![]() ![]() The turbine shown in Figure 18-2 was forced off-line by deposition only 3 months after it was placed in operation. Turbine deposits can accumulate in a very short time when steam purity is poor. In a fouled condition, this 30-MW turbine lost over 5% of its generating capacity. The deposits were caused by the use of contaminated water to attemperate the steam. ![]() Figure 18-1 shows the effect of gradual deposit buildup on stage pressure. Uneven deposition can unbalance the turbine rotor, causing vibration problems.Īs deposits accumulate on turbine blades, stage pressures increase. Where conditions are severe, deposits can cause excessive rotor thrust. Distortion of steam passages alters steam velocities and pressure drops, reducing the capacity and efficiency of the turbine. These deposits, often rough or uneven at the surface, increase resistance to the flow of steam. Adherent deposits form in the steam passage, distorting the original shape of turbine nozzles and blades. ![]() Close tolerances in the turbines, the use of high-strength steels, and impure steam all contribute to these conditions.Īlthough several factors influence the formation of deposits on turbine components, the general effect is the same no matter what the cause. The development of modern, high-efficiency steam turbines has led to an increase in deposition, erosion, and corrosion problems. ![]()
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