Power Plant Pollution Control

Other Unique Engineering Ideas

The electric utilities are currently faced with simultaneous demand for increased power, and the demand for the elimination of all the objections attributed to hydro-electric power, fossil fuels and nuclear energy. The electric power demand is continuously increasing and it is expected that the demand would be doubled after every 7 to 10 years and the pollution of the environment would be rapid in the coming years.

1. Description

2. Why

3. How

4. Future Trends

5. Related Links

Useful links: Control of mercury emissions, pollutioncontrols, Environmental Health 

Description  

A coal fired power plant includes a coal gasification zone where coal is gasified in the presence of an oxidant-lean atmosphere under partial coal gasifying conditions to produce 

  • Carbonaceous char and a crude gas stream,

  • An acid separating zone where sulfur-containing compounds are separated from the crude gas stream to produce a combustible gas stream,

  • A converting zone where the sulfur-containing compounds are converted to elemental sulfur. 

Why: Ill Effects 

Over recent years, as it has become evident that the atmosphere cannot continue to absorb increasing loads of pollutants without consequence, a number of technologies have been devised to reduce both NOx and sulfur dioxide emissions. 

  • The ash is also a problem as it also emits heat to the atmosphere as well as small diameter pollutants carried by the air.

  • The pollution from the thermal plant is also large quantity of heat discharged to the atmospheric air and water used for condensing the steam. 

  • The pollution from the nuclear power plants is radio-active waste in form of gases, liquids and solids whose radio active property may retain number of years. 

An increased concentration of man's activity in to any area is another cause of air pollution. In USA, 50% of the total emissions are released over leas than 1.5% of the country's area. No. doubt, presently the percentage pollution by electric plants is considerably less (15% of total) but it is estimated that the source of pollution will increase rapidly as the power demand increase is very very rapid.

How: Major pollutants

New technologies being developed world-wide to reduce NOx and sulfur dioxide. An elegant, cost-effective process that allows power plant scrubbers, designed to remove sulfur dioxide only, also to capture nitrogen oxides. Indeed the process transforms these pollutants into valuable commercial chemicals.Attempts to diminish ozone levels by reducing auto hydrocarbon emissions may be futile. Instead, it may be necessary to limit the oxides of nitrogen being discharged into the atmosphere.The combustible gas stream and the carbonaceous char are fed into a boiler which drives a generator to produce electricity; portions of the carbonaceous char product and the combustible gas stream are diverted into a gypsum desulfurization zone.

  • SO2 -containing flue gas from the boiler is fed into a flue gas desulfurization zone. 

  • There, the SO2 -containing flue gas is contacted with lime and limestone to produce gypsum.

The SO2 -containing gas stream is recycled back to the coal gasification zone to provide at least a portion of the oxidant-lean atmosphere air used in the coal gasification zone.The main pollutants from the thermal plants are dust and objectionable gases like CO, CO., SO2, NO2 and many others.The gypsum is fed to the gypsum desulfurization zone where it is heated with the diverted carbonaceous char under reducing conditions utilizing the diverted combustible gas stream to provide energy to produce a SO2 -containing gas stream

Future Trends

The IEP program is focused on R&D in post-combustion and oxycombustion technology for CO2 capture from existing plants. The program will also invest in R&D in the related areas of CO2 compression and the beneficial alternative uses of CO2.Water and energy are inextricably linked. Because thermoelectric generation and fossil fuel extraction can impact water resources, it is critically important to protect U.S. water supplies while providing the energy needed to power the nation into the future.

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