초록 ▼

A method for in-field improvement or repair of a stationary gas turbine is carried out by successive removal of the gas turbine discs including its multiplicity of blades (buckets) from the common drive shaft. The overlying ring of tip shoes (shroud) and gas feed nozzles (stationary buckets) are sim

A method for in-field improvement or repair of a stationary gas turbine is carried out by successive removal of the gas turbine discs including its multiplicity of blades (buckets) from the common drive shaft. The overlying ring of tip shoes (shroud) and gas feed nozzles (stationary buckets) are similarly sequentially removed. Each disc is axially and circumferentially index marked with respect to the common drive shaft prior to removal of a portion of the drive shaft and substitution of a dummy drive shaft. The dummy shaft in turn is similarly indexed to the turbine disc index marks. Such marking assures that the turbine discs may then be reassembled to the common drive shaft so that no field rebalancing of the common drive shaft, and its assembled air compressor stages, is required for vibration control. The tip shoes, including the labyrinth knife edge, are then replaced by recoated shoes for control of erosion resistance and progressive abradability of the edges to accommodate centrifugal and thermal expansion of the blade tips. Deposition of the abradable material on the blade tips or erosion of the blades is avoided by reducing the clearance between the tip shoe edges and the blade tips with such progressive hardness of the abradable material on the tip shoes. Such reduction greatly increases efficiency of the engine by enhance of power out put and reduced fuel consumption.

대표청구항 ▼

In the operation of a gas turbine engine wherein a common drive shaft assembly includes a hot gas section comprising a plurality of hot gas stages, each of which includes a turbine disc axially spaced apart from the other turbine discs along said drive shaft and an air compressor section axially spa

In the operation of a gas turbine engine wherein a common drive shaft assembly includes a hot gas section comprising a plurality of hot gas stages, each of which includes a turbine disc axially spaced apart from the other turbine discs along said drive shaft and an air compressor section axially spaced apart from said hot gas section having a multiplicity of axially adjacent air compressor discs, and a combustion chamber surrounding said drive shaft intermediate said hot gas and said air compressor sections, said common drive shaft extending beyond either one or both of said air compressor and hot gas sections of said engine for connection to rotary drive power means, or auxiliary means, or both, and wherein said turbine engine includes a removable exhaust gas diffuser housing extending beyond the last turbine discs of said hot gas section to expose a sufficiency of each turbine disc supported on a portion of said common drive shaft being independently removable from said hot gas section, a method for in-field restoring or improving the efficiency of the hot gas stage of said gas turbine without displacement or removal of said turbine engine from its normal operating position and without need to re-balance said common drive shaft assembly to avoid destructive vibration of said gas turbine engine operating at normal or ideal temperatures and rotary speeds, which comprises the steps of (a) index marking each of said hot gas turbine discs relative to its axial and circumferential position on said removable drive shaft portion; (b) withdrawing said removable drive shaft portion from said common drive shaft through said plurality of turbine discs by unthreading the connection between said portion and said common drive shaft, (c) replacing said drive shaft section with a dummy drive shaft section, said dummy drive shaft being substantially identical to said drive shaft portion, including a threaded end for connection to said common drive shaft except that the rearward end of said dummy drive shaft having a diameter to permit the hubs of each said turbine disc to pass axially over said dummy drive shaft end, (d) index marking the circumferential and axial positions of each turbine disc on said dummy shaft, and measuring the space or gap between the tips of the turbine blades and the opposed tip shoe surfaces at a multiplicity of locations around the full circumference of said turbine blade tips, (e) then, successively removing each of said hot stage assemblies from said turbine engine by independently sliding the turbine disc over the rearward end of said dummy shaft, removing the associated tip shoe means as a unit, and followed by removal of the corresponding nozzle ring supplying hot gas to the related turbine disc, (f) re-assembling said multiplicity of hot stages in the reverse order of step (e) wherein each turbine disc is oriented around and along said dummy shaft by said index markings previously recorded on said dummy shaft and said turbine discs, and (g) after each turbine disk is replaced, substituting a modified tip shoe means for each of the plurality of original tip shoes around at least said first and second stage turbine discs, each of said modified tip shoe means including an abradable surface coating forming a plurality of labyrinth edges having a Mohr scale hardness not less than about 40 and not greater than about 80, and said labyrinth edges having a radial width toward the opposed turbine blade tips to substantially full the space therebetween, and the hardness of said labyrinth edges of said substituted tip shoes having maximum abradability at the outer end thereof and each shoe means having a maximum hardness at the support ends of said tip shoe to permit self adjustment of said space between the turbine disc tips and said labyrintive edges to minimize abrasion of said labyrinth edges to the maximum radial expansion of said turbine blade tips under operating conditions and without damage to said blade tips, and (h) unthreading the end of said dummy drive shaft from said common drive shaft, and threadably reconnecting said drive shaft portion to said common drive shaft so that each of said index markings on said discs and their index markings on said drive shaft portion may be torqued to said common drive shaft, whereby said drive shaft and the reassembled discs thereon do not require dynamic rebalancing of said common drive shaft prior to operation of the re-assembled gas turbine.