【作者】 邵志国；

【导师】 祁佩时；

【作者基本信息】 哈尔滨工业大学 ， 环境科学与工程， 2011， 博士

【摘要】 随着北方河流沿岸能源石化工业的迅速发展和原油航运及穿越河道的输油管道的布设,江河溢油已成为生态环境和居民用水安全的严重威胁,制约北方经济发展的重要隐患,建立突发溢油污染事故后的预警预报和应急处置系统是减小环境危害和降低经济损失的重要措施。因此,本文开展了针对低温江河水域突发溢油污染时,油团在水面风化和迁移扩展的模拟预测研究,在获知溢油水域环境参数和溢油量的条件下,即可迅速预测油团位置、岸边吸油量与水面残油量,以期为溢油拦截点的选取及截油方式和吸油材料数量的确定提供理论指导,并为同类水域溢油的预测提供参考数据。本文详尽分析了目前较为流行的溢油风化和扩展预测模型各自适应条件与预测效果,针对低温江河溢油特点,选取适宜模型进行改进,通过模拟试验确定了模型中的相应参数,建立了适于模拟低温江河溢油风化和迁移扩展的预测模型,以松花江流域突发溢油污染为例,预测了不同季节,油团的蒸发、乳化及溢油性质的改变等风化过程,岸边及冰层对油团的吸附情况,沿江迁移扩展行为,水面残油量。分析原油蒸发机理可知:低温条件下,油膜蒸发主要受体相易挥发组分向液体表相的迁移过程控制,挥发组分液相阻力随温度的降低而增加,挥发组分所处油膜的厚度随温度的降低而减小,进而导致蒸发量的降低。在Fingas提出的蒸发模型上增加1个与温度有关的衰减因子e^-k/Δθ,建立了低温溢油蒸发模型。通过浅盘蒸发试验,确定了当环境温度与溢油凝点温差小于10℃时应采用低温溢油蒸发模型,0#柴油和大庆原油的阻力增加系数k分别为1.07和2.64。对于有冰江面,溢油蒸发受暴露于大气中的油膜面积A_f影响较大,引入衰减系数(A_f h_oe^-k/Δθ)/V改进Fingas模型以模拟有冰水面溢油蒸发过程,并通过浅盘蒸发试验对改进模型进行了验证。采用水槽吸附试验研究了河岸对水面浮油的吸附过程,顺直河道细沙、粘土和毛石型河岸对水面浮油的吸附符合二级吸附动力学方程,吸附等温性能符合Langmuir型吸附等温式。泥、沙等多孔颗粒材质型河岸对水面浮油的吸附机理为物理吸附,是粘附作用、活性离子吸附作用和毛细吸附综合作用的结果,此外,泥沙颗粒相互堆积,内部空隙为吸附的油滴提供了巨大的“贮油空间”。毛石型河岸主要依靠柴油的粘滞力使其附着在粗糙的表面之上。随着浪高的增大,细沙和粘土型河岸的吸油量先增大而后降低,波高在30⁶0 mm时吸油量最大,毛石型河岸吸油量则逐渐降低。随岸边坡度（θ）的增大,河岸的吸油量均逐渐降低,当θ从5°增至30°时,毛石型河岸吸油量降幅最大,高、低水力条件下分别为63.4%和73.3%。比较了转弯河道内侧、外侧和顺直河道河岸的吸油量,大小顺序为:外侧河岸>顺直河岸>内侧河岸,建立了沿江河岸对浮油吸附量的计算模式。考察了冰层对浮油的吸附特性,结果表明冰层的吸油速率较高,吸附平衡时间约为15 min,符合二级吸附速率模型。高、低水力条件下,光滑冰层的平衡吸油量分别为0.0008 ml/cm²和0.00117 ml/cm²,吸油等温吸附性能符合Langmuir-Freundlich型吸附等温方程。采用粘性流体边界层运动方程描述了油膜扩展,得出了流动水面上油膜的运动由依靠水流拖曳产生的等压流动和静止水面上油膜自身扩展两种运动形式组成的结论,给出了以无量纲压力梯度p*为参变量的油膜内速度分布公式。结果表明:泄油中心前部油膜为顺压流动,后部油膜为逆压流动,压力梯度的绝对值随时间与扩展半径的增加而减小。添加油膜离散尺度改进Fay模型,建立了预测油膜扩展初期的扩展-离散模型,通过循环水槽试验确定了离散系数K_x:随着流速的增加,无冰水面上油膜的K_x从5.04 cm²/s增至22.08 cm²/s,有冰水面上油膜的K_x从2.80 cm²/s增至5.64 cm²/s。并考察了浪高和温度对K_x的影响,并通过试验对对模型进行了验证,藉此,提出了江河溢油二阶段扩展迁移模型。以拟发生在松花江哈尔滨上游段的10 t级溢油污染事件为例,采用本文建立的河岸吸油模式和二阶段扩展模型,分别模拟了丰水期、平水期、枯水期和冰封期溢油在48 h内流经模拟江段时的时空分布情况,预测了模拟终期的水面残油量。结果表明:枯水期河岸吸油量最大:10 t,50 t,100 t和200 t等级溢油的岸边吸油量分别是溢油总量的2.45%,1.39%,1.03%和0.61%。冰层吸油量不大,分别为溢油总量的0.39%,0.23%,0.16%和0.084%。冰封期水面残油量最大,接近9.5 t;盛行东南风向的丰水期水面残油量最小,低于2.2 t。江河流速、风场和河段宽度的差异都会影响油膜扩展长度。本文还模拟了江心岛和支流汇入口附近等复杂水域油膜的扩展情况。更多还原

【Abstract】 With the development of petrochemicals industry along the Songhua River and crude oil transportation as well as the laying of oil pipes through the river, potamic oil spill accidents have already become a threat to the security of the entironment and water drinking of inhabitants. It is an important measure to establish the forecast and lash-up treatment system to emergent oil spill accidents for reducing the harm to environment and economic loss. Although many researchers have done some study on the oil weathering and spreading, the oil spills in low-temperature rives still have their own characteristics such as the fast oil spreading due to the high flow velocity, and the contaminative area would be lager; the influence on oil spreading from the interaction between oil and banks; the great difficulty in the tracing and counteraction to the oil spill due to he ice cover on the river in winter. Therefore, this paper developed the study on the oil weathering, spreading and drifting on the low-temperature river in order to provide the guidance on the prediction of polluted area and counteraction to an emergent oil spill.On the base of exhaustive analysis about the applied conditions and predictive effects of the prevalent mathematic models on the oil weathering and spreading, this paper improved the most condign model with considering the characteristics of potamic oil spills. And the parameters in the models were determined via the experimental simulation tests. It was the fist time to establish the oil weathering, spreading and drifting models in the low-temperature river. And they were used to predict the oil evaporation, dissolving, the changing process of oil qualities, oil spreading, remnant oil on the water surface and the oil adsorption on river banks in different seasons and the interaction between oil and ice cover.It can be concluded that the evaporation process is mainly controlled by the moving of volatile component from main body to the surface of liquid at low-temperature condition from the academic analyses about the evaporation mechanism of mixed liquid. The liquid resistance would become larger as the temperature gets lower, and the slick where the volatile component exists would be thinner, and the evaporation amount is smaller. Therefore, the environmental temperature is an important factor for the oil evaporation. An attenuation coefficient e^-k/Δθ related to the temperature was added to the Fingas’model. It was the first time to establish the evaporation model for the high-viscosity or semiliquid oil at the temperature close to the solidifying point. It was found that the improved model should be adopted when the temperature difference between environmental temperature and solidifying point was smaller than 10℃via the shallow pan evaporation test. The resistance coefficients of 0# diesel oil and Daqing crude oil were 1.07 and 2.64, respectively. The slick area exposed to the air A_f played an important role on the oil evaporation in river with ice cover. In this condition, an attenuation coefficient (A_f h_oe^-k/Δθ)/V was added to Fingas’model to simulate the oil evaporation, and these model were all validated via the shallow pan evaporation tests.It was the fist time to study the oil sorption on sand, clay and rubble type river banks via the flume tests. They all accorded with the second order kinetics equation and the Langmuir isotherm equation. The sorption mechanism of porous granule banks such as sand and clay is the synthetical action of physical sorption, conglutination, active ion sorption and capillarity sorption. Besides, the holes among the cumulated granules provide the huge“oil storage space”. And the oil sorption on the rubble bank mainly depends on the viscous force.The sorption amount of oil on sand and clay banks would increase at fist and then decrease as the wave height increasing. The amount reached the maximal value while the wave height is at the range of 30⁶0 mm. The oil sorption amount on rubble bank would decrease as the wave height increasing. And the sorption amounts for these there kinds of banks all decreased as the bank gradient （θ） increases. Whenθrises from 5°to 30°, the amplitude reduction of the rubble bank is the largest, are 63.4% and 73.3% in high and low hydraulic conditions, respectively. We also compared the oil sorption amount among the inboard, outboard and straight banks. And results are: sorption amount of outboard bank > sorption amount of straight bank > sorption amount of inboard bank. It was the fist time to establish the oil sorption calculated mode for river banks. It was also the fist time to discuss the sorption behave of floating oil on the ice cover. The results sh_owed that sorption velocity was very high, and the time of adsorption was less than 15 min and it accorded with the second order kinetics equation. The saturated adsorption amount was 0.0008 ml/cm² and 0.00117 ml/cm² in high and low hydraulic conditions, respectively. And it accorded with the Langmuir-Freundlich isotherm equation.The transportation of oil on moving water is the combination of isotonic flow due to the daggle action of the current and the mechanical spreading on the calm water due to the asymmetry in the oil slick thickness. The velocity profile across the vertical section within the slick with dimensionless pressure gradient p* being the parameter was also given. The first half part before the slick center was down-pressure flow and the other part behind the slick center was called against-pressure flow. As the slick was spreading, the absolute value of dp/dx decreased gradually. The dispersion dimension was added into the Fay’s model to establish the oil spreading-dispersion model for the early stage. The dispersion coefficient K_x was determined via the circulating flume test. With the increasing of flow velocity, K_x increased from 4.34 cm²/s to 20.08 cm²/s in the open wager and increased from 2.80 cm²/s to 5.64 cm²/s under ice. The effect of wave height and temperature on K_x was also investigated. The improved model was validated by using the experimental results, on the base of which a new two-phase oil spill model made up of improved Fay’s model and oil particle theory was put forward.Emergent oil spills of 10 t were pretended to occur at upriver reach of Harbin in Songhua River. The oil sorption mode and the two-phase oil spill model in this paper were used to simulate oil spreading and space-time distribution for 48 h during the high water period, average water period, low water period and icebound period, respectively. The rudimental oil amount on the water was predicted. The study showed that the oil sorption amount on banks during low water period was the largest: 2.45%, 1.39%, 1.03% and 0.61% for 10 t, 50 t, 100 t and 200 t, respectively. The sorption amount on the ice cover was small: 0.39%, 0.23%, 0.16% and 0.084%. The rudimental oil on water surface during the icebound period was as more as 9.5 t. And the rudimental oil amount during the high water with SE wind was the smallest, less than 2.2 t. The flow velocity, wind field and width of river would affect the length of oil slick. The oil spreading in waters near islands and anabranch collection was also simulated.更多还原