某1050MW超超临界燃煤机组深度调峰运行经济性与末级叶片安全性研究

Study on Operating Economy and Safety of the Final Stage Blade of a 1050 MW ultra-supercritical coal-fired unit with deep peaking

随着以新能源为“主体能源”新型电力系统建设的加速推动,电力系统灵活性不够、调节能力不足等短板和问题愈发凸显,新能源随机性和间歇性的特点要求燃煤发电机组逐步从主体能源向辅助性调峰调频电源转变。燃煤火电机组深度调峰运行下的经济性与安全性是当前研究的重点。本文以某1050 MW超超临界燃煤机组为研究对象,对机组在30%、20%额定负荷深度调峰运行的主要设备性能、运行经济性进行了试验研究,对小容积流量下汽轮机末级叶片安全性进行了试验和仿真研究。结果表明:机组从50%额定负荷分别深调至30%和20%额定负荷运行时运行供电煤分别增加34.50 g(/kW·h)和76.14g(/kW·h)。通过深度调峰幅度试验对比,1050 MW超超临界燃煤机组在30%额定负荷以下时,随着深度调峰幅度的增加,锅炉性能、汽轮机性能、厂用电率和机组运行经济性呈加速恶化趋势。通过小容积流量下汽轮机低压缸末级叶片鼓风情况的试验和仿真研究,当循环水流量72000 t/h,环境温度在28℃以下时,机组在20%负荷时高低压侧低压缸的排汽速度均可保持在60 m/s以上,排汽温度在50℃左右,汽轮机可在低压缸不喷水状态下长期运行;环境温度高于28℃时,高低压侧低压缸的排汽速度均降低至60 m/s以下,末级鼓风加重,此时需投入低压缸减温水,将引起叶片水蚀风险,对机组末级叶片产生不利影响。研究结果可为超超临界燃煤湿冷机组灵活性改造和经济运行提供一定的借鉴。

With the acceleration of the construction of a new power system with new energy as the"main energy",the lack of flexibility and regulating ability of the power system are becoming increasingly prominent.The randomness and intermittency of new energy require the coal-fired generating units to gradually change from the main energy source to the auxiliary peak-frequency modulation power source.The economy and safety of coal-fired thermal power units under deep peak-load operation are the focus of current research.In this paper,a 1050 MW ultra-supercritical coal-fired unit is taken as the research object,and the main equipment performance and operation economy of the unit are tested and studied at 30%and 20%rated load depth.And the safety of turbine final stage blade under small volume flow is studied by experiment and simulation.The results show that the power supply coal increases by 34.50g/(kW·h)and 76.14g/(kW·h)respectively when the unit is deeply adjusted from 50%rated load to 30%and 20%rated load respectively.Through the contrast test of depth peak regulation amplitude,when the 1050 MW ultra-supercritical coal-fired unit is below 30%rated load,with the increase of depth peak loading amplitude,the boiler performance,turbine performance,plant power consumption rate and unit operation economy show an accelerated deterioration trend.Through the test and simulation study on the wind blast of the final stage blade of the low-pressure cylinder of the turbine under small volume flow rate,when the circulating water flow rate is 72000 t/h and the ambient temperature is below 28℃,the exhaust speed of the low-pressure cylinder on the high and low pressure side of the unit can be maintained above 60m/s and the exhaust temperature is about 50℃at 20%load.The steam turbine can run for a long time without water spraying in the low-pressure cylinder.When the ambient temperature is higher than 28℃,the exhaust speed of the low-pressure cylinder on the high and low pressure side is reduced to less than 60m/s,and the wind blast at the final stage is aggravated.At this time,the low-pressure cylinder needs to be injected with desuperheating water,and the risk of blade water erosion is caused,which has an adverse effect on the final stage blade of the unit.