Combustion characteristics of high ash coal in a pulverized coal combustion test furnace
At present, bituminous coal is used in thermal power stations in Japan. Since the demand for coal utilization is increasing worldwide, low rank coal, which is rich in moisture or ash, will be a major resource for thermal power plants in the near future. Problems in the utilization of high ash coal include not only the large amount of ash discharge, but also the difficulty of ignition and control of NOx formation. This paper describes the influence of ash content on pulverized coal combustion characteristics by using three kinds of high ash coal with similar combustible components, the same fuel ratio and elements of carbon and hydrogen on the dry ash free basis, but a different ash content (36, 44 and 53 wt%), in a pulverized coal combustion test furnace (coal combustion capacity; 100 kg/h). The test results showed NOx concentration at the furnace exit became high and combustion efficiency decreased with the increase of ash content in the standard combustion condition (an air ratio of 1.24 and a ratio of air volume for two-stage combustion to the total one at 0 %). O{sub 2} consumption occurred late and NOx formation and reduction were delayed in the flame. It was considered that the delay of O{sub 2} consumption was due to the covering of combustible matter with ash and the large sensible heat of the ash. In two-stage combustion, O{sub 2} consumption was due to the covering of combustible matter with ash and the large sensible heat of the ash. In two-stage combustion. O{sub 2} consumption occurred much later and NOx reduction region before the air injection port in two-stage combustion became narrow for the high ash coal. As the ash content increased, NOx reduction in two-stage combustion decreased and the increase of the uncombustion fraction in two-stage combustion became high.
- Research Organization:
- Central Research Inst of Electric Power Industry, Kenagawa (JP)
- OSTI ID:
- 20006886
- Resource Relation:
- Conference: 1999 International Joint Power Generation Conference, Burlingame, CA (US), 07/25/1999--07/28/1999; Other Information: PBD: 1999; Related Information: In: Proceedings of the 1999 international joint power generation conference (FACT-vol. 23). Volume 1: Fuels and combustion technologies; Gas turbines; and Nuclear engineering, by Penfield, S.R. Jr.; Moussa, N.A. [eds.], 651 pages.
- Country of Publication:
- United States
- Language:
- English
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