CN104951659B - Method for determining equipment damage factor in naphthenic acid and sulfur coexistence environment - Google Patents

Abstract

The invention discloses a method for determining equipment damage factors in a naphthenic acid and sulfur coexisting environment, which is characterized in that the equipment damage factors DF (t) in the multiple failure mechanism coexisting environment are as follows:

Description

The determination method of the equipment damage factor in aphthenic acids and sulfur coexisted environment

The application is Application No. 2010102064334, and the applying date is 10,6,21, and it is to apply for that artificial Hefei is general to invent The determination method of the divisional application device damage factor in coexistence of multiple failure mechanisms of mechanical investigations institute and its application.

Technical field

The present invention relates in the environment of it there are inefficacy mechanism, the determination method of the equipment damage factor, more specifically It is the determination method of equipment damage factor under one kind of multiple inefficacy mechanism coexisted environments.

Background technology

The determination of corrosion of steel speed in media environment is selected to design phase material with the determination of physical dimension to closing weight Will, and in operational phase, the determination of equipment failure probability is for unit check cycle and the estimation even more act of residual life Sufficient weight.

In 2008 editions API 581 (inspection technology based on risk), the failure likelihood of equipment is calculated as follows：

P_f(t)=G_ff×DF(t)×F_MS (1)

In formula：P_fT () is equipment failure probability；

G_ffFor same category of device average probability of failure on demand, be given by 581 tables 4.1 of API；

F_MSIt is that management level affect coefficient, enterprise management level is investigated according to the application form be given in API 581 Scoring, then fraction is converted to into a numerical value between 0.1～10, i.e. management level impact coefficient；

The inefficacy mechanism with time correlation that DF (t) refers to causes the probability parameter of equipment failure, is referred to as damage factor.

Every kind of corresponding inefficacy mechanism in the k kind failure modes existed to a certain equipment in API 581 is all given One probability parameter DF_k, when with corrosion thinning by leading inefficacy mechanism when this parameter mainly determined by thinning speed, When with stress corrosion cracking as leading inefficacy mechanism, this parameter is then mainly determined by Sensitivity of Stress Corrosion, damage factor More big then failure likelihood is bigger.In API581, when various (k kinds) inefficacy mechanisms coexist, using the method for simple superposition To calculate total damage factor, i.e.,

Such as, in actual crude oil media environment, aphthenic acids are always simultaneous with sulfur.In API581, this two When kind medium coexists, the determination of corrosion rate is exactly that the corrosion rate of two kinds of Single Medium independences is carried out simple superposition, its mistake By the failure likelihood simple superposition of two Single Mediums, i.e., effect probability is alsoBut practical situation is this Processing mode has unreasonable factor.

Related experimental study has been found that with field investigation, under identical flow velocity, during 350 DEG C of temperature below, sulfur is to cycloalkanes The corrosion of acid has inhibitory action, because the FeS that sulfur corrosion is formed has certain stability, adheres on the metal surface, so as to hinder Further erosion of the aphthenic acids to metal is stopped, so in Processing High-sulfur High-Acidity Crude Oils, the corrosion rate of material is high less than low-sulfur on the contrary Corrosion rate in sour crude oil.If temperature reaches 400 DEG C or so, FeS protecting film is just unstable, and the inhibitory action of sulfur is also Reduce, now the corrosivity of Processing High-sulfur High-Acidity Crude Oils are improve again.Therefore, failure likelihood is obviously in flow velocity, temperature, acid Value, sulfur content are associated.As long as and the irrationality in API581 methods can mislead it is believed that meeting peracid high-sulfur dielectric ring The material in border selects just to be bound to meet peracid low-sulfur environment with the determination of physical dimension, it is clear that can so cause dangerous.

Equally, in the environment that chloride ion and alkali coexist, the leading damage mechanisms of austenitic stainless steel stress corrosion cracking Also differ, when temperature is less than 150 DEG C, Chlorion stress corrosion crack is leading mechanism, and alkali plays certain facilitation, And be that alkali stress corrosion cracking then accounts for leading in 150 DEG C of temperatures above, chloride ion plays facilitation.But these situations are in API All it is not contemplated by 581.

The content of the invention

The present invention is to avoid the weak point existing for above-mentioned prior art, there is provided a kind of aphthenic acids and sulfur coexisted environment The determination method of the middle equipment damage factor, so that with regard to the determination side of equipment failure likelihood under various inefficacy mechanism coexisted environments Method is more scientific and reasonable.

The inventive method is adopted the following technical scheme that：

The characteristics of determination method of device damage factor in coexistence of multiple failure mechanisms of the present invention is：

Various inefficacy mechanism coexisted environments refer to and the i kind masters for causing equipment failure are there are in a certain Service Environment Lead mechanism and the secondary mechanism of k kinds；

The equipment includes steel bearing device and pipeline in various commercial plants；

Device damage factor in coexistence of multiple failure mechanisms DF (t) by formula (1) is：

In formula (1)：

For the independent lesions factor and F of i kind leading mechanisms_miFor i-th kind of leading mechanism independent lesions factor, i is Positive integer more than 1；

For interactional damage factor between various leading mechanisms and U_i’-iIt is the i-th ' kind of leading mechanism to The impact coefficient of i kind leading mechanisms；

For impact damage factor of the various secondary mechanism to leading mechanism and U_k-iFor the secondary mechanism of kth kind Impact coefficient to i-th kind of leading mechanism；

Aphthenic acids of the present invention with sulfur coexisted environment the characteristics of the determination method of the equipment damage factor are：

It is respectively present naphthenic acid corrosion leading mechanism and sulfur corrosion leading mechanism in aphthenic acids and sulfur coexisted environment, two kinds The damage factor of leading mechanism is designated as naphthenic acid corrosion damage factor F respectively_{Aphthenic acids}With sulfur corrosion damage factor F_Sulfur；There is sulfur simultaneously Inhibitory action to naphthenic acid corrosion, is designated as sulfur to naphthenic acid corrosion inhibitory action coefficient U_{Sulfur-aphthenic acids}；Because there is no secondary mechanism, It is designated as：U_k-i=0, therefore：The aphthenic acids with equipment damage factor D F (t) in sulfur coexisted environment by formula (1) are：

DF (t)=F_{Aphthenic acids}+F_Sulfur+F_{Aphthenic acids}U_{Sulfur-aphthenic acids}(2) in formula (2)：

F_{Aphthenic acids}It is that the corrosion rate B.10M chosen by table in API581 Part II Appendix B is computed drawing damage factor Parameter Art, is converted into naphthenic acid corrosion damage factor F further according to table in API581 5.11_{Aphthenic acids}；

F_SulfurIt is corrosion rate, the Jing meters drawn according to " the MeConomy curves of amendment " be given in 3096 Appendix B of SH/T Calculation draws damage factor parameter Art, sulfur corrosion damage factor F is converted into further according to table in API581 5.11_Sulfur；

Sulfur is to naphthenic acid corrosion inhibitory action coefficient U_{Sulfur-aphthenic acids}It is to be respectively provided with different temperature conditionss.

Aphthenic acids of the present invention are lain also in the characteristics of the determination method of the equipment damage factor with sulfur coexisted environment：The sulfur pair Naphthenic acid corrosion inhibitory action coefficient U_{Sulfur-aphthenic acids}It is respectively set under different temperature conditionss：

When temperature is less than 300 DEG C, U_Sulfur=0.106-0.081P_S；

When temperature is between 300 DEG C～400 DEG C, U_Sulfur=-0.054+0.052P_S；

When temperature is more than 400 DEG C, aphthenic acids are decomposed and lose corrosivity, U_{Sulfur-aphthenic acids}=0；

Various middle P_SFor medium sulfur content by weight percentage.

P in formula (2) and (3)_SFor the sulfur content in medium by weight percentage.

Chloride ion of the present invention with alkali coexisted environment the characteristics of the determination method of austenitic steel equipment damage factor is：

In chloride ion with alkali coexisted environment, Chlorion stress corrosion crack ClSCC and alkali stress corrosion cracking are there are Two kinds of mechanism of ASCC；

When temperature is less than 150 DEG C, with ClSCC as leading mechanism, F is designated as_{Chloride ion}, with ASCC as secondary mechanism, while depositing In facilitation of the alkali to Chlorion stress corrosion crack, alkali is designated as to Chlorion stress corrosion crack facilitation coefficient U_{Alkali-chloride ion}；Therefore have：

DF (t)=F_{Chloride ion}+F_{Chloride ion}U_{Alkali-chloride ion}(3) in formula (3)：

F_{Chloride ion}Method according to described by the 13rd chapter of 581 Part II of API determines；

U is set_{Alkali-chloride ion}For：U_{Alkali-chloride ion}=0.5 × T/150 × D_Alkali/20；

In above formula T be temperature DEG C, D_AlkaliFor concentration of lye by weight percentage；

When temperature is more than 150 DEG C, ASCC is leading mechanism, and ClSCC is secondary mechanism, while there is chloride ion should to alkali The facilitation of power corrosion cracking, is designated as chloride ion to alkali stress corrosion cracking facilitation coefficient U_{Chloride ion-alkali}, therefore have：

DF (t)=F_Alkali+F_AlkaliU_{Chloride ion-alkali}(4) in formula (4)

F_AlkaliMethod according to described by the 7th chapter of 581 Part II of API determines；

U_{Chloride ion-alkali}Choosing method be：U_{Chloride ion-alkali}=0.2 (1+D_{Chloride ion}/20)×T/150；

D in above formula_{Chloride ion}For chloride ion percentage by weight.

Compared with the prior art, the present invention has the beneficial effect that：

1st, the inventive method is it is determined that consider that leading mechanism interacts and secondary mechanism is to dominating machine during damage factor The factors such as the impact of system, are improved to the method in API581 so that equipment failure probability point in risk assessment Analysis is more scientific reasonable and meets reality；

2nd, the inventive method is correct in former API581 methods to damaging under peracid high-sulfur media environment and peracid low-sulfur environment Hinder the unreasonable part of factor determination, as long as the oil refining apparatus selection for changing people's formation in the past meets high-sulfur high-acidity medium, It must be just safe erroneous picture under sulfur peracid high acid environment；

3rd, The present invention gives a kind of quickly judge that austenitic stainless steel dominates damage under chloride ion and alkali coexisted environment Mechanism judges the determination method with damage factor, with preferable engineering application value.

Specific embodiment

The determination of device damage factor in coexistence of multiple failure mechanisms：

Various inefficacy mechanism coexisted environments refer to there is the i kind leading mechanisms for causing equipment failure in a certain Service Environment With the secondary mechanism of k kinds；Equipment refers to steel bearing device and pipeline in various commercial plants etc..

Device damage factor in coexistence of multiple failure mechanisms DF (t) by formula (1) is：

In formula (1)：

For the independent lesions factor and F of i kind leading mechanisms_miFor i-th kind of leading mechanism independent lesions factor, i is Positive integer more than 1；

For interactional damage factor between various leading mechanisms and U_i’-iFor the i-th ' kind of leading mechanism pair The impact coefficient of i-th kind of leading mechanism；

For impact damage factor of the various secondary mechanism to leading mechanism and U_k-iFor the secondary mechanism of kth kind Impact coefficient to i-th kind of leading mechanism；

Carried out in being embodied as according to the following procedure：

1st, judge whether equipment operating environment belongs to various inefficacy mechanism coexisted environments；

2nd, determine there is which leading mechanism and secondary mechanism according to experimental study and engineering experience；

3rd, analyse whether there is the impact that influencing each other between leading mechanism and secondary mechanism are present to leading mechanism；

4th, the damage factor of each leading mechanism is determined according to API581 and other technological documents；

5th, U is determined according to experimental study and engineering experience_i’-i, i.e., a certain leading mechanism is to another kind of leading mechanism Affect coefficient and U_k-i, i.e., impact coefficient of a certain secondary mechanism to a certain leading mechanism

6th, DF (t) is calculated by (1) formula

Embodiment 1

The determination of aphthenic acids and the sulfur coexisted environment equipment damage factor

In aphthenic acids with sulfur coexisted environment, there are two kinds of leading mechanisms, respectively naphthenic acid corrosion leading mechanism and sulfur Corrosion leading mechanism, the damage factor of two kinds of leading mechanisms are designated as F respectively_{Aphthenic acids}And F_Sulfur；There is sulfur to naphthenic acid corrosion simultaneously Inhibitory action, is designated as sulfur to naphthenic acid corrosion inhibitory action coefficient U_{Sulfur-aphthenic acids}；Because there is no secondary mechanism, it is designated as：U_k-i=0, because This：

Therefore have：DF=F_{Aphthenic acids}+F_Sulfur+F_{Aphthenic acids}U_{Sulfur-aphthenic acids}

U_{Sulfur-aphthenic acids}Be correspondingly arranged under condition of different temperatures respectively for：

When temperature is less than 300 DEG C, U_{Sulfur-aphthenic acids}=0.106-0.081P_S；

When temperature is between 300 DEG C～400 DEG C, U_{Sulfur-aphthenic acids}=-0.054+0.052P_S；

When temperature is more than 400 DEG C, aphthenic acids are decomposed and lose corrosivity, U_{Sulfur-aphthenic acids}=0；

P_SFor medium sulfur content wt% by weight percentage.

Specific implementation process：

1st, determine the sulfur content and acid number in medium；

2nd, it is computed drawing damage factor according to the corrosion rate B.10M chosen by table in API581 Part II Appendix B Aphthenic acids damage factor F is converted thereof into further according to table in API581 5.11 after parameter Art_{Aphthenic acids}。

3rd, the corrosion rate drawn according to " the MeConomy curves of amendment " that be given in 3096 Appendix B of SH/T is computed The damage factor F of sulfur corrosion is converted thereof into after drawing damage factor parameter Art further according to table in API581 5.11_Sulfur。

4th, U is determined according to equipment operation temperature and the sulfur content in medium_{Sulfur-aphthenic acids}

5th, by DF=F_{Aphthenic acids}+F_Sulfur+F_{Aphthenic acids}U_{Sulfur-aphthenic acids}Calculate and obtain DF (t)

Table 1：TAN：3.0mg/g,274℃

Table 2：TAN：302 DEG C of 4.0mg/g,

With upper table 1 be TAN as 3.0mg/g, 274 DEG C, in the environment of different sulfur content by weight percentage, the present invention The contrast situation of the corrosion rate be given in method and 2008 editions API581, as can be seen from the table, under this environment, we The corrosion rate that method is given is at sulfur content relatively low (0.4% and 0.6%), hence it is evident that higher than the corrosion rate be given in API581, It is more identical with actually detected data.When sulfur content is more than 1.5%, be given in corrosion rate obtained by this method and API 581 Corrosion rate is closer to.

With upper table 2 be TAN as 4.0mg/g, 302 DEG C, in the environment of different sulfur content by weight percentage, the present invention Method is similar with table 1 with the contrast situation of the corrosion rate be given in 2008 editions API581.

Embodiment 2：

The determination of chloride ion and alkali coexisted environment austenitic steel equipment damage factor：

In chloride ion with alkali coexisted environment, Chlorion stress corrosion crack ClSCC and alkali stress corrosion cracking are there are Two kinds of mechanism of ASCC；

When temperature is less than 150 DEG C, it is, with CLSCC as leading mechanism, to be designated as F_{Chloride ion}, with ASCC as secondary mechanism, while There is facilitation of the alkali to Chlorion stress corrosion crack, alkali is designated as to Chlorion stress corrosion crack facilitation coefficient U_{Alkali-chloride ion}, therefore：

Thus：DF=F_{Chloride ion}+F_{Chloride ion}U_{Alkali-chloride ion}

Wherein：F_{Chloride ion}Method according to described by the 13rd chapter of 581 Part II of API determines；

U is set_{Alkali-chloride ion}For：U_Alkali=0.5 × T/150 × D_Alkali/ 20, in formula T be temperature DEG C, D_AlkaliFor concentration of lye wt%.

When temperature is more than 150 DEG C, ASCC is leading mechanism, and CLSCC is secondary mechanism, while there is chloride ion should to alkali The facilitation of power corrosion cracking, is designated as chloride ion to alkali stress corrosion cracking facilitation coefficient U_{Chloride ion-alkali}, therefore：

Thus：DF=F_Alkali+F_AlkaliU_{Chloride ion-alkali}

Wherein, F_AlkaliMethod according to described by the 7th chapter of 581 Part II of API determines；

U_{Chloride ion-alkali}Choosing method be：

U_{Chloride ion-alkali}=0.2 (1+D_{Chloride ion}/20)×T/150；Wherein D_{Chloride ion}For chlorine ion concentration ppm.

Specific implementation process：

When operation temperature is less than 150 DEG C

1st, determine the concentration of the chloride ion and alkali in medium；

2nd, determine the operation temperature of equipment；

3rd, the method first according to described by the 13rd chapter of 581 Part II of API determines that Chlorion stress corrosion crack is sensitive Property, it is then converted into F_{Chloride ion}。

4th, U is calculated according to temperature and alkali concn_{Alkali-chloride ion；}

5th, by DF (t)=F_{Chloride ion}+F_{Chloride ion}U_{Alkali-chloride ion}Calculate and obtain DF (t).

When operation temperature is more than 150 DEG C

1st, determine the concentration of the chloride ion and alkali in medium；

2nd, determine the operation temperature of equipment；

3rd, the method first according to described by the 7th chapter of 581 Part II of API determines alkali stress corrosion cracking sensitivity, then It is converted into F_Alkali。

4th, U is calculated according to temperature and chlorine ion concentration_{Chloride ion-alkali}；

5th, by DF (t)=F_Alkali+F_AlkaliU_{Chloride ion-alkali}Calculate and obtain DF (t).

Claims (2)

1. a kind of aphthenic acids and the determination method of the equipment damage factor in sulfur coexisted environment, is characterized in that：

Naphthenic acid corrosion leading mechanism and sulfur corrosion leading mechanism are respectively present in aphthenic acids with sulfur coexisted environment, two kinds are dominated The damage factor of mechanism is designated as naphthenic acid corrosion damage factor F respectively_{Aphthenic acids}With sulfur corrosion damage factor F_Sulfur；There is sulfur to ring simultaneously The inhibitory action of alkanoic acid corrosion, is designated as sulfur to naphthenic acid corrosion inhibitory action coefficient U_{Sulfur-aphthenic acids}；Due to there is no secondary mechanism, because This, the aphthenic acids with equipment damage factor D F (t) in sulfur coexisted environment by formula (1) are：

DF (t)=F_{Aphthenic acids}+F_Sulfur+F_{Aphthenic acids}U_{Sulfur-aphthenic acids} (1)

In formula (1)：

F_{Aphthenic acids}It is that the corrosion rate B.10M chosen by table in API581 Part II Appendix B is computed drawing damage factor parameter Art, is converted into naphthenic acid corrosion damage factor F further according to table in API581 5.11_{Aphthenic acids}；

F_SulfurBe drawn according to " the MeConomy curves of amendment " be given in 3096 Appendix B of SH/T corrosion rate, be computed Go out damage factor parameter Art, sulfur corrosion damage factor F is converted into further according to table in API581 5.11_Sulfur；

Sulfur is to naphthenic acid corrosion inhibitory action coefficient U_{Sulfur-aphthenic acids}It is to be respectively provided with different temperature conditionss.

2. aphthenic acids according to claim 1 and the determination method of the equipment damage factor in sulfur coexisted environment, is characterized in that The sulfur is to naphthenic acid corrosion inhibitory action coefficient U_{Sulfur-aphthenic acids}It is respectively set under different temperature conditionss：

When temperature is less than 300 DEG C, U_Sulfur=0.106-0.081P_S；

When temperature is between 300 DEG C～400 DEG C, U_Sulfur=-0.054+0.052P_S；

When temperature is more than 400 DEG C, aphthenic acids are decomposed and lose corrosivity, U_{Sulfur-aphthenic acids}=0；

Various middle P_SFor medium sulfur content by weight percentage.