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Pulverized coal-fired boilers have been used for power generation in Korea for decades. Recently, an 870-MW wall-fired boiler with De-NO x TM burners and an air staging system was constructed for use with low-rank coal. The results of a full-scale simulation of its combustion characteristics agreed well with measurements obtained under normal operating conditions for temperature, unburned carbon, and nitric oxide. Contrasting trends in unburned carbon and NOx emissions were observed, depending on the particle size and the location of the standby burner within the boiler. Combustion was also found to shift forward with small particle sizes and backward with large particle sizes. The results of a Thermo-mechanical analysis (TMA) indicated that the actual sticking temperature was lower than that suggested by the initial deformation temperature (ASTM) criteria. A logistic function was used to describe TMA shrinkage. Locations subject to high deposition potential were predicted with reference to soot-blowing phenomena.

Because there has been a recent increase in the use of low calorific coal compared to standard coal, it is crucial to control the char flame length governing the burning life-time of coal in a coal-fired utility boiler. The main objective of this study is to develop a simplified model that can theoretically predict the flame length for burning coal in a laboratory-scale entrained laminar flow reactor (LFR) system. The char burning behavior was experimentally observed when sub-bituminous pulverized coal was fed into the LFR under burning conditions similar to those in a real boiler: a heating rate of 1000 K/s, an oxygen molar fraction of 7.7 %, and reacting flue gas temperatures ranging from 1500 to 2000 K. By using the theoretical model developed in this study, the effect of particle size on the coal flame length was exclusively addressed. In this model, the effect of particle mass was eliminated to compare with the experimental result performed under a constant mass feeding of coal. Overall, the computed results for the coal flame length were in good agreement with the experimental data, particularly when the external oxygen diffusion effect was considered in the model.

With environmental concerns over emitted particulate matters(PM) from combustion systems, various researches have been conducted on reduction and measurement techniques of particulate matters. The LII analysis results from numerical models and experiments in an ethylene/air laminar diffusion flame at elevated pressure up to 2.0 MPa with laser fluence 0.07 J/cm2, detection wavelength 400 nm were compared to validate a modified LII numerical model. The lifetime of the LII signal decreased as the elevated pressure increased, so that LII decay time also decreased in both results. In the aspect of heat transfer mechanism, it becomes earlier that dominant conduction starts. This shows that the results matched well under the pressure conditions. It is concluded that the LII numerical model could be applied to decide particle size in TIRE-LII at the high-pressure condition.