关键词: 垃圾渗滤液, 膜浓缩液, 蒸发, 挥发性有机物, 反应器, 传热

Abstract:

By comparing and analyzing the volatilization characteristics and types of volatile organic compounds in the evaporation of membrane concentrate in landfill at different temperatures and time, the volatilization of organic compounds in the evaporation process was studied. An integrated evaporation device, which utilizes the high-temperature flue gas first-wall heat exchange and then direct heat exchange, was designed. Through the optimization of the temperature, immersion depth and evaporation time of the high-temperature flue gas, the efficient use of flue gas thermal energy and the decompression evaporation under normal pressure are finally realized. The results indicated that the species and the concentration of volatile organic compounds with high boiling points and long carbon chains increased with the increase of evaporation temperature. It was noteworthy that the volatile organic compounds were mainly alkanes. When the temperature exceeded 100℃, the concentration of benzene series and alcohol lipids increased significantly. When the temperature was close to 80℃ and the evaporation time was 0.5h or 1h, organic compounds with low molecular weight were significantly released , however, the organic compounds with high boiling points existed in few. When the evaporation temperature at 400—550℃, the liquid evaporation temperature reached to 85℃, the difference between liquid evaporation temperature and tail gas temperature is maintained at 5—6C. Under the above conditions, the heat and mass transfer was fast and the species of volatile organic compounds were basically consistent with the conclusion of direct evaporation. Meanwhile, the utility of heat energy in the evaporation process at lower temperature was enhanced and the volatile organic compounds were effectively removed after being adsorbed on activated carbon.

Key words: landfill leachate, membrane concentrate, evaporation, VOCs, reactors, heat transfer