Optical Backscatter Probe for Sensing Particulate in a Combustion Gas Stream

• US 20100328663A1
• Filed: 06/25/2009
• Published: 12/30/2010
• Est. Priority Date: 06/25/2009
• Status: Active Grant

• Current Assignee: UT-Battelle LLC
• Original Assignee: UT-Battelle LLC
• Inventors: Parks, James E., Partridge, William P.
• Granted Patent: US 8,451,444 B2
• Time in Patent Office: Days
• US Class Current: 356/338
• CPC Class Codes: G01N 2021/151 Gas blown
• CPC Class Codes: G01N 2021/8578 Gaseous flow IR analysers G01N21/8507
• CPC Class Codes: G01N 21/15 Preventing contamination of the components of the optical system or obstruction of the light path
• CPC Class Codes: G01N 21/474 Details of optical heads therefor, e.g. using optical fibres
• CPC Class Codes: G01N 21/53 within a flowing fluid, e.g. smoke
• CPC Class Codes: G01N 21/85 Investigating moving fluids or granular solids
• CPC Class Codes: G01N 33/0029 cleaning

Abstract

A system for sensing particulate in a combustion gas stream is disclosed. The system transmits light into a combustion gas stream, and thereafter detects a portion of the transmitted light as scattered light in an amount corresponding to the amount of particulates in the emissions. Purge gas may be supplied adjacent the light supply and the detector to reduce particles in the emissions from coating or otherwise compromising the transmission of light into the emissions and recovery of scattered light from the emissions.

Claims

1. A system for sensing particulate in a combustion gas stream disposed in a conduit comprising:

a light transmitting system, having a source of light in communication with a light transmitter positioned proximate the conduit and in fluid communication with the stream of combustion gas for transmitting light into the stream of combustion gas;

a light detection system having a light detector in communication with a light collector positioned proximate the conduit and in fluid communication with the stream of combustion gas for detecting a portion of the transmitted light scattered by the particulate; and

a controller operatively associated with said light transmitting system and said light detection system for sending command signals to the source of light and monitoring signals generated by said light detection system to measure the amount of particulate matter in the stream of combustion gas.

2. The system of claim 1, further comprising a purge gas system for directing a flow of gas proximate the light transmitter and the light collector.

3. The system of claim 2, wherein the controller is operatively associated with said purge gas system and controls the flow of purge gas.

4. The system of claim 1, wherein the source of light comprises a laser diode and the light transmitter comprises an exposed end of a fiber optic cable.

5. The system of claim 4, further comprising a collimating lens disposed between the source of light and the light transmitter.

6. The system of claim 1, wherein the source of light and the light transmitter comprises a laser diode mounted to directly transmit light into the combustion gas stream.

7. The system of claim 1, wherein the light detector comprises a photomultiplier tube detector and the light collector comprises an exposed end of a fiber optic cable.

8. The system of claim 1, further comprising a bandpass filter disposed between the light collector and the light detector.

9. The system of claim 1, wherein the light detector comprises a photodiode detector.

10. The system of claim 1 wherein the light detection system comprises a photodiode light detector mounted to receive light directly from the combustion gas stream.

11. The system of claim 1, wherein the conduit is located either upstream or downstream of an emission control device.

12. A method of sensing the amount of particulate matter in a stream of combustion gas disposed in a conduit, the method comprising the steps of:

transmitting a light source through a light transmitting conduit into the stream of combustion gas;

collecting a portion of the transmitted light source, scattered by particulate matter entrained in the combustion gas, with a second light transmitting conduit;

directing the scattered light portion of transmitted light to a light detector through the second light transmitting conduit; and

monitoring signals generated by the detector to measure the amount of particulate matter in the stream of combustion gas.

13. The method of claim 12, further comprising the step of introducing purge gas between the light transmitting conduits and the combustion gas stream for substantially preventing particulate matter from collecting thereon.

14. The method of claim 12, further comprising the step of using the monitored signals to control operation of a device that is generating the combustion gas.

15. The method of claim 12 further comprising the step of controlling the emissions of at least one cylinder of an internal combustion engine by calculating new operational parameters for the cylinder based on the measured amount of particulate matter in the gas stream.

16. The method of claim 12 further comprising the step of using the monitored signals to control the operation of an emission control device.

17. The method of claim 12 further comprising the step of using the measured amount of particulate matter in the combustion gas stream to control the timing of a regeneration cycle of a particulate filter whereby the filter is periodically cleaned by regeneration.

18. The method of claim 12, further comprising the step of using the monitored signals to detect threshold increases in particulate matter that would signal malfunction of a device that is generating the combustion gas.

19. The method of claim 12, wherein the providing, collecting, directing and monitoring steps are each repeated for multiple combustion gas streams, and further comprising the step of multiplexing the multiple signals generated by the detectors to measure the amounts of particulate matters in the multiple streams of combustion gases.