45. What are the hazards of scaling in the flow passages of a steam turbine?
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45. What are the hazards of scaling in the flow passages of a steam turbine?
When the quality of steam is poor, salt deposits can form on the flow-through parts of the turbine. Scaling is more severe in the high-pressure areas of the turbine, while in the low-pressure areas, scaling is minimal due to the operation under wet steam conditions. The hazards associated with scaling in the turbine’s flow-through parts include: 1. A decrease in the turbine’s efficiency and an increase in steam consumption; 2. Due to scaling, the pressure drop as steam passes through the partitions and blades increases, which in turn increases the reaction degree of the working blades. In severe cases, this can cause overloading of the partitions and thrust bearings； 3. Salt deposits adhering to the valve stem can easily cause the valve stem to stick.
Poor steam quality can cause salt scaling to form in the flow passages of the turbine, especially where scaling is more severe in the high-pressure areas. The hazards of scaling in the flow passages of a turbine are as follows: (1) It reduces the efficiency of the turbine and increases steam consumption. (2) Due to scaling, the pressure drop of the steam flow through the diaphragms and blades increases, which in turn raises the backwork of the working blades; in severe cases, this can cause overloading of the diaphragms and bearing assemblies. (3) Salt scale accumulating on the valve stem can easily cause sticking in the valve stem.
The basic solutions for the upper floor have been covered completely. During operation, it is essential to pay attention to the pressure in the wheel chamber; if scaling is detected, attempts can be made to remove it online without shutting down the system!