Method for repairing or improving absorber tubes with a loss of thermal insulation of or for solar thermal installations

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 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.