Patent GB-802934-A (GB)
Title: Improvements in or relating to apparatus for regulating steam turbine power plants
IPC: F01D17/26
Filed: 1956-05-14
Abstract: 802,934. Turbine plant. SIEMENSSCHUCKERTWERKE A.G. May 14, 1956 [May 13, 1955], No. 15025/56. Class 110 (3). [Also in Group XXIX] A steam turbine power plant comprising a turbine connected as a unit to a boiler of low storage capacity wherein control means responsive to signals dependent upon the rotational speed of the turbine shaft are provided to regulate the turbine and a boiler load-setting device has a further regulator, which in the event of a rapid change of boiler pressure, is arranged to influence the boiler load-setting device by means of a decaying adjusting signal the strength of which is dependent upon the rate of change of the pressure so as to tend to restore the boiler pressure to its original value. The delivery pressure of a pump 3 driven by the turbine shaft 1 is transmitted to a pressure transformer by a conduit 4. The pressure transformer comprises a bellows 5 responsive to the pressure in the conduit 4 which acts on a lever 7 carrying a sleeve 9 formed with control slots which coact with control slots formed on a piston 10. The registration of these slots controls the pressure in the conduit 16 in such a manner that a rising pressure in the conduit 4 increases the amount of registration and thus causes a decrease in the control pressure in the conduits 13 and 16. The piston 10 forms an extension of the piston 11 which is loaded by a spring 12. If the turbine speed rises due to a decrease in load, the pressure in the conduit 4 rises and as a consequence the pressure in the conduit 16 falls. The control piston 17 then moves downwards and allows pressure oil to pass from the conduit 20 to the underside of the piston 18 which then rises and closes the turbine inlet valve 21. An increase in load leads to a rise in pressure in the conduit 16 and to further opening of the valve 21. The conduit 16 is also connected to a boiler load setting device 24 through a teletransmitter 39 and a regulating device 40 which has a specific position for each value of the pressure in the conduit 16. The regulating device 40 has an adjustable presetting arrangement 43. An additional regulator 42 responsive to the live steam pressure in the conduit 28 acts on the device 40 through the presetting arrangement 43. With a rapid increase in load on the turbine the effect of the load setting device 24 is delayed and the pressure in the conduit 28 drops. This causes the regulator 42 acting through the device 40 to adjust the boiler load setting device 24 to a higher output than would correspond to the load condition of the turbine. The boiler pressure then rises again and the presetting arrangement 43 is gradually returned to its nominal setting. A further regulator 25 is provided to control the turbine inlet valves 21 so as to open these valves when the steam pressure rises and vice versa. This regulator comprises a pivoted jet pipe controlled by bellows 27 responsive to the live steam pressure and a spring 30. An increase of the steam pressure above its nominal value causes the jet pipe to be positioned opposite the inlet of the conduit 32. This causes pressure oil to be supplied to the underside of piston 33 which rises and increases the tension in the spring 12. The spring 12 lifts the piston 10 and thereby increases the pressure in the conduit 16 which lifts the piston 17 and thereby causes the valves 21 to be opened still further. A lever 29 controlling the loading of the spring 30 is connected by a rope 38 to the lever 35 so that as the lever is lifted the force of the spring 30 is increased and the jet pipe 26 returned to its neutral position. The loading of the spring 46 may be adjusted by hand or by a motor 45 in response to a control valve such as speed, load, frequency or loading timetable.