HONEYCOMB SEALING PREFERABLY FOR STEAM TURBINE

摘要

The invention relates to sealing engineering and may be used in over-shroud sealing of steam turbines HPC. The objective of the invention is to increase efficiency of the honeycomb sealing while maintaining minimal possible radial gap between surfaces being sealed. This objective is achieved by known forward flow honeycomb sealing, preferably for steam turbine, comprising turbine shroud (3) with honeycomb inserts (4) mounted in a stator casing (1), embracing with radial gap the ring sealing crests (10) of a shell (6) of working blades (7) of rotor (8), wherein, according to the invention, said shroud is made with ring sealing crests (5), embracing shell of said working blades of rotor with a gap, exceeding said radial sealing gap, said honeycomb inserts being arranged between said shroud crests. Honeycomb insert is mounted on the turbine shroud at the depth (h) from 3mm to 6mm, which value is selected from mechanical considerations, on the condition of honeycomb depth h not being cutted through by the shroud crests completely to the shroud surface. Honeycomb insert is made of equilateral tetrahedral or hexahedral cells of about 0.9 mm size (0.9 mm being a diameter of the circumference inscribed in hexahedron or tetrahedron), produced by high-temperature brazing of corrugated strips of heat-resistant material, preferably 0.05 mm thick, both with one another and with cylindrical surface of the shroud. The honeycomb sealing design offered provides for creation of a working flow with multiple changes in flow direction, with nonlinear effects being induced on the honeycomb insert of the above geometry, which increase substantially the hydraulic resistance. Utilization of the invention offered in the industry allows to induce a labyrinth passage of the working medium through the gaps between sealing surfaces, increasing sealing efficiency with minimal possible radial gap. The increase in efficiency amounts to 1-1.5% for every stage of steam turbine HPC.