Numerical Simulation of Dispersion of Emissions from Tema Oil Refinery in Ghana
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Date
2015-07
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University of Ghana
Abstract
The petrochemical industry is a major contributor of industrial air pollutants
which are known to have dire consequences on human health and
the environment, neccesitating research into their dispersion and transport.
The objective of the study, therefore, is to simulate the dispersion and transport
of pollutants emitted during the processing of crude oil by the Tema
Oil Refinery in the Greater Accra region of Ghana using the California
Puff (CALPUFF) modeling system. This thesis couples the Weather Research
and forecasting Model (WRF) with the non-steady state California
Puff(CALPUFF) modelling system to simulate the dispersion and transport
of emissions from the refinery in a coastal urban/industrial area in
Ghana. The mass balance approach was employed to estimate the refinery
emission rates which were used as input for the dispersion model. Emission
rates of five species were estimated - SO2, NO2, PM2:5, CO2 and VOCs.
The transport and dispersion of SO2, NO2 and PM2:5 were modelled over
the period between 2008 - 2013 and their impact on 38 identifed receptors
investigated. Simulation results showed that the radius of impact of the
emissions is approximately 10 km. As a result of the prevailing predominant
south-westerly winds in the study area, concentrations of emissions at
receptors located upwind of the emission source were found to be higher as
the winds carried the pollutant clouds in their direction. Conversely, south
and south-western receptors, relative to the refinery, on the other hand,
were minimally impacted. Concentrations of SO2 and NO2 at 2 out of the
38 receptors exceeded the regulatory limit of the World Health Organisation
and Ghana's Environmental Protection Agency. It can be concluded,
therefore, that SO2 and NO2 emissions from the refinery do not pose any
danger to the larger population and the general environment nearby. PM2:5
levels at 36 receptors however exceeded the WHO guideline value leading
to the conclusion that the refinery operations could pose some dangers
to the environment regarding PM2:5. The dispersion model results were
compared with measurements at the same location in order to validate
the model. Similarly, observations from two meteorological stations were
compared with results from the meteorological model. The performance
evaluation, with the aid of statistical measures revealed that the models'
performance were acceptable.
Description
Thesis (PhD)
Keywords
petrochemical industry, Tema Oil Refinery, Weather Research, forecasting Model, Environmental Protection, Ghana