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周洁,陈晓虎.高温NO气体紫外吸收截面压力碰撞增宽效应的实验研究[J].环境科学学报,2006,26(6):1006-1010
高温NO气体紫外吸收截面压力碰撞增宽效应的实验研究
- Experimental study on pressure collisional broadenings of ultraviolet absorption cross-sections of nitric oxide at high temperature
- 基金项目：国家自然科学基金资助项目(No.50376058)
- 作者
- 单位
- 周洁
- 浙江大学 机械与能源工程学院, 杭州 310027
- 陈晓虎
- 浙江大学 机械与能源工程学院, 杭州 310027
- 摘要：采用高分辨率(0.05nm)光栅单色仪研究了NO气体在烟气排放温度(100～120℃)下200～230nm紫外吸收截面谱线受压力变化而产生的碰撞增宽效应.压力变化分为气样室总压和NO分压改变2种情况,分别通过充入纯N2伴随气体和配置不同浓度的NO标气来实现.测量结果表明,NO气体在此波段内存在的3条近似等间隔分布的吸收带,峰值位置并没有随压力的改变而移动.相比之下,由气样室总压增大所导致的NO吸收截面的Lorentz碰撞增宽效应并不明显;而由NO气体分压增大所导致的Holtzmark碰撞增宽效应则相对显著.当NO分压从67.3Pa增大到200Pa时,吸收截面峰值逐渐减小,3条吸收带中峰值最大减幅约为17.7%;谱线半宽逐渐增大,最大增幅约为11.8%.针对高分压下NO吸收截面逐渐偏离BeerLambert线性吸收定律的特性,提出了基于整个吸收带吸收截面积分的浓度反演修正公式,减小了NO分压对其浓度反演结果的影响,从而提高烟气中NO气体含量在线测量的精度.
- Abstract：Collisional broadenings of ultraviolet (200～230 nm) absorption cross-section arising from variations of total pressure of gas mixture and partial pressure of NO gas at flue gas temperature 100～120 ℃, were studied by using a high resolution grating spectrometer (0.05 nm) and a specially designed measurement cell. Measurement results indicated that, three absorption bands were present in this ultraviolet spectral range with a roughly equivalent wavelength interval and no motion of peak position of these bands was found at various pressures. Lorentz collisional broadening, investigated by charging various amount of pure N2 gas into the measurement cell to various total pressures, exhibited little effect on the peak height of absorption band, whereas Holtzmark collisional broadening effect, studied by changing the partial pressure of NO in gas mixture, was proven comparatively remarkable on the peak height of absorption cross-section of NO. When partial pressure of NO increased from 67.3 Pa to 200 Pa, the largest relative reduction was 17.7% in the peak heights of three absorption bands and the largest relative rise was 11.8% in the half widths of three absorption bands. Finally, a modified Beer-Lambert formula, based on the integral of absorption cross-section in an absorption band, was proposed for purpose of minimizing the nonlinearity effect on NO concentration derivation and further improving the precision of online concentration monitoring of NO in flue gas.
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