油田高含盐污水喷雾干燥的数值模拟研究

发布时间：2018-05-21 03:17

本文选题：油田高含盐污水 + 喷雾干燥　；参考：《中国科学院大学(中国科学院工程热物理研究所)》2017年硕士论文

【摘要】：我国大部分油田已进入开采的中后期,采出液含水量高达80%,使得油田污水的处理量迅速增加。其中,油田污水含盐量已高达上万或数十万mg/L,直接外排和回注都会对周边环境造成严重破坏,其脱盐处理技术的开发研究已成为油田企业亟待解决的任务之一。喷雾干燥技术已在化工、食品、医药等行业得到广泛应用,在工农业生产领域中占有极为重要的地位,与传统的油田污水处理技术相比,具有设备简单、水分蒸发迅速、操作控制方便、适宜大规模生产等优点。本文基于喷雾干燥技术,提出了油田高含盐污水喷雾干燥的处理方法。目前尚无喷雾干燥技术处理油田高含盐污水的工程应用实例,因此首次使用CFD针对油田高含盐污水的喷雾干燥过程进行了深入地研究,探索了将喷雾干燥技术应用于油田高含盐污水处理的可行性,可为理论研究与工程实践提供一定的参考依据。(1)针对含盐量为7× 104mg/L的油田污水,设计了一套处理量为28.8kg/h的逆流型喷雾干燥器。在标准k-ε双方程模型和DPM模型的框架下,基于欧拉-拉格朗日方法,描述了空气与雾化液滴在干燥器内相对运动及传热传质过程,对液滴蒸发过程进行了数值模拟,得到了设备内部各流场分布。通过随机轨道模型追踪了液滴颗粒的运动轨迹及液滴NaCl浓度的变化。结果表明:污水液滴的喷入对空气有明显的扰动作用,近轴线区域扰动最大。离喷嘴越远,速度分布越均匀。由于液滴群与逆流空气的相互作用,在液滴群两侧形成了旋涡回流区。气相温度梯度在液滴群集中的中心轴线区域较大。沿轴线方向自上而下,温度逐渐降低,水蒸气含量逐渐升高,液滴蒸发速率呈增加趋势。液滴一般在3到7秒便可蒸发完毕,在该干燥器结构及工况条件下,设备内蒸发效率可达到 58.9%。(2)研究了入口空气流速、入口空气温度、喷雾锥角、液滴直径等操作参数对干燥器内速度场、温度场和液滴蒸发特性的影响规律。得出以下结论:入口空气流速和入口空气温度是影响蒸发速率的关键操作参数。提高入口空气流速和入口空气温度,均可加快液滴蒸发。但是受液滴颗粒沉降速度的限制,在算例的液滴直径及污水流量条件下,入口空气流速达到0.4m/s后,流速的提高对蒸发速率的提高量显著减小。当入口空气温度达到313K后,再提高空气温度,对蒸发速率的提高作用不大。随喷雾锥角的增大,蒸发速率略微提高。液滴越细化,蒸发速率越高。(3)由于在油田企业的实际工程应用中,需要考虑油田开采现场的场地限制及装置搭建的方便性,因此基于逆流型喷雾干燥器的数值模拟方法,对并流型水平箱式结构喷雾干燥器的污水喷雾蒸发特性也进行了研究,并对比分析了不同喷嘴布置方案的蒸发效果。进一步的,为了给实际工程方案的设定提供一定的参考依据,根据中国石化石油勘探开发研究院在四川德阳的小型试验所使用的箱体结构,研究了操作参数的最佳设置。为了解在四川德阳环境条件下何种工况的蒸发效果较好,采用正交试验设计原理,对各环境工况下的箱式结构进行了数值模拟研究。得出以下结论:在箱式结构中,液滴群向右侧有一定的偏移,速度场分布较不均匀,在箱体右下直角处存在不合理的旋涡回流区。由于在箱体左侧入口处液滴与空气的横向交叉流动,使两相掺混过程主要发生在箱体中部及后部。在该算例箱体体积下,单喷嘴的布置方案是最优方案。当入口空气流速较小,为0.4m/s时,右侧引风方式与上侧引风方式的流场分布差别不大;当流速增加到0.6m/s及0.8m/s时,右侧引风方式优于上侧引风。液滴直径在20μm～150μm范围内时,最佳入口空气流速为 0.4m/s 及 0.6m/s。0.4m/s 的流速适用于直径 25μm、50μm、100μm、150μm的液滴,0.6m/s的流速适用于直径100μm、150μm的液滴。通过正交试验得出较好的环境工况为空气温度30℃、相对湿度60%、空气流速0.6m/s、液滴直径25μm或空气温度20℃、相对湿度40%、空气流速0.6m/s、液滴直径25μm。综上,本文紧密结合了石油企业的实际需要,为喷雾干燥技术在油田高含盐污水处理领域提供了一定的工程设计依据,具有实践指导作用。
[Abstract]:Most of the oil fields in our country have entered the middle and late period of mining. The water content of the extracted liquid is as high as 80%, which makes the treatment quantity of the oilfield sewage increase rapidly. Among them, the salt content of the oilfield sewage is up to tens of thousands or hundreds of thousands of mg/L. The direct outer row and reinjection will cause serious damage to the surrounding environment, and the development and research of the desalting treatment technology has become an oil field enterprise. One of the tasks to be solved urgently. The spray drying technology has been widely used in the industries of chemical industry, food and medicine. It occupies an important position in the field of industrial and agricultural production. Compared with the traditional oilfield sewage treatment technology, it has the advantages of simple equipment, rapid evaporation of water, convenient control and large scale production. Spray drying technology is used to treat the spray drying of high salt wastewater in oil field. At present, there is no spray drying technology to treat high salt wastewater in oil field. Therefore, the spray drying process of high salt water with high salt water in oil field is first studied by CFD, and the application of spray drying technology to oil field high is explored. The feasibility of the treatment of salt containing sewage can provide some reference for theoretical research and engineering practice. (1) a set of reverse flow spray dryer with a treatment amount of 28.8kg/h is designed for the oilfield sewage with a salt content of 7 x 104mg/L. Under the framework of the standard k- e double equation model and the DPM model, the Euler Lagrange method is described. The relative motion and heat and mass transfer process of the air and atomization droplets in the drier are numerically simulated and the distribution of each flow field inside the device is obtained. The trajectory of the droplets and the change of the NaCl concentration are traced by the random orbit model. The results show that the injection of the droplets is obviously disturbing to the air. The moving effect is the largest disturbance in the near axis region. The farther the nozzle is, the more uniform the velocity distribution is. The vortex reflux region is formed on both sides of the droplet group because of the interaction between the droplet group and the countercurrent air. The temperature gradient of the gas phase is larger in the center axis of the droplet cluster. The temperature gradually decreases along the axis direction, and the content of water vapor gradually decreases. The evaporation rate of the droplet is increasing. The droplet can be evaporated in 3 to 7 seconds. The evaporation efficiency in the dryer can reach 58.9%. (2) under the structure and working condition of the dryer. The air velocity, the inlet air temperature, the spray cone angle, the droplet diameter and the other operating parameters are applied to the velocity field, the temperature field and the droplet evaporation in the drier. The following conclusion is drawn: the inlet air velocity and inlet air temperature are the key operating parameters affecting the evaporation rate. Increasing the inlet air velocity and inlet air temperature can accelerate the droplet evaporation. However, the droplet sedimentation velocity is limited by the droplet diameter and the sewage flow condition. When the flow velocity reaches 0.4m/s, the increase of the velocity of the flow increases significantly. When the inlet air temperature reaches 313K and the air temperature is increased, the effect of the evaporation rate is little. With the increase of the spray cone angle, the evaporation rate is slightly improved. The more the droplet is refined, the higher the evaporation rate is. (3) due to the actual engineering of the oil field enterprise In use, it is necessary to consider the site limitation of the field and the convenience of the installation. Therefore, based on the numerical simulation of the reverse flow spray dryer, the evaporation characteristics of the sewage spray drier with the flow type horizontal box type spray dryer are also studied, and the evaporation effect of the different nozzle layout schemes is compared and analyzed. In order to provide some reference for the setting of practical project, according to the box structure used by the Sinopec petroleum exploration and Development Research Institute in Deyang, Sichuan, the optimum setting of operating parameters is studied. In order to understand the better evaporation effect in the conditions of Deyang environment in Sichuan, the orthogonal experiment design is adopted. The numerical simulation of box structure under various environmental conditions is carried out. The following conclusion is drawn: in the box structure, the droplet group has a certain deviation to the right, the distribution of the velocity field is not uniform, and there is an unreasonable vortex reflux area at right right angle of the box body. The two phase mixing process mainly occurs in the middle and rear of the box. Under the volume of the case case, the layout scheme of the single nozzle is the best. When the inlet air velocity is small, the flow field distribution of the right air guide and the upper side is not very different when the inlet air velocity is 0.4m/s. When the velocity is added to the 0.6m/s and the 0.8m/s, the right draft mode is superior to the upper air flow. When the diameter of the droplet is within the range of 20 m to 150 mu m, the flow velocity of the best inlet air flow velocity of 0.4m/s and 0.6m/s.0.4m/s is suitable for the droplets of 25 mu m, 50 mu m, 100 mu m, 150 mu m, and the flow rate of 0.6m/s is suitable for the droplets of 100 mu m and 150 mu m. The better ambient conditions are air temperature 30 and relative humidity 60% through orthogonal test. The air velocity 0.6m/s, the droplet diameter 25 / m or the air temperature 20, the relative humidity 40%, the air velocity 0.6m/s and the droplet diameter 25 mu m. combined, this paper closely combines the actual needs of the oil enterprises, and provides a certain engineering design basis for the spray drying technology in the field of high salt wastewater treatment in the oilfield, and has the practical guiding role.
【学位授予单位】：中国科学院大学(中国科学院工程热物理研究所)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X741

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