天然气水合物是一种类似于冰的具有笼形结构的晶体，输气管道中的天然气中含有 一定的水分，在一定的条件下可以形成水合物。这种水合物一旦形成，将会给天然气的 生产和运输造成极为不利的影响，会导致阀门堵塞、管道停输等严重事故，给企业和国 家带来极大的经济损失。微波加热是将介质损耗变成热能的一种体加热，天然气水合物 是一种极性分子，对微波有一定的吸收作用，在微波辐射下会产生热效应而分解。 报告考虑将微波能应用于输气管道中天然气水合物的解堵，利用输气管道作为微波 传输的波导管将微波传输到水合物堵塞处，对水合物进行加热，达到管道解堵的目的， 从而实现天然气清洁、经济、高效、快速地输送。 首先，通过计算确定不同管径的管线可以传输的微波频率；其次，通过对微波在管 道中传输的衰减规律的研究，确定管道中可传输微波的最优频率，计算并分析理想和非 理想状态下微波在管线中的传输距离；然后，对微波传输时输气管线的温度分布规律进 行研究，建立数学模型，对比计算不同情况下整个管道的温度变化情况；最后，分析天 然气水合物的性质及其在管道中的形成条件，研究微波加热对水合物的影响规律，进而 判断微波解堵的可行性。 研究表明，微波能够在输气管道中进行传输，其能量随传输距离衰减，整个管线的 温度在微波的影响下都有所提升，几十瓦的功率就能较快地提升水合物处的温度，能在 较短时间内达到水合物分解温度。把微波能应用于输气管道的加热在理论上是可行的， 用来提高管线温度来解除水合物堵塞具有一定的现实可行性。 关键词， 天然气水合物 微波 输气管道 衰减 温度分布 报告类型，应用基础III ABSTRACT Natural gas hydrate is a cage-like crystalline compound similar to the ice. In given conditions, the water in natural gas in the pipeline will form hydrate with other parts. Hydrate will bring much disadvantages to the produce of natural gas once it forms, it can impose serious accidents such as the tap’s plugging, the pipeline’s stopping transport, and bring economics loss to enterprise and country. Microwave heating is a penetrating heating method that the dielectric loss is converted thermal energy. Natural gas hydrate is a polar molecule, the dissociation by microwave radiation depended on the thermal effect. The thesis states that microwave energy is applied to solve jam on the process of gas transport, the gas pipeline as a waveguide of microwave transmission can transfer microwave to the position full of hydrate, it can heat and resolve the hydrate, in order to accomplish cleanly, economical, high-effective and fast transportation of natural gas. First of all, we must choose the appropriate microwave frequencies that can be transmitted in the different pipelines by calculating. Followed, find the attenuation law of microwave transmit in the pipeline, and determine the best frequencies, then calculate distance of microwave transmit with the ideal and non-ideal state in the pipeline. Then, study the law of temperature distribution of the gas pipeline with the microwave transmission, establishing the mathematical model. Finally, analyze the nature gas hydrate formation conditions in the pipe and the law of microwave heating the hydrate, and then determine the feasibility of microwave solving blocking. Studies have shown that microwave can transmit in pipeline, its energy attenuate by distance, the temperature of the entire pipeline could be gone up with microwave,and a few dozen watts of power will be able to quickly improve the temperature of the hydrate. Applying microwave energy to the heating of the gas pipeline is feasible in theory; it has practical feasibility by raising the line temperature to solve the hydrate unplugging. Key words: Natural gas hydrate, Microwave, Gas pipeline, Attenuation, Temperature distribution Thesis type: Application foundationIV 目 录 第一章 前 言...........................................................................................................................1 1.1 研究背景.............................................................................................................................. 1 1.2 国内外研究现状.................................................................................................................. 4 1.3 主要研究内容及意义.......................................................................................................... 5 1.3.1 研究内容........................................................................................................................... 5 1.3.2 研究意义........................................................................................................................... 6 1.4 创新点.................................................................................................................................. 6 第二章 微波在输气管道中的传输特性研究.........................................................................7 2.1 圆波导中电磁波的传播...................................................................................................... 7 2.1.1 圆柱坐标系下的场分量................................................................................................... 8 2.1.2 波形分析........................................................................................................................... 9 2.1.3 传播模式分析................................................................................................................. 12 2.2 输气管道的微波传输特性分析........................................................................................ 13 2.2.1 常用微波频率对管道管径的要求................................................................................. 13 2.2.2 常用输气管道的微波传输频率分析............................................................................. 14 第三章 微波在输气管道中的传输距离计算.......................................................................15 3.1 输气管道的微波衰减系数分析........................................................................................ 15 3.1.1 波导中能量的传输与损耗............................................................................................. 15 3.1.2 传输距离分析................................................................................................................. 18 3.2 理想状态下的传输分析.................................................................................................... 20 3.2.1 微波频率 f=2450MHz 时 ............................................................................................... 20 3.2.2 微波频率 f=915MHz 时 ................................................................................................. 25 3.2.3 结果对比分析................................................................................................................. 29 3.3 最优频率选择.................................................................................................................... 29 3.4 非理想状态下的传输分析................................................................................................ 31 3.5 微波在管道中传输的初步结论........................................................................................ 35 第四章 微波在输气管道中的温度分布规律研究...............................................................37 4.1 数学模型的建立................................................................................................................ 37 4.1.1 模型描述......................................................................................................................... 37 4.1.2 单性值条件..................................................................................................................... 38 4.1.3 单位体积内热源生成热................................................................................................. 39 4.2 数学模型的求解................................................................................................................ 39 4.3 参数的确定........................................................................................................................ 44 4.4 数学模型结果计算及分析................................................................................................ 45 4.4.1 数学模型结果计算....................