Patent GB-541840-A (GB)
Title: Automatic boiler feed regulator
IPC: F22D5/24
Filed: 1940-06-05
Abstract: 541,840. Automatic control systems for steam generators. LOUMIET, J. P. June 5, 1940, Nos. 9880 and 9882. Convention dates, June 30, 1939, and Aug. 19, 1939. [Class 38 (iv)] [Also in Groups XIII and XVIII] Fluid level.-A column of conducting liquid such as a solution of sodium chloride in water of specific gravity 1.20, co-operates with contact means to control the rate of water feed to a boiler in accordance with variations in water level. The liquid is confined in a sight gauge between bodies of insulating liquid, e.g. oil, in U-tubes I, U<SP>1</SP> which are connected with the steam and water spaces respectively by water in U-tubes S, S<SP>1</SP>, the two liquids being in proportions to give hydraulic balance. A quantity of mercury may replace the salt solution wholly or in part. The contact means may comprise one electrode m immersed in mercury or salt solution at the foot of the indicating column N and one or more electrodes l in the vicinity of the indicating surface of the liquid column. A low level alarm electrode t may be arranged at the other end of the liquid column. The variation in water level in the boiler produces accentuated movement of one or both ends of the liquid column, its cross section being reduced at q for example. Two modifications of the construction of the water level indicator are described each comprising a similar arrangement of fluid within it ; one is constituted by a metal casting with the necessary passages and the other comprises concentric tubes and a condensing chamber to ensure the upper water space remaining full. The control system shown in Fig. 1 energizes a motor M and lights an indicator L when the level rises ; the motor then operates a valve V against a restoring weight R to reduce the feed water supply. A modification is described Fig. 7 (not shown) in which electrodes above and below the normal position of the top of the indicating column control selectively through relays a reversible A.C. motor to adjust the opening of the valve in the feed water main. In this arrangement one or more auxiliary electrodes respectively above and below the main control electrodes operate through an arrangement of additional electromagnetic relays to reduce the amplitude and oscillation of the control. The system may operate upon a valve controlling the main supply to a feed pump as shown in Fig. 6 within a steam pump B is controlled by the water level in a reservoir R5 taking the surplus water supply to a battery of boilers C 1 -C 3  each of which is controlled as in Fig. 1. The indicating level may co-operate with a resistance variably immersed in the conducting liquid and keying the current in a control circuit for a valve or the speed of an electric motor driving a feed pump. Fig. 6 shows such an arrangement, the indicator Nc controlling the upper level of water in the reservoir R5 whereas a steam pump B is brought into operation when the water reaches a low level. The Specificaton as open to inspection under Sect. 91 comprised also the subject-matter of Specification 544,130 which does not appear in the Specification as accepted.