基于水力旋流器对天然气水合物海底多相分离数值模拟研究

发布时间：2018-09-02 10:08

【摘要】：目前,随着传统化石能源(煤、石油和天然气)的不断开采和使用,人们也在不断的寻找未来可以替代传统化石能源的新型能源。天然气水合物作为一种新型的清洁能源,在极地永久冻土,海洋沉积层和海陆接壤处都赋藏丰富,并且在同等条件下,相同体积的天然气水合物的碳含量远远高于其他化石能源的碳含量,因此天然气水合物作为一种未来可替代化石能源的新型清洁能源而被世界各国所关注。但是由于天然气水合物独特的赋存条件和其自身的物理特性,使得天然气水合物的开采变得非常困难,所以对天然气水合物的开采以及开采过程的相关研究就显得尤为重要。本文主要依据深水浅层天然气水合物固态流化开采技术的思路,总结了除此之外世界上目前开采天然气水合物主流的思路方式,并对比了深水浅层天然气水合物固态流化开采的优势。并基于此开采方式,主要研究了其过程中的水下预分离模块。因为采用海底预分离技术不仅可以降低天然气水合物管道输送的举升动能的能量消耗,而且还可以有效的节省海上工作平台的空间,进而可以降低生产运行的成本。本文分析总结了国内外现有的成熟的水下分离系统及分离工艺,发现有关固态流化开采非成岩天然气水合物的水下分离技术公开发表的文献少到基本可以忽略,所以对于此开采技术的水下分离工艺基本没有成熟的理论或者经验可以借鉴,因此对于此问题的研究具有非常显著的现实意义。本文结合天然气水合物的相关性质以及固态流化开采技术,针对现有技术的不足与空白,提出了一种适合于天然气水合物固态流化开采过程中可以实现水合物高效分离的一种全新分离工艺。基于本文所提出的海底分离工艺,在将天然气水合物混合浆体模型简化为只含有泥砂固体,水合物颗粒固体以及海水的固-固-液分离的前提下,研究了基于水力旋流器对海底天然气水合物混合浆体除砂提纯。利用流场模拟软件Fluent在水力旋流器结构确定的情况下,对水力旋流器的锥角、混合浆体的进给速度和混合浆体中颗粒粒径大小对水力旋流器分离效率的影响分别进行了相应的分析研究。最后再将天然气水合物混合浆体中少量的甲烷气体也考虑进去,以便更为真实的反应实际工况,混合浆体的模型由固-固-液变为了固-固-气-液的分离,由于多了一相气体的存在,所以传统的水力旋流器结构不能再满足分离要求,故本文在此基础上设计了一种适合水合物混合浆体除气除砂的一种水力旋流器——双锥-内锥型水力旋流器。利用流场模拟软件Fluent在该水力旋流器结构确定的情况下,对不同固体颗粒粒径在不同锥角组合下,不同进口压力下,不同进口速度下,不同进口泥砂体积分数下,不同进口气体体积分数下以及进出口压差不变的情况下不同进出口压力对分离效率的影响规律进行了分析研究,为将来设计出更合适,更有效的分离设备提供一定的参考。
[Abstract]:At present, with the continuous exploitation and use of traditional fossil energy (coal, oil and natural gas), people are constantly looking for new energy sources that can replace traditional fossil energy in the future. Under the same conditions, the carbon content of natural gas hydrate is much higher than that of other fossil fuels, so natural gas hydrate as a new clean energy alternative to fossil fuels has attracted worldwide attention. However, the exploitation of gas hydrate becomes very difficult, so it is very important to study the exploitation and exploitation process of gas hydrate. The advantages of deep-water shallow gas hydrate solid-state fluidized mining are compared. Based on this mining method, the underwater pre-separation module in the process is mainly studied. This paper analyzes and summarizes the existing mature underwater separation systems and separation processes at home and abroad, and finds that the published literature on the technology of underwater separation for solid-state fluidized mining of non-diagenetic gas hydrates is almost negligible. There is no mature theory or experience to use for reference, so it is of great practical significance to study this problem. In this paper, combined with the related properties of natural gas hydrate and the technology of solid-state fluidized mining, aiming at the shortage and blank of the existing technology, a kind of solid-state fluidization suitable for natural gas hydrate is proposed. Based on the proposed seabed separation process, the model of natural gas hydrate mixture slurry is simplified as a solid-solid-liquid separation process consisting of only mud-sand solids, hydrate granular solids and seawater. Desanding and purification of natural gas hydrate mixture slurry were carried out by using the flow field simulation software Fluent. The effects of cone angle, feed rate and particle size on the separation efficiency of hydrocyclone were analyzed respectively under the condition that the structure of hydrocyclone was determined. However, a small amount of methane gas in the gas hydrate mixture slurry is also taken into account in order to make the reaction more realistic. The model of the mixture slurry changes from solid-solid-liquid to solid-solid-gas-liquid separation. Because of the existence of more than one phase gas, the traditional hydrocyclone structure can no longer meet the separation requirements, so this paper based on this. A kind of hydrocyclone-double cone-inner cone hydrocyclone suitable for degassing and desanding of hydrate mixture slurry was designed.Under the condition of the structure of the hydrocyclone being determined,the flow field simulation software Fluent was used to simulate the inlet velocity at different inlet pressures and different cone angles with different particle sizes under different inlet pressures. The influence of inlet and outlet pressure on separation efficiency under different inlet gas volume fraction and constant inlet and outlet pressure difference is analyzed and studied, which provides a reference for designing more suitable and effective separation equipment in the future.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE53

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