GB993476A - Improvements in or relating to turbines - Google Patents

Abstract

993,476. Turbines. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. March 10, 1964 [April 17, 1963], No. 15101/63. Heading F1T. At least one ring of interstage guide blades of a turbine is provided with encircling shroud members having inner surfaces provided with openings arranged to intercept and to permit the outward passage of erosive particles travelling along these inner surfaces. The invention is described with reference to a double-flow steam turbine, Fig. 1 (not shown), having two axially-opposed working medium flow passages in each of which are disposed five rings of rotor blades 9 or 10, a further ring of rotor blades 12 at the downstream end of each flow passage and, between each two rings of rotor blades, rings of guide blades 13, the downstream ring of which is designated 13L. In each flow passage, one ring of guide blades 13 is mounted in a diaphragm 25, Fig. 2, including a shroud ring 27 to which is secured a substantially cylindrical shroud plate 29. Near the shroud ring, the shroud plate 29 is provided with slots 39 spaced apart axially and overlapping circumferentially. Water adhering to the inner surface 27S of the shroud ring forms a moving film which is intercepted by the slots 39 and entrained in the steam passing therethrough to the turbine condenser. The outer guide blades 13L, Fig. 3, are bounded by a frusto-conical double walled ring 15 forming a continuation of frusto-conical partitions 19 and 17 carried by the penultimate rings of guide and rotor blades respectively, which partitions together with ring 15 divide the steam flow into radially inner and outer flows. Water droplets adhering to the inner surfaces of the partition 17 are shed onto the ring 15 and pass, together with some steam, through port 57 into an annular space 55 between the two walls of ring 15 and finally to a feed water heater via duct 59. Water adhering to the inner surface of the ring 15 downstream of port 57 is intercepted by and flows through tubular passages 61 in the ring 15 to the radially outer annular flow of steam and thence to the condenser.