| 摘要 |
<p>397,666. Electric resistance furnaces. NATIONAL ELECTRIC HEATING CO., Inc., 154, Nassau Street, New York, U.S.A. Aug. 5, 1932, No. 21976. Convention date, April 16. [Class 39 (iii).] Comminuted material such as coal, or filter clay, is heated by being suspended in a fluid medium and passed through a tubular heater directly heated by electric current, whereby the suspension is raised to a high temperature for a short time. When treating powdered coal, the heater comprises metal tubes 11 having electric terminals 12 midway between the ends which are earthed, the currents in the three tubes being out of phase to neutralize self-induction. Powdered coal from a supply duct 19 is fed by screws 20 to one end of the tubes, the other ends of which open into a separator 14. Gas is supplied through jets 25 to mix with the coal, and the solid residue is separated from the distillates which pass by an outlet 33 to a heat exchanger 46, tar separator 48, fractionating tower 50 for recovery of oils, and ammonia scrubber 52. Part of the gas is returned through pipe 53, pump 55, heat exchanger 46, and pipe 56 to the tube inlets. A weighted valve 57 enables pressure to be maintained in the tubes. The powdered coke which contains 6 to 8 per cent volatiles, is discharged by a screw conveyer 34. Thermostats 26 by means of a controller 27, and voltage regulator 28, adjust the current supply, and maintain the tubes at a uniform temperature. An automatic device 29 subjected to the gas pressure opens a control circuit 30, and cuts off the current to the heating tubes when the gas pressure is reduced. When treating filter clay or cement, the powdered material is supplied through a screw feeder 70, Fig. 6, to a blower, and through the annular space in a preheater 73, before passing by a pipe 78 to an inlet 79 fed with superheated steam and air by pipes 80, 81, combustion taking place in a tube 76, and cooling in a tube 75, the residue passing to a separator 82 and discharge pipe 84 ; a jet 86 of air may be provided to accelerate the combustion of the carbon.</p> |
