VOCs在线监测进样方式对非甲烷总烃测定的影响

采用正压、负压、大气平衡3种进样方式，研究了VOCs在线监测系统对非甲烷总烃测定的影响。探讨在大气平衡进样方式下定量环内压力、平衡时间、进样流量对非甲烷总烃测定的影响，研究结果表明：采用正压进样方式，定量环内正压增大，非甲烷总烃质量浓度偏高；采用负压进样方式，定量环内负压增大，非甲烷总烃质量浓度降低；采用大气平衡进样方式，定量环内压力、平衡时间、进样流量的增大或减小对非甲烷总烃测定没有明显影响。比较3种进样方式，大气平衡进样方式的VOCs在线监测系统能够提高非甲烷总烃在线监测结果的准确性和可靠性，更适用于污染源废气在线监测。

Effects of Injection Methods of VOCs On-line Monitoring on the Determination of Non-methane Hydrocarbons

The effects of volatile organic compounds (VOCs) on-line monitoring system with positive pressure injection,negative pressure injection and atmospheric equilibrium injection of three different injection methods on monitoring the non-methane hydrocarbons (NMHC) were investigated in this paper.Under the atmospheric equilibrium injection mode,the impacts of the pressure of the sample loop,balance time and the flow rate of sample on the determination of NMHC were discussed.The results showed that the concentration of NMHC increased with the increasing sample positive pressure of the sample loop under the positive pressure injection mode,and the concentration of NMHC decreased with the increasing sample negative pressure of the sample loop under negative pressure injection mode.The pressure of sample loop,injection flow rate and balance time had no significant effect on the concentration of NMHC with atmospheric equilibrium injection.A comparison of three different injection methods indicated that VOCs on-line monitoring system with atmospheric equilibrium injection method could improve the accuracy and reliability of on-site monitoring results of NMHC,which might be more suitable for the on-line monitoring of stationary pollution source.