Exhaust gas purification system for denoxing exhaust gases from combustion units

• US 6,301,879 B1
• Filed: 02/22/2000
• Issued: 10/16/2001
• Est. Priority Date: 06/22/1998
• Status: Expired due to Term

• Current Assignee: HJS Fahrzeugtechnik GmbH & Co. KG
• Original Assignee: HJS Fahrzeugtechnik GmbH & Co. KG
• Inventors: Weisweiler, Werner, Huthwohl, Georg, Maurer, Bernd
• Primary Examiner(s): Denion, Thomas
• Assistant Examiner(s): TRAN, BINH Q
• Application Number:
  US09/486,292
• Time in Patent Office: 602 Days
• Field of Search: 602/74, 602/86, 603/03, 602/84, 603/00, 603/01, 603/20, 603/21, 602/95, 602/97, 602/98, 423/212, 423/235, 423/239.1, 423/237, 423/238
• US Class Current: 60/274
• CPC Class Codes: B01D 53/9431 Processes characterised by a specific device
• CPC Class Codes: B01D 53/9495 Controlling the catalytic process
• CPC Class Codes: C01C 1/026 Preparation of ammonia from inorganic compounds
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 2610/06 the substance being in the gaseous form
• CPC Class Codes: F01N 2610/10 the substance being heated, e.g. by heating tank or supply line of the added substance
• CPC Class Codes: F01N 2610/1473 Overflow or return means for the substances, e.g. conduits or valves for the return path
• CPC Class Codes: F01N 2610/1486 Means to prevent the substance from freezing
• CPC Class Codes: F01N 3/2066 Selective catalytic reduction [SCR]
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

An exhaust gas purification system for denoxing exhaust gases has a converter containing a substance thermolytically separable into NH₃, a feed line connecting the converter with an exhaust gas line for supplying NH₃ into the exhaust gas flow therein, a dosing device in the feed line for dosing the NH₃ to be introduced into the exhaust gas flow, a heatable cold-start store connected to the feed line between the converter and dosing device for providing the substance during starting of a combustion unit connected to the exhaust gas line, an air feeding device having two air conduits provided with valves wherein one conduit is connected to the feed line between the cold-start store and dosing device and the other conduit is connected to a mixing chamber located in the feed line after the dosing device, and a reservoir container for storing the substance connected to a filling pipe terminating in the converter.

Claims

1. Exhaust gas purification system for denoxing exhaust gases of combustion units on an SCR catalyst comprising a heatable pressure-tight converter in which a substance or a corresponding substance mixture, thermolytically separating NH₃, is contained, an NH₃ store for the intermediate storage of NH₃ thermolytically separated from the substance or the substance mixture, a feed line connecting the converter with the exhaust gas line for supplying NH₃ into the exhaust gas flow, and a dosing device integrated into the feed line, for dosing the quantity of NH₃ to be introduced into the exhaust gas flow, characterized in that the converter is encompassed by an H₂O jacket, which H₂O jacket is formed by a foamed material filled with H₂O.

2. Exhaust gas purification system for denoxing exhaust gases of a combustion unit on an SCR catalyst comprising a heatable pressure-tight converter containing a substance or a corresponding substance mixture thermolytically separating NH₃, an NH₃ store for the intermediate storage of NH₃ thermolytically separated from the substance or the substance mixture, a feed line connecting the converter with an exhaust gas line for supplying the NH₃ into an exhaust gas flow therein, and a dosing device integrated into the feed line for dosing the quantity of NH₃ to be introduced into the exhaust gas flow, characterized in that a cold-start store is connected to the feed line between the converter and dosing device which during normal operation of the system captures and contains a quantity of the substance or substance mixture and during start of the combustion unit delivers a certain quantity of the substance or the substance mixture to the feed line, and a heating device is associated with the cold-start store and operable to heat the substance or the substance mixture in the cold-start store for thermolytically separating NH₃ for delivery to the feed line.

3. The system as claimed in claim 2, characterized in that the cold-start store is filled with a means for absorbing the NH₃ or the substance mixture thermolytically separating NH₃.

4. The system as claimed in claim 2, characterized in that a second dosing device is provided, a filling pipe-fitting terminates into the converter and is connected to an output of the second dosing device and a reservoir container is provided for storing the substance or substance mixture thermolytically separating NH₃ having an output side that acts upon the dosing device.

5. The system as claimed in claim 4, characterized in that the substance or the substance mixture contained in the reservoir container is in the form of coated pellets.

6. The system as claimed in claim 4, characterized in that the second dosing device is in the form of a bucket wheel and a first isolation valve is disposed between the bucket wheel and the reservoir container and a second isolation valve is disposed between the bucket wheel and the converter.

7. The system as claimed in claim 4, characterized in that the reservoir container is detachably connected with the dosing device.

8. The system as claimed in claim 7, characterized in that the reservoir container is an exchangeable container having an opening to be connected to the dosing device and a closure adapted to close the container when the container is disconnected from the dosing device and adapted to be opened after connecting the container to the dosing device.

9. The system as claimed in claim 2, characterized in that an air feeding device is connected to the feed line for blowing air into the feed line in the direction of NH₃ flow.

10. The system as claimed in claim 9, characterized in that the air feeding device has two air conduits and respective valves disposed in the two air conduits, one of the air conduits terminating in the feed line between the dosing device and exhaust gas line and the other of the air conduits terminating in the feed line between the converter and the dosing device.

11. Exhaust gas purification system for denoxing exhaust gases of a combustion unit on an SCR catalyst comprising a heatable pressure-tight converter containing a substance or a corresponding substance mixture thermolytically separating NH₃, an NH₃ store for the intermediate storage of NH₃ thermolytically separated from the substance or the substance mixture, a feed line connecting the converter with an exhaust gas line for supplying the NH₃ into an exhaust gas flow therein and a dosing device integrated into the feed line for dosing the quantity of NH₃ to be introduced into the exhaust gas flow, characterized in that an air feeding device is connected to the feed line for blowing air into the feed line, the air feeding device having two air conduits and respective valves disposed in the two air conduits, one of the air conduits terminating in the feed line between the dosing device and exhaust gas line and the other of the air conduits terminating in the feed line between the converter and the dosing device.

12. The system as claimed in claim 11, characterized in that a mixing chamber is integrated into the feed line between the dosing device and exhaust gas line and the one air conduit terminates in the mixing chamber.

13. The system as claimed in claim 11, characterized in that the valve disposed in the second air conduit is a check valve, and a heating device is associated with a section of the feed line between the converter and the termination of the first air conduit.

14. Exhaust gas purification system for denoxing exhaust gases of a combustion unit on an SCR catalyst comprising a heatable pressure-tight converter containing a substance or a corresponding substance mixture thermolytically separating NH₃, an NH₃ store for the intermediate storage of NH₃ thermolytically separated from the substance or the substance mixture, a feed line connecting the converter with an exhaust gas line for supplying the NH₃ into an exhaust gas flow therein, and a dosing device integrated into the feed line for dosing the quantity of NH₃ to be introduced into the exhaust gas flow, characterized in that units disposed in the feed line are combined into a constructional unit equipped with a resistance heating mechanism and ports which can be connected to cooling water circulation of a combustion engine.

15. Exhaust gas purification system for denoxing exhaust gases of a combustion unit on an SCR catalyst comprising a heatable pressure-tight converter containing a quantity of ammonium carbamate for thermolytically separating NH₃, an NH₃ store for the intermediate storage of NH₃ thermolytically separated from the ammonium carbamate, a feed line connecting the converter with an exhaust gas line for supplying the NH₃ into an exhaust gas flow therein, and a dosing device integrated into the feed line for dosing the quantity of NH₃ to be introduced into the exhaust gas flow, characterized in that two filling conduits terminate in the converter for filling the converter after consumption of the ammonium carbamate quantity in the converter, one of the filling conduits being connectable to one reservoir tank for supplying NH₃ from the one reservoir tank to the converter and the other of the filling conduits being connectable to another reservoir tank for supplying CO₂ from the other reservoir tank to the converter, the converter being connected to a source of cooling water circulation for cooling the same.

16. The system as claimed in claim 15, characterized in that means is contained in the converter for increasing the surface thereof.

17. The system as claimed in claim 15, characterized in that a second converter is provided with the first converter such that the two converters are alternately heatable as a duplex system.