CN104318055A - Safety evaluation method for delayed-coking coking tower - Google Patents

Abstract

The invention discloses an on-line monitoring and safety evaluation method for a delayed-coking coking tower. Compared with a conventional monitoring and safety evaluation method, the method has the advantages that the on-line monitoring and safety evaluation can be realized according to the operation data of the delayed-coking coking tower; and two methods are newly added to the conventional safety evaluation method, wherein the two methods are respectively safety evaluation methods based on a high-temperature low-cycle-fatigue and creepage linear coupling damage theory and an elastic-plastic damage failure theory. The method mainly comprises two parts including finite element analysis and safety evaluation. On the basis of analysis results of ANSYS modeling analysis software, dangerous points and dangerous time periods of the coking tower in the work process are found out; a sensor is arranged in each dangerous point; real stress of the dangerous points in the dangerous time periods is collected; various evaluation methods are used for carrying out safety evaluation on the coking tower; a finite element model of the coking tower is modified according to the collected latest information; the dangerous points and the dangerous time periods are calculated again; and finally, the on-line monitoring and safety evaluation on the coking tower are realized.

Description

A kind of delayed coking coke drum safety evaluation method

One, technical field

The present invention relates to a kind of petroleum chemical industry tower body on-line monitoring and safety evaluation method, particularly large-scalely to build and newly-built delayed coking coke drum safety evaluation method.

Two, background technology

From nineteen thirty first set delayed coking unit the U.S. go into operation and first set hydraulic decoking in 1938 delayed coking unit birth since, the Delayed Coking Technology headed by the U.S. is rapidly developed.Along with the raising of domestic and international Delayed Coking Technology, manufacturing and designing of delayed coking equipment is also tending towards rationalization of maximizing day by day.From the years development of China's first set 300,000 tons/year of delayed coking units to 2011 year, the total working ability of delayed coking of China is more than 1,100 ten thousand tons/year, and delay coking process has become current domestic topmost heavy oil upgrading means.

Coke drum is as the key equipment of delayed coking link, operating mode is harsh, tower body is inner complicated and changeable at each stage ess-strain of work, and the violent cycling hot that in each work period, each portion of tower body subjects normal temperature and high temperature is impacted, thus make coke drum create the deformation of such as tower body each tower joint in-service, there is the problems such as crackle in skirt place transition section weld seam, tower joint joint girth joint and stifled burnt valve adapter position.

In order to ensure the normal operation of coke drum under arms in the phase, increase economic efficiency, the generation of Accident prevention, just must further investigate in the assessment of carrying out fatigue failure form and fail-safe analysis and residual life of STRENGTH ON COKE tower structure.

The routine inspection detection means that current existing safety in production specification specifies is carry out metallographic detection, Magnetic testing, ultrasonic flaw detection, the measurement of total powerstation physical dimension etc. to it after regular equipment downtime.Check by the regular shutdown of above means thus make device security qualitative evaluation.Routine inspection detection means is cycle off-line type, qualitative material structure safety evaluation, can not timely and effective judgment device operating risk point, and equipment must regular shutdown inspection, brings difficulty to China's oil chemical industry delayed coking equipment long-term operation.

Existing appraisal procedure is generally high temperature low-cycle fatigue or creep damage theory, and fatigue damage and creep impairment exist in the damage inefficacy of Metal material simultaneously, high-temerature creep recovers to have material impact to housing structure, and coke drum also also exists the damage of elastic-plastic deformation simultaneously.But also fewer to the quantitative examination of these problems at present, thus in the structure analysis of reality, above-mentioned effect does not all consider.

Therefore; the present invention can realize the on-line monitoring of STRENGTH ON COKE tower; do not need shutdown inspection; STRENGTH ON COKE tower runs efficiently for a long time and brings very large benefit; simultaneously; the present invention has also used linear coupling appraisal procedure in conjunction with high temperature low-cycle fatigue and creep and the appraisal procedure based on elastoplastic Damage theory of failure on the basis of routine assessments means, and STRENGTH ON COKE tower has carried out comprehensive safety assessment.

Three, summary of the invention

The invention provides a kind of delayed coking coke drum on-line monitoring and safety evaluation method, to solve the problem of prior art STRENGTH ON COKE tower off-line and monitoring shutdown, improve existing coke drum safety evaluation method, the technical solution used in the present invention is as follows:

A kind of delayed coking coke drum on-line monitoring and safety evaluation method, relatively with existing monitoring and safety evaluation method, the method can carry out monitoring and safety assessment according to delayed coking coke drum service data online, and in existing safety evaluation method, newly increased two kinds of methods, be respectively high temperature low-cycle fatigue and creep linear Coupling Damage theory α coefficient appraisal procedure and based on elastoplastic Damage theory of failure safety evaluation method.The method is according to the Accurate Model of STRENGTH ON COKE tower and Finite element analysis results and coke drum Real-time Collection result, use classical low-cycle fatigue failure theory of failure, creep damage failure theory and appraisal procedure, and high temperature low-cycle fatigue and the linear Coupling Damage of creep is theoretical and based on the appraisal procedure of elastoplastic Damage theory of failure, STRENGTH ON COKE tower carries out safety assessment, and concrete steps are as follows:

A, select Von Mises equivalent plastic strain ranges, equivalent stress strain value and equivalent stress range of strain as assessing characterization parameter;

B, mechanical test is carried out to the coke drum material of main part that will study, gather its characterization parameter and analyze;

C, carry out finite element simulation modeling according to tower body unique apparatus structure, material and manufacturing condition will be studied, model hypothesis in charging, admission and water inlet process in tower medium circumference uniformity of temperature profile constant, the little perforates of checkout equipment such as tower wall material position meter, thermopair are ignored, peripherals, wind carry not to be considered with seismic (seismal, all the other physical dimensions and condition are all complete carries out Accurate Model according to tower body practical operation situation, and simulation calculation determines work dangerous point and work critical time section;

D, according to simulation result at dangerous point sensor installation, gather temperature and the stress value of its critical time section;

E, by simulation analysis result and tower body real time status contrast verification, classical low-cycle fatigue failure theory of failure, creep damage failure theory and appraisal procedure is used in conjunction with the truly stressed and characterization parameter of composition of tower shell material recorded in real time, and high temperature low-cycle fatigue and the linear Coupling Damage of creep theoretical and carry out safety assessment, to realize the real time on-line monitoring of STRENGTH ON COKE tower based on elastoplastic Damage theory of failure appraisal procedure STRENGTH ON COKE tower;

F, adjust accordingly renewal according to the real time data STRENGTH ON COKE tower finite element model collected in the coke drum course of work, and recalculate analysis according to the finite element model after adjustment, find new dangerous point and dangerous periods, and sensor is adjusted, to collect latest data, finally realize online safety assessment.

Compared with prior art, its beneficial effect is in the present invention:

A. present invention employs sensor installation on coke drum dangerous point; gather the temperature in its dangerous periods and stress parameters; real-time condition according to coke drum is analyzed; realize the on-line monitoring of STRENGTH ON COKE tower; and adjust accordingly renewal according to latest data STRENGTH ON COKE tower finite element model, inaccurate and need the problem of shutdown inspection to solve coke drum off-line analysis.

B. the present invention is on the high temperature low-cycle fatigue defect theory of routine and the basis of creep damage theory, newly add two kinds of appraisal procedures of elastoplastic Damage theory and high temperature low-cycle fatigue and the linear Coupling Damage theory of creep, more fully analyze to realize STRENGTH ON COKE tower.

Four, accompanying drawing explanation

Fig. 1. Technology Roadmap

Five, embodiment

Below in conjunction with accompanying drawing, the present invention is described in detail, but they are not to further restriction of the present invention.

As shown in Figure 1, the method mainly comprises ANSYS simulation analysis and safety assessment two parts, solid finite meta-model set up by contrast daily work report and structural design drawing, the physical parameter of input associated materials, whole process is divided into Four processes and loads respective loads, with or corresponding stress result, try to achieve the dangerous point in coke drum operational process and dangerous periods, at dangerous point place sensor installation, gather true stress and the temperature conditions of dangerous periods.Safety assessment part experimentally or the physical parameter of coke drum material of main part and corresponding theory framework, in conjunction with the real time data that simulation analysis result and dangerous point place gather, use classical low-cycle fatigue failure theory of failure, creep damage failure theory and appraisal procedure, and high temperature low-cycle fatigue and the linear Coupling Damage of creep is theoretical and based on the appraisal procedure of elastoplastic Damage theory of failure, STRENGTH ON COKE tower carries out on-line monitoring and safety assessment.And according to the result of Real-time Collection, finite element analysis is adjusted accordingly, try to achieve new dangerous point and dangerous periods, adjustment sensing station, finally realizes real time on-line monitoring and the safety assessment of STRENGTH ON COKE tower.

Claims (1)

1. a delayed coking coke drum on-line monitoring and safety evaluation method, relatively with existing monitoring and safety evaluation method, the method can carry out monitoring and safety assessment according to delayed coking coke drum service data online, and in existing safety evaluation method, newly increased two kinds of methods, be respectively high temperature low-cycle fatigue and creep linear Coupling Damage theory α coefficient appraisal procedure and based on elastoplastic Damage theory of failure safety evaluation method, the method is according to the Accurate Model of STRENGTH ON COKE tower and Finite element analysis results and coke drum Real-time Collection result, use classical low-cycle fatigue failure theory of failure, creep damage failure theory and appraisal procedure, and high temperature low-cycle fatigue and the linear Coupling Damage of creep is theoretical and based on the appraisal procedure of elastoplastic Damage theory of failure, STRENGTH ON COKE tower carries out safety assessment, concrete steps are as follows:

A, select Von Mises equivalent plastic strain ranges, equivalent stress strain value and equivalent stress range of strain as assessing characterization parameter;

B, mechanical test is carried out to the coke drum material of main part that will study, gather its characterization parameter and analyze;

C, carry out finite element simulation modeling according to tower body unique apparatus structure, material and manufacturing condition will be studied, model hypothesis in charging, admission and water inlet process in tower medium circumference uniformity of temperature profile constant, the little perforates of checkout equipment such as tower wall material position meter, thermopair are ignored, peripherals, wind carry not to be considered with seismic (seismal, all the other physical dimensions and condition are all complete carries out Accurate Model according to tower body practical operation situation, and simulation calculation determines work dangerous point and work critical time section;

D, according to simulation result at dangerous point sensor installation, gather temperature and the stress value of its critical time section;

E, by simulation analysis result and tower body real time status contrast verification, classical low-cycle fatigue failure theory of failure, creep damage failure theory and appraisal procedure is used in conjunction with the truly stressed and characterization parameter of composition of tower shell material recorded in real time, and high temperature low-cycle fatigue and the linear Coupling Damage of creep theoretical and carry out safety assessment, to realize the real time on-line monitoring of STRENGTH ON COKE tower based on elastoplastic Damage theory of failure appraisal procedure STRENGTH ON COKE tower;

F, adjust accordingly renewal according to the real time data STRENGTH ON COKE tower finite element model collected in the coke drum course of work, and recalculate analysis according to the finite element model after adjustment, find new dangerous point and dangerous periods, and sensor is adjusted, to collect latest data, finally realize online safety assessment.