Research of Low NOx Combustion with Large-Angle Counter Flow of a Fuel-Rich Jet and Its Particle-Dynamics Anemometer (PDA) Experiment

On the basis of counter flow of primary air with fuel rich in company with overall air-staged technology, this paper introduces a new pulverized coal combustion technology that can realize low NOx emission, high combustion efficiency, slagging, and high-temperature corrosion prevention by employing overall air-staged combustion, large-angle counter flow of primary air with a fuel-rich jet and forming a partial area of high-temperature and high pulverized coal concentration in the furnace. To verify technical data, research has been conducted on a 1025 t/h tangential firing boiler adopting this technology and a three-dimensional particle-dynamics anemometer (PDA) is employed on this prototype for measurement of the characteristics of two-phase gas/particle flows in the burner area. The distribution of the particle concentration and size distribution of the primary air, as well as the gas/particle velocity field were obtained. The experiments also measure the flowing characteristics of over-fired air (OFA) and secondary air. The results show that, with counter flow of fuel-rich jet technology, more particles can be injected into the high-temperature side in the furnace, the concentration of the particle is higher at the high-temperature side than that near the water wall, and the particle concentration of large particles is also lower near the water wall. The research shows that the counter-flow technology combined with overall air-staged technology of the tangential firing boiler can realize low NOx emission and high efficiency combustion and can prevent slagging on the surface of the water wall and high-temperature corrosion.