Back-pressure steam turbine, problems with the steam seal cooler
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As the title suggests, it’s a unit steam turbine with two steam seal coolers; one of them is equipped with an air extractor while the other isn’t. Why is that? Seeking help from experts
Steam seal extractor – a brief explanation: it is a tee-shaped pipe with a changing diameter; one path carries steam, another leads to the discharge port of the machine, and through the third path, the steam carries away the gases discharged from the machine. In foreign systems, the exhaust gas is directed to a water seal tank, after which it is incorporated into the condensate water network. Before starting the turbine, there is air inside it, and the pressure inside the turbine is roughly equal to the atmospheric pressure. If vacuuming is not performed, the air cannot be removed, and as a result the exhaust pressure increases. In such a situation, to get the turbine to rotate, the amount of steam supplied to it must be increased significantly in order to overcome the friction and inertial forces of the compressor bearings; this results in large shock forces acting on the blades. After the turbine starts rotating, the heat transfer rate decreases due to the presence of air, the exhaust pressure rises, which may cause damage to the internal components. Therefore, the steam seal extractor must be turned on before starting the backpressure turbine.