为有效利用燃机排烟热量,探索燃煤锅炉与燃机烟气耦合燃烧可行性。根据燃烧学基本理论,分析燃机烟气混入对燃煤锅炉的燃烧理论空气量、烟气量、燃烧器喷口速度等参数影响,提出燃机烟气与燃煤锅炉耦合燃烧技术方案。运用全尺寸数值模拟技术,分析烟气耦合对燃煤锅炉燃烧特性影响。数值模拟结果表明,烟气耦合后燃煤锅炉火焰切圆直径变大;煤粉气流初始温度增加,挥发分析出提前,煤粉着火提前;燃煤锅炉烟气量增大,锅炉炉膛温度降低,水冷壁吸热量下降;炉膛出口NOx排放质量浓度由222.1mg/m3升至229.5mg/m3,焦炭燃尽率由98.91%降至96.9%。结合数值模拟结果,分析烟气耦合后发电机组能耗。虽然机组发电煤耗较耦合前升高2.0g/kWh,但燃机烟气的余热利用效率由约80%提升至约93%,折算机组煤耗降低10.98g/kWh,全厂能耗降低8.98g/kWh,表明燃机烟气与燃煤锅炉耦合燃烧技术方案可行。燃机烟气替代了大部分燃煤锅炉二次风量,通过燃煤锅炉空预器的风量大幅降低,造成空预器换热量大幅下降,排烟温度大幅升高,需在空预器后增加余热利用装置。

and gas turbines flue gas was explored. Based on the basic theory of combustion, detailed calculations were conducted on the theoretical airvolume, flue gas volume, burner nozzle velocity and other parameters of coal - fired boiler combustion after mixing with gas turbineflue gas. A coupling combustion technology scheme of gas turbine flue gas and coal - fired boiler was proposed. The influence of fluegas coupling on the combustion characteristics of coal-fired boiler was analyzed using full-scale numerical simulation technology.The numerical simulation results indicate that after flue gas coupling,the tangential diameter increases. As the initial temperature of pulverized coal flow increases, the volatile releases earlier, and the pulverized coal ignites earlier,The temperature of the boiler furnace decreases, and the heat absorption of the water wall decreases. The NO emission at the furnace outlet increases from 222. 1 mg/ m to229.5 mg/ m, and the burnout rate decreases from 98.91% to 96.9%. Based on numerical simulation results, the energy consumption ofthe whole plant after flue gas coupling was analyzed, it can be concluded that although the coal consumption of boiler power generation increases by 2.0 g/ kWh,the waste heat utilization efficiency of gas turbine flue gas has increased from about 80% to about 93%, representing a reduction of 10.98 g/ kWh in the coal consumption of boiler power generation, so the energy consumption of the whole plant has decreased. The results indicate that coupling combustion technology of coal-fired boilers and gas turbines is feasible. After flue gas coupling,the gas turbine flue gas replaces most of the secondary air, significantly reducing the air flow through the air preheater, resulting in a significant decrease in the heat of the air preheater and a significant increase in the flue gas temperature. It is necessary to add a waste heatutilization device after the air preheater.

0 引言

1 试验设计

2 烟气耦合技术路线分析

   2.1 燃机烟气引入转向室出口（燃煤锅炉后包墙）

   2.2 燃机烟气直接引入炉膛

   2.3 燃机烟气混入燃煤锅炉二次风引入炉膛

3 数值模拟工况

4 数学模型及网格划分

5 数值模拟计算结果及分析

   5.1 数值模型验证

   5.2 烟气耦合对锅炉燃烧特性的影响

6 结论