合成气甲烷化固定床反应器的数值模拟研究
发布时间：2018-11-09 16:19
【摘要】：天然气由于安全清洁的低碳优质特性,成为能源产业转型发展中具有吸引力的选择,利用煤炭资源制天然气过程中甲烷化催化剂和反应器工艺是至关技术,其中前者研究和应用逐渐成熟。采用计算流体力学(CFD)的方法研究合成气制天然气反应器对于认识涵盖复杂物理化学变化和强放热特性的甲烷化反应过程可以节省实验研发成本和人力物力,为传统反应器的研发和进一步工业化放大提供辅助和预测。本文建立了合成气甲烷化平板式反应器二维几何模型,运用Fluent软件,利用CO甲烷化和水煤气变换为体系独立反应的动力学方程模型,建立了数值计算方法。首先验证工艺条件下的反应,模拟结果与实验值接近,说明了数学模型和计算方法的有效性。基于此,模拟研究不同工艺(温度,CO、H2气体分压、流量)和气体组成(含有CO2、H2O、CH4)以及实际工业原料气时平板反应器内的甲烷化反应,分析上述因素下反应系统的特征。应用CFD方法结合计算机软件进行模拟可以直观的了解薄层床反应器内各组分气体的分布规律和流场分布。数值研究结果表明：对于本文研究的固定床平板式反应器,在考察温度范围(553K-613K),气体流量0.30L/min,操作压力2atm,进料条件为Ar:0.40、H2:0.50、CO:0.10、CO2:0、CH4.0、H2O:0,CO基本反应转化完全,当温度从553K增加到613K时,化学反应速率变快,出口甲烷体积分数小幅增加变化不明显,从10.35%增加到12.83%；反应器内气体分布从未达到稳定到反应器长度方向上0.075m、0.055m和0.045m位置处稳定。其他条件相同时,增大原料气中CO和H2的分压有利于向生成甲烷的方向进行,会改变反应器内气体稳定段的长度和出口CH4体积分数。原料气流速在温度较低为553K时,对气体组成影响较大,流速从0.20L/min增加到0.60L/min,出口CH4体积分数从11.68%降低到5.02%；反应温度573K-613K时,主要影响气体分布稳定的位置。CH4和H2O对体系影响体现在反应器内气体分布和出口CH4的体积分数。CO2参与水煤气逆反应生成CO促进甲烷化反应,进口含CH4会增加出口CH4体积分数,H2O会影响气体分布；气体分布的共性都是从553K和573K下未达到稳定到593K和613K时逐渐在不同位置分布稳定。实际原料气组成有相同的变化规律和趋势,改变工艺条件会影响反应器出口气体组成和流场分布。
[Abstract]:Natural gas has become an attractive choice in the transformation and development of energy industry because of its safe and clean low carbon quality, and the methanation catalyst and reactor process is the most important technology in the process of using coal resources to produce natural gas. Among them, the former research and application gradually mature. The use of computational fluid dynamics (CFD) method to study syngas to produce natural gas reactor can save the cost of experimental research and development and manpower and material resources for understanding the methanation reaction process which covers complex physical and chemical changes and strong exothermic characteristics. It provides assistance and prediction for the research and development of traditional reactors and further industrialization amplification. In this paper, a two-dimensional geometric model of methanation plate reactor for syngas is established. Using Fluent software and CO methanation and water gas transformation as the kinetic equation model of independent reaction, a numerical calculation method is established. The simulation results are close to the experimental data, which shows the validity of the mathematical model and the calculation method. Based on this, the methanation reaction in a plate reactor with different processes (temperature, partial pressure of CO,H2 gas, flow rate) and gas composition (containing CO2,H2O,CH4), as well as actual industrial feedstock gas, was simulated and studied. The characteristics of the reaction system under the above factors are analyzed. CFD method combined with computer software can be used to simulate the gas distribution and flow field in a thin-bed reactor. The numerical results show that for the fixed bed plate reactor studied in this paper, the temperature range (553K-613K), gas flow rate 0.30 L / min, operating pressure 2 atm and feed condition are Ar:0.40,H2:0.50,. When the temperature increased from 553 K to 613 K, the chemical reaction rate became faster and the volume fraction of methane outlet increased slightly. From 10.35% to 12.83%; The gas distribution in the reactor was never stable to the position of 0.075mg 0.055m and 0.045m in the length direction of the reactor. When other conditions are the same, increasing the partial pressure of CO and H _ 2 in the feedstock gas is favorable to the direction of methane formation, which will change the length of the gas stable section in the reactor and the CH4 volume fraction at the outlet. At a low temperature of 553 K, the gas composition was greatly affected by the gas flow rate, the flow rate increased from 0.20L/min to 0.60 L / min, and the volume fraction of CH4 at the outlet decreased from 11.68% to 5.02%. The influence of CH4 and H _ 2O on the gas distribution and the volume fraction of the outlet CH4 in the reactor is reflected in the reaction temperature 573K-613K. CO2 takes part in the reverse reaction of water gas to form CO to promote the methanation reaction. The volume fraction of export CH4 will be increased when CH4 is imported and the distribution of gas will be affected by H2O. The commonness of gas distribution is that the gas distribution is stable at different locations from 553 K to 593 K and 613 K. The actual raw gas composition has the same change law and trend, and changing the process conditions will affect the gas composition and flow field distribution at the outlet of the reactor.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ052
本文编号：2320925
[Abstract]:Natural gas has become an attractive choice in the transformation and development of energy industry because of its safe and clean low carbon quality, and the methanation catalyst and reactor process is the most important technology in the process of using coal resources to produce natural gas. Among them, the former research and application gradually mature. The use of computational fluid dynamics (CFD) method to study syngas to produce natural gas reactor can save the cost of experimental research and development and manpower and material resources for understanding the methanation reaction process which covers complex physical and chemical changes and strong exothermic characteristics. It provides assistance and prediction for the research and development of traditional reactors and further industrialization amplification. In this paper, a two-dimensional geometric model of methanation plate reactor for syngas is established. Using Fluent software and CO methanation and water gas transformation as the kinetic equation model of independent reaction, a numerical calculation method is established. The simulation results are close to the experimental data, which shows the validity of the mathematical model and the calculation method. Based on this, the methanation reaction in a plate reactor with different processes (temperature, partial pressure of CO,H2 gas, flow rate) and gas composition (containing CO2,H2O,CH4), as well as actual industrial feedstock gas, was simulated and studied. The characteristics of the reaction system under the above factors are analyzed. CFD method combined with computer software can be used to simulate the gas distribution and flow field in a thin-bed reactor. The numerical results show that for the fixed bed plate reactor studied in this paper, the temperature range (553K-613K), gas flow rate 0.30 L / min, operating pressure 2 atm and feed condition are Ar:0.40,H2:0.50,. When the temperature increased from 553 K to 613 K, the chemical reaction rate became faster and the volume fraction of methane outlet increased slightly. From 10.35% to 12.83%; The gas distribution in the reactor was never stable to the position of 0.075mg 0.055m and 0.045m in the length direction of the reactor. When other conditions are the same, increasing the partial pressure of CO and H _ 2 in the feedstock gas is favorable to the direction of methane formation, which will change the length of the gas stable section in the reactor and the CH4 volume fraction at the outlet. At a low temperature of 553 K, the gas composition was greatly affected by the gas flow rate, the flow rate increased from 0.20L/min to 0.60 L / min, and the volume fraction of CH4 at the outlet decreased from 11.68% to 5.02%. The influence of CH4 and H _ 2O on the gas distribution and the volume fraction of the outlet CH4 in the reactor is reflected in the reaction temperature 573K-613K. CO2 takes part in the reverse reaction of water gas to form CO to promote the methanation reaction. The volume fraction of export CH4 will be increased when CH4 is imported and the distribution of gas will be affected by H2O. The commonness of gas distribution is that the gas distribution is stable at different locations from 553 K to 593 K and 613 K. The actual raw gas composition has the same change law and trend, and changing the process conditions will affect the gas composition and flow field distribution at the outlet of the reactor.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ052
【参考文献】
相关硕士学位论文 前1条
1 程金燮;合成气制天然气高效催化剂的制备及性能研究[D];北京化工大学;2014年
，本文编号：2320925
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