Patent GB-548309-A (GB)
Title: An improved method and apparatus for regulating an installation comprising at least two steam generators
IPC: F22D11/00
Filed: 1941-04-03
Abstract: 548,309. Fluid-pressure servomotor-control systems. SULZER FRERES SOC. ANON. April 3, 1941, No. 4462. Convention date, April 6, 1940. [Class 135] A servomotor-system for regulating the feedwater supply to an installation comprising at least two steam generators, more particularly generators with small liquid content, which are supplied with feed water from at least one feed pump, adjusts the whole quantity of feed water in accordance with the requirements of the generator on which is the heaviest load while the separate quantity fed to each other generator is adjusted in accordance with the requirements of the load on these generators individually. The loading of the several generators is determined by the amount of fuel supplied to the individual generators. As shown all the generators are supplied with feed water delivered through a single conduit 6 supplied by main and stand-by pumps 4, 5. The branch conduits 9, 10 leading to the generators 1, 2 fitted with regulating device 7, 8. Each of these devices has two valves 18 19 arranged in series. The valves 18 are actuated by servomotors 21 controlled by thermo-sensitive regulators 17 in the steam pipes of the generators. The valves 19 are actuated by spring-loaded pistons 30 under the control of relay valves actuated against the action of spring loads by variable fluid pressure acting on pistons 29 under the control of piston valves actuated by diaphragms 25 subject to the pressure differential across the valves 18. The pressures acting on the pistons 29 are also used to actuate relay valves 31, 32, 33, 34. The valves 31, 32 and 33, 34 are arranged in series and one or other of each pair control power pistons 35, 36 adapted to vary the loading on the governors 15, 16 of the turbines 11, 12 driving the pumps 4, 5. Assuming the generator 2 is set to carry the heavier load its feed pressure will be greater than that of the other generator and as both generators are fed by the same the fall of pressure in the device 8 will be less than that in the device 7. The springs 38, 39 of the valves 31, 32 are set so that they reach a central regulating position with a greater fall of pressure at the valves 18 than the valves 33, 34. The regulators 17 control the valves 18 in accordance with the steam temperature in such a way that a constant steam temperature is maintained corresponding to the quantity of fuel set for the generator in question. If the quantity of feed water fed is less than the total required the pressure differential falls and the valves 31, 32, and if it falls sufficiently, the valves 33, 34 are operated to increase the speed of the turbines and so increase the total quantity of feed. As the pressure differential associated with the generator 1 is greater than that associated with the generator 2 the valve 29 assosciated with the generator 1 is brought into the regulating position while that associated with the generator 2 is not sufficient to bring its valve 29 into the regulating position and the valve 19 remains wide open. If the main load is carried by the generator 1 then this generator controls the total feed and the partial quantity fed is regulated by the steam generator 2. By releasing the tension of the springs 38, 39 and increasing the tension of the springs 40, 41 the order in which the turbines 11, 12 are started up can be reversed.