Method for removing pollutants from a combustion gas

A method for removing pollutants from a combustion gas taken from a boiler plant, which combustion gas contains light ashes, sulphur dioxide and nitrogen oxides as pollutants, which comprises:

• cooling the combustion gas in a heat exchanger to about 110.degree. C.;
• removing at least most of the light ashes from the combustion gas in at least one electrostatic precipitator;
• energizing the combustion gas by means of electrons generated by impulsive electric fields to convert most of the sulphur dioxide and the nitrogen oxides into sulfuric acid and nitric acid, respectively, with the presence of residual sulphur dioxide;
• adding dry ammonia prepared in a gas environment and stored at a temperature of about 100.degree. C. to the combustion gas to convert the sulfuric acids and nitric acids into the ammonium salts of these acids, producing a combustion gas containing ammonium sulphate, ammonium nitrate, sulphur dioxide, and ammonia;
• introducing hydrogen peroxide into the combustion gas to convert the residual sulphur dioxide into sulfuric acid, which reacts with the ammonia to produce ammonium sulphate;
• removing the ammonium salts from the combustion gas in an electrostatic precipitator;
• and passing the combustion gas to a chimney.