Technologies for Pollution Control Industry

THERMAL POWER PLANTS

Thermal Power Plants can be classified based on the type of fuel used. The main categories of the power plants are coal/lignite based; gas/Naphtha/oil based and Nuclear power plants.

Coal/lignite based thermal power plants

Particulate matter, sulphurdioxide and oxides of nitrogen are the main pollutants emitted form these plants which lead to air pollution. The suspended solids, oil and grease are main pollutants in effluent generated besides higher temperature in cooling water discharge.

The pollution control systems in practice and the requirements are tabulated below :

Technologies/Current Practices

Requirements

- Electrostatic Precipitators have been provided to control the emission of particulate matter with appropriate stack height for adequate dispersion of gaseous pollutants.

- High efficiency ESPs with EPIC controller should be provided. Further, based on background concentration or future development of power generation in cluster areas, space provision for installation of flue Gas Desulphurisation (FGD) system and DeNOx system, for control of SO2 and NOx emissions are needed so that the same control be provided where needed. For controlling smaller particulate emissions from stacks i.e. PM10/PM2.5, bag filters may be used as ESP would not trap small particles efficiently. Bag filters may also be used in combination with mechanical collectors or ESPs.

- To reduce ash content in coal, use of beneficiated coal has been made mandatory w.e.f June 2001.

- Fluidised Bed combustion (FBC)/CFBC technology for the solid fuel containing higher ash and sulphur.

- Integrated Coal Gasification combined cycle (IGCC) technology should be tried.

- Wet ash disposal system (lean phase) has been adopted. Some of the plants have dry ash disposal/collection system vis-a-vis wet disposal in ash pond with wastewater recycling system.

  • Dense Phase wet ash disposal system. Ash pond wastewater should by recycled hundred percent by the new plants.
  • To promote utilisation of flyash, provision for dry collection and storage (Silos) should be made an integral part of the ash management system.

- Once through cooling system is in practice in some plants. However, new plants have provided cooling towers (which discharge less quantity of hot water) .

- In water scarce areas and in locations where power plants are sited near lakes/reservoir, cooling towers should be provided.

Index

Gas/Naphtha based Thermal Power plants

Oxides of nitrogen and noise are the main pollutants from these plants. In combined cycle power plants, cooling water discharge at high temperature is a problem for the recipient water bodies.

The available and required pollution control measures in such plants are tabulated below:

Technologies/Current Practices

Requirements

- Low NOx burner and steam injection for control of oxides of nitrogen.

High efficiency catalysts based fuel gas denitrification (selective catalytic reduction, SCR) system.

- Turbines in acoustic enclosures (in door) to control noise.

Low noise and low vibration turbines.

- Once through cooling system

 

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