Method and system for NO
View Patent ↗A method for removing NO x from flue gas by SCR includes supplying a reagent for the SCR reaction of NO x into the flue gas, then contacting the flue gas with a catalyst. Supplying the reagent includes supplying a less than stoichiometric amount of reagent, and after contacting the flue gas with a catalyst a final NO x removal step is provided.
1. A method for removing NOx from flue gas by SCR, the method comprising:
at least a first NOx removal step, the first NOx removal step comprising
compressing the flue gas to a first selected pressure;
supplying a reagent for SCR reaction of NOx into the compressed flue gas,
contacting the compressed flue gas and reagent with a catalyst to form a treated flue gas, and
wherein supplying the reagent includes supplying a less than stoichiometric amount of reagent,
and providing the treated flue gas to a final NOx removal step and
wherein the final NOx removal step comprises:
supplying an oxidizer into the treated flue gas to convert NO to NO 2 in presence of the oxidizer, forming an oxidized flue gas;
contacting the oxidized flue gas with water for removal of NO 2 with water.
2. The method of claim 1 , wherein the less than stoichiometric amount of reagent is arranged to remove at least 80% of NOx by volume from the flue gas.
3. The method of claim 1 , wherein the final NOx removal step includes compressing the flue gas in a plurality of compression stages.
4. The method of claim 1 , further comprising supplying the oxidizer before compressing the flue gas.
5. The method of claim 1 , further comprising the steps of:
compressing the flue gas in a first multi-stage compression process upstream from the SCR reaction;
compressing the flue gas in a second multi-stage compression process downstream from the SCR reaction;
wherein the oxidizer is supplied between two compression stages of the second multi-stage compression process.
6. The method of claim 5 , further comprising cooling the flue gas after compressing the flue gas or after each compression stage.
7. The method of claim 1 , further comprising determining the less than stoichiometric amount of reagent on the basis of measured NOx content of the flue gas.
8. A method for removing NOx from a flue gas, the method comprising:
removing NOx in a first stage, the first stage comprising:
compressing the flue gas in a first multi-stage compression process;
supplying a less than stoichiometric amount of reagent into the compressed flue gas;
contacting the compressed flue gas and reagent with a catalyst in an SCR reactor to convert NO to NO 2 , and form a treated flue gas
removing NOx in a second stage, the second stage comprising:
compressing the treated flue gas in a second multi-stage compression process, to form a compressed treated flue gas;
supplying an oxidizer into the compressed treated flue gas between compression stages of the second multi-stage compression process to convert NO to NO 2 , wherein the second NOx removal stage comprises the removal of NO 2 with water; and
cooling the compressed treated flue gas.
9. The method of claim 2 , wherein the less than stoichiometric amount of reagent is arranged to remove more preferably between 80-95% of NOx by volume from the flue gas.
10. The method of claim 2 , wherein the less than stoichiometric amount of reagent is arranged to remove more preferably between 85-90% of NOx by volume from the flue gas.
11. The method of claim 2 , wherein the less than stoichiometric amount of reagent is arranged to remove more than 85% of NOx by volume from the flue gas.