Optimization study on combustion in a 1000-MW ultra-supercritical double-tangential-circle boiler

Abstract

The combustion process of one 1000-MW ultra-supercritical double-tangential-circle boiler was numerically studied and the three-dimensional full-size structure of the boiler was full considered. The influences of primary and over-fire air velocity as well as the jet structure on NOx generation characteristics were examined. In addition, the NOx generation characteristics of the improved burner structure were compared with those of the original one. Numerical results show that there exist two inverse elliptical flow fields and temperature fields. Moreover, the NOx generation and distribution characteristics are related to the temperature field to a certain extent. For different burner jet structures and arrangements, NOx distribution curves of the horizontal cross section are all W-shaped, but the NOx generation and distribution performance are correspondingly different, while the NOx emission changes are unobvious for different design schemes of the boiler burner. When we arrange one layer of auxiliary air from the burner undersurface, the flow area of the primary coal powder jet is enlarged by 100% and the coal feeding is increased by 20%. As a result, the temperature around the burner zone rises significantly. However, when two layers of auxiliary air are adopted, the combustion characteristic is promoted and NOx generation increases slightly. Based on the arrangement of the burner in the ultrasupercritical boiler, NOx generation does not vary obviously at different boiler loads. To achieve a better scheme, numerical and experimental studies are both performed in this study, and identical results are obtained. The current results may provide a theoretical basis for burner design improvement.

Leakage of water-cooled wall tube in subcritical boiler

“…Differences in oxygen concentration between the part buried in the ceiling pouring material and the part exposed to the air resulted in significant differences in electrode potential between different areas of the front water wall tube passing through the ceiling and formed an oxygen concentration difference battery. In this way, the water-cooled wall steel pipe was continuously corroded and thinned; finally, perforation leakage occurred under the pressure of the internal high-temperature medium [18,19].…”

A Review of the Numerical Modeling of Pulverized Coal Combustion for High-Efficiency, Low-Emissions (HELE) Power Generation

“…Extensive literature exists on the effects of boiler configuration or operating conditions on their performance, particularly NOx emissions at the pilot-scale and HELE utility boilers with one or more implemented low-NOx combustion technologies. Several numerical studies over the past decade have demonstrated the effectiveness of low-NOx combustion technologies, including low-NOx swirl burners, ,, the optimized ratio and position of OFA, LNCFSs, and air staging, , the sub air technique, HBC and OFA, the double-tangential-circle boiler, and advanced firing systems for down-fired boilers . Various parameters must be considered to evaluate their effects on low-NOx combustion in different boilers.…”

Archives of Environmental Protection

“…The volume of pollution generated by a boiler mainly depends on the amount and characteristics of the fuel burnt, and the type of furnace, which determines the temperature of combustion and the concentration of oxygen in the first part of the flame (Montanari 2003, Ma 2010, Liu et al 2017. Fuel quality directly influences boiler operation, efficiency, combustion processes and volume of emissions.…”