摘 要

石油危机和能源短缺是现今人类所面临的难题，随着在发动机代替燃料方面上的发展，天然气作为一种燃烧热值高、排放污染低、储存量大的清洁能源具有广泛的应用前景。天然气其主要成分是甲烷，次要成份为部分乙烷、丙烷以及少量稀释气等，而且天然气成分及含量因产地不同而存在一定差异，从而也将造成天然气氧化特性产生一定变化。为了研究其氧化特性，国内外的学者运用不同的化学动力学模型对天然气以及主要成分的氧化特性进行研究，但是在天然气成分甲烷、乙烷、丙烷的氧化特性方面研究还比较有限。因而本文用不同掺混比的甲烷-乙烷-丙烷混合物为研究对象，在压力1 atm、当量比0.5、平均停留时间为1.4 s的初始条件下模拟进行甲烷-乙烷-丙烷混合物JSR氧化特性研究。

本文的模拟实验是通过CHEMKIN PRO软件中PSR模块来实现的，筛选合适的化学动力学机理，在900-1200 K的条件下分析了不同掺混比甲烷-乙烷-丙烷混合物氧化过程中重要组分浓度随温度变化的变化情况，在1000 K的条件下进行了不同掺混比甲烷-乙烷混合物和甲烷-乙烷-丙烷混合物氧化过程中反应物的主要反应路径分析和敏感性分析，探讨三种燃料之间相互影响的机制，结果表明：

（1）乙烷和丙烷都有提高甲烷氧化活性的作用，在不同掺混的甲烷-乙烷-丙烷混合物中不论降低丙烷含量还是同时降低乙烷和丙烷含量，都会出现甲烷氧化初始温度延后的现象。

（2）当在甲烷-乙烷和甲烷-乙烷-丙烷混合物中增加掺混乙烷或丙烷比例时，甲烷和乙烷的主要反应路径基本是没有改变的，而且只影响具体物质生成和消耗的百分比，其中基元反应R207、R217可分别产生H、HO₂自由基；增加掺混乙烷或丙烷比例，R207、R217基元反应比例增大，H、HO₂自由基增多，对整个自由基池的建立有促进的作用。

（3）在甲烷-乙烷混合物中，抑制甲烷消耗较大的基元反应为R194 2CH₃( M)lt;=gt;C₂H₆( M)，对甲烷、乙烷消耗促进作用较大的基元反应为R3 H₂ OHlt;=gt;H H₂O和R91 CH₃ O₂lt;=gt;CH₂O OH。在甲烷-乙烷-丙烷混合燃料氧化过程中的基元反应R27 HO₂ Hlt;=gt;2OH和R28 HO₂ Hlt;=gt;H₂ O₂对甲烷、乙烷、丙烷消耗抑制作用较大；基元反应R248 C₂H₄ OHlt;=gt;C₂H₃ H₂O、R21 H₂O₂( M)lt;=gt;2OH( M)和R36 CO OHlt;=gt;CO₂ H对甲烷、乙烷、丙烷消耗促进作用较大。

关键词：天然气成分；模拟研究；掺混比；化学动力学分析

Abstract

Oil crisis and shortages are the problems facing mankind today, with the development of on engine instead of fuels, natural gas as a kind of clean energy with high burning calorific value, low emission pollution and large storage capacity, has a wide application prospect, its main composition is methane, gas secondary ingredients for part of ethane, propane, and a small amount of dilute gas, and gas composition and content of certain differences because of different origin, which has certain changes will cause oxidative gas properties. Domestic and foreign scholars use different chemical dynamics models to study the oxidation characteristics of natural gas and its main components. However, studies on the oxidation characteristics of natural gas components methane, ethane and propane are still limited. Therefore, in this paper, methane-ethane-propane mixtures with different mixing ratios were used as the research object, and the oxidation characteristics of methane-ethane-propane mixture JSR were simulated under the initial conditions of pressure 1 atm, equivalent ratio 0.5 and average residence time 1.4 s.

The simulation experiment carried out in this paper was realized by PSR module in CHEMKIN PRO software, chemical kinetics mechanism of the filtered through, the change of concentration of important components with temperature in the oxidation process of methane-ethane-propane mixture with different mixing ratios was analyzed at 900-1200 K, the main reaction path and sensitivity analysis of reactants in the oxidation process of methane-ethane mixture and methane-ethane-propane mixture with different mixing ratios were carried out at the condition of 1000 K, and the interaction mechanism between the three fuels was discussed. The results showed that:

(1)Both ethane and propane have the effect of increasing the oxidation activity of methane. In the mixture of methane-ethane and propane with different mixing ratios, the initial temperature of methane oxidation will be delayed whether the content of propane is reduced or the content of ethane and propane is reduced simultaneously.

(2)When mixing ethane or propane in methane-ethane and methane-ethane-propane mixtures is increased, the main reaction path of methane and ethane is basically unchanged and it only affects the percentage of specific substances that are produced and consumed, H and HO₂ free radicals can be produced by elementary reactions R207 and R217, increasing the content of mixed ethane or propane, increasing the reaction ratio of R207 and R217, increasing H and HO₂ free radicals, and promoting the establishment of the whole free radical pool.

(3)In the methane-ethane mixture, the primitive reaction that inhibited the large consumption of methane was R194 2CH₃( M)lt;=gt;C₂H₆( M), the major elementary reactions of methane and ethane were R3 H₂ OHlt;=gt;H H₂O and R91 CH₃ O₂lt;=gt;CH₂O OH. In the mixture of methane-ethane-propane, the primitive reactions R27 HO₂ Hlt;=gt;2OHand R28 HO₂ Hlt;=gt;H₂ O₂ have a great inhibitory effect on the consumption of methane, ethane and propane, the elementary reactions R248 C₂H₄ OHlt;=gt;C₂H₃ H₂O, R21 H₂O₂( M)lt;=gt;2OH( M) and R36 CO OHlt;=gt;CO₂ H promoted the consumption of methane, ethane and propane.

Key Words：natural gas composition; Simulation research; The mixing ratio; Chemical kinetic analysis

目 录

第1章 绪论 1

1.1 研究背景 1

1.2 目的及意义 2

1.3 国内外的研究现状 2

1.3.1 天然气燃烧特性研究现状 2

1.3.2 射流搅拌反应器试验装置研究现状 3

1.4 研究的目标、基本内容、拟采用的技术方案及措施 4

1.4.1 研究的目标 4

1.4.2 研究的基本内容 4

1.4.3 研究拟采用的技术方案及措施 4

第2章 射流搅拌反应器试验装置与数值模拟方法 6

2.1 射流搅拌反应器试验装置介绍及原理 6

2.2 数值模拟方法 7

2.2.1 CHEMKIN系列软件的介绍及选用 7

2.2.2 数值计算模型的建立 8

2.3 本章小结 8

第3章 不同掺混比甲烷-乙烷-丙烷混合物氧化特性的研究与模拟 9

3.1 化学动力学机理的简介及选择 9

3.1.1 化学动力学机理的简介 9

3.1.2 化学动力学机理的选择 9

3.2 不同掺混比甲烷-乙烷-丙烷混合物氧化过程中重要浓度组分变化 10

3.2.1 甲烷-乙烷和甲烷-丙烷混合物氧化过程中重要浓度组分变化 11