# US 5,700,420 A · Non-oxidizing heating method and apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,700,420 A - Document ID: US5700420A - Status: Granted - Kind: A - Application number: 08/624,642 - Filed: 1996-04-08 - Granted: 1997-12-23 - Earliest claimed: 1994-12-02 - Assignees: Kawasaki Steel Corporation - Inventors: Tsuguhiko Nakagawa; Ryosuke Yamaguchi; Hisashi Osanai; Junichi Hasunuma; Takemi Yamamoto - Web page: https://patentgrep.com/patent/US5700420A ## CPC - F27B 3/26: Arrangements of heat-exchange apparatus - B22D 11/11: Treating the molten metal - B22D 41/015: with external heating, i.e. the heat source not being a part of the ladle - C21D 1/74: Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material - C21D 1/767: with forced gas circulation; Reheating thereof - F27B 3/20: Arrangements of heating devices - F27B 3/263: {Regenerators} - F27D 7/06: Forming or maintaining special atmospheres or vacuum within heating chambers (supplying steam, vapour, gases or liquids F27D7/02) - C21D 1/76: Adjusting the composition of the atmosphere - F27D 2007/063: {Special atmospheres, e.g. high pressure atmospheres} - F27B: FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS - B22D: CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES (shaping of plastics or substances in a plastic state B29C; metallurgical processing, selection of substances to be added to metal C21, C22) - C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B) - F27D: DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE ## Abstract A non-oxidizing heating method and apparatus in which a non-oxidizing gas of high temperature is continuously generated and supplied into a furnace by changing over a plurality of heat storage type heaters alternately while repeating an operation in which one heater stores heat and the other heater heats and blows the non-oxidizing gas. Since it is possible to heat by producing a completely non-oxidizing atmosphere within the furnace, the method and apparatus can be effectively utilized in furnaces which require heating in a non-oxidizing atmosphere, for example, various furnaces such as a ladle, tundish, etc. used in a field of steel manufacturing and continuous casting, and various furnaces used in a field of heating and heat treatment of metallic materials, and thus, it is effective to achieve reduction of operational cost, improvement of product quality, and improvement of product yield. ## Claims ### Claim 1 A non-oxidizing heating method characterized in that in heating the inside of a furnace which requires a non-oxidizing atmosphere by a high temperature non-oxidizing gas, an operation to heat a non-oxidizing gas to between 1200.degree. to 1300.degree. C. is repeated while changing over a plurality of heat storage type heaters alternately, and the obtained high temperature non-oxidizing gas is continuously supplied. ### Claim 2 (depends on 1) A non-oxidizing heating method according to claim 1, wherein a part of the high temperature non-oxidizing gas supplied into said furnace is recirculated for re-use to heat the inside of the furnace. ### Claim 3 (depends on 1) A non-oxidizing heating method according to claim 1, wherein said high temperature non-oxidizing gas supplied into the furnace is generated by heat exchange with a combustion gas within the furnace, said heat exchange being performed through said heat storage type heaters. ### Claim 4 (depends on 1) A non-oxidizing heating method according to claim 1, wherein said furnace which requires a non-oxidizing atmosphere is a tundish. ### Claim 5 (depends on 4) A non-oxidizing heating method according to claim 4, wherein in re-using said tundish having residual steel developed on an inner wall thereof, the heat within said tundish is preserved by using a non-oxidizing gas which has been heated to 850.degree. C. or higher by a heating means external to said tundish. ### Claim 6 (depends on 1) A non-oxidizing heating method according to claim 1, wherein said furnace which requires a non-oxidizing atmosphere is a heating furnace for a steel material. ### Claim 7 (depends on 6) A non-oxidizing heating method according to claim 6, wherein a high temperature non-oxidizing gas, which is preheated to a temperature not lower than a temperature of the steel material being heated or to a temperature substantially equal to a temperature of the furnace, is supplied around the steel material in said heating furnace. ### Claim 8 (depends on 7) A non-oxidizing heating method according to claim 7, wherein the supply of the high temperature non-oxidizing gas into the heating furnace is performed by a method of blowing to the vicinity of the steel material to surround the steel material in the heating zone in which a surface temperature of the steel material exceeds 700.degree. C. or in the uniform heating zone, or by a method of replacing an oxidizing gas within the furnace by the high temperature non-oxidizing gas by the blowing. ### Claim 9 (depends on 1) A non-oxidizing heating method according to claim 1, wherein said furnace which requires a non-oxidizing atmosphere is an annealing furnace. ### Claim 10 (depends on 1) A non-oxidizing heating method according to claim 1, wherein trace amounts of reducing gas equal to an explosion limit or less is introduced into the furnace in addition to the non-oxidizing gas to change the atmosphere within the furnace to a non-oxidizing or reducing atmosphere. ### Claim 11 (depends on 10) A non-oxidizing heating method according to claim 10, wherein as said non-oxidizing gas, a sole N.sub.2 or Ar, or a mixture of N.sub.2 and Ar is used, and as said reducing gas, a sole H.sub.2 or CO, or a mixture or H.sub.2 and CO is used. ### Claim 12 (depends on 2) A non-oxidizing heating method according to claim 2, wherein said high temperature non-oxidizing gas supplied into the furnace is generated by heat exchange with a combustion gas within the furnace, said heat exchange being performed through heaters having a storage body. ### Claim 13 (depends on 2) A non-oxidizing heating method according to claim 2, wherein said furnace which requires a non-oxidizing atmosphere is a tundish. ### Claim 14 (depends on 3) A non-oxidizing heating method according to claim 3, wherein said furnace which requires a non-oxidizing atmosphere is a tundish.