Study on the Applicability of Photoionization Detection Technology for VOCs Monitoring in Industrial Areas
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摘要: 目前在使用光离子化气体检测器(PID)设备对工业园区挥发性有机物(VOCs)进行监测过程中,设备间监测数据普遍存在偏差大、准确度和稳定性不足等问题,影响了园区VOCs的监测评价与管控. 为探究偏差产生的原因,本文选取了市售4个品牌的8套PID监测设备,在工业园区进行实地测试,对其适用性进行研究. 结果表明:① 在安装了除湿装置后,PID设备在高湿阶段监测正常,同时通过在现场对不同湿度标准气体的测试可知,除湿装置对测试数据的准确性无影响. 因此,在高湿度地区采用除湿装置,可提高PID设备监测数据的准确性. ② 环境空气实测时,虽然与气相色谱仪/氢火焰离子化检测器(GC-FID)设备原理不同,但经过一系列改进措施后,8台PID设备测得总VOCs体积分数变化趋势与GC-FID设备基本一致;同时,同品牌设备间平行性较好,各PID设备与GC-FID设备所测结果的相关系数均在0.82以上,最高可达0.96,但在GC-FID设备监测的VOCs体积分数<50×10−9时,二者相关性不理想. ③ 针对工业园区VOCs监测,本研究提出了将PID设备和GC-FID设备监测数据的比对计算方法,与将PID设备和GC-FID设备的监测数据经过简单求和后进行比对的方法相比,前者的相关性优于后者. 研究显示,可通过规定PID设备在工业园区进行报警的浓度,明确与常用设备比对的内容以及增加冷凝装置等方式来提高PID设备的监测准确性,从而提升工业园区O3前体物的管控效果.
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关键词:
- PID /
- 监测 /
- 挥发性有机物(VOCs)
Abstract: During the grid monitoring of volatile organic compounds (VOCs) in industrial parks using low-cost PID equipment, the monitoring data deviation between equipment is large, resulting in insufficient accuracy and stability. This is a common problem affecting the evaluation and control of VOCs in the parks. To investigate the cause of this deviation, eight sets of PID monitoring equipment of four different brands were selected for field testing in an industrial park to study their applicability. The results showed that: (1) After installing a dehumidifier, the PID monitoring equipment worked normally in high humidity stages. Moreover, the field test of standard gases with different humidity showed that the dehumidifier had no effect on the accuracy of the test data. Therefore, using a dehumidifier can improve the accuracy of PID monitoring data in high-humidity areas. (2) During environmental air testing, the total VOC concentration measured by the eight PID equipment showed a similar trend to that measured by GC-FID equipment. The correlation coefficients between each PID equipment and the FID equipment were all above 0.82, with the highest correlation coefficient reaching 0.96. However, the correlation between the two pieces of equipment was not ideal in the low-concentration stage (50×10−9) of GC-FID equipment, indicating that PID equipment is suitable for rapid alarm detection with concentrations above 50×10−9. (3) For the monitoring of VOCs in industrial parks, this study proposes the method of comparing the monitoring data from PID equipment and GC-FID equipment after corresponding calculation, and the correlation of the former method is better than that of the latter method, compared with the method of comparing the monitoring data from PID equipment and GC-FID equipment after simple summation. (4) The research shows that the accuracy of PID monitoring can be improved by specifying the concentration of PID devices to trigger alarms in industrial parks, clarifying the comparison with commonly used devices, and adding condensation devices. This helps to determine the application positioning of PID devices in the industrial park and lay the foundation for managing O3 precursor substances in industrial parks.-
Key words:
- PID /
- monitoring /
- volatile organic compounds (VOCs)
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表 1 设备测试期间的性能评估结果
Table 1. Performance evaluation results of the equipment during the comparison period
设备名称 有效数据量 体积分数平均值/10−9 相关系数(与GC-FID设备所测数据) 斜率 截距 均方根误差/10−9 标准偏差/10−9 GC-FID 915 23.4±36.4 Y-2 858 50.4±34.7 0.87 0.94 −22.9 30.9 38.0 Z-1 915 74.3±5.7 0.96 6.07 −427.8 59.6 36.4 A-1 915 28.2±38.5 0.90 0.82 −3.3 19.4 38.5 A-2 915 28.2±38.5 0.89 0.84 −0.2 18.7 37.5 A-3 915 33.5±40.2 0.92 0.83 −4.5 18.7 38.7 S-1 915 22.5±19.0 0.82 1.58 −12.1 23.3 29.0 S-2 915 24.4±19.2 0.83 1.58 −15.2 22.9 29.1 S-3 915 20.7±18.8 0.84 1.63 −10.3 23.1 29.0 表 2 设备比对期间GC-FID所测体积分数小于50×10−9时的性能评价结果
Table 2. Performance evaluation results of the equipments when GC-FID monitoring data smaller than 50×10−9 during the comparison period
设备名称 有效数据量 体积分数平均值/10−9 相关系数(与GC-FID设备数据) 斜率 截距 均方根误差/10−9 标准偏差/10−9 GC-FID 811 13.5±11.6 Y-2 754 41.1±17.5 0.72 0.48 −6.0 28.8 20.2 Z-1 811 72.8±1.9 0.83 4.93 −345.2 60.2 30.8 A-1 811 18.6±15.3 0.78 0.54 1.5 13.8 15.1 A-2 811 18.6±15.3 0.68 0.51 3.9 12.4 13.8 A-3 811 23.0±17.4 0.79 0.53 1.3 14.3 15.5 S-1 811 18.0±11.1 0.44 0.46 5.2 12.8 11.6 S-2 811 19.8±11.2 0.46 0.48 3.9 13.4 11.8 S-3 811 16.2±10.7 0.46 0.50 5.3 11.9 11.2 表 3 报警时段内PID设备与GC-FID设备数据比较
Table 3. Comparison of PID equipment and GC-FID equipment during the alarm period
时段 GC-FID设备所测
体积分数/10−9A-3设备所测
体积分数/10−9A-3设备整小时
体积分数/10−9A-3设备体积分数
最大值出现时刻A-3设备体积分数
最大值/10−912月15日03:00—03:59 69.2 71.2 70.8 03:00 105.0 12月15日04:00—04:59 74.3 110.8 103.9 04:21 132.0 12月15日05:00—05:59 162.2 142.2 136.6 05:33 169.5 12月15日06:00—06:59 139.6 152.2 162.9 06:10 227.0 12月15日07:00—07:59 201.0 242.6 226.8 07:55 303.5 12月15日08:00—08:59 72.5 77.6 122.4 08:00 275.0 12月15日09:00—09:59 36.3 37.4 59.7 09:00 337.0 -
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