CYLINDER OF MEDIUM PRESSURE IN STEAM TURBINE

摘要

FIELD: machine building.;SUBSTANCE: cylinder of medium pressure in steam turbine consists of case with chamber, of steam inlet connected to cavity of lower pressure via separator, of guiding mechanism of first step with working blades arranged behind it with inter-rim gap, of ferrule of stator with radial packing positioned over band of working blades secured to guiding mechanism of first step. The ferrule forms a circular cavity with case of cylinder, while with diaphragm of second step it forms an open inter-step gap communicated with circular cavity. Separate circular chambers positioned opposite the inter-rim gap of the first step are made in the ferule, opposite to an inlet edge of the working blades band of this step and over pins of the working blades between the steps of radial packing. The separate circular chambers are communicated with the circular cavity of the case by means of drain channels beneath the ferrule. Outlet sections of the drain channels are arranged in the ferrule with set-off in a sequence corresponding to the position of the circular chambers in the ferrule. To external surface of the ferrule at a back end wall there is attached a circular screen separating a part of the circular cavity of the case with the outlet sections of the drain channels from the part of the circular cavity with an open gap between the first and the second step. Additional circular chambers located opposite to packing collars of the band of the first step blades can be made in the ferrule.;EFFECT: decreased abrasive wear of over-band packing and leaks through it in first step, also increased reliability of working wheel due to reduced wear of working blade pins, thus increasing service life of cylinder of medium pressure at presence of abrasive flows in it; improved indices of efficiency and reliability of turbine at continuous operation in whole.;2 cl, 5 dwg