ECE5320 Mechatronics Assignment#01: Literature Survey on Sensors and Actuators Topic: Flame Sensor

1. ECE5320 MechatronicsAssignment#01: Literature Survey on Sensors and Actuators Topic: Flame Sensor Prepared by: Jeremy Viula Dept. of Electrical and Computer Engineering Utah State University 3/11/2005

2. Outline • Reference list • To probe further • Major applications • Early flame scanners • Basic working principle illustrated • A typical sample configuration in application (application notes) • Major specifications • Sensor Selection • Limitations • Where to buy ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

3. Reference list • www.durag.net/downloads/broflamemonitoringuk.pdf • http://asme.pinetec.com/ijpgc2000/data/pdfs/15041.pdf • http://www.durag.net/downloads/brodug660uk.pdf • http://www.oit.doe.gov/bestpractices/steam/pdfs/steamdigest2003_boilersafety.pdf ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

4. To explore further (survival pointers of web references etc) • http://www.babcock.com/pgg/tt/pdf/BR-1612.pdf • http://www.isa.org/Content/ContentGroups/Training3/Training_Course_Descriptions/ES16.pdf • http://preview.ametek.com/content-manager/files/pip/2100772.pdf • http://www.forneycorp.com/flame.shtml ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

5. Major applications • Coal Boilers • Oil Boilers • Gas Boilers • Industrial Furnaces ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

6. Early Flame Sensors In the early 1900s, operators controlled boiler flame by periodic inspection. In the mid-1900s, a tremendous increase in boiler construction and demand for variable steam increased burner ligh-offs and shutdowns, resulting in a substantial increase of boiler explosions. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

7. Early Flame Sensors The earliest flame detectors were simple thermocouples with very poor response time. Flame rod sensors, commonly used in home furnaces, had good response time but were impractical to maintain in an industrial setting. Most boiler explosions were caused by a loss of flame and then delayed re-ignition. A better method of flame detection was needed. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

8. Early Flame Sensors • The first optical detector, the UV tube, contained two electrodes mounted in a quartz glass tube filled with an inert gas. When voltage was applied in the presence of UV radiation, a pulsating electric signal was generated. An amplifier could then process this signal and provide flame on/off output. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

9. Early Flame Sensors • The UV tube was useless in coal fired boilers because UV radiation can be absorbed by moisture and recirculation gasses. • The lead sulfide optical detector was introduced in the 1960 to detect infrared radiation produced by oil and coal flames. This sensor was also only partially affective for it often gave false reading do to hot surfaces such as burner walls that created the illusion of real flame. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

10. Basic Working Principle • A new type of sensor was needed to accommodate modern day multiple burner boilers. A non-lit burner adjacent to a lit burner can have the same IR and UV intensity as the lit burner due to the superheated boiler wall. • The actual UV sensor was not drastically changed, however a new flicker frequency detector was added to the sensor to allow safe discrimination between burners. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

11. Basic Working Principle • Due to the recent efforts to reduce greenhouse gasses, the flame sensors purpose has been extended from flame detection to flame recognition. • Flame recognition is a young, complex and developing field. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

12. Basic Working Principle • A flame scanning sensor must have the ability to accurately sense the criteria in the illustration to the left. • These properties are measured in different ways from one sensor to another. The following two slides show some of the sensor elements in use today. Source: www.durag.com ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

13. Photo Element Types By Application Different fuels that boilers use emanate different energy wavelengths, therefore the photo element type must be chosen correctly to minimize wavelength detection error. Source: www.durag.com ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

14. Basic Working Principle At least one if not all of these sensor elements will be incorporated in a modern flame sensor. Source: www.durag.com ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

15. Basic Working Principle • Most photo elements used in flame sensors today are in essence photo transistors. This means that the base is activated by the radiation that is absorbed which allows a proportional current to flow from collector to emitter. Source: www.durag.com ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

16. Basic Working Principle Arranging flame sensors in the following configuration will allow accurate detection of each individual burner. Source: www.durag.com ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

17. Basic Working Principle • Some high-end flame scanning sensor have become extremely complex. This illustration shows the adjustment interface that exists on the Durag D-LE 603 flame sensor. Source: www.durag.com ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

18. A Typical Sample Configuration In Application This Figure shows the recommended configuration for the Durag D-LE 600 flame sensor. Source: www.durag.com ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

19. Major Specifications • Minimum direct light intensity: The minimum light emission intensity that the sensor can accurately detect from a flame. • Maximum direct light intensity: The maximum light emission intensity that the sensor can accurately detect from a flame. • Minimum alternating light intensity: The minimum intensity of the alternating light portion that the sensor can accurately detect from a flame. • Maximum alternation light intensity: The maximum intensity of the alternating light portion that the sensor can accurately detect from a flame. • Correct light wavelength area: The wavelength of the light emission that is in the UV range or the IR range that the sensor can accurately detect from a flame. • Minimum flicker frequency: The minimum flicker frequency the sensor can accurately detect. Usually adjustable to as low as 20 Hz for each sensor. • Maximum flicker frequency: The Maximum flicker frequency the sensor can accurately detect. Usually adjustable up to 400 Hz for each sensor. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

20. Sensor Selection • Due to the government regulations and the specialization of the sensor to each application, each manufacturer will have a selection chart such as the one below. It can be used to select the appropriate sensor for your application. Source: www.durag.com ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

21. Limitations • Sensors need periodic cleaning to maintain promised accuracy. • Overheating can cause sensor failure. • Excessive light intensity can cause calibration error or sensor failure. • Federal law requires operator to have ability to monitor burners to unsure that burner is running. • Specific algorithms for maximum combustion are not yet well defined. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

22. Where To Buy response@linearsystem.net http://www.gepower.com http://www.honeywell.com http://www.durag.com/html/blr/blrprod.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators