Claims
- 1. A method for treating a gas-flow from a combustion engine in connection with a NOx reducing catalyst, said method comprising:
guiding an exhaust gas-flow through an exhaust gas treatment unit including a plurality of ducts having an exchange of heat between said ducts and wherein said ducts are connected to an inlet and an outlet of said exhaust gas treatment unit so that the gas-flow occurs during exchange of heat between incoming and outgoing flows; and reducing NOx compounds in said gas-flow using said NOx reducing catalyst and adapting a temperature of said exhaust gas treatment unit to a prevailing operating condition of said NOx reducing catalyst by controlling operation of the combustion engine.
- 2. The method according to claim 1, further comprising:
adapting said temperature of said exhaust gas treatment unit according to prevailing operating condition of the combustion engine and said exhaust catalyst.
- 3. The method according to claim 2, further comprising:
adapting said temperature of said exhaust gas treatment unit so that an essentially lean exhaust gas mixture flows through the exhaust catalyst and sulphur regeneration of said exhaust catalyst is affected.
- 4. The method according to claim 1, further comprising:
increasing and lowering the temperature of said gas-flow passing through said exhaust gas treatment unit.
- 5. The method according to claim 4, wherein said increase in temperature of said gas-flow is provided via at least one of the following measures:
i) controlling injection time and ignition sequence of said engine so that an increased exhaust gas temperature is obtained; ii) controlling said engine so that an additional injection of fuel is made during the exhaust stroke of the engine; iii) periodically controlling said engine between rich and lean operation; iv) admitting air from an external source into said exhaust gas treatment unit during rich operation of the engine; v) controlling each cylinder of said engine so that the exhaust gases from at least one cylinder of the engine is operated in a rich manner while the rest of the cylinders are operated in a lean or stoichiometric manner; vi) supplying heat via a heating element provided in the exhaust gas treatment unit; and vii) injecting fuel into the exhaust gases downstream from said engine.
- 6. The method according to claim 4, wherein said lowering of the temperature of said gas-flow is provided via at least one of the following measures:
i) supplying a liquid or air from an external source to the exhaust gas treatment unit; ii) guiding the gas-flow past specially arranged cooling flanges in the exhaust gas treatment unit; iii) supplying air from said inlet duct of said engine; and iv) supplying cooled exhaust gases from said engine's exhaust manifold.
- 7. The method according to claim 1, wherein said reduction of NOx compounds in said gas-flow is provided via at least one of the following measures:
i) operating said engine with an essentially rich exhaust gas mixture; ii) injecting fuel or some other reducing agent into the exhaust gases; and iii) injecting ammonia or urea, or generating ammonia which is supplied to the exhaust gases.
- 8. The method according to claim 1, further comprising:
determining the temperature of said exhaust gas treatment unit by means of predetermined calculation models which define a relationship between said temperature and the prevailing operating condition of the engine.
- 9. The method according to claim 1, further comprising:
determining the temperature of said exhaust gas treatment unit by means of a separate temperature sensor which is provided in connection with the exhaust gas treatment unit.
- 10. The method according to claim 2, further comprising:
providing a band to said exhaust gas treatment unit that is folded into a package and by means of which said ducts are formed.
- 11. The method according to claim 2, further comprising:
integrating said NOx reducing exhaust catalyst and said exhaust gas treatment unit into a single unit.
- 12. The method according to claim 2, further comprising:
providing a separate temperature sensor connected to said control unit and which is adapted to determine the temperature of said exhaust gas treatment unit.
Priority Claims (1)
Number |
Date |
Country |
Kind |
0000019-0 |
Jan 2000 |
SE |
|
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of International Application No. PCT/SE00/02672, filed Dec. 25, 2000, which claims priority to Swedish Application No. 0000019-0, filed Jan. 5, 2000. Both applications are expressly incorporated herein by reference in their entireties.
Continuations (1)
|
Number |
Date |
Country |
Parent |
PCT/SE00/02672 |
Dec 2000 |
US |
Child |
10064310 |
Jul 2002 |
US |