GB1289483A - - Google Patents

Abstract

1289483 Measuring a condition of boiler tubes electrically APPARATKEMISKA A B AKA 12 Dec 1969 60770/69 Heading G1N A condition, for example the temperature or wall thickness, of a boiler tube 1 is determined by supplying current from a constant current source 10 to terminals 5, 6, on the tube and measuring the voltage drop between terminals 7, 8. The heat transference through a boiler tube wall to water inside depends inter alia on the boiler scale and wall corrosion, and hence a portion of wall 4 adjacent a source of heat may attain excessive temperatures liable to cause damage. Current from the source 10 divides via the paths 3, 4,1, 3, 2,1 and the voltage between 7 and 8 is indicative of the resistance (and hence the temperature and/or wall thickness) at the part 4, prior measurements under isothermal conditions having been made. The temperature of the part 2 which follows the internal water temperature is measured for example by thermocouple, this temperature being used to evaluate the main measurements. The water temperature is measured separately. The supply terminals may be used also for the measurement, and the supply and measurement terminals may be longitudinally disposed on the tube. Several pairs of supply and measurement terminals may be provided, and measurements may be made across several adjacent tubes Fig. 2 (not shown). The measurements may be made manually or automatically by cyclic switching, and abnormal conditions may indicated by an alarm and result in shutdown.