喷雾汽化器汽化效率优化的数值研究

Numerical study on optimization of vaporization efficiency of spray vaporizer

为进行喷雾汽化器内多相流动和汽化效率的优化研究,基于计算流体力学(CFD)方法,对高沸点的碳酸乙烯酯(EC)液体在富氢气体中的混合和汽化过程进行了三维数值模拟。结果显示,汽化器内按流型可分为回流过渡区和管流区,其轴向分界点可通过计算气相介质中径向温差或喷雾介质径向浓差随轴向距离变化率的最大值求得;通过优化管流区结构可增大汽化效率,同时减小汽化器高度。当气体初始温度为220℃时,回流过渡区占整个汽化容积的40%,其中的EC汽化量占汽化器总汽化量的83%,回流过渡区单位汽化容积的汽化效率约为管流区相应效率的7.3倍。对占汽化器有效容积60%的管流区进行结构优化后,显著增大了汽化效率,可因此缩减汽化器高度约22%。

In order to optimize the multi-phase flow and vaporization efficiency in a spray vaporizer, the mixing and vaporization processes of high boiling point ethylene carbonate(EC) liquids in hydrogen-rich gas were numerically simulated by computational fluid dynamics(CFD) method. The results showed that the vaporizer internal space could be divided into two parts according to the flow pattern, namely the reflux transition zone and the tube flow zone. The axial boundary point between the former and the latter could be obtained by analyzing the maximum value of the first derivative of the radial temperature difference or the radial concentration difference of vaporized liquid with the axial distance. The vaporization efficiency could be increased and the height of the vaporizer could be reduced by optimizing the structure of the flow zone. When the initial temperature of the gas was 220 ℃, the reflux transition zone accounted for 40% of the total vaporization volume, in which the EC vaporization accounted for 83% of the total vaporization of the vaporizer. And the vaporization efficiency of the unit vaporization volume in the reflux transition zone was about 7.3 times of the corresponding efficiency in the tube flow zone. After the structure optimization of the tube flow zone which accounts for 60% of the effective volume of the vaporizer, the vaporization efficiency was significantly increased, and the vaporizer height could be reduced by about 22%.