不同加热方式下储罐内原油传热特性研究

发布时间：2018-10-29 10:43

【摘要】：随着国内大量原油储备库的建设,油库运行管理也受到严重的挑战,尤其是寒冷地区冬季低温环境下原油储存问题更加引起重视。对于寒冷地区冬季低温环境下,由于储罐周围环境温度低于罐内原油的凝点,若不对其进行加热,罐内原油将会发生凝固,严重影响储罐的安全运行。为了避免盲目加热,需要对不同加热方式下罐内原油的温度变化规律进行研究,为实际生产运行管理提供理论指导和支持。本文以大庆地区某油库中浮顶油罐为研究对象,建立了原油储罐在管式加热、收发油及热油循环加热方式下的物理和数学模型,提出基于有限体积法的数值离散方法,模拟冬季低温环境下浮顶油罐的加热过程。通过模拟储罐在不同加热方式下罐内原油的流场及温度场分布情况,分析罐内原油的流动及传热特性,并建立了热能利用率、储罐散热功率及温升速率等评价指标,对不同加热方式下储罐内原油的传热进行评价分析。对管式加热方式进行研究得到,罐内原油加热顺序依次为加热管周围、罐壁附近、罐顶附近及油罐中心区域;罐内原油会形成漩涡流,由不同数量、不同方向、不同大小的漩涡组成;罐壁附近存在40mm的热边界层,罐顶下方会形成80mm或者120mm的热边界层,且边界层厚度不随加热过程的进行发生变化。对收发油方式进行研究得到,收发油过程具有热浮力射流特性,沿着射流轨迹及射流与罐顶碰撞位置附近冷油先被加热,径向油温变化较均匀,轴向油温呈现分层分布。对热油循环加热方式进行分析得到,射流轨迹及罐顶附近的原油温度最先升温,然后从上而下对罐壁及罐顶以下原油进行加热,最后整个罐内原油温度趋于均匀。在热油循环加热过程中,罐内原油在射流轨迹左侧罐壁附近、射流轨迹右侧储罐中心区域各形成一个低温区域,其大小会随着射流流速、射流温度及储油液位的不同而发生变化,且随着加热过程的进行,低温区域逐渐减小直至消失。
[Abstract]:With the construction of a large number of crude oil reserves in China, the operation and management of oil depots have also been seriously challenged, especially in cold regions, where the storage problem of crude oil is paid more attention to in the low temperature environment in winter. Because the ambient temperature of the tank is lower than the freezing point of the crude oil in the cold region in winter, if it is not heated, the crude oil in the tank will solidify, which will seriously affect the safe operation of the tank. In order to avoid blind heating, it is necessary to study the temperature variation law of crude oil in the tank under different heating modes, and to provide theoretical guidance and support for actual production and operation management. In this paper, the physical and mathematical models of a floating roof oil tank in Daqing oil depot under pipe heating, receiving and sending oil and hot oil cycle heating are established, and a numerical discretization method based on finite volume method is proposed. The heating process of floating roof oil tank in low temperature environment in winter was simulated. By simulating the flow field and temperature distribution of the crude oil in the tank under different heating modes, the flow and heat transfer characteristics of the crude oil in the tank are analyzed, and the evaluation indexes such as thermal energy utilization rate, heat dissipation power and temperature rise rate are established. The heat transfer of crude oil in different heating modes was evaluated and analyzed. The results show that the order of crude oil heating in the tank is the heating pipe, the tank wall, the top of the tank and the central area of the tank. The crude oil in the tank will form a whirlpool, which is composed of different quantities, different directions and different sizes of swirls. There is a thermal boundary layer of 40mm near the wall of the tank. The thermal boundary layer of 80mm or 120mm will be formed under the top of the tank, and the thickness of the boundary layer does not change with the heating process. It is found that the oil receiving and sending process has the characteristics of thermal buoyant jet. The cold oil is heated first along the jet trajectory and near the collision position between the jet and the top of the tank. The radial oil temperature changes uniformly and the axial oil temperature presents a stratified distribution. By analyzing the heating mode of hot oil cycle, it is found that the jet path and the crude oil temperature near the top of the tank are heated first, and then the crude oil from the top to the bottom is heated, and the crude oil temperature in the whole tank tends to be uniform. In the heating process of hot oil cycle, the crude oil in the tank is located near the left wall of the jet trajectory, and the central region of the tank on the right side of the jet trajectory forms a low temperature region, and the size of the crude oil in the tank will vary with the flow velocity of the jet. The temperature of jet and the level of oil storage changed, and with the heating process, the low temperature region gradually decreased and disappeared.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE972

【相似文献】