COMBUSTION CHARACTERISTICS OF UPGRADED BROWN COAL (UBC)
Half of the world’s coal resources consist of so-called low rank coal. It is difficult to utilize efficiently due to its low heating value and high propensity of spontaneous combustion. However, there exists coal with low nitrogen, low sulfur and low ash content in low rank coal, and the utilization of such low rank coal is attractive from the view point of environmental concerns. Kobe Steel has developed a coal upgrading process, the UBC (Upgraded Brown Coal) process, for low rank coal. The UBC technology that evaporates moisture of coal in oil can be convert low rank coal into high grade fuel with higher heating value and less propensity of spontaneous combustion. The purpose of this paper is to report on the combustion characteristics of Indonesian UBC. The combustion tests were carried out using the refractory furnace. The combustion characteristics of bituminous coal and UBC on NOx generation, the unburnt ratio and ash constituents were quantitatively investigated using the refractory furnace. The following results were obtained: 1) The NOx concentration in the case of the UBC combustion is 20％ lower than that in the case of bituminous coal combustion. In a large-scale burner, it is expected that the NOx concentration lowers more. 2) Even if the OFA ratio (two-stage combustion ratio) is raised, UBC can maintain a very low unburnt ratio (approximately zero) differing from bituminous coal. 3) The relationship of the NOx concentration on the mixing ratio of UBC and bituminous coal is a linear one. However, the unburnt ratio is lower than that of a linear relationship. 4) Even if UBC and bituminous coal is mixed, the ash constituents of coal and the fly ash constituents are almost the same. From the experimental results, we can conclude that UBC is applicable to the conventional coal-fired boiler and its combustion characteristics are effective in reducing the impact on the environment.
Low Rank Coal Upgraded Brown Coal(UBC) Mizing Ratio Combustion Characteristics NOz Unburnt Ratio
Katsuya Akiyama Toshiya Tada
Fluid & Thermal Engineering Research Section, Mechanical Engineering Research Laboratory, KOBE STEEL,LTD.Japan
国际会议
第六届煤燃烧国际会议(The 6th International Symposium on Coal Combustion)
武汉
英文
527-532
2007-12-01（万方平台首次上网日期，不代表论文的发表时间）