Method for purifying exhaust gas

Patent metadata

Field	Value
Publication number	US-9802155-B2
Application number	US-201414907962-A
Country	US
Kind code	B2
Filing date	Jul 18, 2014
Priority date	Jul 25, 2013
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

Abstract

The present invention provide a method for purifying exhaust gas in which nitrogen oxides (NOx) gas is removed from a combustion exhaust gas. The method for purifying exhaust gas according to the invention is characterized in that water vapor is further added to raw exhaust gas to be processed to increase the water vapor concentration in the exhaust gas and the resulting moisture-adjusted exhaust gas is introduced into a denitration catalyst layer. The water vapor concentration in the moisture-adjusted exhaust gas is preferably 22.0% by volume or less in the total of the water vapor originally contained in the raw exhaust gas and the added water vapor.

First claim

The invention claimed is:

1. A method for purifying exhaust gas in which nitrogen oxides in exhaust gas is removed by bringing a combustion exhaust gas having an alcohol added as a reducing agent into contact with a denitration catalyst, wherein water vapor is further added to a raw exhaust gas to be processed, thereby increasing a water vapor concentration in the exhaust gas to give a moisture-adjusted exhaust gas, and the moisture-adjusted exhaust gas is introduced into a denitration catalyst layer, wherein the denitration catalyst is a denitration catalyst of cobalt supported on a ZSM-5 (MFI) type zeolite.

2. The method for purifying exhaust gas according to claim 1 , wherein the water vapor concentration in the moisture-adjusted exhaust gas is 22.0% by volume or less in the total of the water vapor originally contained in the raw exhaust gas and the added water vapor.

3. The method for purifying exhaust gas according to claim 2 , wherein the addition of water vapor to the raw exhaust gas is performed by introducing liquid or gaseous water into the combustion exhaust gas.

4. The method for purifying exhaust gas according to claim 2 , wherein the addition of water vapor to the raw exhaust gas is performed by introducing an alcohol aqueous solution into the combustion exhaust gas.

5. The method for purifying exhaust gas according to claim 4 , wherein the alcohol is ethanol, and a concentration of the ethanol aqueous solution introduced into the raw exhaust gas is 5.0% by volume or less.

6. The method for purifying exhaust gas according to claim 2 , wherein the exhaust gas is a combustion exhaust gas from a marine diesel engine.

7. The method for purifying exhaust gas according to claim 1 , wherein the addition of water vapor to the raw exhaust gas is performed by introducing liquid or gaseous water into the combustion exhaust gas.

8. The method for purifying exhaust gas according to claim 7 , wherein the exhaust gas is a combustion exhaust gas from a marine diesel engine.

9. The method for purifying exhaust gas according to claim 1 , wherein the addition of water vapor to the raw exhaust gas is performed by introducing an alcohol aqueous solution into the combustion exhaust gas.

10. The method for purifying exhaust gas according to claim 9 , wherein the alcohol is ethanol, and a concentration of the ethanol aqueous solution introduced into the raw exhaust gas is 5.0% by volume or less.

11. The method for purifying exhaust gas according to claim 10 , wherein the exhaust gas is a combustion exhaust gas from a marine diesel engine.

12. The method for purifying exhaust gas according to claim 9 , wherein the exhaust gas is a combustion exhaust gas from a marine diesel engine.

13. The method for purifying exhaust gas according to claim 1 , wherein the exhaust gas is a combustion exhaust gas from a marine diesel engine.

Assignees

• Hitachi Shipbuilding Eng Co

Inventors

• Nishi Tsugumi
• Hino Naoe
• Yamamoto Seigo
• Hikazudani Susumu

Classifications

• F01N2610/03

  the substance being hydrocarbons, e.g. engine fuel · CPC title

• F01N2610/14

  Arrangements for the supply of substances, e.g. conduits · CPC title

• F01N2570/14

  Nitrogen oxides · CPC title

• F01N13/004

  specially adapted for marine propulsion, i.e. for receiving simultaneously engine exhaust gases and engine cooling water (for submerged exhausting F01N13/12; treating exhaust by using liquids F01N3/04) · CPC title

• F01N2590/02

  for marine vessels or naval applications · CPC title