Manufacturing process of a large-sized nickel alloy double-tube sheet heat exchanger

Abstract

The invention discloses a manufacturing process for a large-sized nickel alloy double-tube-sheet heat exchanger. The manufacturing process comprises the following steps: (1) performing overlay welding on an external tube sheet; (2) drilling into an internal tube sheet and the overlay welded external tube sheet; (3) welding a shell side cylinder with the drilled internal tube sheet; (4) mounting a heat exchanging pipe in a penetrating manner; (5) pairing an effusion layer shell with the drilled internal tube sheet; (6) pairing the effusion layer shell with the drilled external tube sheet; (7) welding the effusion layer shell with the drilled internal and external tube sheets; (8) expanding the drilled internal tube sheet for connection; (9) welding the heat exchanging pipe with the drilled external tube sheet; and (10) performing a pressure-resisting test, wherein electro-slag strip overlay welding is utilized in step (1), positioning blocks are welded around the tube sheets before the overlay welding, the tube sheets are fixedly connected with a welding tool; the directions of two continuous overlay welding processes are opposite, and stress-relief heat treatment is performed after overlay welding of a transition layer is completed. By adoption of the manufacturing process disclosed by the invention, the large-sized nickel alloy double-tube-sheet heat exchanger can be successfully manufactured.

Description

technical field [0001] The invention belongs to the field of preparation of double-tube-sheet heat exchangers, and in particular relates to a manufacturing process of a large-scale nickel alloy double-tube-sheet heat exchanger. Background technique [0002] Double-tube-sheet heat exchanger (see structural diagram figure 1 ) adopts the double tubesheet structure design of the outer tubesheet 1 and the inner tubesheet 2, and also includes the shell side cylinder 3, the heat exchange tube 4 and the liquid accumulation layer shell 5, etc., and the tube side and the shell side respectively use their own tube sheets The connection breaks through the sharing of a connecting tube plate between the tube side and the shell side of the traditional tube-and-tube heat exchanger, which minimizes the risk of cross-contamination between the tube side and the shell side media, and facilitates the timely detection of hidden dangers of leakage to ensure production. [0003] The diameter of do...

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Problems solved by technology

[0003] The diameter of domestic double-tube-sheet heat exchangers is generally less than 2m. When the diameter is larger, the following problems are likely to occur in the production process: 1. The processing of the tube sheet and the control of the concentricity, parallelism, twist, and expansion quality of the double-tube sheet come with great difficulty

When the diameter of the tube sheet is large, it is difficult to control the welding deformation of the tube sheet during surfacing welding. At the same time, the efficiency of traditional manual surfacing welding is low, and the fusion of submerged arc welding wire surfacing welding is relatively large. It is difficult to control the composition of the surfacing layer.

3. During the welding of the circular seam connected with the tube sheet and the welding of the heat exchange tube, if the welding sequence is improper, the tube sheet will be deformed, which will cause the size of the equipment not to meet the process requirements, and at the same time, a large welding stress will be generated, which will affect the service life of the equipment

Compared with ordinary low-alloy steel and stainless steel heat exchange tubes, nickel alloy heat exchange tubes are harder and more difficult to expand

The expansion of the inner tube sheet will cause the change of the size of the heat exchange tube, which will cause stress in the joint weld between the heat exchange tube and the tube sheet, and affect the life of the weld

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