23-09-2014, 11:43 AM
Various methods to reduce SO2 emission- a review
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Abstract
—The emission of SO2 as a result of burning of
fossil fuels, especially coal, causes harmful impacts on the
environment, human health, livestock, and plants. Various
techniques have been employed to cut off the emission of
SO2 during the last generations. However, the amount of
SO2 discharged in the atmosphere is huge and its emission
is estimated to augment sharply in the years to come. In
this paper, a review of various flue gas desulphurization
(FGD) processes has been presented with a view to help
develop a novel and green process for the removal of SO2.
The FGD processes have been described, their applications
have been assessed and their costs have been analyzed. The
effect of parameters such as temperature, SO2
concentration in flue gas and pH has also been presented
and optimum conditions for achieving high efficiency have
been reviewed
INTRODUCTION
Flue gas emissions, which are exhaust gases produced at
power plants, have been a cause of serious air pollution since a
long time [1]. These emissions generally consist of H2O, O2,
SO2, CO2, CO and a variety of particulates. As SO2 is a major
problematic constituent in flue gas due to its deleterious
impact on both health and environment, its abatement in flue
gases is of significant concern. SO2 is a hazardous gas that is
generated by industrial activities like electric power
generation, combustion of fossil fuels and roasting of
sulphideore in metallurgy. A great amount of SO2 is also
added to air due to volcanic eruption. Moreover, these oxides
react with the moisture in air forming sulfuric acid, which then
leads to acid rain.
Due to the lowering of the permissible emission limits,
various SO2 removal techniques have been explored by
researchers and a large number of flue g
METHODS OF SO2 REMOVAL
Lutpi et al. investigated a technique that helps to solve the
problems occurring due to SO2 emissions in environment, and
also to neutralize the caustic and hazardous red mud in
economical ways. This study was carried out by using a
laboratory scale reactor to examine the absorption of SO2 with
red mud slurry and liquor samples. These samples undergo
alkalinity tests to determine the intensity of carbonate and
hydroxide ions present, before the absorption study. In their
research, they examined the efficiency of red mud as an
adsorbent for the absorption of SO2 and investigated the
ability of these gases to neutralize the red mud. It was
observed that the alkalinity of the red mud slurry and liquor
decreased slowly with the increase of acid. Moreover, the
results for absorption study showed that SO2 gas neutralized
the red mud liquor faster than the red mud slurry.Thus, further
research can be considered using red mud as an absorbent as it
exhibited good performance with respect to sulphur capacity
CONCLUSION
The present study deals with the removal of SO2 from flue
gases using various techniques.The review describes the
practical FGD processes, their characteristics, assesses their
use, determines which of these are feasible, characterizes the
SO2 removal performance of the processes and analyses their
costs. Processes using limestone slurry as an absorbent are the
most widely applied FGD technologies. According to the data,
most wet limestone systems are designed for about 90% SO2
removal. However, newer technologies and methods are
available that are capable of achieving SO2 removal
efficiencies of more than 95%. The appropriate method can be
selected based on the energy consumption, cost analysis, SO2
removal efficiency, reaction controllability, etc.
The removal of SO2 from exhaust gases from various
industrial sources has received considerable attention over the
years. Research and development of the FGD technology has
been focusing on improving the efficiency of removal of SO2,
minimizing energy consumption and cost. At the present
world level of 95% of SO2 removal efficiency by existing
technologies, the amount of SO2 discharged in the atmosphere
is huge. Thus, the aim of this review paper is to help find the
right direction in exploring new solutions.