estimate the concentration and the mass emission rate of NOx if a coal containing 1.5% nitrogen is combusted at 1400 k using an air/fuel ratio that is 1.5 times the stoichiometric ratio. Consider only fuel NOx and assume that only NO is formed. The combustion rate of coal is 600 kg/hr, and the flue gas (with an average molecular weight of 27.5) is produced at the rate of 13000 kg/hr.