Flue Gas Desulphurisation - The Hindu - 03/12/22

Context:
According to study conducted by Centre for Research on Energy and Clean Air (CREA), Seven years after the December 2015 emission standard notification for coal-based power stations, not one single power station in West Bengal has installed Flue Gas Desulphurisation (FGD) technology to reduce SO2 emissions.
The emission standards were notified for the first time in December 2015 in India for coal-based power stations to limit emissions of sulphur dioxide (SO2), nitrogen oxides (NOx), and mercury (Hg), along with tightening particulate matter emissions standards and setting water consumption limits.
Relevance:
GS1 - Environment
About:
Key findings of the report:
-None of the coal-based power stations in West Bengal installed SO2 control technology over the past seven years since the emission standard notification for coal-based power stations was published in December 2015.
-Private sector power generation units are the worst when it comes to retrofits to control SO2 emissions; not one of them has awarded the bids after seven years of emission norms being in force.
-The coal consumption for grid-connected power generation in West Bengal has increased from 44 MT in 2015 to 54 MT in 2021.

Flue Gas Desulphurisation (FGD):
-Flue-gas desulfurization(FGD) is a set of technologies used to remove Sulphur dioxide (SO2) from exhaust flue gases of fossil-fuel power plants and from the emissions of other Sulphur dioxide-emitting processes such as waste incineration.
-FGD systems may involve wet scrubbing or dry scrubbing.
-In wet FGD systems, flue gases are brought in contact with an absorbent, which can be either a liquid or a slurry of solid material. The Sulphur dioxide dissolves in or reacts with the absorbent and becomes trapped in it.
-In dry FGD systems, the absorbent is dry pulverized lime or limestone; once absorption occurs, the solid particles are removed by means of baghouse filters.