BY SYED SHAHBAZ SHAH

11MN93

“ADOPTION OF CLEAN COAL TECHNOLOGY” IN COAL-FIRED POWER PLANTS

PRESENTATION ON

General Perception For Coal-fired Power Plants

It is general perception that Electricity generation by Coal is an environmental threat and also increasing Green house Effect.

The burning of Coal causes :

Air Pollution

Acid rain

Ground-level ozone and smog.

Environmental Issues In Coal-fired Power Plants

Coal-Fired Power Plants are the major contributors of hazardous air pollutants.

Air Pollutants Include:

Emission of Particulate matter (soot).

(insufficient combustion )

Emissions of sulphur dioxide (SO2).

(Sulphur content)

Emissions of Oxides of Nitrogen (NOx) (When coal is burnt at high temp)

Carbon Dioxide CO2

These environmental Issues occur:

When,

Coal contains impurities like:

Sulfur

Specks of Minerals.

Common Dirt

To Minimize the Impacts of particulate matter & other Green House Gases emitted by Coal-fired power plant, it is necessary to adopt

“Clean Coal Technology”

This technology offers significant benefits when Coal is used to generate Electricity and also it can reduce the environmental impacts of coal fired power plants.

Clean Coal Technology falls into Three main categories:

1) Pre-combustion Technology 2) Combustion Technology

3) Post Combustion Technology

CLEAN COAL TECHNOLOGY

1) Pre-combustion Technology:

Coal Beneficiation (Coal Washing):

Coal washing involves:

crushing the coal into smaller pieces and passing it through a process called gravity separation.

This technique involves feeding the coal into barrels containing a fluid that has a suitable density which causes the clean coal particles to float, while the coal particles containing unwanted material sink and are removed from the feeding fuel.

2) Combustion Technology: Fluidized Bed Combustion (FBC) FBC allows coal combustion at relatively low

temperatures, which reduces nitrogen oxides (Nox) formation.

A sorbent {generally lime (CaO) or limestone (CaCO3)} is used to absorb sulphur because some sulfur remains chemically bonded in the coal and cannot be physically removed by washing.

The removal of this sulfur is targeted during burning.

3) Post Combustion Technology

i. Carbon Capture & Storage Technology

ii. DeNOx or De-nitrification Process

iii. Flue Gas Desulphurization (FGD)

iv. Fly Ash or Particulates Removal System

i. Carbon Capture & Storage

Technology:

This allows emission of Carbon dioxide to capture & Stored preventing CO2 from entering atmosphere.

ii. DeNOx or De-nitrification Process:

DeNOx or de-nitrification process to reduce the NOx and convert it into nitrogen and water allowing cleaner emission through the stack.

iii. Flue Gas Desulphurization(FGD):

Flue Gas Desulphurization

is a technology used for

removing sulfur dioxide (SO2)

from the exhaust flue gases of

Coal-fired power plants.

The removal of gaseous (SO2)

from flue Gases may be achieved

by Using Wet & Dry Scrubbers.

iv. Fly Ash or Particulates Removal System:

i. Cyclone collector: Cyclone is efficient in removing large particles d>10µm

ii. Bag Filter: Bag Filters is Effective for particles of diameter larger

than 1µm.

iii. Electrostatic precipitator: ESP is Effective for particles of d>1µm. Electrostatic

precipitators are highly efficient filtration devices and can easily remove fine particulate matter such as dust and smoke from the air stream.

Conclusions To meet increasing demand of power generation

in Pakistan with minimal environmental impacts, it is very necessary to install Coal Fired power plants.

Existing coal based power plants should be monitored by the Government for a cleaner environment.

Emphasis on clean Coal technology for Existing & new power plants.