| 摘要 |
PROBLEM TO BE SOLVED: To permit the improvement of abrasion resistance of a heat transfer tube easily and facilitate the repairing of the same by covering the heat transfer tube, provided in the fluidized bed of a fluidized bed boiler, with a detachable permanent magnet. SOLUTION: A pair of half segmental magnets 11 are attached to a heat transfer tube 10, provided in the fluidized bed of a fluidized bed boiler and consisting of ferrite steel, so as to cover the tube from the outer peripheral side. The inner diameter of respective half segmental magnets 11 are specified so as to be smaller slightly than the outer diameter of the heat transfer tube 10 so that the magnets are permitted to be contacted with the outer surface of the tube 10 closely. Two pieces of half segmental magnets 11 are attached in such a manner whereby the heat transfer tube 10 can be protected from abrasion by the materials of the fluidized bed. A single domain particulate type magnet having a high coercive force is employed preferably as the magnet while the thickness of respective magnets 11 is specified so as to be 0.5 mm or less, for example, whereby the faulty heat transfer of the heat transfer tube 10 due to the mounting of the magnets 11 can be prevented. On the other hand, an abrasion material is adhered to the outer surface of the magnet 11 if necessary whereby the durability of the magnet can be improved.
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