Coal-fired thermopower plants use absorption technology to cut emissions

In order to thoroughly treat gases and waste generated during the burning of coal, an absorption method using seawater is being used in new thermal power plants.

The modern SO2 removal technology is used in Vung Ang 1, Vinh Tan 2 and Duyen Hai 1. 

This technology uses seawater to cool condensers to absorb and neutralize SO2 in the boiler exhaust fumes. SO2, when dissolved in seawater, will be converted to sulfate ions (SO42-). 

Ion sulphate is a natural element in seawater, so the reduction process does not adversely affect seawater quality and does not pollute the environment. 

The SOx removal efficiency of this technology can be up to 90 percent. 

Coal-fired thermal power makes up a large proportion of Vietnam’s electricity generation. Although the country wants to use more renewable energy, the number of projects was still in the majority in the recently released electricity generation development plan (Plan 7).

The biggest advantage of coal-fired thermal power is a stable coal supply and lower prices than other fossil fuels. 

The coal firing in the boiler’s combustion chamber generates gases that pollute the environment and have negative effect on human health, including nitrogen oxide (NOx) and sulphur dioxide (SO2). 

In addition, coal ash particles (in the form of dust) are also dispersed. The dust, plus other types of waste from coal-fired thermal power plants (waste water, noise and ash), must be controlled to protect the environment. 

The national standards on emissions from coal-fired thermal power plants were drawn up by the Ministry of Natural Resources and the Environment.

Under the QCVN22 Standard, the maximum permissible concentration of pollutants in emissions from thermal power plants is determined depending on the type of fuel used, location of the plant, and capacity.

Most of the coal-fired thermal power plants in Vietnam are equipped with emission treatment systems.  However, the systems still have defects due to the types and quality of coal, the availability of chemicals, as well as the initial investment and O&M costs of conventional equipment and systems used in coal-fired thermal power plants in Vietnam.

Vietnam had a bumper year in attracting FDI (foreign direct investment) into the thermopower sector in 2017. The three projects registered by Japanese investors alone had total capital of $7 billion. The projects - Van Phong I, Nghi Son II and Nam Dinh I – accounted for 40 percent of total FDI capital registered in the year.

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Kim Chi