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Prediction method of crack initiation life and crack propagation life of coking tower

A technology of crack propagation life and prediction method, which is applied in the prediction field of crack initiation life and crack propagation life of coke drum, and can solve the problems of difficulty in predicting fatigue damage of coke drum.

Inactive Publication Date: 2017-08-25
GUANGZHOU SPECIAL PRESSURE EQUIP INSPECTION & RES INST +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] Moreover, practical experience shows that due to the complexity of the coke drum structure and operating process, it is very difficult to predict the fatigue damage of the coke drum based on the results of theoretical analysis

Method used

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  • Prediction method of crack initiation life and crack propagation life of coking tower
  • Prediction method of crack initiation life and crack propagation life of coking tower
  • Prediction method of crack initiation life and crack propagation life of coking tower

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0059] see figure 1 , is the prediction method of crack initiation life of the coke tower provided by the present invention, including

[0060] Step S101: Establish a probability distribution model of the coke tower wall strain amplitude.

[0061] Step S102: For a given cycle N, according to the probability distribution model of the strain amplitude, perform Monte Carlo random sampling on the strain amplitude to generate a strain amplitude data sample Δε i / 2, and calculate the corresponding fatigue life and fatigue damage for each strain amplitude.

[0062] In this step, the Manson-Coffin low cycle strain fatigue life formula is used:

[0063]

[0064] Calculate the crack initiation fatigue life corresponding to each Δε / 2, ε′ f Represents the fatigue ductility coefficient, c represents the fatigue ductility index number, and represents the i-th strain amplitude (i=1, 2,..., N) under a given cycle N, the fatigue test shows that the fatigue ductility coefficient and fatig...

Embodiment 2

[0077] see figure 2 , this embodiment is based on Embodiment 1, and one of the differences is that step S101 establishes a probability distribution model of the strain amplitude of the coke tower wall, which specifically includes the following steps:

[0078] S1011: Obtain the strain data of the cycle sample volume of the dangerous point on the wall of the coke tower.

[0079] In this step, high-temperature-resistant strain gauges and dynamic strain gauges are used to obtain the strain data on the outer wall of the coke tower. Each measuring point is equipped with a high-temperature-resistant strain gauge in the axial and circumferential directions. Measurement channel connections.

[0080] S1012: Calculate the strain amplitude of each cycle according to the strain data, and the strain amplitude is calculated by the formula (2-1),

[0081]

[0082] in, are the maximum and minimum Von Mises equivalent strains in each cycle, respectively, and the calculation expressions ...

Embodiment 3

[0088] This embodiment describes in detail the prediction method of the crack initiation life of the coke tower through a specific embodiment, the method includes the following steps:

[0089] S301. Carry out the low cycle fatigue experiment of coke tower material 15CrMor, thereby obtain the low cycle fatigue coefficient of 15CrMoR; The fatigue data is as shown in table 1:

[0090] Table 1 Low cycle fatigue test data

[0091]

[0092] In this embodiment, the MTS-810 material testing machine is used for the fatigue tensile test, and the design of the test piece, the method of the test and the data analysis are all in accordance with the requirements of the national standard GB / T15248-94. The test is divided into 6 groups, and the strain levels of each group are as follows: 0.4%, 0.6%, 0.8%, 1.0%, 1.2% and 1.5%; the load spectrum of the triangular waveform is used, and the strain ratio is R ε =-1.

[0093] S302. The data in Table 1 is fitted by the least squares method to o...

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Abstract

The invention discloses a prediction method of crack initiation life of a coking tower. The method comprises the steps that a probability distribution model of the strain amplitude of the wall of the coking tower is built; based on the model, a strain amplitude data circulation sample is sampled according to a monte-carlo random method, and fatigue life and fatigue damage corresponding to each crack initiation of a given circulating period are calculated; if the fatigue damage of the given circulating period is accumulated to or above 1.0 under given iteration times, the fatigue damage is considered as crack initiation; according to the ratio of the crack initiation cumulative number to the given iteration times, the crack initiation probability is obtained; according to the given circulating period, the crack initiation probability and the given confidence degree, the relation between the crack initiation probability of the wall of the coking tower and the residual life is calculated and predicted. The invention further comprises a prediction method of crack propagation life of the coking tower. A probability distribution model of the stress amplitude is built to predict the crack propagation life of the coking tower on active duty. The method is low in cost and can evaluate risks of coking tower service.

Description

technical field [0001] The invention relates to the field of petrochemical industry, in particular to a method for predicting crack initiation life and crack extension life of a coke tower. Background technique [0002] Coke tower, also known as coking tower or thermal cracking reactor, is the key equipment for delayed coking in oil refining industry. It converts low-value low-quality oil into high-value gasoline and middle distillates, producing huge economic benefits. [0003] Due to the characteristics of the delayed coking process, the coke tower undergoes a cyclical heating and cooling process, which changes cyclically between room temperature and 495°C within 16 to 48 hours. At the same time, the medium carried by the container changes from gaseous to liquid to solid. The working environment is complex and harsh. As a result, after several years of operation of the coke tower, there is generally bulging of the cylinder, and cracking of the cylinder, welds and skirts. ...

Claims

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Application Information

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IPC IPC(8): G01N3/32G01N19/08G06F17/50
CPCG01N3/32G01N19/08G01N2203/0066G01N2203/0073G06F30/20
Inventor 叶伟文宁志华刘人怀王璠汪文锋李茂东杜南胜杨波董雪林梁自生
Owner GUANGZHOU SPECIAL PRESSURE EQUIP INSPECTION & RES INST
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