No abstract

Fugitive emissions are one of the largest sources of volatile organic compounds (VOCs) from petrochemical and chemical plants. However, how to quantify the total fugitive VOC emissions from numerous and mostly inaccessible sources is a time consuming and costly task. This study presents a feasible approach to quantify the fugitive VOC emissions by integrating OPFTIR measurements and the well-developed Industrial Source Complex Short Term Model (ISCST3). A mobile OPFTIR system was set up for 190 hours in the downwind location of a 1,3-butadiene manufacturing process, which has unidentified fugitive sources and should be responsible for the elevated atmospheric 1,3-butadiene concentrations. Wind speeds and directions were found to be the most important factors in the dispersion of the emissions. Therefore, when using trial and error to predict the fugitive 1,3-butadiene emission rates, we divided the field measurement data based on the wind directions and excluded that obtained during lower wind speeds. Then the correlation coefficients between the field data (from the mobile OPFTIR system) and the modeling data (from the ISCST3) were found to be up to 0.529, and the slope of the correlation equation was close to unity. Therefore, integrating the OPFTIR measurement and ISCST3 is a feasible approach to predict the amount of fugitive VOC emissions.

The petrochemical complex examined in this work includes a great variety of facilities and factories that emit various odorants. A stationary open-path Fourier transform infrared (OPFTIR) system can be used for routine VOC and odor monitoring. However, when odor episodes occur, only multiple mobile OPFTIR systems are able to identify the odorant sources effectively and efficiently. In this study, N,N-dimethyl formamide (DMF) was found to be the most commonly detected odorant emitted from the investigated petrochemical complex by routine monitoring of a stationary OPFTIR system. Then the sequential deployments of a pair of mobile OPFTIR systems were carried out both upwind and downwind of the different sections of the focal area. The pollution rose plots derived from the data obtained by the pair of mobile OPFTIR systems identified the DMF sources. By conducting correlation analyses on the data obtained from the mobile OPFTIR situated at the downwind location of the DMF emission sources, we found that besides DMF, the dry PU synthetic leather process of plant B was also the major odorant source of 2-butanone, ethyl acetate and isopropanol. The source identification measure developed in this study can be used to clarify possible odorant sources not only for petrochemical industrial complexes but also for other areas associated with various emission sources.