Back to results
US 8,425,866 B2Granted
Control of emissions
AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorsClyde F. Parrish, Landy Chung
Life of this patent
Estimating the term…
Abstract
Methods and apparatus utilizing chlorine dioxide and hydrogen peroxide are useful to reduce NOx emissions, as well as SOx and mercury (or other heavy metal) emissions, from combustion flue gas streams.
Claims31
A method of treating a gas stream for removal of at least oxides of nitrogen, the method comprising:
- a) oxidizing the gas stream in an oxidizer including:
- i) generating chlorine dioxide in a continuous reaction process;
- ii) diluting the chlorine dioxide with air or inert gas concurrent with generating the chlorine dioxide;
- iii) mixing the diluted chlorine dioxide with the gas stream upon generation into the oxidizer to convert nitric oxide to nitrogen dioxide;
- and
- iv) maintaining a desired level of nitric oxide in the gas stream by regulating a generation rate of the chlorine dioxide;
- b) after oxidizing the gas stream, scrubbing the gas stream in a scrubber including:
- i) reacting the gas stream with a hydrogen peroxide solution to convert nitrogen dioxide to nitric acid in an acidic hydrogen peroxide scrubber liquor, thereby producing a first scrubber liquor;
- ii) maintaining a desired hydrogen peroxide concentration in the first scrubber liquor by regulating a flow of the first hydrogen peroxide solution;
- and
- iii) removing a stream containing the nitric acid in the acidic hydrogen peroxide scrubber liquor from the scrubber.
8 more elements
A method of treating a gas stream for removal of at least oxides of sulfur and oxides of nitrogen, the method comprising:
- a) scrubbing the gas stream in a first scrubber to remove oxides of sulfur including:
- i) reacting oxides of sulfur in said gas stream with a first hydrogen peroxide solution to form sulfuric acid in the first scrubber, thereby producing a first scrubber liquor;
- ii) maintaining a desired hydrogen peroxide concentration in the first scrubber liquor by regulating a flow of the first hydrogen peroxide solution;
- iii) removing a by-product stream containing sulfuric acid from said first scrubber after attaining a desired sulfuric acid concentration in the first scrubber liquor;
- b) after scrubbing in the first scrubber, oxidizing the oxides of nitrogen in the gas stream in an oxidizer including:
- i) generating chlorine dioxide and diluting the chlorine dioxide with air or inert gas to generate a chlorine dioxide mixture adapted to convert nitric oxide to nitrogen dioxide;
- ii) oxidizing the oxides of nitrogen in the gas stream using the chlorine dioxide mixture to convert nitric oxide to nitrogen dioxide;
- c) after oxidizing the gas stream, scrubbing the gas stream in a second scrubber including:
- i) reacting the gas stream with a second hydrogen peroxide solution to convert nitrogen dioxide to nitric acid in an acidic hydrogen peroxide scrubber liquor;
- and
- ii) removing a stream containing the nitric acid in the acidic hydrogen peroxide scrubber liquor from said second scrubber.
8 more elements
Dependencies are inferred from the claim text.