A kind of self-adjusting steam seal and its installation and debugging method

Abstract

The invention discloses a self-fine-adjusting steam seal and a mounting and debugging method thereof. The automatic self-fine-adjusting steam seal comprises arc sections, and a circumferential spring arranged between the arc sections; a radial spring assembly is arranged on a large rear arc of each of the arc sections; when in a start / stop stage of a steam turbine, a clearance between the self-fine-adjusting steam seal and a rotor is 0.8 to 2mm; when in normal running stage, steam flows into the back part of the seam seal through a steam inlet groove so as to provide a centripetal closing force, and the clearance is automatically reduced to be 0.3 to 0.5mm; in addition, the total avoiding clearance of the steam seal is 2.5 to 4mm. According to the self-fine-adjusting steam seal and the mounting and debugging method, a locating lip is also arranged at the steam inlet groove; the phenomenon that a steam sealing block deflects can be avoided by adjusting on site, thus the steam leakage at the back part of the steam seal can be reduced, the sealing performance can be greatly improved, and centripetal closing can be easily realized as requirement, and as a result, the closing reliability of the arc sections of the steam seal is improved.

Description

technical field [0001] The invention belongs to the field of steam turbine steam seals, and relates to a self-fine-tuning steam seal and an installation and debugging method thereof. Background technique [0002] There is a steam seal between the rotor and the stator of the steam turbine. The common steam seal is processed into a comb shape, and the surface of the rotor is processed into a concave-convex structure. The above-mentioned steam seals are generally called comb-toothed steam seals, and each circle of steam seals is divided into 4 to 12 sections to adapt to the horizontally split cylinder block, and slide into the T-shaped groove of the stator in sequence during installation. The steam seal maintains a certain gap with the rotor under the support of the spring leaf. During normal operation, the steam seal and the rotor are in a non-contact state, but once it is rubbed, the steam seal can elastically retreat to ensure the safety of the steam turbine operation. [0...

AI Technical Summary

Problems solved by technology

[0007] The gap between Braden steam seals during start-up and shutdown is generally 2-4mm, which is much larger than the gap of 0.5-0.8mm in traditional comb-toothed steam seals, which causes the steam turbine rotor to heat up too quickly, resulting in a large expansion difference, which is currently recognized in the industry Disadvantages of the Breden seal

Therefore, after the modification of the Braden steam seal, the unit usually takes longer to warm up, which undoubtedly increases the economic loss

[0008] Usually mentioning the Braden seal, the industry also believes that there may be a problem that the seal cannot be closed

Once it cannot be closed, the leakage of the Braden gland seal will be much larger than that of the traditional comb gland seal, which greatly affects the enthusiasm of the power plant to implement the steam seal transformation

[0009] The data in the table below comes from the article "Application and Effect Evaluation Method of Different Steam Seal Structures in Steam Turbines" published by Xi'an Thermal Engineering Institute. Seven 300MW turbogenerators (A~G) of the same type were selected for comparison and analysis. There are indeed big problems in the actual application of the Layden steam seal. Compared with the traditional comb-toothed steam seal, the sealing performance has not been significantly improved. On the contrary, the amount of steam leakage has increased in some transformations. The sealing mechanism of the seal is inconsistent with the

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