压载水处理工艺中驱氧技术的停留分析

Residence Analysis Timeliness of De-oxygen technology in Ballast Water Treatment System

驱氧法处理船舶压载水,在压载舱的进水时加入超量氮气来驱除水中的氧,通过舱顶阀门作用,使水中氧气离开舱内水体:一部分通过气阀顶出水舱,一部分依然保持与剩余空间的空气混合。在没有达到整个舱充满压载水的情况下,24 h内,水舱中持续有氧被氮气驱出,此阶段P/V阀持续向外有气体溢出,这一过程在24 h内逐步停止,而后水舱中仍保持正压,而水面以上空余部分保持有氮气和氧气;在相对静止情况下,这些氮气和氧气都无法再回到水中,因为水中水分子间的间隙被氮气填充,这一平衡状态在没有搅动、对流等剧烈的运动下将不会改变。

When the ship ballast water is treated by oxygen displacement method,excess nitrogen is added into the water entering the ballast tank to remove the oxygen in the water.The pressure is generated through the valve to drive the oxygen out of the water body.Part of the water is discharged from the water tank through the top of the air valve,while the other part is still mixed with the air in the remaining space.In the case that the tank is not fully filled,oxygen in the water is continuously driven out by nitrogen within 24 h.The process is phased out within 24 h.Since there is positive pressure in the tank,there are nitrogen and oxygen in the remaining spaces above water surface.Neither nitrogen and oxygen can’t go back into the water when it's at rest.Because,the gap between the water molecules in the water have been filled with nitrogen molecules.This equilibrium state will not be change without stirring up the violent motion of the convection.