微型填充床燃烧器中二甲醚的铂催化燃烧数值模拟

Numerical simulation of dimethyl ether catalytic combustion over platinum in a micro-scale packed bed combustor

微型圆管填充床式燃烧器既能实现催化燃烧又能稳定内部流场和温度场,二甲醚燃烧性能较好且污染物排放较低。本文采用数值模拟这种有效且节约资源的方法,建立微型圆管填充床式燃烧器中二甲醚在铂(Pt)上的催化燃烧模型,并研究利于之后引起气相反应的最优工况。结果表明:流速在0.2~1.0 m/s,当量比小于1时,有利于催化段的燃烧;流速大于3.0 m/s,当量比大于3时,利于之后引起气相反应;378~380 K为二甲醚在Pt上催化燃烧的着火点;二甲醚在催化剂上的吸附能力比氧气强,适量提高氧气的浓度能够促进催化反应的进行,而过量的二甲醚则会抑制催化反应的发生。

The micro-cylindrical packed bed combustor can realize not only catalytic combustion but also stable internal flow field and temperature field, dimethyl ether has good combustion performance and low pollutant emissions. The method of numerical simulation which is effective and can save resources is adopted to establish the model of dimethyl ether combustion over Pt catalyst in micro-cylindrical packed bed combustor. The optimal working condition conductive to the subsequent gas-phase reaction is investigated. The research shows that, when the flow velocity is between 0.2 m/s and 1.0 m/s and the equivalent ratio is less than 1, the catalytic combustion is better. Besides, when the flow velocity is greater than 3.0 m/s and the equivalent ratio is greater than 3, it＇s beneficial for the subsequent gas-phase reaction. The ignition temperature of the catalytic combustion of dimethyl ether over Pt is 378 K to 380 K. In addition, the adsorption ability of dimethyl ether on the catalyst is stronger than that of oxygen. Moderately increasing oxygen concentration can promote the catalytic reaction, and excess dimethyl ether may inhibit the occurrence of the catalytic reaction.