Seasonal variation of toxic benzene emissions in petroleum refinery.

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.

Monitoring of hydrocarbon emissions in a petroleum refinery.

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.

Air pollution modeling: a tool for management of regional air quality.

Ambient air composition over the earth has undergone several changes. Anthropogenic pollutants generated locally often have regional air quality affected significantly. In addition to the short-term episodic effects, atmospheric pollutants are known to generate long-term adverse effects, which are difficult to forecast statistically. The air pollution dispersion modeling exercise forecasts fairly accurate air quality for a given emission scenario, incorporating geographical and meteorological conditions. Industrial Source Complex Dispersion Model is used to forecast ground level concentrations (GLC) of an industrial region as case study. The usefulness of mathematical modeling and computational simulation techniques used to predict the horizontal and vertical pollutant concentrations of pollutants are explained in this paper. Finally a case study of an industrial area in Gujarat region is presented to arrive at setting up of air quality monitoring station for monitoring/management of regional air quality.