合成气制天然气反应器模拟和优化

发布时间：2018-12-30 19:36

【摘要】：通过对甲烷化反应系统分析,建立了一个第一甲烷化反应器出口部分循环的三级绝热固定床甲烷化工艺流程。选取一氧化碳甲烷化和水煤气变换反应为独立反应,CH4和CO2为关键组分,建立了绝热式固定床甲烷化反应器的一维拟均相数学模型。用Matlab采用Runge-Kutta法求解一维拟均相数学模型微分方程组。原料气流量800kmol/h,各组分摩尔分率CH4-0.0149, CO2-0.1010, CO-0.1290, H2-0.7515, H2O-0.0000, N2-0.0036,循环比为3.0,第一甲烷化反应器进口操作压力为3.0MPa,三级反应器进口温度都为553K时,第一、二、三甲烷化反应器出口温度分别为879K,725K和611K,CO转化率分别为86.48%,99.20%和100%,第三反应器出口CH4干基摩尔含量为95.49%。然后以一维拟均相数学模型为基础,建立二维拟均相数学模型,对径向反应温度和浓度分步进行初步研究,得到垂直于流动方向的温度差和浓度差很小,可不予考虑。基于甲烷化反应系统数学模型,考察了各工艺条件对反应器的影响。结果表明,原料气进料流量越大甲烷化反应位置越往后移；进料温度越高,反应器出口温度越高,CO转化率会相应降低；氢碳比对甲烷化反应影响不大,H/C在2.5-3.5之间都满足生产需要；H2O的加入会降低反应器出口温度和CO转化率,可以改变水的加入量调节反应器出口温度；操作压力越大越有利于甲烷化反应；循环比越大,反应器的出口温度明显降低,CO转化率和CH4干基摩尔含量都增大。用Aspen中转化率反应器模拟计算了一段循环、二段循环、三段循环和原料气分流二段循环工艺过程中产生的高压过热蒸汽、中压过热蒸汽和循环功耗,得到甲烷化工艺流程中余热回收最多、经济性最好的工艺流程是原料气分流二段循环工艺。一段循环副产高压过热蒸汽最多。
[Abstract]:A three-stage adiabatic fixed bed methanation process with partial circulation at the outlet of the first methanation reactor was established by systematic analysis of the methanation reaction. The one-dimensional quasi-homogeneous mathematical model of adiabatic fixed-bed methanation reactor was established by selecting carbon monoxide methanation and water gas shift reaction as independent reactions and CH4 and CO2 as key components. Matlab is used to solve the differential equations of one dimensional quasi homogeneous mathematical model by Runge-Kutta method. The flow rate of raw gas is 800 kmol / h, the molar fraction of each component is CH4-0.0149, CO2-0.1010, CO-0.1290, H 2-0.7515, H 2O -0.0000, N 2-0.0036, the cycle ratio is 3.0, When the inlet operating pressure of the first methanation reactor is 3.0 MPA, and the inlet temperature of the tertiary reactor is 553K, the outlet temperature of the first, second and third methanation reactors is 879KN 725K and 611KN CO conversion rate is 86.48, respectively. 99.20% and 100%, the dry mole content of CH4 at the outlet of the third reactor was 95.49. Then, based on the one-dimensional quasi-homogeneous mathematical model, a two-dimensional quasi-homogeneous mathematical model is established. The temperature and concentration of radial reaction are studied step by step. It is found that the temperature difference and concentration difference perpendicular to the flow direction are very small and can not be considered. Based on the mathematical model of methanation reaction system, the effects of various process conditions on the reactor were investigated. The results showed that the methanation reaction position moved backward with the increase of feed gas flow rate, the higher the feed temperature, the higher the reactor outlet temperature, and the lower the CO conversion rate. The ratio of hydrogen to carbon has little effect on the methanation reaction, and H / C can meet the needs of production between 2.5-3.5. The addition of H _ 2O can reduce the reactor outlet temperature and CO conversion, and can change the water addition to adjust the reactor outlet temperature. The higher the operating pressure, the better the methanation reaction, the higher the circulation ratio, the lower the outlet temperature of the reactor, the higher the CO conversion rate and the CH4 dry base molar content. The high pressure superheated steam, medium pressure superheated steam and cycle power consumption produced in the process of one-stage cycle, two-stage cycle, three-stage cycle and two-stage circulation of feed gas were simulated with Aspen conversion reactor. In methanation process, the waste heat recovery is the most, and the best economic process is the two-stage circulation process of feedstock gas. The first cycle produces the most superheated steam at high pressure.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE665.3

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