GB429672A - Improvements relating to the accommodation of the output of steam power plants to different loads thereon - Google Patents

Abstract

429,672. Feedwater and fuel regulation for steam boilers. SIEMENSSCHUCKERTWERKE AKT.-GES., Siemensstadt, Berlin. Sept. 28, 1933, No. 26742. Convention date, Sept. 30, 1932. Drawings to Specification. [Class 123 (ii)] [See also Group XXVI] In steam power plants, particularly those employing forced flow tubulous steam generators, the output of the plant is accommodated to different loads by regulating the servicing of the boiler so that, with a substantially constant throttle opening, the specific volume of the steam is varied to maintain substantially constant the volume of steam flowing from the boiler. For example, in the regulation of a turbo-generating set supplied with steam from a forced flow tubulous steam generator, the turbine and electric generator are designed to give the best efficiency at the basic load. The throttle valve is almost full open at this load and slight variations in load above and below the basic load are compensated by varying the position of the throttle valve by known methods. For large increases of load above the basic valve, the production of steam in the boiler is regulated. The variations in load are detected by variations in speed, or frequency of the plant, or by the use of an output meter or by measuring the variations in pressure on either side of the throttle valve or a baffle plate arranged in the steam pipe. The variation in these valves is employed to control the fuel and air supplies and the pressure and quantity of water fed to the boiler. The fuel only may be adjusted and the air supply controlled to maintain perfect combustion. The temperature of the superheated steam is employed as an additional control to maintain constant the volume of steam leaving the boiler. When the boiler pressure is made to vary directly with the load, a correcting pressure regulator may be employed whereby a device responsive to steam pressure is balanced against the device responsive to load. The plant is provided with means to increase the flow of circulating water in the condenser at high loads. In order to overcome the difficulties that will be encountered in the L.P. stages of the turbine, the steam is tapped and employed for feed heating or driving the auxiliary machines. One auxiliary turbine may be employed to drive a generator supplying current to the motors driving the auxiliaries, whereby the speed of the auxiliaries is proportional to the load on the plant. The electric generator may be cooled either by increasing the flow of air or liquid at high loads or by cooling by refrigerating arrangements wherein brine is cooled and stored during the basic load operations. Coal dust firing for the boiler may be employed during the peak loads, the grinding operation being carried out during basic load operation.