火电基础
一、火电基础概念 | Thermal Power Fundamentals
二、蒸汽参数与等级 | Steam Parameters & Classifications
三、主要设备 | Major Equipment
四、燃料与燃烧 | Fuel & Combustion
USC Unit Design — Steam Parameters and Efficiency
Hua, this project is a 2×660 MW ultra-supercritical coal- fired power plant. The client is looking for world-class efficiency. What are the target steam parameters, and what net efficiency can we guarantee?
华工，这个项目是2×660 MW超超临界燃煤电厂。业主要在效率上达到世界 一流。目标蒸汽参数是多少，我们能保证多少净效率？
华工: We're designing for main steam conditions of 28 MPa, 600°C with a single reheat to 620°C. The feedwater temperature will be 295°C. These parameters place us in the upper range of USC technology — significantly above the critical point of water at 22.064 MPa and 373.95°C. Above the critical point, there's no phase change between liquid and steam — the working fluid is a supercritical fluid that transitions continuously, eliminating the two-phase boiling region and its associated inefficiencies.
设计主蒸汽参数28 MPa、600°C，一次再热到620°C。给水温度295°C。这 些参数属于USC技术的上段——明显高于水在22.064 MPa和373.95°C的临界点。 临界点以上液态和气态之间没有相变——工质是超临界流体、连续过渡，消除了 两相沸腾区及其相关的低效。
OEM代表: With these parameters, the gross turbine heat rate is about 7,500 kJ/kWh — that's 7,110 BTU/kWh. The boiler efficiency at 94.5% and a plant auxiliary power consumption of 4.8% gives a net plant efficiency of 44.5% on an LHV basis. For comparison, a typical subcritical plant of the same size operates at about 35-36% net efficiency. The USC design saves approximately 20% in fuel consumption for the same power output — and reduces CO₂ emissions by the same proportion.
用这些参数，汽轮机毛热耗约7,500 kJ/kWh——即7,110 BTU/kWh。锅炉效率 94.5%、厂用电率4.8%，全厂净效率在LHV基准下为44.5%。对比而言，同规模 典型亚临界机组净效率约35-36%。USC设计在同样出力下节省约20%燃料—— CO₂排放也同比例减少。
What materials are required for the 600°C / 620°C steam temperatures? That's beyond the capability of standard ferritic steels.
600°C / 620°C的蒸汽温度需要什么材料？这超出标准铁素体钢的能力了。
华工: Correct. For the superheater and reheater outlet sections, we'll use austenitic stainless steels — Super 304H and HR3C for the highest-temperature zones. The main steam piping will be P92 (9%Cr ferritic-martensitic steel) for the thick-walled sections, transitioning to P91 where the temperature drops after the first turbine stage. The turbine rotor is a forged 12%Cr steel with advanced heat treatment for creep strength. Material selection at these temperatures is all about creep rupture life — we need 100,000-hour creep strength at temperature.
对。过热器和再热器出口段用奥氏体不锈钢——最高温区用Super 304H和 HR3C。主蒸汽管道厚壁段用P92（9%Cr铁素体-马氏体钢）、在第一级汽轮机 后温度降低处过渡到P91。汽轮机转子是锻制12%Cr钢、采用先进热处理获得蠕 变强度。这个温度下选材全看蠕变断裂寿命——我们需要在运行温度下10万小时 的蠕变强度。
Combined Cycle Configuration — Gas Turbine and HRSG
华工，联合循环按二拖一配置——两台燃机各带余热锅炉、共用一台汽轮机。 燃机每台350 MW、汽机350 MW、每块总1,050 MW。预期联合循环效率多少？
燃机单循环效率在ISO工况下约41%。联合循环的关键是余热锅炉——它捕集 630°C的燃机排气、产生16.5 MPa、565°C的高压蒸汽、再加上中压回路和低 压回路。这是三压再热型HRSG设计。汽轮机零额外燃料消耗增加350 MW出力。 联合循环净效率LHV基准62.5%——接近这类技术的理论极限。
燃机是成熟的F级机型，17级轴流压气机、压比19:1。燃烧器用于式低氮 (DLN)技术，无注水或注蒸汽的情况下将NOx排放控制在15 ppm以下。透平入口 温度1,425°C，通过对第一级叶片和导叶采用压气机抽气冷却和热障涂层来实 现。
电厂还有带切换挡板的旁路烟囱——如果HRSG或汽轮机不可用、燃机可以 在单循环模式运行。这种灵活性对电网可靠性至关重要。在启动指令后15分钟 内两台燃机就能送出700 MW、还不用等蒸汽循环上线。