关键词: 燃煤锅炉, 钠碱法脱硫废水, 氨氮, SNCR, SCR, 氨逃逸, 低氮燃烧, 喷氨量

Abstract: The coal-fired boiler of a company adopts sodium alkali desulfurization process and SNCR+SCR denitration technology. The ammonia escape value of denitration system is high, and the escaped ammonia is removed by water washing of desulfurization tower, which leads to high and fluctuating ammonia nitrogen value of desulfurization wastewater, and affects the economic and stable operation of subsequent units. The low-NO_x combustion transformation is carried out for pulverized coal boiler to stabilize the boiler operation parameters, optimize the boiler operation mode, reduce the NO_x production from the source, and control the NO_x mass concentration at the furnace outlet not higher than 500 mg/m³. The SCR denitration system is reformed by precise ammonia injection, and the automatic control and optimization debugging of denitration system are carried out to realize efficient operation of SNCR+SCR. The ammonia injection amount is reduced by 25%, and the ammonia escape value is reduced to 3.47 mg/m³. The desulfurization external drainage pump is upgraded by adding bypass pipeline and increasing the desulfurization liquid displacement amount to the design value of 37.5 t/h to reduce the ammonia nitrogen concentration in the wastewater. Through the above control measures, the average mass concentration of ammonia nitrogen in sodium alkali desulfurization wastewater is 200 mg/L, which is stable within 300 mg/L, meeting the operation requirements of subsequent treatment unit.    

Key words: coal-fired boiler, sodium alkali desulfurization wastewater, ammonia nitrogen, SNCR, SCR, ammonia escape, low-NO_x combustion, ammonia injection amount