Steam quality for industrial steam turbines
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Dear colleagues: Our company manufactures turbines for Hangzhou Automobile Industry. These turbines have been in operation for over 4 years now, and during this major maintenance session, it was found that some of the turbine blades showed signs of erosion; it is suspected that this was caused by low steam temperature. The design pressure and temperature are 3.43 MPa and 435 degrees. The main pressures can be maintained at present, but the temperature is around 400 degrees. What is an appropriate operating temperature for the turbine?
First, the pressure of the steam is also important; low pressure increases the humidity of the steam. The second one is temperature
Is yours an S2 steam unit? It seems that the steam pressure is a bit low; higher pressure increases the humidity of the steam per unit volume, and over time this will definitely cause erosion. It is best for the steam temperature to remain consistently at 400
Because at high temperatures, the mechanical properties of metals decline rapidly, which reduces the service life of various components in the turbine, such as throttle valves, nozzles and blades in the speed stages and the first few pressure stages, shaft seals, and bolts. It may also cause the earlier stages of the impeller assembly to become loose. Therefore, an excessively high steam inlet temperature is not allowed. Temperatures below the design value increase the blade flutter amplitude, thereby increasing the axial thrust. Operating at excessively low temperatures increases steam consumption and affects economic efficiency. Furthermore, a decrease in the inlet steam temperature will cause water erosion of the blades in the latter stages of a condensing steam turbine, thereby reducing its service life. Generally, it is required that the superheat at startup be above 50°C, and the superheat at operating temperature be above 100°C; the design values should still be followed.