Effect of Clearance Leakage Loss on Economics of Steam Turbine

The leakage loss is very important to the economics of steam turbine. But in the practical operation process, the radial clearance often is enlarged in steam turbine flow passage. Aimed at this phenomenon, the influences of clearance leakage on the relative internal efficiency and the power of steam turbine are studied in this paper. The results show that, not only in the impulse stage, but also in the reaction stage, the diaphragm leakage loss and the blade tip leakage loss are serious for the high pressure stage. Furthermore, the output loss increases and the relative internal efficiency of stage decreases linearly with the increasing radial clearance under the diaphragm or over the blade tip. The studying results provide basis for condition maintenance and energy conservation of steam turbine flow path. It is necessity that the condition monitoring for the radial clearance of steam turbine flow path be carried out.