GB436087A - Improvements in or relating to the control of feed water to forced feed tubulous steam generators - Google Patents

Abstract

436,087. Instantaneous steam boilers. DEHN, F. B., 103, Kingsway, London.- (Doble Steam Motors, Ltd.; 4053, Harlan Street, Emeryville, California, U.S.A.) April 3, 1934, No. 10071. [Class 123 (ii)] In a forced feed boiler comprising a long tube coil through which water is forced, steam issuing from the outlet end, the feedwater control comprises two thermostats one increasing or throttling the inlet in response to the temperature of the inlet end section without completely closing it, and the other being capable of effecting a complete stoppage of feedwater supplied to an intermediate point. Feedwater is supplied from a tank 16 to a primary inlet 12 and a secondary inlet 41 of the boiler tubing 6. The boiler is fired by means of a blower 9 which forces air over a carburetter 10. At low temperatures a rocker arm 24 separates contacts 36, 37 in an electrical circuit which includes the solenoid 38 of a valve 39 in the secondary feed supply : on a predetermined temperature rise a thermostat 21 forces the rocker arm to permit the contacts to abut with the result that water is supplied at inlet 41 and the temperature normally falls. Should conditions be such that the temperature rises materially above the predetermined value the thermostat is caused to separate contacts 33, 34 in the blower circuit. A second thermostat 46 is disposed on the main inlet side of the secondary feed supply and controls through a bell-crank 48 and rod 49 the main feed valve 51 so as to throttle this supply to a rate corresponding to the temperature in the primary portion of the boiler. A constant pressure drop is maintained across the valve as by means of a spring-loaded piston 56 associated with a lever controlling a valve 63 in the pipe conveying operating fluid to the feed pump 17. In a modification a varying portion of the feedwater is passed through a valved conduit byepassing valve 51 in accordance with a steam outlet throttle 4, and the thermostat 46 is caused to separate contacts in the blower circuit if the temperature at this point becomes excessive.