School of Energy and Power Engineering, Shandong University
Design Department, Shandong Lurun Thermal Energy Technology Co.

富煤贫油少气的能源结构决定了我国以煤为主的能源格局短期难以改变，而燃煤电厂的排烟损失占锅炉热损失一半以上，充分利用烟气余热资源，不仅能降低对环境的污染，还可提高能源利用率，降低发电煤耗。依据国家标准对某1 000 MW超超临界二次再热燃煤机组进行多工况性能考核试验，全面分析设有空气预热器旁路烟道的烟气余热利用系统运行参数对机组经济性的影响；基于试验运行数据建立了Ebsilon系统仿真模型，通过变工况模拟数据与试验数据对比，验证了模型的准确性；基于仿真模型探索了高、低旁省煤器不同进水流量、空气预热器和旁路烟道的烟气比例对机组热力性能的影响规律，并探究不同负荷下高、低旁省煤器的最佳进水流量。优化结果表明：① 不同负荷下，最佳机组热经济性判据为给水主路和给水旁路混合点前基本无温差，以及低旁省煤器和6号低加混合点前的出水温差在0～5 ℃，此时高、低旁省煤器的进水流量为最佳进水流量；② 随着机组负荷升高，不同工况的高、低旁省煤器的最佳进水流量也随之增大；③ 运行时应保证磨煤机出口温度在70 ℃以上的前提下，增大旁路烟气比例来提高机组的经济性。同时，模型模拟所得影响规律及参数优化设置，可为超超临界二次再热燃煤机组深度节能提供参考。

China’s energy sector is characterized by rich in coal, poor in oil and little in gas, which determines that China’s coal-based energy pattern is difficult to change in the short term, and the heat loss in flue gas from coal-fired power plants accounts for more than half of the boiler heat loss. Making full use of the waste heat resources of flue gas can not only reduce environmental pollution, but also improve the energy utilization rate and reduce the coal consumption in power generation. According to the national standards, a 1 000 MW ultra-supercritical double reheat coal-fired unit was tested under multiple operating conditions to comprehensively analyze the impact of the operating parameters of the flue gas waste heat utilization system with air preheater bypass flue on the unit economic performance. Based on the test operation data, the Ebsilon system simulation model was established. The accuracy of the model was verified by comparing the simulation results with the test data. The influence of different inlet flow rates of high and low bypass economizers and the proportion of flue gas in air preheater and bypass flue on the thermal performance of the unit were explored through simulation models, and the optimal inlet flow rates of high and low bypass economizers under different loads were also obtained. The optimization results show that: ① Under different loads, the optimal criteria for economic performance of the unit include that the temperature difference between the main water supply pipeline and the bypass water supply pipeline is close to 0 ℃, and the outlet temperature difference between the low bypass economizer and the No.6 LP heater is within the range of 0−5 ℃. At this time, the inlet flow rate of the high bypass economizer and the low bypass economizer are the optimal flow rate; ② The optimal inflow flow of high and low bypass economizers under different conditions will also increase with the increase of unit load; ③ During operation, it is necessary to ensure the outlet temperature of the coal pulverizer is above 70 ℃. In addition, the bypass flue gas flow can be increased to improve the unit economic performance. Meanwhile, the influence law and parameter optimization setting obtained from the model simulation can provide a reference for the deep energy saving of ultra-supercritical double reheat coal-fired units.

山东省自然科学基金面上资助项目(ZR2022ME008)

杜晓楠，白如雪，桑鹏，等. 燃煤机组烟气余热利用系统优化运行研究[J]. 煤炭学报，2023，48(7)：2682−2690.

DU Xiaonan，BAI Ruxue，SANG Peng，et al. Experimental and simulation study on optimal operation of flue gas waste heat utilization system of coal-fired unit[J]. Journal of China Coal Society，2023，48(7)：2682−2690.