烟气中CO_(2)在Laval喷管内部的非平衡凝结  

Nonequilibrium condensation of CO_(2)in flue gas inside Laval nozzles

作　　者：陈佳男 李安娜 黄柱 席光[1] CHEN Jianan;LI Anna;HUANG Zhu;XI Guang(School of Energy and Power Engineering,Xi'an Jiaotong University)

机构地区：[1]西安交通大学能源与动力工程学院

出　　处：《环境工程技术学报》2025年第2期523-530,共8页Journal of Environmental Engineering Technology

基　　金：国家自然科学基金项目(523B2067,12102331)。

摘　　要：基于相变动力学理论建立了一种用于预测在高压超音速流动中非平衡凝结的数学模型,针对经过脱硫脱硝除湿处理后的烟气(主要成分为N_(2)和CO_(2)),预测了Laval喷管中CO_(2)的非平衡凝结过程,阐明了初始饱和度对流动行为和非平衡凝结的影响。结果表明:热力学系统在Laval喷管喉部下游进入到非平衡状态,在x为0.09 m处出现凝结冲波现象,成核率从0迅速增加到6.33×10^(22)m^(−3)·s^(−1)。之后,亚稳态分子在凝结核表面聚集导致液滴生长,液滴生长速率在很短的时间内由0增加至0.04 m/s。当初始饱和度由0.11增加至0.19时,CO_(2)液滴半径由3.72×10^(−8)m增加到1.74×10^(−7)m,增加了2.67倍;CO_(2)液相质量分数由0.044增加到0.081,增加了84.1%。可以适当增加烟气中CO_(2)气体的初始饱和度以获得更大的液相质量分数与液滴半径,进而实现更好的碳捕集效果。A mathematical model for predicting nonequilibrium condensation in high-pressure supersonic flows was established based on phase transition kinetics theory.The nonequilibrium condensation of CO_(2)in Laval nozzle was predicted for flue gas(mainly composed of N_(2)and CO_(2))after desulphurization,denitrification and dehumidification,and the influence of initial saturation on flow behavior and nonequilibrium condensation was elucidated.The results showed that the thermodynamic system entered a nonequilibrium state downstream of Laval nozzle throat,a condensation shock phenomenon occurred at x=0.09 m,and the nucleation rate rapidly increased from 0 to 6.33×10^(22)m^(−3)·s^(−1).After that,metastable molecules aggregated on the surface of condensation nuclei,leading to droplet growth,and the droplet growth rate increased from 0 to 0.04 m/s in a short time.When the initial saturation increased from 0.11 to 0.19,the drop radius of CO_(2)increased from 3.72×10^(−8)m to 1.74×10^(−7)m,an increase of 2.67 times,and the liquid mass fraction of CO_(2)increased from 0.044 to 0.081,an increase of 84.1%.Therefore,the initial saturation should be appropriately increased to obtain a larger liquid mass fraction and droplet radius,thus achieving a better carbon capture effect.

关 键 词：碳捕集 超音速气流 传质传热 非平衡凝结 

分 类 号：X505[环境科学与工程—环境工程] X701