Under what circumstances is thermal shock in turbines likely to occur?
Thread Content
(1) Mismatch between steam temperature and metal temperature at startup. If the temperature of the steam and that of the cylinder do not match at startup, or if a certain rate of temperature increase cannot be controlled, significant thermal shock will occur ； (2) Thermal shock caused by startup in an extremely hot state. During the extremely hot-state startup of unit-based large turbines, due to various constraints, startup is often carried out under conditions of low steam parameters, which easily leads to thermal shock in the cylinders and rotors ； (3) Thermal shock caused by significant load changes. When a turbine suddenly loses most of its load, the steam temperature drops significantly, causing the cylinders and rotor to experience severe thermal shock due to the cooling effect. During short-term, significant load increases, the steam temperature rises (the heat release coefficient increases greatly), and a large amount of heat is exchanged between the steam and the metal in a short period of time, resulting in greater thermal shock ； Thermal shock caused by water ingress into the cylinder and shaft seals. Cold water enters the cylinder and shaft seal chambers, and the intense heat exchange causes significant thermal shock, often leading to deformation of metal components.
(1) Mismatch between steam temperature and metal temperature at startup. During normal starting, it is required that the starting parameters match the metal temperature, and a certain rate of temperature rise must be controlled; if the temperatures do not match and the difference is large, significant thermal shock will occur. (2) Thermal shock caused by starting in an extremely hot state. During the extremely hot-start of unit-based large turbines, due to various constraints, startup is often carried out under conditions of low steam parameters, which easily leads to thermal shock in the cylinders and rotors. (3) Thermal shock caused by significant load changes: When a turbine operating at its rated full load loses a large portion of its load, the steam temperature in the flow passage drops significantly, causing the cylinder and rotor to cool down and experience substantial thermal shock. When a load is applied suddenly, the steam temperature rises and the heat release coefficient increases significantly; a large amount of heat exchange occurs between the steam and the metal in a short period of time, resulting in greater thermal shock. (4) Thermal shock caused by water ingress into the cylinder and shaft seal. Cold water enters the cylinder and shaft seal chambers, and the intense heat exchange causes significant thermal shock, often leading to deformation of metal components.