Patent ID: 11859911
Assignee: VALMET TECHNOLOGIES OY
Field: Thermal processes and apparatus (Mechanical engineering)
Classification: CPC F | IPC F

Claim 0:
1. A method for manufacturing a coaxial heat transfer tube, the method comprising the steps of:
arranging an inner heat transfer tube and an outer heat transfer tube,
inserting at least a part of the inner heat transfer tube into the outer tube such that the inner heat transfer tube extends at least through the outer heat transfer tube to form a straight coaxial heat transfer tube,
arranging thermally insulating material in between the inner heat transfer tube and the outer heat transfer tube,
hardening the thermally insulating material at a temperature of 100° C. to 400° C.,
after hardening the thermally insulating material, bending the straight coaxial heat transfer tube to form a first primary curved part to the coaxial heat transfer tube, and
before said bending, forming first protrusions on at least one of an inner surface of the outer heat transfer tube or an outer surface of the inner heat transfer tube,
wherein, after said hardening, a thermal conductivity of the thermally insulating material is from 1 W/mK to 10 W/mK at a temperature of 20° C.