This work surveyed five process regions inside a petrochemical plant in Taiwan to characterize the profiles of airborne volatile organic compounds (VOCs) and locate emission sources. Samples, taken with canisters, were analyzed with gas chromatography-mass spectrometry according to the TO-14 method. Each region was deployed with 24 sampling sites, sampled twice, and 240 samples in total were measured during the survey period. All of the data were consolidated into a database on Excel to facilitate retrieval, statistical analysis, and presentation in the form of a table or graph, and, subsequently, the profile of VOCs was elucidated. Emission sources were located by mapping the concentration distribution of either an individual or a type of species in terms of contour maps on Surfer. Through the cross-analysis of data, the abundant VOCs included alkenes, dienes, alkanes, and aromatics. A total of 19 emission sources were located from these five regions. The sources for alkanes stood inside first, third aromatic, and fourth naphtha cracking regions, whereas the ones for alkenes were inside two naphtha cracking regions. The sources for dienes were found inside the third naphtha cracking region alone; in contrast, the sources for aromatics were universally traced except inside the third naphtha cracking region. The measured intensity for sources mostly ranged from 1000 to 7000 ppb.
INTRODUCTIONThe volatile organic compounds (VOCs) emitted from refineries and petrochemical plants were another environmental concern second to vehicle exhausts. 1 The VOC concentration from a petrochemical complex were reported 4-to 20-fold higher than those at a suburban site. 2-7 It was pointed out that, in a petrochemical plant, Ͼ90% of VOCs came from 10% equipment components. Therefore, locating emission sources was the first step to abate VOC emissions. 8 To locate the emission sources more quickly, the downwind concentrations were inverted by an atmospheric dispersion model to reconstruct distribution. 9 PONG-2, a Gaussian plume modeling technique, was applied to map possible odor sources. 10 Isopleths contour of concentration was used to estimate emission sources, and a large number of data were managed by using database or geographical information system. 11-14 Chemical mass balance model using multiple linear least-square regression has been widely used for identification and source apportionment of VOCs. [15][16][17] The principal component analysis/absolute principal component score receptor model was another source appointment technique, which requires a minimum of inputs regarding source characteristics but provides quantitative information regarding both source profiles and their impacts; this model has been applied to estimate source contributions to ambient VOCs in Hong Kong and Eastern China, respectively. [18][19][20] An overall survey of a petrochemical plant at Kaohsiung, Taiwan, has been accomplished and emission sources for VOCs have been found, located inside process regions and a tank farm. 21 To remedy th...
