What is the effect of silica in steam on turbines?
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An excessive amount of silica in the steam can cause scaling in the turbine. How does the efficiency of the turbine change as a result of this scaling? How should this phenomenon be understood?
The steam quality entering the turbine is as follows: Iron (Fe) mg/kg ≤20, Copper (Cu) mg/kg ≤5, Sodium (Na) mg/kg ≤10, Silica (SiO2) mg/kg ≤20. Conductivity (25°C) ms/cm ≤0.3. Check out this post: http://bbs.hcbbs.com/thread-411052-1-1.html
Scaling occurs on the turbine steam nozzles and rotor blades, resulting in reduced turbine efficiency, increased steam consumption, and higher turbine exhaust temperatures.
Scaling can occur on the turbine steam nozzles and rotor blades, leading to a decrease in turbine efficiency and an increase in steam consumption. When the temperature of the turbine exhaust rises significantly, vibrations can occur; these vibrations, if intensified, can cause the equipment to be damaged.
If the accumulated dirt falls off, it will affect the impeller and cause abnormal noises!
Excess SiO2 can lead to elevated levels of SiO2 in the steam, which then deposits in the superheaters, steam pipelines, and turbines. Such deposits accelerate the damage to the superheaters and reduce the efficiency of the turbines.
In addition to the above results, turbine work decreases, steam consumption increases, and vibration increases in severe cases.
Scaling on the turbine steam nozzles and rotor blades reduces the efficiency of the turbine and increases steam consumption. Meanwhile, during normal operation of the turbine, the speed control valve gradually opens until it is fully open; in cases of severe scaling, the turbine is unable to reach the load required for production. The common approach is to clean the cylinder after stopping the machine; of course, depending on the hardness of the scale, it is possible to use the manual main steam valve to control the turbine’s speed during its low-speed warm-up phase. The automatic main steam valve and the throttle valve are then opened fully, and nearly saturated steam is used to clean the turbine.
It is generally required that SiO2 in the steam not exceed 20 mg/m3. If the SiO2 level in the steam is too high, it will deposit in the valves, pipelines, and turbines of the steam system. Such deposits accelerate the damage to the superheaters and reduce the output of the turbines. Operating experience with steam systems shows that, even though the quality of the steam is guaranteed, it is often not possible to ensure that the turbines remain free from deposits over an extended period of time. To prevent excessive sediment from compromising the safe operation of the turbine, regular cleaning is necessary.