The method of purification of combustion gases from nitrogen oxides with simultaneous conditioning of the flue gas before the electrostatic precipitator

 

(57) Abstract:

The invention relates to the purification of the products of combustion and can be used for cleaning of flue gases of thermal power, chemical, metallurgical and other industries with regard to equipment, equipped with electrostatic precipitators. Ammonia or compounds that produce ammonia, which is injected into the high temperature zone in quantities exceeding those necessary for the reduction of nitrogen oxides from a volume concentration of ammonia at the inlet to the electrostatic precipitator within required in the mixture contained in the combustion products with sulfur trioxide conditioning cleaned gases before the electrostatic precipitator. With a volumetric content in the combustion products before the electrostatic precipitator of sulfur trioxide less than 3 ppm, it is additionally injected into the high temperature zone, maintaining the volumetric concentration of sulfur trioxide at the inlet to the electrostatic precipitator within 3 - 70 ppm at a molar ratio of ammonia and sulfur trioxide in the range of 0.3 to 1.5. The invention allows to reduce the size and cost of electrostatic precipitators. 3 C.p. f-crystals.

The invention relates to the field of purification of the products of combustion and can be used for flue gas cleaning in t is own cleaning products of combustion from nitrogen oxides by selective non-catalytic recovery last in high temperature zone ammonia or compounds, produce ammonia by thermal decomposition [1] - prototype.

The present invention is empowerment purification of combustion gases from nitrogen oxides to simultaneously provide conditioning of the flue gas before feeding them into the electrostatic precipitator.

This is achieved in that in the method of purification of the products of combustion from okiedog nitrogen by selective non-catalytic recovery last in high temperature zone ammonia or compounds that produce ammonia by thermal decomposition, for products of combustion, predergast in the low-temperature zone of clearing in the electrostatic precipitator from the solid particles, according to the invention, ammonia or compounds that emit ammonia, is injected in quantities exceeding those necessary for the reduction of nitrogen oxides from a volume concentration of ammonia at the inlet to the electrostatic precipitator within, required in the mixture contained in the combustion products with sulfur trioxide conditioning cleaned gases before the electrostatic precipitator to optimize their electrical properties.

Ammonia is advisable to enter in an amount to provide its bulk concentration at the entrance to power the IDA sulfur less than 3 ppm, it is additionally injected into the high temperature zone, maintaining the volumetric concentration of sulfur trioxide at the inlet to the electrostatic precipitator within required in the mixture with ammonia for conditioning the cleaned gases.

The sulfur trioxide is advisable to enter in an amount to provide its bulk concentration at the inlet to the electrostatic precipitator within 3 - 70 ppm at a molar ratio of ammonia and sulfur trioxide in the range of 0,3...1,5.

The method according to the present invention on the example of a steam boiler, equipped with an electrostatic precipitator for cleaning of flue gases from solid particles, as follows. When burning high-sulfur fuels in high temperature zone of the furnace chamber of the boiler is injected ammonia or compounds that produce ammonia by thermal decomposition, such as ammonia water or carbomide. The amount of injected reagent regulate, on the basis of measuring the concentration of ammonia in the flue gas at the inlet to the electrostatic precipitator, which is maintained in the range of 5 to 30 ppm. Entered or formed in the high temperature zone, the ammonia restores toxic oxides of non-toxic nitrogen to molecular nitrogen, and excess within the established amount of ammonia, proccacia in the low-temperature zone, in a mixture containing water and improve the adhesion properties of fly ash and other solid impurities, it results in suppression of the reverse kronirovaniye and reduced secondary ash deposited on the collecting electrodes of the precipitator dust.

When burning low-sulfur fuels, causing volumetric content in the combustion products before the electrostatic precipitator of sulfur trioxide less than 3 ppm, it is additionally injected into the high temperature zone, for example, in the form of ammonium sulfate, formed during thermal decomposition in addition to the ammonia sulfur trioxide. Maintaining the concentration of sulfur trioxide at the inlet to the electrostatic precipitator within 3 - 70 ppm at a molar ratio of ammonia and sulfur trioxide in the range of 0.3 to 1.5 provides a significant increase in the efficiency of the electrostatic precipitator. Gross emissions of high resistivity fly ash such as fly ash Kuznetsk coal, in the environment under these conditions can be reduced to 4-6 times.

The design of new thermal power plants application of the method according to the present invention will allow approximately one third to reduce the size and cost of electrostatic precipitators, while ensuring regulatory emission of fly ash.

Sources of information

1. EP 0287224 A2, 19.12.88, B 01 D 53/54.

1. The method of purification of the products of combustion from okacom or compounds, produce ammonia by thermal decomposition, characterized in that in relation to the products of combustion which are exposed in the low-temperature zone of clearing in the electrostatic precipitator from particulate matter, ammonia or compounds that emit ammonia, is injected in quantities exceeding those necessary for the reduction of nitrogen oxides from a volume concentration of ammonia at the inlet to the electrostatic precipitator within required in the mixture contained in the combustion products with sulfur trioxide conditioning cleaned gases before the electrostatic precipitator.

2. The method according to p. 1, characterized in that the ammonia is injected in an amount to provide its bulk concentration at the inlet to the electrostatic precipitator in the range of 5 to 30 ppm.

3. The method according to p. 1 or 2, characterized in that the bulk of the content in the combustion products before the electrostatic precipitator of sulfur trioxide less than 3 ppm, it is additionally injected into the high temperature zone, maintaining the volumetric concentration of sulfur trioxide at the inlet to the electrostatic precipitator within required in the mixture with ammonia for conditioning the cleaned gases.

4. The method according to p. 3, characterized in that the sulfur trioxide is administered in an amount to provide its bulk concentration at the entrance to elec

 

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