GB552591A - Improvements in and connected with electrical systems for heating fluids in pipes and in containers - Google Patents

Abstract

552,591. Electrically heating liquids. CRITTALL & CO. Ltd , R., and ADSHEAD, B. Nov. 5, 1941, No. 14230. [Classes 39 (iii) and 75 (i)] Oil is circulated by a pump 1 in a closed system 2 and is heated by passing a current through the pipe which may be connected to the secondary of a step-down transformer 5. Pipes 6 leading the oil to a burner 3 are in parallel across an insulating section of pipe 13 and are electrically in series with the pipe 2. Alternatively, one pipe is arranged within another to form the electric circuit, or the current may flow through a single pipe and return through another pipe or conductor. The heating effect is greater in the pipes 6 than in the pipe 2. The oil temperature may be controlled by a thermostat 7 acting on a switch 8 across the insulating section 13. Variations in the total resistance may be compensated by employing suitable tappings on the transformer 5. If a single branch pipe to the burner is employed, the oil temperature may be controlled by a thermostat governing the supply of cooling air to the annular space between the outer current-carrying pipe and the inner oil carrying pipe. A separate transformer may be employed for each burner branch. The oil temperature in the main pipe may be controlled by a thermostat controlling the transformer. The oil system may be drained to the storage tank by reversing the pump, or by valves 11 to a sump. The pipe may be immersed in a container to heat the liquid therein.