摘要
一直以来，放空在天然气长输管道系统安全运营中都有着重要的作用，而随着新建长输天然气管道的口径越来越大、压力越来越高，其地处环境也越来越复杂，由放空带来的安全隐患已经引起了广泛重视，因此展开天然气管道系统放空技术研究，明确不同因素对放空的影响，对管道系统的安全运行有着十分重要的意义。
因此，本文在对天然气放空标准调研、天然气扩散过程分析的基础上，通过PHAST 和FLUENT软件对冷放空和热放空的影响因素进行了研究，并提出了不同放空条件下的安全距离，主要完成了以下工作。
（1）冷放空
①分析了天然气冷放空气体扩散情况的影响因素和扩散特性；
②确定了不同因素（风速、大气稳定度、初始放空压力和立管直径）下的冷放空气体浓度分布规律；
③分析了不同障碍物因素对气体浓度分布的影响规律；
④确定了不同工况下的闪燃与爆燃的安全距离，并提出当放空速率大于20×104m3/h 时，应采用热放空；
⑤提出了根据噪声声级确定最大放空压力的方法。
（2）热放空
①确定了不同因素（风速、大气稳定度、初始放空压力和立管直径）下的热辐射分布规律；
②分析了不同障碍物因素对热辐射分布的影响规律；
③结合泗阳站和大铲岛的热放空实例，给出了热放空安全范围的确定方法。
④根据热放空现场实测环境温度，给出了金属的强度变化范围，并利用CEASARII 软件校核其应力，均满足要求。
关键词：天然气，冷放空，热放空，热辐射，安全距离
Analysis of diffusion path and safety of evacuating natural gas
Guo Shuai (Oil & Gas Engineering)
Directed by Prof. Cao Xuewen & Zhang Xingsheng
Abstract
Evacuation system in natural gas station plays an important part for all the time. However, becau of the greater diameter of newly build pipe, higher operation pressure and more complexity of environment, the hidden danger of evacuation has gotten wide attention. Therefore, it is necessary to study the evacuation system of natural gas and clear the influence on evacuation of different factors, that has an significant meaning on safe operation of pipe.
Therefore, in this paper, bad on the analysis of regulations of evacuation and gas diffusion process, influence on vent and flare of different factors such as wind velocity was studied by PHAST and FLUENT software, and then safe distance was put forward in different conditions. The work has been finished by following.
(1) Vent
①Influence factors and diffusion characteristics of natural gas were analyzed.
②Gas concentration distribution rules were determined in different factors including wind velocity, atmospheric stability, initial vent pressure and diameter of vent pipe.
③Influence on gas concentration distribution rules of obstacle was analyzed.
④Safe distance of flash and explosion was determined under the different conditions, and flare was suggested when evacuation velocity was over 20×104m3/h.
⑤Method to determining maximal vent pressure was put forward by noi level.
（2）Flare
①Thermal radiation distribution rules were determined in different factors including wind velocity, atmospheric stability, initial vent pressure and diameter of flare pipe.
②Influence on thermal radiation distribution rules of obstacle was analyzed.
2022上海高考作文③Method to determining flare safe range was put forward according to the examples of Siyang station and Dachandao.
④According to the measured temperature of flare, strength range of metal was given, and it met the requirements by using CEASARII software check its stress.
Key words: Natural gas, Vent, Flare, Thermal radiation, Safe distance
目录
第一章绪论 (1)
1.1 研究背景及意义 (1)
1.2 研究现状 (1)
1.2.1 天然气放空模拟软件 (2)
1.2.2 国内外放空标准对比分析 (4)
1.2.3 存在的问题及发展趋势 (7)
年总工作总结1.3 本文框架结构 (7)
1.3.1 研究目标 (7)
1.3.2 研究内容 (8)
第二章天然气扩散特性及数学模型分析 (9)
2.1 天然气扩散过程 (9)
2.1.1 紊动射流的形成 (9)
2.1.2 射流区域及轴心速度 (10)成都曲
2.1.3 射流浓度场 (12)
2.1.4 扩散范围的计算 (13)
2.2 天然气扩散的数学模型 (13)
2.2.1 冷放空模型 (14)软件测试总结
2.2.2 热辐射模型 (16)
2.3 放空方式及影响因素 (21)
2.3.1 热放空 (21)
2.3.2 冷放空 (23)
第三章天然气冷放空影响因素分析 (27)
3.1 气体扩散影响因素分析 (27)
3.1.1 风速 (27)
3.1.2 大气稳定度 (28)
3.1.3 初始放空压力 (29)
3.1.4 立管出口直径 (31)
3.1.5 多因素影响 (32)国计民生
3.2 障碍物对气体扩散的影响 (33)
3.2.1 有无障碍物 (33)
3.2.2 障碍物距离 (35)
3.2.3 障碍物高度 (35)
个人房屋租赁合同范本3.3 闪燃与爆燃 (37)
3.3.1 闪燃范围分析 (37)
3.3.2 爆燃范围分析 (40)
3.3.3 安全距离 (41)
3.4 冷放空噪声影响分析 (42)
3.4.1 冷放空噪声计算方法 (43)
3.4.2 由噪声声级确定最大放空压力 (45)
3.5 冷放空现场测试分析 (46)
3.6 本章小结 (49)
第四章天然气热放空影响因素分析 (52)描写雪的唯美诗句
4.1 热辐射影响因素分析 (52)
4.1.1 风速 (52)
4.1.2 大气稳定度 (55)
4.1.3 初始放空压力 (56)
4.1.4 立管出口直径 (58)
4.2 障碍物对热辐射分布的影响 (62)
4.3 安全距离测试与分析 (65)
4.4 临海地区热放空分析 (67)
4.5 温变对管道及设备的影响分析 (68)
4.5.1 金属材料在高温下的力学行为特点 (68)
倪连山4.5.2 热放空现场管道及设备的适应性分析 (69)
4.6 本章小结 (72)
