Thermal management of exhaust systems

• US 6,871,489 B2
• Filed: 04/16/2003
• Issued: 03/29/2005
• Est. Priority Date: 04/16/2003
• Status: Expired due to Term

• Current Assignee: ET US Holdings LLC
• Original Assignee: Arvin Technologies, Inc. (Meritor, Inc. (Nevada))
• Inventors: Crawley, Wilbur H., Nohl, John P., Tumati, Prasad
• Primary Examiner(s): Tran, Binh Q.
• Application Number:
  US10/417,392
• Publication Number:
  US 20040206069A1
• Time in Patent Office: 713 Days
• Field of Search: 602/74, 602/85, 602/86, 602/95, 602/97, 602/98, 603/00, 603/01, 603/03, 603/11, 603/20
• US Class Current: 60/285
• CPC Class Codes: F01N 11/002 the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus
• CPC Class Codes: F01N 13/009 having two or more separate purifying devices arranged in series
• CPC Class Codes: F01N 13/0097 the purifying devices are arranged in a single housing
• CPC Class Codes: F01N 2230/04 Catalytic converters
• CPC Class Codes: F01N 2240/02 a heat exchanger
• CPC Class Codes: F01N 2240/40 a hydrolysis catalyst
• CPC Class Codes: F01N 2260/024 using a liquid
• CPC Class Codes: F01N 2590/08 for heavy duty applications, e.g. trucks, buses, tractors, locomotives
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 3/025 using fuel burner or by adding fuel to exhaust
• CPC Class Codes: F01N 3/035 with catalytic reactors , e.g. catalysed diesel particulate filters
• CPC Class Codes: F01N 3/105 General auxiliary catalysts, e.g. upstream or downstream of the main catalyst
• CPC Class Codes: F01N 3/106 Auxiliary oxidation catalysts
• CPC Class Codes: F01N 3/2066 Selective catalytic reduction [SCR]
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

The present invention involves thermal management of an integrated emission reduction system for the removal of particulate matter (PM) and nitrogen oxides (NOx) from diesel engine exhaust streams. The inventive integrated emission reduction system may include a diesel particulate filter (DPF), a heat source for adjusting the temperature of the exhaust stream entering the DPF, at least one selective catalytic reducer of NOx, a heat exchanger for adjusting the temperature of the exhaust stream entering the NOx reducer, and a computing device for monitoring the temperature and/or pressure of the exhaust stream entering the DPF and the NOx reducer, and for controlling the operation of the heat exchanger and heat source, thereby improving the efficiency of the DPF and the NOx reducer.

Claims

1. An exhaust emissions reduction system for diesel engines, the diesel engine producing an exhaust stream containing particulate matter and emissions, the exhaust emissions reduction system comprising:

an emissions oxidation device;

a heat exchanger downstream from said emissions oxidation device, said heat exchanger adapted to change a temperature of the exhaust stream;

a selective catalytic reduction device adapted to chemically alter emissions in the temperature adjusted exhaust stream, said selective catalytic reduction device placed downstream from said heat exchanger;

a filter to remove particulate matter from the exhaust stream;

heater placed downstream from said selective catalytic reduction device and upstream from said filter for regenerating said filter;

at least one sensor disposed in the exhaust stream and sensing the temperature of the exhaust stream; and

a controller coupled to said heat exchanger and said heater, said controller adapted to control operations of said heat exchanger and said heater based upon the temperature sensed by said sensor.

2. The exhaust emissions reduction system of claim 1 wherein the selective catalytic reduction device is configured to remove NOx from the exhaust stream, and the heater comprises a fuel-fired burner that is placed between the selective catalytic reduction device and the filter and is coupled to the controller.

3. The exhaust emissions reduction system of claim 1 wherein the sensor is a first temperature sensor placed between the selective catalytic reduction device and the heater, further comprising a second temperature sensor placed between the emissions oxidation device and the heat exchanger, a third temperature sensor placed between the heat exchanger and the selective catalytic reduction device, and a fourth temperature sensor placed downstream from the filter, the first, second, third, and fourth temperature sensors being coupled to the controller.

4. A method of reducing emissions produced by a diesel engine comprising:

producing an exhaust stream from the diesel engine;

determining whether a temperature of an upstream portion of the exhaust stream is between a predetermined lower temperature and a predetermined upper temperature and adjusting the temperature of the upstream portion of the exhaust stream to be between the predetermined lower temperature and the predetermined upper temperature in response thereto;

removing NOx from the temperature adjusted upstream portion of the exhaust stream;

increasing the temperature of a downstream portion of the exhaust stream to a particulate matter oxidation temperature; and

oxidizing particulate matter with the increased temperature downstream portion of the exhaust stream.

5. The method of claim 4 wherein adjusting the temperature of the upstream portion of the exhaust stream comprises decreasing the temperature of the upstream portion of the exhaust stream.

6. The method of claim 4 comprising sensing the temperature of the exhaust stream (i) upstream from a heat exchanger, (ii) between the heat exchanger and a NOx removal device placed downstream from the heat exchanger, (iii) between the NOx removal device and a diesel particulate filter placed downstream from the NOx removal device, (iv) and downstream from the diesel particulate filter.

7. The method of claim 6 wherein the temperature increasing step comprises operating a fuel-fired burner placed downstream from the NOx removal device and upstream from the diesel particulate filter.

8. The method of claim 6, comprising oxidizing emissions in the exhaust stream upstream from the heat exchanger.

9. An exhaust emission reduction system adapted to reduce the emissions produced in the exhaust stream of a diesel engine, comprising:

a series flow arrangement comprising a cooler for cooling the exhaust stream, a NOx removal device placed downstream from the heat exchanger for removing NOx from the exhaust stream, a heater placed downstream from the NOx removal device, and a diesel particulate filter downstream from the heater for removing particulate matter from the exhaust stream, the heater being for heating the exhaust stream to a filter regeneration temperature for regenerating the diesel particulate filter, and

a controller coupled to the cooler and the heater for controlling operation of the cooler and the heater.

10. The exhaust emission reduction system of claim 9 further comprising at least one sensor disposed in the exhaust stream and adapted to sense a temperature of the exhaust stream and pass the sensed temperature to said controller.

11. The exhaust emission reduction system of claim 10 wherein said sensed temperature is compared to a desired temperature range and the temperature of the exhaust stream is adjusted by said controller and said cooler.

12. The exhaust emission reduction system of claim 10 wherein one said sensor is placed in the exhaust stream prior to said cooler and a second said sensor is placed after said cooler such that a temperature of the exhaust stream is sensed prior to and after the exhaust stream is passed through said cooler.

13. The exhaust emission reduction system of claim 9 further comprising a diesel oxidation catalyst upstream from the cooler wherein the exhaust stream passes through said diesel oxidation catalyst prior to passing through said cooler.

14. The exhaust emission reduction system of claim 9 wherein said heater comprises a fuel-fired burner for heating said diesel particulate filter.

15. The exhaust emission reduction system of claim 9 wherein the cooler comprises a heat exchange system placed upstream from the NOx removal device and comprising an exchange path and a bypass path in a parallel flow arrangement with the exchange path, the exchange path comprises a heat exchanger coupled to the controller, and the bypass path comprises a bypass valve coupled to the controller.

16. The exhaust emission reduction system of claim 15 wherein the heat exchanger comprises a coolant valve coupled to the controller.

17. The exhaust emission reduction system of claim 9 further comprising a first temperature sensor upstream from the cooler, a second temperature sensor placed between the cooler and the NOx removal device, a third temperature sensor placed between the NOx removal device and the diesel particulate filter, and a fourth temperature sensor placed downstream from the diesel particulate filter, and the first, second, third, and fourth temperature sensors are coupled to the controller.

18. The exhaust emission reduction system of claim 17 further comprising a diesel oxidation catalyst upstream from the cooler, and the first temperature sensor is placed between the diesel oxidation catalyst and the cooler.

19. The exhaust emission reduction system of claim 9 wherein the NOx removal device comprises a selective catalytic reduction catalyst placed between the cooler and the heater, a hydrolysis catalyst placed between the selective catalytic reduction catalyst and the cooler, an ammonia slip catalyst placed between the selective catalytic reduction catalyst and the heater, and a urea supplier for introducing urea into the exhaust stream between the selective catalytic reduction catalyst and the cooler.

20. The exhaust emission reduction system of claim 9 wherein the series flow arrangement comprises a muffler downstream from the diesel particulate filter.