Following the previous news, the following problems exist after the transformation of the low-nitrogen combustion technology sorted by the low-nitrogen burner manufacturers:
3. The steam parameters deviate from the design value, the amount of desuperheating water for overheating and reheating increases, and the screen overheating or reheater overtemperature
After the boiler burner adopts the air-staged low-nitrogen combustion technology, on the one hand, the combustion is delayed, the flame center moves upward, the flue gas temperature at the furnace outlet rises, and the boiler superheated steam temperature and reheated steam temperature rise. The problem of hot steam temperature exceeding the design value is aggravated, and the amount of overheating and reheating desuperheating water increases. On the other hand, the temperature of the main combustion zone decreases, and the temperature distribution in the furnace becomes more uniform. If the contamination and slagging of the original furnace water wall is serious, it will be improved. The heat absorption of the water wall increases, the flue gas temperature at the furnace outlet decreases, and the superheater temperature The temperature rise of the reheater and the reheater decreases, and the original problems of the overheated steam temperature and the low reheated steam temperature cannot reach the design value.
4. Thermal automatic control performance is degraded, steam parameters fluctuate greatly, and the unit AGC response rate is slow
After the transformation of the low-nitrogen burner, under the same coal type and the same load, the combustion reaction of the fuel in the furnace slows down, and the flue gas temperature distribution and heat absorption of the heating surfaces at all levels change. The specific manifestations are that the thermal automatic control is slow and moderate. The overshoot phenomenon has increased significantly, resulting in large fluctuations in steam parameters; for some areas, the AGC response rate of the unit is required to be high, and the AGC response rate is often slow, which cannot meet the requirements of the power grid. The main reason is that the control system setting and control curve of thermal engineering have not been optimized and adjusted accordingly, such as: the original static and dynamic load-coal volume control curve, the decoupling control system of the cold and hot air doors of the pulverizing system, and the automatic control system of desuperheating water ; Primary control feedforward system for boiler with primary frequency modulation.
