GB1105658A - Improvements in or relating to turbines - Google Patents

Abstract

1,105,658. Fluid-pressure servomotor systems. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. July 14, 1965 [July 22, 1964], No.29590/64. Heading G3P. [Also in Divisions F1 and F2] A steam turbine plant has servo means by which at least one turbine cylinder and its rotor can be moved relatively to one another to maintain internal clearances. The plant has in flow series super-critical and higher pressure turbine cylinders SPC, HPC and intermediate and lower pressure cylinders IPC, LPC, the respective rotors SPR, HPR etc. being rigidly inter-connected by flanged couplings such as 21. A fixed thrust bearing 31 locates the rotors axially. The lower pressure cylinders LPC are contained within a casing 15 fixed by an anchor point 41 to the foundation 35. The cylinder IPC is also fixed to the foundation. In order to compensate for axial expansion or contraction of the rotors so as to maintain desired running clearances in the cylinders SPC, HPC, bearing housing 67 carrying rotor bearings 63, 69 is axially slidable on its support 81. Housing 67 is rigidly connected to cylinders SPC, HPC which are respectively connected to bearing housing 65 and axially slidable on an extension of bearing housing 73 so that axial movement of housing 67 effects corresponding movement of cylinders SPC, HPC. A sensor 85 detects axial movement of the rotor SPR. The sensor is in the form of a thrust bearing and comprises, Fig.2, a flange 83 on the rotor SPR co-operating with front and rear thrust pads 87, 89 respectively mounted on the housing 67. Channels 91, 93 communicate with ports in the pads 87, 89 respectively and with chambers on the opposite sides of pistons 97 in two cylinders 95, illustrated also in Fig.3 (not shown). Pumps 115, 117 supply oil to the front and rear chambers respectively. Rods 99, 101 extending from each piston 97 co-operate with fixed front and rear abutments 107, 109 on support 81. Thus axial movement of rotor SPR to the left causes flanges 83 to move against thrust pads 87 causing a rise in oil pressure in the chamber to the left of each piston 97. The increase in pressure forces rod 101 against abutment 109 and moves bearing housing 67 to the left carrying with it cylinders SPC, HPC so as to restore the axial running clearance in these cylinders. In a modification, Figs.4, 5 (not shown), the sensor 85 is positioned between the cylinders IPC and LPC, and actuates a piston (97) in a fixed cylinder (95'). Movement of the piston in response to axial movement of the rotor IPR detected by sensor 85 causes a-corresponding axial movement of bearing housing 73 and the connected cylinders HPC, SPC and bearing housing 67 which in this case carries the thrust bearing 31. Thus all the rotors are displaced axially to restore axial running clearances in the cylinders IPC, LPC.