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Our Business / Thermal Power StationsAir Pollution Countermeasures

When fuel burns in the boiler, the sulfur content in the fuel becomes sulfur oxides (SOx). Nitrogen in the air combines with oxygen to generate nitrogen oxides (NOx), as well as soot. These substances causing of air pollution are stipulated by emission standards and others, according to environmental preservation agreement concluded with laws and environmental municipalities.
At our power stations, we take various measures to make sure that these standards are not exceeded.

Desulfurizer

This device removes SOx in exhaust gas by reacting this with limestone.

Desulfurizer
Desulfurizer

Denitrator

This exhaust gas denitrator injects ammonia into the exhaust gas containing NOx from the boiler and decomposes the gas into N2 and H2O by catalytically promoted chemical reaction.

Denitrator
Denitrator

Electric Precipitator

All the thermal power stations, except gas dedicated thermal power stations emitting no soot, installs electric precipitator having high performance.
Soot passing between the high voltage discharging electrodes is electrified to be collected by electric force in the direction of the dust collecting electrodes.

Electric Precipitator
Electric Precipitator

Combustion Improvement

We suppress the generation of NOx by control of the combustion temperature inside the boiler, gas turbine combustor and such. Specifically we use a combination of the following methods to strive to suppress NOx.

〇 Method to Improve Combustion for the Boiler

  • Method for slow combustion, where exhaust gas is partially mixed into the combustion air and lowering the concentration of oxygen in the combustion air (exhaust gas mixing method)
  • Method for slow combustion, where the combustion gas is led into the boiler in 2 stages (2 stage combustion method)
  • Method where a burner suppressing high-temperature combustion zone is used (low NOx burner)

〇 Method to Improve Combustion for the Gas Turbine

  • Method for uniform and stable combustion, where the fuel and air is pre-mixed and combusted (pre-mixed combustion method)

Environmental Initiatives