GB567404A - Improvements in or relating to turbine power plant - Google Patents

Abstract

567,404. Steam generators. MASCHINENFABRIK OERLIKON. May 27, 1943, No. 8523. Convention date, June 11, 1942. [Class 123 (ii)] [Also in Group XXVI] In a plant having a steam turbine 7 and a steam generator 1, and an air or other gas turbine 13, an external machine 16 may be used to start up the turbine 13, compressor 14 and driven machine 15 driven by the turbine. The machine 16 may be an electric motor supplied with current from an external source, and is switched off when the turbine 13 is running normally. If the driven machine 15 operates in parallel with other machines, it must be connected up to the network, after reaching its operating speed. When running normally, the turbine 13 is driven by compressed air which is heated in a heater 12 by gases from a furnace 4 after passing the steam generator 1. Regulation of the air turbine is secured by byepassing one or more stages by the opening of a valve 17, controlled by a governor 22. When the valve 17 is fully open, the output of the turbine 13 is just sufficient to drive its compressor 14. This requires about three-quarters of the normal turbine output. The turbine 7 is a backpressure turbine whose exhaust can be utilised for heating and cooking. The feed water for the generator is preheated in a heater 101, in the smoke stack, and a heater 10 <5>, heated by exhaust air from the turbine 13. A fan 21 supplies air for starting up the furnace 4, or when the air turbine plant is out of action. The starting motor 16 can be dispensed with where the turbine 7 is first started at low steam pressure, and the machine 8 supplies current to the machine 15 which acts as a motor to drive the set 13, 14. The turbines 7, 13 can be used to drive a single useful output machine, in which case the starting motor is dispensed with. To shut down the air plant, a valve 18 is opened, allowing the air to pass to the furnace 4. The output of the air turbine and compressor 14 ceases, the furnace fire dies down or the steam plant is shut down. To prevent over-heating of the heater 12, the gases from the furnace can be byepassed to the stack 11, by opening a damper 23. Cold air may also be supplied by the fan 21. The valve 18 can be used for regulating the air turbine plant. Fig. 2 shows an alternative lay-out with air turbines 131 and 13<2> coupled as shown. The low-pressure turbine 13<2> operates on the same current generator 8 as the steam turbine 7. The starter motor 16 is used to start up the compressor set 13<1>, 14. The furnace is arranged in two parts. A regulator 22 controls a valve 17<1> in the byepass conduit of the turbine 13<1>. At low load of the plant, the valve 17<1> opens to reduce the speed of the turbine 13<1>, causing the output of the compressor 14 to be reduced and thus the output of the turbine 13<2>. When the desired low load is reached the valve 17 closes. In order to balance the outputs of the turbines 13<1> and 13<2>, at low loads, a valve 17<2> is provided to byepass some air from the turbine inlet. When the load is to be increased, a valve 17<3> is opened. The valves 17<2> and 17<3> may be controlled by a governor 25.