Enyu Wang

A Simplified One-Dimensional Model of Low NOx Ignition for the Direct Flow of Pulverized Coal

This study developed a new model for the low NOxignition for the direct flow of pulverized coal, which enabled the influence of the primary air and internally recirculated flue gas (RFG) on NOx formation to be investigated. A model of the preignition zone was discussed in detail. Three new parameters, the Local Stoichiometric Ratio of Volatiles(LSRV), the Virtual Temperature of Ignition (VTI) and a Gxnumber to indicate NOx reduction potential were introduced to analyze the influence of the primary air/RFG parameters on low NOx ignition. It was found that coal volatiles and size had a major impact on establishing the primary air parameters and ignition position which are favorable for low NOxcombustion. The model can be used to determine the necessary mixing parameters for the design or modification of boilers for low NOx coal combustion.

Research on the secondary air position for the one-dimensional model of low NOx combustion

This study developed a new model of low NOx combustion for the direct flow of pulverized coal, which enabled the relationships among gas temperature, oxygen concentration, time consumption, and distance to be investigated. A model of the ignition and combustion zone was discussed in detail. It was shown that the gas temperature and the oxygen concentration change with the distance. The proper position of the secondary air injection can be obtained according to the gas temperature and the oxygen concentration which significantly affect NOx formation. The model can be used to determine the injection position of the secondary air for the design or modification of boilers for low NOx coal combustion. Application of the model to a power plant boiler together with pre-ignition model and reburning technology enabled an overall 48% reduction of NOx to be obtained.

Effect of Recirculated Flue Gas Position on Combustion and NO Emission for High Temperature Air Combustion

High temperature air combustion (HTAC)technology is a high efficient, low pollution of combustion technology being widely studied. The mathematical model for HTAC is built and the effect of recirculated flue gas position on combustion and NOx emission is investigated by using numerical simulation. The results show that recirculated flue gas can effectively reduce the oxygen concentration in combustion air. With the change of recirculated flue gas position, the furnace temperature and NOx concentration are changed, and the both appear peak values when the position is at the middle section of furnace. The beginning section of the furnace is an ideal position of recirculated flue gas to be chosen for low NOx emission, however, the end section is good for temperature uniformity.