GB430346A - Improvements in or relating to steam generating plant - Google Patents

Abstract

430,346. Indirectly heated steam boilers. BAUMANN, K., Lacey Oaks, Styal Road, Wilmslow, Cheshire, and STUBBS, A., 390, Wilbraham Road, Chorlton-cum- Hardy, Manchester. Dec. 8, 1933, No. 34657. [Class 123 (ii)] A once - through steam-boiler comprises a number of superheater elements 4, 6, 8, 10, and one or a number of desuperheater elements 5, 7, 9, alternating therewith, the latter being disposed in one or more water evaporating chambers 11 .. 13 of surface contact type steam from which is admitted into the once through circuit and in which the amount of heat exchange is regulated. A feed pump 1 supplies economizer and generating portions 2, 3 in front of the superheating elements and the evaporators are supplied through a pipe 14. Steam from the evaporators is passed into the once through circuit at a point 19, and optionally at other points along its length, its entry being controlled by a valve 20 responding to temperature and pressure variations at the generator outlet 21. The additional connections may have their own thermostats. With the pressure constant a temperature fall tends to close valve 20 and depress the water level in the evaporators so reducing the desuperheating effect. A rise in temperature on the other hand increases the amount of desuperheating. In the case of a suddenly increased demand, however, resulting in a fall in temperature and pressure, valve 20 is prevented from closing whilst the pressure is falling. A fall in temperature being permitted in order to maintain the pressure as high as possible. Inversely, pressure increases prevent valve 20 from opening by reason of temporary increases in temperature. Instead of or in addition to the control by throttling, byepasses for the desuperheaters may be manually or automatically operated. Feedwater may be supplied to the evaporators from several sources and may be injected into the superheated steam at one or more points. The Provisional Specification describes also the provision of steam to the superheated steam circuit from an external source for starting up and the diminution of the water heating portion of the tubing.