Petroleum refineries are largest chemical industries that are responsible for the emission of several pollutants into the atmosphere. Benzene is among the most important air pollutants that are emitted by petroleum refineries, since they are involved in almost every refinery process. Volatile organic compounds (VOCs) are a major group of air pollutants, which play a critical role in atmospheric chemistry. These contribute to toxic oxidants, which are harmful to ecosystem, human health and atmosphere. The variability of pollutants is an important factor in determining human exposure to these chemicals. The ambient air concentrations of benzene were measured in several sites around the Digboi petroleum refinery, near the city of Gowahati in northeast India, during winter and summer 2004. The seasonal and spatial variations of the ambient air concentrations of this benzene were investigated and analyzed. An estimation of the contribution of the refinery to the measured atmospheric levels of benzene was also performed. The ambient air mixing ratios of benzene in a large area outside the refinery was generally low, in ppbv range, much lower than the ambient air quality standards. This article presents the temporal and spatial variation of air pollution in and around petroleum refinery and showed that no health risk due to benzene is present in the areas adjacent to the refinery.
High-temperature filtration is one of the most promising developments in particle collection technology. Process gases if cleaned (filtered) at elevated temperatures, then processes can be made more efficient in terms of energy and more integrated in terms of process technology. The present study embodies the effect of high temperature and dust concentration on the performance of different filter media (P84 with PTFE scrim and P84 with P84 scrim) in terms of emissions, filtration efficiency, pressure drop and other related factors. At low temperature and higher feed dust concentration level of 90 g/m 3 , P84/PTFE shows lower emissions in comparison to P84/P84, but at higher temperature the emissions were similar with different dust concentration levels for both the fabrics. However, at lower feed dust concentration (5 g/m 3 ), the emissions from both fabrics are similar in the experimental region of gas temperature. Filtration efficiency was found to increase at elevated temperatures but at the cost of increased residual pressure drop. In order to predict the performance of filter fabric at high temperature by testing at lower temperature, empirical equations were developed taking into account the operating temperature and dust concentration.
In a petroleum refinery the hydrocarbon emissions which are mostly fugitive in nature are emitted from process, offsites and periodic accidental releases such as: materials storage & handling, process, equipment leaks, solvent evaporation, combustion sources, waste treatment etc. In India, the monitoring of such emissions in a refinery are limited as also the standards are not set for its limit in ambient air. Hence there is an urgent need for generating a database for such emissions. Recently in India, MoEF/CPCB has set some guidelines under CREP rules for monitoring such emissions in a refinery. A detailed monitoring of the hydrocarbon emissions from different sources in a typical 10.5 MMTPA Indian refinery is undertaken during 1999-2001 and the results are presented. It is observed that the storage tank emissions alongwith process leaks form the major contributor towards fugitive hydrocarbon emissions.
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