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Title: Furnace installation operated by direct electrical heating according to the resistance principle in particular for preparation of silicon carbide
Claims: What is claimed: 1. Furnace installation of the type operated by direct electric heating according to the resistance principle, for the preparation of silicon carbide from silica and carbonaceous material in intermittent operation, the current being supplied by means of electrodes through a resistance core of carbon horizontally inserted in a load consisting of a mixture of granulated coke, quartz sand and added materials, the improvement wherein the electrodes are arranged below the load as bottom electrodes and wherein a substantially vertical electric conducting means is arranged on top of each electrode connecting the electrodes to the resistance core, said connection being constructed separately of the resistance core and having a higher electric conductivity than the latter. 2. Furnace installation according to claim 1, wherein the upper contact surfaces of the bottom electrodes are level with the furnace floor. 3. Furnace installation according to claim 1, wherein the conducting means is of a material having a higher specific conductivity than the core. 4. Furnace installation according to claim 1, wherein the conducting means has a greater cross-section than the core. 5. Furnace installation according to claim 1, wherein the upper contact surfaces of the bottom electrodes are up to 10 cm below the bottom of the furnace. 6. Furnace installation according to claim 1, wherein the conducting means comprises a ballast of coke and graphite vertically mounted on the electrodes. 7. Furnace installation according to claim 6, wherein the ballast comprises tamped coke and graphite. 8. Furnace installation according to claim 1, wherein the conducting means comprises a ballast of graphite vertically mounted on the electrodes. 9. Furnace installation according to claim 8, wherein the ballast comprises tamped graphite. 10. Furnace installation according to claim 1, wherein the conducting means comprises a ballast of anthracite coal, graphite, and a binder vertically mounted on the electrodes. 11. Furnace installation according to claim 10 wherein ballast is tamped. 12. Furnace installation according to claim 1, wherein the conducting means comprises a compact material mounted on the electrodes. 13. Furnace installation according to claim 1, wherein the load is distributed over the bottom electrodes and the resistance core according to its natural cone and the installation is operated as a resistance furnace without walls. 14. Furnace installation according to claim 1, wherein the installation is equipped with walls. 15. Furnace installation according to claim 1, wherein graphite electrodes equipped with electrical current and cold water connections are used as said bottom electrodes. 16. Furnace installation according to claim 1, wherein carbon electrodes equipped with electrical current and cold water connections are used as said bottom electrodes. 17. Furnace installation according to claim 1, wherein tamped mass electrodes of graphite equipped with current and cold water connections are used as said bottom electrodes. 18. Furnace installation according to claim 1, wherein tamped mass electrodes of coke graphite and a binder equipped with current and cold water connections are used as said bottom electrodes. 19. Furnace installation according to claim 18 wherein said tamped mass is formed by carbonizing in an annealing furnace by heating to about 600.degree. C. 20. Furnace installation according to claim 17, wherein metal conductors are embedded in the tamped mass electrodes. 21. Furnace installation according to claim 17, wherein metal cooling coils are embedded in the tamped mass electrodes. 22. Furnace installation according to claim 17, wherein current supply and cooling system in the form of cooled metal pipes are combined in the tamped mass electrodes. 23. Furnace installation according to claim 22, wherein the cooled metal pipes are made of streamlined copper tubes. 24. Furnace installation according to claim 1, wherein metal electrodes equipped with current and cold water connections are used as said bottom electrodes. 25. Furnace installation according to claim 24, wherein the electrodes are made of copper. 26. Furnace installation according to claim 18, wherein metal cooling coils are embedded in the electrodes. 27. A resistance heating furnace, comprising a furnace bottom, a pair of bottom electrodes, in said furnace bottom extending no higher than said furnace bottom, an electrically conductive connecting means extending substantially vertically from each of said electrodes, and a resistance core extending between said conductive connecting means above said furnace bottom, said connecting means having a higher conductivity than said core, and having inclined faces directed toward each other, said resistance core being positioned with its ends abutting said inclined faces. Other info: Inventors: Korsten, Andreas (Balkhausen, DT) Benecke, Theodor (Grefrath, DT) Korndorfer, Eugen (Heiligblut, DT) Petersen, Fritz (Grefrath, DT) Wiebke, Gunter (Munich, DT) Application Number: 531236 Filing Date: 1974-12-10 Publication_date: 1976-04-13 Assignee: Elektroschmelzwerk Kempten GmbH (Munich, DT) Primary Class(es): 373/114 373/132 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Envall, Jr., R. N. Assistant Examiner: Attorney: Burgess Ryan and Wayne |
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