap was 1.0 mm and 1.5 mm. The increase of salinity of salt-containing sewage had adverse effects on heat and mass transfer in the evaporator tube. Especially the increase of temperature drop near the wall leads the increase of internal turbulence intensity within the range of 0-19 mm from the center of the tube in the radial direction and the increase of velocity within the range of 4 mm from the wall near the wall of the tube.

Key words: refinery, salt-containing waste water, falling film evaporator tube, numerical simulation