Abstract:

Complex wet denitrification by Fe^ⅡEDTA is a promising process to remove nitric oxide (NO) from flue gas, in which the desorption of NO from Fe^ⅡEDTA-NO solution is of great importance for the reuse of Fe^ⅡEDTA solution. In this paper, vacuum desorption technology was first employed for denitrification system of mixed Fe^ⅡEDTA and ascorbic acid (VC). The effect of operating factors including vacuum degree and temperature on NO desorption performance was thoroughly investigated in a lab-scale reactor. The experimental results showed NO could be desorbed from Fe^ⅡEDTA-NO rich solution by direct heating or vacuum, and the increase of vacuum degree and temperature could significantly improve the desorption performance. In addition, compared with direct heating regeneration, vacuum desorption could improve desorption rate and lower the total energy consumption. The kinetics study showed that the desorption process presented first-order kinetics regarding Fe^ⅡEDTA-NO. Meanwhile, the activation energy, activation entropy, and activation enthalpy of Fe^ⅡEDTA-NO desorption were calculated to be 2.83kJ/mol, 196.90J/(K·mol), and 159.76kJ/mol, respectively. Finally, the absorption-desorption recycling experiments showed that Fe^ⅡEDTA-NO rich solution, after vacuum desorption of NO, could continue to capture NO, while the average NO removal efficiency would decrease below 90% after 11 cycles.

Key words: nitric oxide, evaporation, desorption, flue gas

摘要：

Fe^ⅡEDTA络合湿法脱硝是一种非常具有前景的烟气脱硝工艺，其中Fe^ⅡEDTA-NO液的NO解吸对Fe^ⅡEDTA的循环利用具有重要意义。本文首次将真空解吸技术应用于Fe^ⅡEDTA/抗坏血酸（VC）混合脱硝系统。在实验室规模的反应器中，深入研究了真空度和温度等操作因素对NO解吸性能的影响。实验结果表明，Fe^ⅡEDTA-NO液的NO可以通过直接加热或真空进行解吸，真空度的大幅度上升可以显著提高解吸性能，且高温有利于NO的解吸。此外，与直接加热再生相比，真空解吸可提高解吸速率并降低总能耗。动力学结果表明，Fe^ⅡEDTA-NO的解吸过程为一级动力学，同时，Fe^ⅡEDTA-NO解吸的活化能、活化熵、活化焓分别为2.83kJ/mol、196.90J/(K·mol)、159.76kJ/mol。最后，解吸吸收循环实验过程表明，脱硝富液Fe^ⅡEDTA-NO在NO真空解吸后仍能捕获NO，而且在循环实验中，经过11个循环后，NO的平均去除率降至90%以下。

关键词: 一氧化氮, 蒸发, 解吸, 烟道气