US 11,747,048 B2
Method for repairing or improving absorber tubes with a loss of thermal insulation of or for solar thermal installations
José Carlos Cancho Vera, Badajoz (ES); and Francisco Sánchez Matamoros, Badajoz (ES)
Assigned to COBRA INSTALACIONES Y SERVICIOS, S.A, Madrid (ES)
Filed by COBRA INSTALACIONES Y SERVICIOS, S.A., Badajoz (ES)
Filed on Nov. 18, 2021, as Appl. No. 17/529,844.
Claims priority of application No. ES202031171 (ES), filed on Nov. 23, 2020.
Prior Publication US 2022/0163237 A1, May 26, 2022
Int. Cl. F24S 40/46 (2018.01); F24S 10/40 (2018.01); F24S 20/20 (2018.01)
CPC F24S 40/46 (2018.05) [F24S 10/45 (2018.05); F24S 20/20 (2018.05)] 11 Claims
OG exemplary drawing
 
1. A method for repairing or improving absorber tubes with loss of thermal insulation of or for solar thermal installations, wherein the absorber tubes are of the type comprising: an inner tube through which a heat transfer fluid circulates; an outer tube coaxial with the inner tube, a chamber comprising getter material to absorb hydrogen, said chamber defined between the inner tube and the outer tube and initially under vacuum conditions; and a metallic support, at least one end, which supports the outer tube and is in contact with the chamber; comprising at least the steps:
a) making a hole in the metallic support, said hole being of a diameter such that it allows a vacuum level capable of removing hydrogen from the chamber in a time of less than 20 minutes by sweeps with an inert gas to be established,
b) putting a vacuum pump in fluid communication with the chamber of the absorber tube through the hole,
c) actuating the vacuum pump to generate a vacuum in the chamber until reaching a predetermined vacuum threshold,
d) performing sweeps by introducing an inert gas into the chamber, thus removing hydrogen, allowing the accumulation of said hydrogen inside said chamber to be reduced or removed, wherein after each sweep, the vacuum pump is actuated again to generate a vacuum in the chamber, and as a result at least part of the hydrogen absorption capacity of the getter material is recovered,
e) interrupting fluid communication between the chamber and the vacuum pump, without losing the vacuum of said chamber,
wherein the step of putting the vacuum pump in communication with the chamber comprises a step of welding an access tube to the support, wherein at least part of the access tube, which comprises a free end, projects from the support, and then putting the vacuum pump in fluid communication with the free end of the access tube,
wherein prior to putting the vacuum pump in fluid communication with the free end of the access tube, the hole is formed, and new getter material is added through said hole; next, the access tube is assembled in the support, and then the vacuum pump is put in communication with the chamber.