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Effects of Swirl Numbers and Spray Angles on Combustion Characteristic and Concentration of Pollutants in a Boiler

Abstract
The combustion characteristics and the pollution of the exhausting products under various designing and operating conditions are studied in this research. In our experiments, the furnace fuel is diesel oil. By adjusting the flow rate of both axial air and tangential air the different equivalence ratios and swirl numbers can be obtained. The controlling ranges of the various experimental parameters include equivalence ratio from 0.8 to 1.1, swirl number from 0 to 1.0, recirculated flue gas from 0% to 12%, and jet spray angle 45?and 80? The effect of the controlling variables on the combustion characteristics and pollutant formations within combustion chamber are studied in this reseacher. A photographic technology is used to study the flame structures to help us understanding the behaviors of the flame under various operating condition.
Form the experimental results, we find that the recirculation generated by swirl influence the produce temperature and its distribution with combustion chamber. The swirl is useful for flame expanding, and increases the mixing of fuel and air, so that the complete reaction can achieve near the burner. When the jet spray angle is 80? and swirl number is 0.6, the exhaust rate of NOx in the exhaust duct is the lowest, and the combustion in combustion chamber is the best.
At equivalence ratio 0.9, the effects of the flow rate of the recirculating flue gason the flame structure and the exhaust emission is not too much. Our experiments display that the optimized operating condition is jet spray angle 80? swirl number 0.6 and flue gas recirculation 8%. NO can be reduced about 15~20% in this condition.
When no swirl occurs, the color of flame displays white-yellow due to the burning of soot in this region. For the condition with swirl, the color of the outside flame displays orange-yellow. In primary combustion zone, the flame exhibits the red color which is due to the radiation of CO2 and water vapor.

Identiferoai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0706100-101213
Date06 July 2000
CreatorsYang, Sheng-Yu
ContributorsMing-San Lee, Shih-Ming Chiang, Long-Jeng Cheng
PublisherNSYSU
Source SetsNSYSU Electronic Thesis and Dissertation Archive
LanguageCholon
Detected LanguageEnglish
Typetext
Formatapplication/pdf
Sourcehttp://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0706100-101213
Rightsunrestricted, Copyright information available at source archive

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