等离子体射流裂解甲烷制乙炔的数值模拟

Numerical simulation of methane conversion to acetylene in plasma jet reactor

针对漏斗形射流反应器中热等离子体法裂解天然气制乙炔的过程进行研究.采用k-ε双方程模型对体系中的传递过程进行模拟,并通过甲烷裂解系列反应的宏观动力学模型对反应过程进行耦合.运用CFD方法进行数值求解,得到了反应器内的速度场、浓度场、温度场和反应速率分布.研究结果表明,漏斗形结构有利于反应器中温度和浓度的良好混合,使得甲烷充分反应;甲烷与乙烯的裂解反应主要沿温度混合面进行,炭黑浓度则沿反应器轴向逐渐增多.对应于本反应器,在等离子体发生器功率为100kW,甲烷体积流量为10m3·h-1时,甲烷转化率和乙炔收率同时达到最大.模拟结果与实验数据吻合较好,验证了模型与模拟结果的合理性.

Methane conversion to acetylene in a plasma jet reactor was studied. The k-ε two equations model was employed to simulate transport phenomena in the reactor, and macro kinetics of the series of pyrolysis reactions was introduced into the model. The coupled model of transport model and kinetics was calculated by using the CFD method, and distributions of velocity, mass fraction, temperature and reaction rates in the reactor were obtained. It was shown that the structure of funnel was beneficial to heat and mass transport to complete the pyrolysis of methane. Methane and ethylene were pyrolyzed mainly on the temperature mixing surface, and the mass fraction of carbon increased along the reactor axis. In this funnel reactor, when the power of plasma generator was 100 kW and the volume flow rate of methane was 10m^3 ·h^-1, the conversion rate of methane reached 100% and the yield of acetylene reached the maximum also. The experimental results obtained were considerably consistent with the simulation results.