Fuel Staging and Air Staging To Reduce Nitrogen Emission in the CFB Combustion of Bark and Coal

Abstract

Nitrogen oxide (NO) and nitrous oxide (N 2 O) formation in the circulating fluidized bed (CFB) combustion can be controlled by air staging and fuel staging. An extensive test campaign was carried out with a pilot-scale CFB test rig to observe the possibilities of the methods in the spruce bark and bituminous coal combustion as well as in co-combustion. Fuel staging with liquid petroleum gas (LPG) was done alternately from three locations with three intensities. Air staging was studied alone and during the fuel staging experiment. The experimental trends for NO and N 2 O emission formation during fuel staging and air staging are presented in this study. It was observed that air staging and fuel staging can have opposing effects on nitrogen oxide emission formation, and thus, when used together, a clear understanding of the fuel behavior and conditions, as well as NO x chemistry in the combustor, is needed. Under the tested conditions, it was observed that if air staging is effective, then fuel staging does not bring further benefits in the NO reduction. Instead, the LPG feed can increase the emission in the lack of oxygen. However, if it is not possible to carry out air staging, then fuel staging can be used in generating oxygen-lean reducing zones for NO. The N 2 O concentration was also further reduced with LPG in the tests with effective air staging.

Heating and emission characteristics from combustion of charcoal and co-combustion of charcoal with faecal char-sawdust char briquettes in a ceramic cook stove

“…However according to Hayhurst and Lawrence (1996) , formation of prompt NO which normally result from reaction between N 2 and hydrogen radicals from the fuel is small. The formation of thermal NO on the other hand occurs at very high temperatures (≥1300 °C), since thermal dissociation of N 2 to N radicals is needed to start NO formation ( Saastamoinen and Leino, 2019 ). The highest temperature (475 °C) attained during the co-combustion of briquettes with charcoal in this study could not result to the release of thermal NO.…”

“…Cooling process does not exist in a furnace or in the experimental set-up adopted in our study and thus possibly the reason as to why NO 2 wasn't detected. NO 2 is therefore mostly formed under normal ambient conditions in the atmosphere ( Saastamoinen and Leino, 2019 ).…”

Advances in De-NOx Methods and Catalysts for Direct Catalytic Decomposition of NO: A Review

“…Control during combustion refers to improving combustion technology, designing new burners and air distribution systems, and changing the atmosphere of the fuel combustion area to achieve low nitrogen combustion. The improvement of combustion technology mainly includes fuel classification, air classification, and thick and thin separation to reduce the generation of thermal NO. − These new combustion technologies are partly effective, but it still cannot meet the increasingly stringent emission standards. For the de-NO x of diesel vehicles, there are mainly two methods.…”

Valorization of Biomass Power Generation System: Noble Use of Combustion and Integration with Energy Storage

“…Figures and ). In addition, (4) other pollutants such as NO x , − SO x , , particulate matter, , volatile organic compounds (VOC), inorganics, and metals and metalloids − are emitted after combustion. Thus, it is strongly preferable to avoid an unneeded simple combustion and to valorize the combustion technology even if renewable biomass fuel is used.…”