US 12,435,873 B2
Radiant tube
Tomoyuki Kawashima, Tokyo (JP); Akihiro Kobayashi, Tokyo (JP); and Noriko Ozawa, Tokyo (JP)
Assigned to JFE Steel Corporation, Tokyo (JP)
Appl. No. 17/799,726
Filed by JFE Steel Corporation, Tokyo (JP)
PCT Filed Feb. 3, 2021, PCT No. PCT/JP2021/003974
§ 371(c)(1), (2) Date Aug. 15, 2022,
PCT Pub. No. WO2021/166651, PCT Pub. Date Aug. 26, 2021.
Claims priority of application No. 2020-028033 (JP), filed on Feb. 21, 2020.
Prior Publication US 2023/0071781 A1, Mar. 9, 2023
Int. Cl. F23D 14/12 (2006.01); F23C 3/00 (2006.01); F28F 13/12 (2006.01)
CPC F23D 14/12 (2013.01) [F23C 3/00 (2013.01); F28F 13/12 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A radiant tube comprising: a conduit configured to be heated by a fluid gas flowing in the conduit; and one or two or more heat transfer promoters disposed in the conduit along an axis of the conduit, wherein:
the heat transfer promoter includes a body part disposed on a center side of the conduit, and a plurality of protruding parts protruding from the body part toward an inner wall surface of the conduit,
the plurality of protruding parts is formed on an outer periphery of the body part to be arranged in a circumferential direction of the conduit,
the plurality of protruding parts includes a plurality of first protruding parts each having a distal end portion facing the inner wall surface of the conduit across a gap ΔL, and a second protruding part as a remainder,
the number of first protruding parts is set to be greater than the number of second protruding parts, and
when a ratio (ΔL/Dt) of the gap ΔL to an equivalent diameter Dt of a conduit portion, where the heat transfer promoter is disposed, of the conduit is given by x[%] in percentage, formula (1) is satisfied:
0.3% <x<7%   (1).