Nature protection technologies

1.3.2. Technologies of emissions reduction

Part 1. AIR PROTECTION FROM POWER INDUSTRY EMISSIONS

1.3. Sulfur oxide emission reduction

1.3.2. Technologies of sulfur oxide emission reduction

Shmigol I.N., JSC “VTI”

Brief description of desulfurization technologies and installations

More than 400 methods based on different chemical and physical principles are proposed to remove sulfur dioxide from flue gases:

  • chemical binding with formation of the recoverable and unreclaimable wastes;
  • selective sorption by solid substances (activated carbon, zeolites, resins) with the following regeneration of sorbents;
  • selective liquid-phase sorption by specific organic liquids;
  • conversion of sulfur dioxide to trioxide in the gas phase using catalysts or special electrical discharges;
  • liquid-phase catalytic reduction of sulfur dioxide to elemental sulfur.

Part 1. AIR PROTECTION FROM POWER INDUSTRY EMISSIONS

1.3. Sulfur oxide emission reduction

1.3.2. Technologies of sulfur oxide emission reduction

1.3.2.1. Dry limestone technology

Shmigol I.N., Open JSC “VTI”

Dry limestone technology is based on burning of the finely crushed limestone in furnace at the temperature of 1000 ... 1100°C until lime is formed with its following reaction with sulfur dioxide. The main chemical reactions of this technology are as follows:

СаСO3 + Q —> СаО + СO2­;

СаО + SO2 + 1/2O2 = CaSO4.

Part 1. AIR PROTECTION FROM POWER INDUSTRY EMISSIONS

1.3. Sulfur oxide emission reduction

1.3.2. Technologies of sulfur oxide emission reduction
1.3.2.2. Dry limestone technology

1.3.2.3. Dry soda technology

Shmigol I.N., Open JSC “VTI”

In dry limestone technology finely crushed lime – calk CaO or burnt lime Ca(OH)2 is used. It’s injected into the boiler convective shaft at a temperature range of about 850°C. The reagent binds sulfur dioxide:

CaO + SO2 + 1/2O2 = CaSO4;

Ca(OH)2 + SO2 = CaSO41/2H2O + 1/2H2O.

1.3.2.3. Dry soda technology

Soda is a very active, but an expensive reagent. It is applied just as well as lime, but the SO2 catching effect achieved is higher in comparison with lime. 

Part 1. AIR PROTECTION FROM POWER INDUSTRY EMISSIONS

1.3. Sulfur oxide emission reduction

1.3.2. Technologies of sulfur oxide emission reduction

1.3.2.4. Simplified wet-dry technology (E-SOx technology)

Shmigol I.N., Open JSC “VTI”

E-SOx technology is based on binding of sulfur oxides with the finely dispersed aqueous slurry of lime, followed by evaporation of drops in the purified flue gases.

Part 1. AIR PROTECTION FROM POWER INDUSTRY EMISSIONS

1.3. Sulfur oxide emission reduction

1.3.2. Technologies of sulfur oxide emission reduction

1.3.2.5. Technology with the hollow absorber-dryer

Shmigol I.N., Open JSC “VTI”

This technology is based on the same principles as the simplified one. But the difference is in application of the hollow absorber-dryer before the electrostatic precipitator (or the bag filter), which provides significantly more prolonged contact of flue gases with the reagent and, consequently, collection of sulfur dioxide up to 90 ... 92%.

Part 1. AIR PROTECTION FROM POWER INDUSTRY EMISSIONS

1.3. Sulfur oxide emission reduction

1.3.2. Technologies of sulfur oxide emission reduction

1.3.2.6. Technology with circulating inert mass

Shmigol I.N., JSC “VTI“

The described wet-dry technology with the hollow absorber has a significant drawback - it requires a large volume of the absorption zone, which provides a high degree of desulfurization at the simultaneous complete evaporation of water and exclusion of deposit formation on walls of the apparatus. However wet-dry process can be arranged in another way: a large amount of inert material is fed into furnace gases, and the reagent is applied on its surface. At that a mass of the inert material should not lose its particulate properties.

Part 1. AIR PROTECTION FROM POWER INDUSTRY EMISSIONS

1.3. Sulfur oxide emission reduction

1.3.2. Technologies of sulfur oxide emission reduction

1.3.2.7. Ammonia-cyclical technology

1.3.2.8. Magnesite cyclical technology

1.3.2.9. Natrium sulfite-bisulfite technology

Shmigol I.N., JSC "VTI"

1.3.2.7. Ammonia-cyclical technology

A chemical basis for this technology is a balanced reaction between the saluted sulfite and ammonium bisulfite and sulfur dioxide, removed from the furnace gases:

(NH4)2SO3 + SO2 + H2O = 2NH4HSO3.

1.3.2.8. Magnesite cyclical technology

The essence of magnesite cyclical technology lays in binding of sulfur dioxide by a slurry of magnesium oxide:

MgO + SO2 = MgSO3.

1.3.2.9. Natrium sulfite-bisulphite technology

This method (also called - Wellman-Lord process) is similar to the ammonia-cyclical, but instead of ammonium salts, sulfurous natrium salts are used:

SO2 + Na2SO3 + H2O = 2NaHSO3.

Part 1. AIR PROTECTION FROM POWER INDUSTRY EMISSIONS

1.3. Sulfur oxide emission reduction

1.3.2. Technologies of sulfur oxide emission reduction

1.3.2.10. Application of Venturi scrubbers

Shmigol I.N., JSC “VTI“

Application of Venturi scrubbers for sulfur dioxide collection is based on washing of flue gases with soda solution accompanied by conversion of the reaction product in calcium sulfate. The main chemical reactions of the technology are the following:

2NaOH + SO2 = Na2SO3 + H2O;

Na2CO3 + SO2 = Na2SO3 + CO2;

Na2SO3 + Ca(OH)2 + 2H2O + 1/2O2 = CaSO4·2H2O + 2NaOH.

Part 1. AIR PROTECTION FROM POWER INDUSTRY EMISSIONS

1.3. Sulfur oxide emission reduction

1.3.2. Technologies of sulfur oxide emission reduction

1.3.2.11. Wet limestone technology

Shmigol I.N., JSC "VTI"

Wet limestone technology (WLT) is based on binding of sulfur dioxide and trioxide with the limestone slurry, during which calcium sulfite is formed, which is oxidized to the double water sulfate (gypsum).

Part 1

AIR PROTECTION FROM POWER INDUSTRY EMISSIONS

1.3. Sulfur oxide emission reduction

1.3.2. Technologies of sulfur oxide emission reduction

1.3.2.12. Wet lime technology

Shmigol I.N., JSC "VTI"

Wet lime technology is based on binding of sulfur oxides SO2 and SO3 with water suspension of lime with formation of calcium sulfite and its subsequent oxidation to the double water sulfate (gypsum).

Part 1. AIR PROTECTION FROM POWER INDUSTRY EMISSIONS

1.3. Sulfur oxide emission reduction

1.3.2. Technologies of sulfur oxide emission reduction

1.3.2.13. Ammonium-sulphate technology (AST)

Shmigol I.N., JSC "VTI"

AST technology is based on binding of sulfur dioxide and trioxide with water solution of ammonia with the following oxidation of the formed products of substances interacting until the stable ammonium sulfate is not obtained.