The removal of nitrogen oxides under a high pressure has been widely accepted as an effective method for the treatment of oxy-fuel combustion flue gas. The high pressure promotes the oxidation of NO to NO₂, subsequently removed by water to form nitric acid. However, both the measurement and modeling of nitrogen oxides absorption shows uncertainties. To quantify the nitrogen mass balance, gas-phase NO/NO₂ and HNO₂ were measured online, whereas liquid-phase HNO₂ and HNO₃ were analyzed offline. Nitrogen mass balance was achieved with a relative error within ±8%. To improve modeling accuracy, a novel multiparameter optimization method was proposed. Mass transfer coefficients of NO₂/NO, rate constant of NO oxidation, surface area, and volume of liquid were optimized. The absorption of NO₂ into a liquid was dominated by gas-phase mass transfer with the mass transfer coefficient decreasing from 1.77 × 10^―4 mol m⁻² s^-1 Kpa^-1 to 1.26 × 10^―4 mol m⁻² s^-1 Kpa^-1 with the increase of reactor pressure from 5 bar to 20 bar. The pressure dependent rate constant for NO oxidation agreed with gas-phase NO oxidation experimental measurement. It first decreased with the reactor pressure from 5 bar to 15 bar followed by an increase from 15 bar to 20 bar. The surface area of liquid decreased while the liquid volume increased with the rising reactor pressure indicating that liquid droplets were formed by gas bubbling and attached onto the inner surface of the reactor. This study resolved the uncertainties in measurement and modeling of the nitrogen oxides absorption process.

在高压下除去氮氧化物已被广泛接受为处理氧-燃料燃烧烟道气的有效方法。高压促使NO氧化为NO ₂，随后被水去除以形成硝酸。然而，氮氧化物吸收的测量和建模都存在不确定性。为了量化氮质量平衡，在线测量了气相NO / NO ₂和HNO ₂，而离线分析了液相HNO ₂和HNO ₃。达到氮质量平衡，相对误差在±8％之内。为了提高建模精度，提出了一种新颖的多参数优化方法。NO _2的传质系数/ NO，NO氧化速率常数，表面积和液体体积均得到优化。NO的吸收₂到液体通过用传质系数从1.77×10降低气相的传质为主^-4摩尔米^-2小号^-1千帕^-1至1.26×10 ^-4摩尔米^-2小号^{- 1} Kpa ^-1反应器压力从5 bar增加到20 bar。NO氧化的压力依赖性速率常数与气相NO氧化实验测量结果一致。它首先随着反应器压力从5 bar降至15 bar而下降，然后从15 bar升高至20 bar。随着反应器压力的升高，液体的表面积减小，而液体的体积增加，这表明液滴是通过气体鼓泡形成的，并附着在反应器的内表面。这项研究解决了氮氧化物吸收过程的测量和建模中的不确定性。