Experiments were conducted under a hot condition of bituminous coal ignition in a 250 kW pilot-scale bias combustion simulator. The effects of the primary air velocity (PAV) on the ignition characteristics of bias pulverized coal jets in a reducing atmosphere were investigated to develop a better new burner for experimental bituminous coal. Multiple means of measurement and sampling were used for the axial and radial temperatures, flame spectrum, flue gas components, and residual solid inside the furnace. The standoff distance changed nonmonotonically between axial distances of 90 and 330 mm with increasing PAV and was shortest for a PAV of 16 m/s. The radiation heat transfer from the hot environment had more effect on the ignition than the convection heat transfer from high-temperature flue gas in the initial stage, while the convection heat transfer from the high-temperature flue gas played a greater role in the subsequent combustion of the char. At PAVs of 13 and 16 m/s, there was volatile and char homogeneous–heterogeneous combined ignition and one-mode combustion; at PAVs of 20 and 23 m/s, there was volatile-phase homogeneous ignition and two-mode combustion. The ignition of the fuel-rich jet lagged that of the fuel-lean jet at a PAV of 13 m/s. A PAV that is lower could not take advantage of bias pulverized coal combustion technology. The ignition of the fuel-rich jet was ahead of that of the fuel-lean jet at PAVs of 16, 20, and 23 m/s. At a PAV of 13 m/s, the position of stable ignition was the shortest, the temperature of stable ignition the highest, and the boundary of the stable flame the smallest. The PAV of 16 m/s provided the best ignition characteristics for bituminous bias pulverized coal jets, which is suitable to be selected as design PAV for the new burner development.

In this study, pulverized coal bias ignition experiments were conducted in a 250 kW pilot-scale bias combustion simulator to investigate the effects of the combustion conditions on the particulate matter (PM) formation characteristics in a reducing atmosphere; the amount of PM10 was determined using an electrical low-pressure impactor. The particle size distributions of PM10 from pulverized coal bias ignition under various combustion conditions in a reducing atmosphere differ from those in the tail flue gas of a coal-fired boiler. Mainly PM0.38 is produced when the pulverized coal concentration (PCC) is 0.53, the lowest amounts of PM0.38 and PM0.38–10 are produced when the PCC is 0.4, and mainly PM0.38–10 is produced when the PCC is 0.33; the PCC significantly affects formation of PM0.5–0.794. As the bias concentration ratio (BCR) of the pulverized coal increases, the pulverized coal jets are prone to releasing viscous minerals, which easily coalesce into supercoarse particles of size greater than 10 μm; this decreases the formation of PM0.38 and PM0.38–10. The released viscous minerals are the main sources of PM0.38, and the BCR significantly affects PM0.205–0.5 formation. Volatiles and char burn most intensely at a primary air velocity (PAV) of 17 m/s, resulting in maximum production of PM0.38 and PM0.38–10. PM0.38 was mainly produced in the volatile combustion stage, and PM0.38–10 was mainly produced in the char combustion stage; the PAV significantly affects the formation of PM0.041–0.317. More PM10 with a larger fraction of ultrafine PM was produced at the optimum PAV, which was selected based on the ignition characteristics.

In the process of power control and commissioning of supercritical unit boiler system, there are some problems such as large steady-state error and slow response speed. In order to optimize the control performance of supercritical unit boiler system, the power supply loop model and sliding mode control method of supercritical unit boiler system debugging power supply are proposed. Firstly, the power supply circuit model is established according to the data of voltage doubling rectifier circuit, inverter circuit, high frequency transformer and LC resonant circuit. Secondly, the capacitance voltage value and the inductance current value are calculated in the power supply circuit model. Finally, based on the numerical results, a terminal sliding mode controller and a linear sliding mode controller are established to complete the double closed-loop terminal sliding mode control and realize the power control of the debugging power supply. The experimental results show that when the input voltage is 50 V and the current is 14 V, the input voltage and current waveforms remain stable. When the input voltage is between 40 and 50 V, the change of switching frequency is small, only increasing from 22 to 26 kHz. The steady state of the power supply is high, and when the input voltage increases, the DC offset is 21.2. The convergence time in the calculation process is less than 200 ms. The instantaneous change of inductance is 0.7 A. The steady-state error is less than 0.005 V. The output voltage distortion rate is less than 4%. It is proved that this method has strong control performance in the supercritical unit boiler system.

Nowadays, NO x emission was taken more and more seriously, Emission standard of air pollutants for thermal power plants was enacted newly by Chinese State Environmental Protection Department which is considered to be the strictest NO x emission standard up to now, but similar to other NO x controlling regulations in the world, the present NO x emission metering form mostly base on concentration limit value without referring to power plant efficiency. Thus, this paper proposes a new NO x emission evaluation index as Power Generation Emission Rate and Power Supply Emission Rate for first time, then proceed to study NO x emission characteristic by two experimental parts, first part was carried out under unit different load via 6 experimental cases, second part was carried out under unit same load via the other 6 experimental cases. The results indicates that, whether under different unit load, or under same unit load, the new NO x emission index can evaluate boiler de-nitration technology more precisely in a quantitative way and owns a better applicability than traditional NO x concentration value, Power Supply Emission Rate of NO x can evaluate NO x emission characteristic more directly while unit supply per kilowatt-hour power to grid, which offers a new direction for objective evaluation to different kinds of de-nitration technologies.