Inspection of water wall tube cuts
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For a 75T/H circulating fluidized bed boiler, the water wall tubes need to be cut open in order to check for internal scaling; the operating load is generally around 50T. Where should I cut the tube?
How long has this boiler been in operation before the water wall tube bundle needs to be inspected? Our boiler has been in operation for 7 years, and the scaling of its tube bundles has never been checked. I mean, why do you need to conduct inspections? Is it because the cooling effect of the water wall has deteriorated?
Due to a leak in the turbine condenser, the boiler feed water remains hard, and there is concern about scaling inside the water wall
(1) A comprehensive inspection should be carried out in conjunction with the boiler shutdown for maintenance, in accordance with DL/T 438-2016 \"Regulations on Metal Technology Supervision in Thermal Power Plants\" and DL/T 939-2005 \"Technical Guidelines for Supervision and Inspection of Boiler Heating Surface Tubes in Thermal Power Plants\". (2) A monitoring section shall be installed at the point where the heat load on the boiler’s water wall is highest (usually 1 m to 5 m above the burner), and the monitoring tubes shall be regularly inspected by cutting; the length of the cut section of each monitoring tube shall be at least 0.5 m. (3) Contents of tube cutting inspection: scaling and corrosion conditions on the inner wall of the water wall tubes, as well as the amount of scale on the fire-side and backfire-side; the scaling rate is calculated, and a compositional analysis is performed on the scale samples. (4) Decide whether to expand the inspection area based on the degree of corrosion or any suspicious areas identified through visual inspection. (5) When the scale accumulation on the inner wall exceeds the limits specified in DL/T 794-2012 \"Guidelines for Chemical Cleaning of Boilers in Thermal Power Plants\", chemical cleaning of the heating surfaces should be carried out.