GB1374764A - Electrode boiler - Google Patents

Abstract

1374764 Electrode boilers BRITISH RAILWAYS BOARD 10 Dec 1971 [23 Dec 1970] 61176/70 Heading H5H An electrode boiler comprises two or more power electrodes adapted for connection to a power supply and one or more movable transfer electrodes insulated from each other and from said power electrodes and each positioned in a current flow path between two power electrodes. In Figs. 1 and 2, power electrodes 4, 5, 6 separated by insulating strips 10 form a truncated cone. Transfer electrodes 7, 8, 9 held on an axially movable insulating support 12 and insulated by strips 14 which engage in slots 13 of support 12 form a truncated cone coaxial with the truncated cone formed by power electrodes 4, 5, 6. The power output of the through flow boiler is adjusted by varying the spacing between the inner and outer electrodes by axial movement of support 12. In Fig. 3 (not shown), the power is adjustable by rotating the support 12 relative to the outer electrodes. The insulating supports separating the inner and outer electrodes bridge the gap between the inner and out electrodes. In Fig. 4 (not shown) a boiler for a coin operated vending machine comprises a pair of power electrodes in the form of an annulus surrounding a disc or two semicircular disc members on the foot of a tank. A circular transfer electrode provided with a float lies above the power electrodes and a thermostat is positioned between the power and transfer electrodes. Water is initially admitted between the electrodes until the thermostat switches off a flow valve and is then rapidly heated. At a preset operating temperature the thermostat opens the flow valve to admit more water until the temperature of water in the tank cools sufficiently for the thermostat to close the flow valve. The water is again heated to the preset operating temperature whereupon fresh water is admitted. This process continues until the tank is full whereupon the hot water is syphoned off. In Fig. 5 (not shown) the transfer electrode is in the form of a closed cylinder resting on the truncated coaxial floor of a container provided with annular power electrodes on its cylindrical upper wall. A cold water inlet is provided at the apex of the truncated conical floor and directs a jet of water at the closed end of the transfer electrode thus raising it between the annular power electrodes. The position of the transfer electrode relative to the power electrodes depends on the flow rate. In Fig. 6 (not shown) two semi-conical power electrodes surround a spring mounted conical transfer electrode. A metal rod fixed to the transfer electrode projects out of the housing and is surrounded by a solenoid in series with the power electrodes. As the water temperature increases its conductivity increases and thus the current flow increases. This increased current flow causes the solenoid to attract the transfer electrode and thus increase the gap between the power electrodes and transfer electrode and hence the resistance of the current flow path. In Fig. 7 (not shown) a hot water tank comprises a pair of coaxial cylindrical power electrodes surrounding a cylindrical transfer electrode. A water outlet pipe protrudes through the tank into the space between the power electrodes and transfer electrode so that it receives water at the highest temperature. The boiler may be used to pasteurize milk.