Ultra supercritical boiler super-heat and re-heater heating surface life evaluation method

An ultra-supercritical boiler and life evaluation technology, applied in the direction of applying stable tension/pressure to test the strength of materials, can solve problems such as inability to describe complex behavior, large consumption, and fracture

Active Publication Date: 2014-11-12
ELECTRIC POWER RES INST OF GUANGDONG POWER GRID +1
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Problems solved by technology

The disadvantage of these two models is that they cannot describe the complex behavior after overloading, such as acceleration and "delay delay" propagation behavior, and most fatigue crack growth models under variable amplitude loading need to introduce test fitting parameters to con

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  • Ultra supercritical boiler super-heat and re-heater heating surface life evaluation method
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  • Ultra supercritical boiler super-heat and re-heater heating surface life evaluation method

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[0093] Calculation example

[0094] The present invention takes the three-stage superheater T92 tube with cracks on the heating surface of a 1000MW ultra-supercritical unit as the research object. The steam parameter is 26.25MPa, 603℃ / 605℃, and the pipe specification is (Φ×S / mm) 48.3×7.82. The crack is located on the radial outer wall of the pipe, and the initial crack length is 0.1mm, and it is considered to be destroyed when it penetrates the pipe wall.

[0095] The size of the heating surface pipe along the length of the pipe is much larger than its diameter. In the calculation process, the end effect of the pipe is not considered, and it is considered that there is no strain in the axial direction, so this problem can be simplified as a plane strain problem. figure 2 It is a pipe model with radial cracks.

[0096] In variable load operation, such as image 3 As shown, the dotted curve represents the change of internal pressure with time; the triangular curve represents the chang...

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Abstract

The invention discloses an ultra supercritical boiler super-heater and re-heater heating surface life evaluation method. The method comprises the steps (1) a mathematic relation between a fatigue damage accumulation process and the crack growth rate is determined based on the circulation crack tip fatigue damage continuous accumulation process and the linear damage accumulation theory; (2) a polynomial is adopted for carrying out fitting on a da/dN-a curve, the maximum curvature point is obtained, the crack length a of a fatigue crack growth rate acceleration turning point is obtained, and the crack length a is the critical crack length; (3) after the crack length a of the turning point is determined, the ratio a/(S-a0) of the a to the difference (S-a0) between the heating surface pipeline wall thickness S and the initial crack length a0 is obtained, and then the fatigue crack growth service life loss of the heating surface pipeline on the actual running condition is a/(S-a0); the fatigue crack growth residual service life of the heating surface pipeline on the actual running condition is obtained by carrying out numerical integration between the turning point crack length a and the pipeline wall thickness S. According to the ultra supercritical boiler super-heater and re-heater heating surface life evaluation method, service life losses produced on any load and overload condition can be described, time and materials are saved, and the effective result is obtained.

Description

technical field [0001] The invention relates to a method for predicting the fatigue crack growth life of the super-reheater heating surface of an ultra-supercritical boiler under actual operating conditions. Background technique [0002] Ultra-supercritical boilers have become an inevitable trend in the development of thermal power units. With the improvement of steam parameters, more stringent requirements have been put forward for the heating surface tubes. The load of the power grid is erratic, which requires thermal power units to have greater flexibility. Therefore, in ultra-supercritical parameter units, peak-shaving operation has been widely concerned. During the peak-shaving operation, high parameters and rapid fluctuations of parameters cause great changes in the complex stress on the heating surface tube, which accelerates the crack growth until the heating surface tube leaks or bursts, which seriously affects the use of the heating surface tube life. [0003] Mo...

Claims

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Application Information

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IPC IPC(8): G01N3/18
Inventor 王伟钟万里林介东汪淑奇陈冬林邓平
Owner ELECTRIC POWER RES INST OF GUANGDONG POWER GRID
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