ZHU Hongqing, GUO Feng, QU Jiangyuan. Heat-mass transfer and chemical reaction characteristics during carbon dioxide absorption by amine solution in spray scrubber[J]. Thermal power generation, 2025, 54(6): 139-147.
ZHU Hongqing, GUO Feng, QU Jiangyuan. Heat-mass transfer and chemical reaction characteristics during carbon dioxide absorption by amine solution in spray scrubber[J]. Thermal power generation, 2025, 54(6): 139-147. DOI: 10.19666/j.rlfd.202412268.
喷淋塔内醇胺溶液吸收二氧化碳热质交换与化学反应特性
摘要
以工业规模喷淋塔内醇胺溶液吸收CO_2为研究对象,基于欧拉-拉格朗日方法建立了烟气-液滴气液两相流动、相间传热传质和液相化学反应耦合的计算流体力学(CFD)模型。通过与乙醇胺(MEA)溶液吸收CO_2实验数据对比验证了CFD模型可靠性,在此基础上分析了CO_2吸收过程所伴随热质交换和化学反应的基本规律,以及吸收剂化学组成、气液两相流动特性和操作压力对喷淋塔内CO_2脱除效率的影响。模拟结果表明:随塔体高度增加烟气中CO_2体积分数下降,而烟温和水蒸气体积分数均呈先上升后下降趋势;当贫液中CO_2负荷由0.1增至0.4,塔内烟温最大值由70℃降至54℃,贫液负荷大于0.25时喷淋塔脱碳效率显著下降;表观气速大于2.5m/s时烟气停留时间显著缩短且液相侧传质系数减小,传质比表面积的增加对CO_2吸收效率提升作用减弱;喷淋塔操作压力由101 k Pa降至70 k Pa
CO_2脱除效率降低约15.9百分点。
Abstract
Taking CO_2 absorption by amine solutions in industrial-scale spray towers as the research object
a computational fluid dynamics(CFD) model is established to describe the gas-liquid two-phase flow
interphase heat and mass transfer
and chemical reaction process in industrial-scale spray scrubber
based on the Euler-Lagrange method. The reliability of the CFD model is validated by experimental data of CO_2 absorption by monoethanolamine(MEA) solution. On this basis
the fundamental laws of heat and mass transfer and chemical reactions accompanying the CO_2 absorption process
as well as the effects of the absorbents' chemical composition
gas-liquid phase flow characteristics
and operating pressure on the efficiency of CO_2 removal in a spray tower were investigated. The numerical results indicate that
the volume fraction of CO_2 in flue gas decreases with the increase of scrubber height
while both the gas temperature and water vapor pressure firstly increase and then decrease with the increase of elevation. With the increase of CO_2 load in lean solution from 0.1to 0.4
the highest gas temperature in the scrubber declines from 70 ℃ to 54 ℃. The overall decarbonization efficiency for the spray scrubber significantly decreases when the load of lean solution is greater than 0.25. When the superficial gas velocity is greater than 2.5 m/s
the enhancement of increased mass transfer specific interface area on CO_2 absorption is restricted ascribed to the declines of gas residence time and mass transfer coefficient.For the decrease of operating pressure in spray scrubber from 101 kPa to 70 k Pa
the CO_2 removal efficiency decreases by about 15.9 percentage points.