汽车零配件涂装过程VOCs排放特征与案例分析

VOCs（挥发性有机物）现已被列为我国大气环境领域的核心污染物.随着汽车零配件制造行业减排要求的提出，于2018年6月选取典型汽车零配件制造企业，采用美国TO-15方法分析VOCs物种，采用FID（氢离子火焰检测器）对NMHC（非甲烷总烃）进行实测，分析汽车零配件涂装过程的VOCs排放特征.结果表明:①由于分析方式的不同，有组织排放的ρ（NMHC）比ρ（VOCs）高1.3~1.9倍，其中末端未安装VOCs处理设施的排气筒排放的ρ（NMHC）最高.②汽车零配件涂装过程排放的主要VOCs物种质量浓度占比范围分别为46.72%~98.33%（芳香烃）、1.20%~52.90%（含氧VOCs），其中ρ（二甲苯）、ρ（苯系物）超标（DB 31/933—2015《大气污染物综合排放标准》）情况较为严重.③未进入VOCs处理装置前的VOCs物种组成与原辅料中VOCs物种组成一致，二者主要VOCs物种的质量分数大致相同，说明生产工艺的不同对VOCs的排放组成影响较小.④比较RTO（蓄热式热力燃烧装置）和活性炭吸附装置处理VOCs前、后废气组成的差异发现，活性炭吸附装置处理对VOCs排放的组成基本无影响，经RTO处理后排放物种以芳香烃和含氧VOCs为主，但是w（芳香烃）和w（含氧VOCs）变化不一致，说明RTO对芳香烃和含氧VOCs处理效率不同.研究显示，为满足国家对汽车零配件制造行业VOCs的减排要求，源头使用高固分涂料或水性涂料替代溶剂型涂料，优化过程收集系统，增强末端处理技术的净化效果、安全性和稳定性，是实现汽车零配件制造行业全过程减排的重要手段. 

Emission Characteristics and Case Study of Volatile Organic Compounds (VOCs) in Typical Auto Parts Painting Processes

Volatile organic compounds (VOCs) have become the key pollutants in the atmospheric environment of China. With the emission reduction requirements, the present paper aims to provide useful information for the coating process which plays a dominant role in the VOCs emission in the auto parts manufacturing industry. In this study, a typical enterprise was selected to analyze the emission characteristics of VOCs by TO-15 method, none-methane hydrocarbon (NMHC) was measured by hydrogen ion flame detector in June 2018. Our results revealed that: (1) The detected ρ(NMHC) was 1.3-1.9 times higher than ρ(NMHC) at all the links due to the different analysis methods, the ρ(NMHC) in the exhaust funnel without the VOCs treatment facility was the highest. (2) The major species of VOCs are aromatics and oxygenated species, among which xylene and aromatics seriously exceeded the limit value. The proportion of aromatics and oxygenated species was 46.72%-98.33%, 1.20%-52.90%. (3) The chemical composition of VOCs before entering the VOCs purification device was consistent with that of the raw materials, w(VOCs) were approximately the same, indicating that different coating processes had little effect on the composition of the VOCs emission. (4) The difference in the VOCs compositions before and after regenerative thermal oxidizer (RTO) and activated carbon adsorption was compared. For activated carbon adsorption, no difference in the VOCs compositions was observed before and after the treatment, while in the case of RTO, the main emission species were still dominated by aromatics and oxygenated species, but changes of w(aromatics) and w(oxygenated species) were inconsistent, indicating that RTO had different treatment efficiency for aromatics and oxygenated species. In order to satisfy the national requirements of VOCs emission reduction for auto parts manufacturing industry, this study provides some suggestions for the manufacturing processes to achieve whole-process emission reduction, including the use of high-solid components coating or water-based coating instead of solvent-based coating at the source, optimization of the collection system, enhancement of the purification efficiency, and safety and stability of the terminal treatment facilities.