GB775265A - Electric heaters for gases - Google Patents

Abstract

775,265. Heating gases by electricity. BROWN FINTUBE CO. Nov. 2, 1955 [Nov. 18, 1954], No. 31329/55. Class 39(3) An electric heater particularly suitable for heating gases to high temperatures at high pressures comprises heating wire 21 wound on ceramic tubular members 22 supported from a ceramic plate 25 which is suspended from the lower end of a gas outlet pipe 18 by means of straps 26, the straps being extended downwardly to support a bottom ceramic plate 31 through which the members 22 pass. A tube 35 secured at its top end has a plurality of radial fins 36 for the greater portion of its length, but above the level at which gas from an inlet pipe 17 enters the outer shell 10 of the heater, studs 38 are welded to the tube. Cool gas entering the heater flows round the top of the tube 35, down the outside of the tube, then through and around the tubular members 22, the heated gas finally passing from the outlet pipe 18. The tube 35 prevents the shell 10 from becoming excessively hot and thus reduces heat losses therethrough, the fins and studs serving to increase heat transfer from the heating wire to the gas. In a modification, Figs. 3, 4, heating elements 53 comprise silicon carbide bars disposed in a circle concentric with a finned heat transfer member 77, the bars being sprayed with copper at the top and bottom areas 85, 86 to. reduce the resistance of the elements and to thus localize the heating between the sprayed end portions. Three-phase current supply is specified. A further modification, Fig. 6 (not shown), has heating elements consisting of helically coiled wire wound on grooved ceramic tubes of which the upper ends are slidably located on metal tubes to allow for expansion during heating.