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Show NOx Formation and Reduction in Pulverized Coal Combustion N.Ohyatsu, S.Nomura, N.Meguri and K.Shoji Kure Research Laboratory, Babcock Hitachi K.K. ABSTRACf A simple reaction model is proposed for NOx formation and reduction occurred during coal combustion. These reaction rates are to be expressed by the Arrhenius type rate constant and the gas phase volatile, HeN, NH3, NOx and O2 concentrations. Experiments were conducted using a drop tube furnace (vertical laminar flow furnace) for various bituminous and anthracite coals ranging from 1.0 to 11 in the fuel· ratio (fixed carbon/ volatile nlatter). Although the rate constant of volatile evolution depends upon the coal type, those for NOx formation and reduction were found to be invariant with respect to the coal type. 1. Introduction One subject of the development in pulverized coal burner is to achieve low NOx emission for environmental requirements. It is well known that nitrogen in coal (fuel- N) influences NOxrformation and reduction in pulverized coal combustion. I), 2) That is, fuel-N forms NOx in the oxidation (or volatile combustion) zone and the disappearance of r NOx occurs in the reduction zone.3 ) The mechanism of NOx formation and reduction during coal combustion is very complicated and affected by the flame structure and the volatile evolution behaviour near the burner exit. 4) Althouth the rate of volatile evolution has been researched elsewhere, 5) ~ 8) the effects of coal type on NOx formation and reduction are unclear. For the NOx formation and reduction occurred during coal cOlnbustion, we propose a simple reaction model. The objective of our study is to clarify experimentally the reaction rates of volatile evolution, NOx formation and NOx reduction based on the model.. The experiment uses a drop tube furnace for various bituminous and anthracite coals ranging from 1.0 to 11 in the fuel ratio (fixed carbon/volatile matter ratio). |
