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US 8,147,785 B2Granted
Combustion flue gas NOx treatment
AssigneeFMC Corporation
InventorsHenry A. Pfeffer, David E. Smith
Life of this patent
Estimating the term…
Abstract
Combustion flue gas containing NOX and SOX is treated to remove NOX in a multistep system in which NOX is reduced in the flue gas stream via selective catalytic reduction or selective non-catalytic reduction with ammonia or an ammonia-forming compound, followed treatment with hydrogen peroxide to remove residual ammonia and, optionally, treatment with an alkali reagent to reduce residual NOX in the flue gas stream. The NOX-depleted flue gas stream may also be subjected to a desulfurization treatment for removal of SOX.
Claims18
A method for removing NOX from a flue gas stream comprising
- injecting ammonia or an ammonia-forming compound into a combustion flue gas stream containing NOX, wherein an excess of ammonia is introduced into the flue gas stream as an agent for reducing the NOX, to yield a flue gas stream containing unreacted residual ammonia and a reduced concentration of NOX;
- thereafter injecting hydrogen peroxide into the flue gas stream containing unreacted residual ammonia, the flue gas having a temperature of about 250° F. to about 800° F.,in an amount sufficient to react with residual ammonia present in the flue gas stream, to yield an ammonia-depleted flue gas stream;
- and
- contacting the ammonia-depleted flue gas stream with an alkali reagent in an amount sufficient to remove NOX present in the gas stream, yielding a flue gas stream with reduced concentrations of ammonia and NOX.
1 more element
Dependencies are inferred from the claim text.