【作者】 谷建龙；

【导师】 张芝涛；

【作者基本信息】 大连海事大学 ， 环境科学， 2009， 博士

【摘要】 外来生物入侵性传播是海洋生态环境面临的四大威胁之一。海洋外来生物在新的适宜生存环境中异常繁殖,会对近岸海域的生态系统带来灾难性破坏,甚至导致本地土著物种的灭绝,严重威胁海洋生态系统的安全。船舶压载水的给排过程是造成地理性隔离水体间海洋生物传播的最主要途径,压载水携带的入侵物种已经给全球经济带来了巨大损失。据不完全统计,这种损失每年以近百亿美元的速度递增。因此,对船舶压载水在排放前进行有效处理已势在必行。以羟基自由基为主的高级氧化技术在水处理技术应用中取得了较大进展,目前的研究表明,在所处理压载水量较少且保证羟基自由基与压载水及时快速均匀混合的条件下,羟基自由基杀灭入侵微小生物具有速度快、无二次污染的特点,因此,利用其快速氧化能力在排放管路中治理船舶压载水成为可能,该方法已受到国际海事组织(IMO)的高度关注。然而在远洋船舶压载水羟基自由基治理技术开发研究中发现,①船舶压载水的注排管路直径大,管内水流流速高、流量大,给处理压载水所需的自由基气液快速达到阈值混合带来了挑战;②船舶压载水注排管路长度有限,加之自由基寿命短,因此,自由基只有在极短的时间内、极短的路径上实现快速达到阈值混合才能保证外来入侵微小生物的灭活效果;③只有保证自由基气液与压载水快速混合时不影响外排管路的过流能力,才能避免增大压载泵功率和大幅加大压载水管路直径。以至于自由基气液同压载水快速均匀混合程度决定了船舶压载水的最终处理效果,成为工程化处理船舶压载水的制约因素之一。本文首次提出少量自由基气液与大量高流速压载水快速达到阈值混合是制约工程技术开发的关键因素之一。因此以自由基气液与压载水快速达到阈值混合为目的,对比各种管路混合器,在不影响压载水排放管路过流能力的基础上,确定了混合过程压力损失较小的T型管作为自由基气液与压载水快速混合的方式。运用Elurian-Elurian两相流模型对其展开数值研究,深入分析了射流与横流动量比、管径比及双支T型管间距比对混合过程的影响,其结果表明射流主体在主管路中的及时扩散程度主要受动量比和管径比的影响。在有限长的横流管路中,单支T型管下游横断面上的“混合死区”始终存在,说明不能满足在船在线处理压载水时快速达到阈值混合的要求;而双支T型管射流与横流的及时均匀混合程度除受动量比和管径比影响外,还受两支管间距的影响,在保证间距比为R_L=0.05,且满足动量比R_m≥6.40及管径比R_d≥0.10的条件下,在横流流经1s的距离内,断面未混合度可降低到0.5;同时,对T型管混合器压力损失分析发现,虽然射流主体的压力损失较高,但是对横流的压力损失影响较小,即混合过程对压载水管路的过流能力影响轻微。针对自由基气液同压载水快速达到阈值混合决定船舶压载水最终处理效果的“瓶颈”问题,本文设计出了一种交错对喷T型管混合器,该混合器的横流压力损失较小,对于现有船只及在造船只仅需要对混合段进行改造,无需增大压载泵的扬程及压载水排放管路的直径;在喷口下游横流流经1s的距离内射流与横流的未混合度低于0.5,突破了制约羟基自由基杀灭致死入侵微小生物最终效果的“瓶颈”,并为在船在线处理船舶压载水的工程技术开发提供必要的数据参考。更多还原

【Abstract】 Invasive spread of alien organism is one of the four threats against marine environment. Alien species can flourish in suitable environment,posing devastating impact on the ecosystem and local species.Ship ballast water,which is the most important channel of alien species spreading,has lead to massive loss to global economy,it is urgent to ensure proper treatment of ship ballast water.Significant progress has been achieved in water treatment with advanced oxidation technology like hydroxyl radical,research results showed that the hydroxyl radical can effectively kill microorganism in the provision of rapid mingling with ballast water. The method has drawn attention from International Maritime Organization.However, problems are discovered in the research on the treatment of ship’s ballast water by hydroxyl radicals.①The diameter of the pipeline for ballast water emptying is great, in which the velocity and the flux is high,taking challenge on the fast and uniform gasliquid mixture of radicals and the ballast water.②The length of the pipeline for ballast water emptying is limited and the lifetime of the radical is short,therefore,only when the radicals and the ballast water are mixed fast and uniformly in the extremely short time and extremely short way,is the good result of the external invasion small biology deactivation guaranteed.③Only the conveyance capacity of pipe is not affected when the radicals and the ballast water are mixed fast and uniformly,can the increasing of the ballast pump power and the diameter of the pipeline be avoided.So the extent that the fast and uniform gas-liquid mixture of radicals and the ballast water determines the final effect of the ballast water treatment,which becomes one of the restriction factors to engineering process ballast water.It is proposed for the first time that the key factor for industrial application is homogenous mixture of hydroxyl radical and ballast water.After evaluation of various mixers,Tee pipe is picked us as the mixer of hydroxyl and ballast water.Elurian-Elurian model is used to investigate Tee mixer,and deep research into ratio of jet into crossflow, diameter ratio and etc is conducted,the results showed that the diffuse degree is affected by momentum ratio and diameter ration.As for the single Tee mixer,there is always a dead zone,and can not realize rapid mixture of hydroxyl radical and ballast water. For the double Tee mixer,mixture degree is influenced by momentum ration,diameter ratio and width between two tubes.A nonuniform degree of 0.5%is reached under the following conditions,R_L=0.05,R_m≥6.40,R_d≥0.10.The process of mixture poses almost no impact on the tube.In the paper a Tee mixer is designed for allowing rapid mixture of hydroxyl radical and ballast water.The mixture facility can be easily fitted into the existing pipeline,and a nonuniform degree of 0.5 is achieved,thus the bottle neck restricting the treatment of alien organism is broken,and necessary data are collected for the development of online treatment facility.更多还原