Effect of different fuel NO models on the prediction of NO formation/reduction characteristics in a pulverized coal combustion field

Abstract

To investigate the effects of fuel NO formation models on the prediction of NO concentrations in a coal combustion field, numerical simulations for a coal combustion field in a 760 kW test furnace were performed. Three models, those proposed by De Soete, Chen et al. and Mitchell et al. were employed to calculate fuel NO formation originating from volatile matter. The results show that the model proposed by Mitchell et al. reproduces the tendency of the experimental data better than the other two models. In addition, the difference between the NO conversion ratios of bituminous coal and sub-bituminous coal that contains a high level of moisture was examined in detail using simulation results from the model of Mitchell et al. It was found that the formation of a region with a low oxygen mole fraction immediately downstream of a region with a high NO production rate is essential to realize a low NO conversion ratio.

Effects of Fuel Type and Operation Parameters on Combustion and NOx Emission of the Iron Ore Sintering Process

“…The overall reaction rate of gaseous combustion is calculated using a combined model considering chemical kinetics and eddy dissipation, as shown in Equation 17 [12,18]:…”

“…Since the NO x released from atmospheric coke combustion is mainly NO, and the concentrations of NO 2 and N 2 O are very low [18], only the formation of NO was considered in this study. Before performing the NO prediction, a converged solution of the combustion flow field was calculated.…”

“…In the formation process of fuel NO x , we only consider the conversion of coke-N to NO x , but ignore the conversion of volatile-N to NO x [11]. For the calculation of NO formation from coke combustion, the following formula has been given in previous works [18,26] and was employed in the present model:…”

“…In recent years, most simulation models for sintering have focused on the combustion behavior and heat and mass transfer in the sinter bed [12][13][14][15][16][17]. In order to investigate the NO x formation/reduction behaviors of sintering, the calculation of a series of NO x formation/reduction mechanisms, i.e., the thermal NO x , prompt NO x , and fuel NO x mechanisms, is adopted [18]. Due to a large proportion of NO x originating from the fuel NO x mechanism, the fuel NO x mechanism is the most important among these mechanisms, and the fuel NO x mechanism is further divided into that NO x which is generated from volatile-N and that NO x which is generated from coke-N.…”

Formation of Nitrogen Mono Oxide (NO) during Iron Ore Sintering Process

“…The total emission of NOx ultimately depends on the oxidation of fuel-N and the reduction of NO. [5][6][7][8] The research of NOx's generation and discharge in sintering process has drawn much attention in recent years. Studies have shown that sintering parameters such as water ratio, fuel ratio, quicklime ratio and the thickness of bed layer had important influences on the NOx concentration in flue gas.…”