SYSTEM AND A METHOD FOR REDUCING NITROGEN DIOXIDE (NO2) CONTENT IN FLUE GAS

20240416277

18/704323

December 27, 2022

A system and a method for reducing nitrogen dioxide (NO2) content of a flue gas are provided. The system comprises a wash column that is designed to receive a flue gas containing nitrogen dioxide and treat the flue gas with a first water stream. The first water stream contains a thiosulfate salt reactant. The thiosulfate salt reactant reacts with the nitrogen dioxide to remove the nitrogen dioxide from the flue gas. The wash column can provide a treated flue gas that is substantially free of nitrogen dioxide, or a treated flue gas that contains less nitrogen dioxide than untreated flue gas.

1. A system for reducing nitrogen dioxide (NO2) content of a flue gas, the system comprising: a wash column designed to: receive the flue gas containing the nitrogen dioxide (NO2); and treat the flue gas with a first water stream, the first water stream including a thiosulfate salt reactant.

2. The system of claim 1, wherein the flue gas is provided to the wash column at a first temperature, the first water stream is provided to the wash column at a second temperature, and wherein the first temperature is greater than the second temperature.

3. The system of claim 2, wherein the first water stream is in fluid communication with a heat exchanger designed to remove heat absorbed by the first water stream from the flue gas.

4. The system of claim 1, wherein the wash column further includes a top portion and a bottom portion, and wherein the top portion and the bottom portion are in fluid communication with a water stream recycling conduit.

5. The system of claim 1, the system further including a dosing mechanism in communication with a controller, wherein the dosing mechanism is designed to provide the thiosulfate salt reactant to the first water stream, and wherein the controller is designed to control an amount of the thiosulfate salt reactant provided to the first water stream by the dosing mechanism.

6. The system of claim 1, wherein the wash column further includes a gas cooling section and a reaction section, and wherein the gas cooling section is positioned adjacent to a bottom section of the wash column and the reaction section is positioned adjacent to a top section of the wash column.

7. The system of claim 6, wherein the first water stream is provided to the reaction section, and wherein a second water stream is provided to the gas cooling section.

8. An apparatus for reducing nitrogen dioxide content of a flue gas, the apparatus comprising: a wash column in fluid communication with a water stream, the wash column having an inlet via which the flue gas is provided to the wash column from a source; and a dosing mechanism designed to provide a thiosulfate salt reactant to the water stream, wherein the thiosulfate salt reactant reacts with the flue gas to remove the nitrogen dioxide therefrom.

9. The apparatus of claim 8, wherein the wash column is defined by a top portion and a bottom portion, and the inlet for the flue gas is coupled to the bottom portion of the wash column and the water stream is provided to the top portion of the wash column.

10. The apparatus of claim 8, wherein the apparatus further includes a water stream recycle conduit in fluid communication with the wash column, and the water stream is provided to the wash column via the water stream recycle conduit.

11. The apparatus of claim 8, wherein the apparatus further includes a water stream recycle conduit in fluid communication with the wash column, and the dosing mechanism is coupled to the water stream recycle conduit.

12. The apparatus of claim 8, wherein the apparatus further includes a flue gas discharge line coupled to the wash column, and the flue gas discharge line is in fluid communication with an analyzer designed to measure at least one parameter of the flue gas.

13. The apparatus of claim 12, wherein a first parameter of the at least one parameter is a nitrogen dioxide concentration of the flue gas, and the analyzer measures a value of the first parameter, and wherein an amount of thiosulfate salt reactant provided to the water stream by the dosing mechanism is adjusted based on the value of the first parameter.

14. The apparatus of claim 8, wherein the apparatus further including a controller that is designed to change an amount of thiosulfate salt reactant provided to the water stream by the dosing mechanism based on a measurement of at least one parameter of the flue gas by an analyzer.

15. A method of reducing nitrogen dioxide content of a flue gas, the method comprising: providing the flue gas to a wash column; dosing a water stream with a thiosulfate salt reactant; and contacting the flue gas with the water stream.

16. The method of claim 15 further including a step of circulating the water stream through a water stream recycle conduit, wherein the water stream recycle conduit is in fluid communication with the wash column and a dosing mechanism.

17. The method of claim 15 further including a step of measuring a parameter of the flue gas via an analyzer.

18. The method of claim 15 further including steps of: measuring a nitrogen dioxide concentration of the flue gas using an analyzer; and adjusting an amount of thiosulfate salt reactant provided to the water stream when the nitrogen dioxide concentration of the flue gas is at or above a threshold value.

19. The method of claim 15 further including steps of: cooling the flue gas to condense water therefrom; and providing condensed water to a bleed member.

20. The method of claim 15, wherein the thiosulfate salt reactant comprises at least one of a sodium thiosulfate (Na2S2O3) salt reactant, a potassium thiosulfate (K2S2O3) salt reactant, a magnesium thiosulfate (MgS2O3) salt reactant, a calcium thiosulfate (CaS2O3) salt reactant, or an ammonium thiosulfate ((NH4)2S2O3) salt reactant.

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