Analysis on the Influence of Coal Properties on NOx Emissions of Large-Scale Boilers Equipped with Advanced Low-NOx Combustion Systems

Author(s):  
Shen Yue-yun ◽  
Gao Xiao-tao ◽  
Zhang Ming-yao
2010 ◽  
Vol 10 (14) ◽  
pp. 6645-6660 ◽  
Author(s):  
P. Huszar ◽  
D. Cariolle ◽  
R. Paoli ◽  
T. Halenka ◽  
M. Belda ◽  
...  

Abstract. In general, regional and global chemistry transport models apply instantaneous mixing of emissions into the model's finest resolved scale. In case of a concentrated source, this could result in erroneous calculation of the evolution of both primary and secondary chemical species. Several studies discussed this issue in connection with emissions from ships and aircraft. In this study, we present an approach to deal with the non-linear effects during dispersion of NOx emissions from ships. It represents an adaptation of the original approach developed for aircraft NOx emissions, which uses an exhaust tracer to trace the amount of the emitted species in the plume and applies an effective reaction rate for the ozone production/destruction during the plume's dilution into the background air. In accordance with previous studies examining the impact of international shipping on the composition of the troposphere, we found that the contribution of ship induced surface NOx to the total reaches 90% over remote ocean and makes 10–30% near coastal regions. Due to ship emissions, surface ozone increases by up to 4–6 ppbv making 10% contribution to the surface ozone budget. When applying the ship plume parameterization, we show that the large scale NOx decreases and the ship NOx contribution is reduced by up to 20–25%. A similar decrease was found in the case of O3. The plume parameterization suppressed the ship induced ozone production by 15–30% over large areas of the studied region. To evaluate the presented parameterization, nitrogen monoxide measurements over the English Channel were compared with modeled values and it was found that after activating the parameterization the model accuracy increases.


2020 ◽  
Author(s):  
Jun Liu ◽  
Dan Tong ◽  
Yixuan Zheng ◽  
Jing Cheng ◽  
Xinying Qin ◽  
...  

Abstract. China is the largest cement producer and consumer in the world. Cement manufacturing is highly energy-intensive, and is one of the major contributors to carbon dioxide (CO2) and air pollutant emissions, which threatens climate mitigation and air quality improvement. In this study, we investigated the decadal changes of carbon dioxide and air pollutant emissions for the period of 1990–2015, based on intensive unit-based information on activity rates, production capacity, operation status, and control technologies, which improved the accuracy of the cement emissions in China. We found that, from 1990 to 2015, accompanied by a 10.9-fold increase in cement production, CO2, SO2, and NOx emissions from China's cement industry increased by 626 %, 59 %, and 658 %, whereas CO, PM2.5 and PM10 emissions decreased by 9 %, 66 %, and 63 %, respectively. In the 1990s, driven by the rapid growth of cement production, CO2 and air pollutant emissions increased constantly. Then, the production technology innovation of replacing traditional shaft kilns with the new precalciner kilns in the 2000s markedly reduced SO2, CO and PM emissions from the cement industry. Since 2010, the growing trend of emissions has been further curbed by a combination of measures, including promoting large-scale precalciner production lines and phasing out small ones, upgrading emission standards, installing low-NOx burners (LNB) and selective noncatalytic reduction (SNCR) to reduce NOx emissions, as well as adopting more advanced particulate matter control technologies. Our study highlighted the effectiveness of advanced technologies on air pollutant emission control, however, CO2 emissions from China's cement industry kept growing throughout the period, posing challenges to future carbon emission mitigation in China.


Author(s):  
Finn Lückoff ◽  
Moritz Sieber ◽  
Christian Oliver Paschereit ◽  
Kilian Oberleithner

Abstract The reduction of polluting NOx emission remains a driving factor in the design process of swirl-stabilized combustion systems, to meet strict legislative restrictions. In reacting swirl flows, hydrodynamic coherent structures, such as periodic large-scale vortices in the shear layer, induce zones with increased heat release rate fluctuations in connection with temperature peaks, which lead to an increase of NOx emissions. Such large-scale vortices can be induced by the helical coherent structure known as precessing vortex core (PVC), which influences the flow and flame dynamics of reacting swirl flows under certain operating conditions. We developed an active flow control system, which allows for a targeted actuation of the PVC, to investigate its impact on important combustion properties. In this study, the direct active flow control is used to actuate a PVC of arbitrary frequency and amplitude, which facilitates a systematic study of the impact of the PVC on NOx emissions. In the course of the present work, a perfectly premixed flame, which slightly damps the PVC, is studied in detail. Since the PVC is slightly damped, it can be precisely excited by means of open-loop flow control. In connection with time-resolved OH*-chemiluminescence and stereoscopic PIV measurements, the flame and flow response to PVC actuation as well as the impact of the actuated PVC on flow and flame dynamics are characterized. It turns out that the PVC rolls up the inner shear layer, which results in an interaction of PVC-induced vortices and flame. This interaction considerably influences the measured level of NOx emissions, which grow with increasing PVC amplitude in a perfectly premixed flame. Nearly the same increase is to be seen for a partially premixed flame. This in contrast to previous studies, where the PVC is assumed to reduce the NOx emissions due to vortex-enhanced mixing.


Author(s):  
João Cassiano ◽  
Manuel Heitor ◽  
António Moreira ◽  
Tito Silva

Author(s):  
Steve J. Brookes ◽  
R. Stewart Cant ◽  
Iain D. J. Dupere ◽  
Ann P. Dowling

It is well known that lean premixed combustion systems potentially offer better emissions performance than conventional non-premixed designs. However, premixed combustion systems are more susceptible to combustion instabilities than non-premixed systems. Combustion instabilities (large-scale oscillations in heat release and pressure) have a deleterious effect on equipment, and also tend to decrease combustion efficiency. Designing out combustion instabilities is a difficult process and, particularly if many large-scale experiments are required, also very costly. Computational fluid dynamics (CFD) is now an established design tool in many areas of gas turbine design. However, its accuracy in the prediction of combustion instabilities is not yet proven. Unsteady heat release will generally be coupled to unsteady flow conditions within the combustor. In principle, computational fluid dynamics should be capable of modelling this coupled process. The present work assesses the ability of CFD to model self-excited combustion instabilities occurring within a model combustor. The accuracy of CFD in predicting both the onset and the nature of the instability is reported.


2014 ◽  
Vol 953-954 ◽  
pp. 730-733
Author(s):  
Jun Li ◽  
Wei Wei Li

The mechanism of NOx formation in coal combustion, NOx control methods and key DeNOx technologies is to be introduced. Denitrification is very significant for saving energy and carbon sources. By analysis of NOx production mechanism, the principles of controlling NOx production and lowering emission of NOx by classified combustion are described. Combined with actual operation, low-NOx combustion rehabilitation programs and relevant test to be done is to be proposed. The actual operation of the unit achieved good results after the transformation, provide a reference for similar units.


1992 ◽  
Vol 24 (1) ◽  
pp. 1399-1405 ◽  
Author(s):  
Graham J. Nathan ◽  
R.E. (Sam) Luxton ◽  
John P. Smart

Author(s):  
Tomohiro Asai ◽  
Satoschi Dodo ◽  
Mitsuhiro Karishuku ◽  
Nobuo Yagi ◽  
Yasuhiro Akiyama ◽  
...  

Successful development of oxygen-blown integrated coal gasification combined cycle (IGCC) technology requires gas turbines capable of achieving dry low-nitrogen oxides (NOx) combustion of hydrogen-rich syngas for low emissions and high plant efficiency. The authors have been developing a “multiple-injection burner” to achieve the dry low-NOx combustion of hydrogen-rich syngas. The purposes of this paper are to present test results of the multi-can combustor equipped with multiple-injection burners in an IGCC pilot plant and to evaluate the combustor performance focusing on effects of flame shapes. The syngas fuel produced in the plant contained approximately 50% carbon monoxide, 20% hydrogen, and 20% nitrogen by volume. In the tests, the combustor that produced slenderer flames achieved lower NOx emissions of 10.9 ppm (at 15% oxygen), reduced combustor liner and burner plate metal temperatures, and lowered the combustion efficiency at the maximum load. The test results showed that the slenderer flames were more effective in reducing NOx emissions and liner and burner metal temperatures. These findings demonstrated that the multiple-injection combustor achieved dry low-NOx combustion of the syngas fuel in the plant.


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