Abstract:

To intensify the CO₂ absorption process, a reactor based on swirling and multi-staged liquid-gas contact was used to examine the mass transfer performance of long-concentration span CO₂ (2.5%—15%) capture with NaOH solution. The effects of absorbent concentration, absorbent flow rate, CO₂ concentration, gas flow rate and reaction temperature on volumetric overall mass transfer coefficient (K_ga) were experimentally investigated. The mass transfer coefficient varied from 4.53×10^-5 to 9.22×10^-5 kmol·m^-3·s^-1·kPa^-1 under the experimental conditions. Compared with axial spray with double stages and swirling spray with single stage, swirling-based multi-staged spray reactor was able to effectively enhance the performance of absorption of long-concentration span CO₂. A high concentration and a high flow rate of the absorbent, and a high reaction temperature helped to increase K_ga. K_ga increased with the increase of CO₂ concentration, but decreased while CO₂ concentration was more than 5%. K_ga increased and then stabilized with increase of gas flow rate.

Key words: swirling flow, absorption, carbon dioxide, gas-liquid flow, mass transfer

摘要：

为强化二氧化碳的吸收过程,采用一类旋流逆向气液多级接触的方式,以NaOH溶液为吸收剂,研究其与大跨度浓度CO₂(2.5%～15%)接触反应的传质性能。分别探讨了吸收剂浓度、吸收剂流量、烟气CO₂浓度、烟气流量及反应温度对气相总体积传质系数(K_ga)的定量影响。结果表明,在实验条件下,其K_ga可达(4.53×10^-5)～(9.22×10^-5)kmol·m^-3·s^-1·kPa^-1。与双级直流喷雾和单级旋流喷雾相比,旋流逆向气液多级接触能够有效强化大跨度浓度CO₂的吸收过程。K_ga随吸收剂浓度、流量和反应温度的增加而增加,随CO₂浓度增加呈现先增加后减小(CO₂浓度大于5%)的非线性关系,随气体流量增加先增加后趋于稳定。

关键词: 旋流, 吸收, 二氧化碳, 气液两相流, 传质