ã€Abstract】Aiming at the problem of welding deformation caused by welding of 1000M W ultra-supercritical air-cooled coal-fired generating unit boiler water wall, reasonable welding order, anti-deformation and other anti-deformation measures are taken and implemented effectively in this project. The effect of preventing welding deformation of the component is achieved.
1 Overview
The 4th unit of the second stage (2×1000MW) ultra-supercritical air-cooled coal-fired generating unit of Lingwu Power Plant, the boiler is the DG3100/26.15-II1 ultra-supercritical parameter variable-pressure running DC furnace produced by Dongfang Boiler Co., Ltd. The furnace is single furnace, one reheat, balanced ventilation, solid slag discharge, all steel frame, full suspension structure; the boiler furnace section size of this project is large, the furnace width is 33 973.4mm, the depth is 15 558.4mm, the division The water-cooled wall assembly has a large geometrical size. The water-cooled wall pipe has the specifications of φ 31.8mm×7.5mm, φ 38.1mm×7.5mm, and the fin size is 6.4mm×12.7mm; the module width is 12m on average; after the upper and lower tube screens are opposite, at the counterpart Apply sealing strips to weld. As the pipe diameter becomes smaller and the welding engineering increases, the pipe and its accessories are likely to cause serious welding deformation of the pipe after welding, so that the water wall pipe is scrapped. Therefore, large units have put forward higher requirements for the welding process of water wall.
2. Welding characteristics of boiler water wall
(1) Pipe diameter The diameter of the small water wall is generally 31.8~38.1mm, the wall thickness is 7.5m, the inner diameter is 16.8~23.1mm, and the inner diameter of the pipe is extremely small. The smaller the pipe diameter, the worse the rigidity and the more easily deformed after welding.
(2) Welding amount The welding of large water-cooled wall mainly includes pipe-to-mouth welding, water-cooled wall joint welding, fin welding at the time of mouth-cutting, and welded joint sealing, and all welds are double-sided welded. The number of welds is large and the probability of deformation after welding increases.
(3) Difficulty in on-site welding According to the actual situation of the installation site, the welding method of the water wall attachment (fin seal) is electrode arc welding, and the boiler factory adopts submerged arc automatic welding. In comparison, the field welding is more likely to produce welding deformation ( see picture 1).
(4) The water-cooled wall is constructed with a large cross-section of the furnace. The furnace width is 33 973.4 mm and the depth is 15558.4 mm. The water-cooled wall components have large geometrical dimensions, which increases the difficulty of preventing deformation of the water-cooled wall components during welding.
(5) The installation of the water wall from the ground and the installation through the entire heating surface of the construction process, quality process control is difficult.
Figure 1 Water-cooled wall tube row deformed after welding
For more details, please refer to the attachment or read the contents of the 18th issue of Metalworking (Hot Processing).
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