KR101084637B1 - Method for preventing corrosion in chemical plants - Google Patents

Abstract

The present invention is applied to various chemical plants that are concerned about the accidents caused by corrosion, to prevent the accidents caused by corrosion, etc., and to minimize the cost of corrosion, a corrosion prevention method, a recording medium and a management device storing the program recorded the method It is about. According to the method of the present invention, it is possible to reliably derive major management and monitoring variables related to corrosion occurring in a chemical plant, and to quantify the risks and accidents that may occur due to corrosion, and to estimate the risks. Precise guidelines on the priority, method and frequency of facility inspections can be established. In the present invention, by establishing a management system in conjunction with the established guidelines in conjunction with risk-based inspection, and the like, the unexpected process downtime and downtime that may occur in the chemical plant, the risk reduction to the worker or the surrounding environment, the product yield It can enable increased and improved quality, chemical plant maintenance and optimization of safety management systems.

Chemical Plants, Oil Refineries, Petrochemical Plants, Corrosion Resistant, Material Selectivity, Process Flowchart, Key Variables, National Petroleum Institute Standard 571

Description

Method for preventing corrosion in chemical plants

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of preventing corrosion in various chemical plants where an accident due to corrosion is concerned, a recording medium storing a program on which the method is performed, and a management apparatus.

Recently, due to the enlargement and directization of chemical plant facilities such as oil refineries or petrochemical plants, the possibility of accidents due to corrosion is increasing. In fact, accidents due to corrosion, which causes enormous human and economic losses, have been reported continuously at home and abroad.

In the United States, for example, it was reported in 1998 that $ 27.6 billion, or about 3.1% of GDP, was consumed as corrosion cost. A major incident in the United States was the explosion of a storage tank at an oil refinery in Delaware, USA, in 2001. The cause of the accident was high pressure gas that leaked due to corrosion of the pipes connected to the storage tank.

In Korea, a representative example of a chemical plant accident caused by corrosion is a high temperature sulfur corrosion accident in the UC (unicracking) process tube of the first heavy oil cracking plant in 2003. In this case, as the tube thinned due to corrosion ruptures due to internal pressure, the distilled heavy oil leaked inside, causing a fire due to a high temperature of the heater.

As such, accidents due to corrosion occur frequently in chemical plants, and economic and human damages are very serious.

Therefore, there is a need for a systematic system for reducing corrosion accidents and minimizing corrosion costs. However, in Korea, processes and systems for inspection and control of corrosion-related accidents in oil refining and petrochemical plant facilities are often only formally established or are not established at all, and are expected to cause corrosion. Information on the location of the equipment is not well maintained.

The present invention has been made in consideration of the above-described problems of the prior art, is applied to various chemical plants to prevent accidents due to corrosion, etc., corrosion prevention method that can minimize the cost of corrosion, the stored program stored therein A medium and a management apparatus are provided.

The present invention as a means for solving the above problems, the first step of establishing the material selectivity of the chemical plant equipment; A second step of identifying a damage mechanism of the chemical plant equipment based on the material selectivity established in the first step; And

Provided is a method for preventing corrosion in a chemical plant comprising a third step of deriving key variables that affect the corrosion of the chemical plant equipment based on the damage mechanism identified in the second stage.

As another means for solving the above problems, the present invention provides a recording medium in which a program capable of performing the above-described method according to the present invention is recorded and readable by an electronic device.

The present invention is another means for solving the above problems, the processing unit capable of presenting the inspection guidelines of the chemical plant equipment for the main parameters calculated by the above-described method according to the present invention; A measurement unit linked to the processing unit and configured to monitor main variables of the facilities of the chemical plant according to the inspection guidelines presented by the processing unit; And

A chemical plant, which is linked to the measuring unit and the processing unit and includes a control unit for adjusting an operating state of the chemical plant or a monitoring condition of the main variable when the main variable monitored by the measuring unit deviates from the guidelines presented by the processing unit. Provides a management device.

According to the method of the present invention, it is possible to reliably derive key management and monitoring parameters related to corrosion occurring in chemical plants, thereby quantifying the risks and accidents that may occur due to corrosion in chemical plants, and estimating the risk Thus, accurate guidelines can be established for equipment inspection priorities, inspection methods and inspection intervals. In the present invention, by establishing a management system in conjunction with the established guidelines in conjunction with risk-based inspection, and the like, the unexpected process downtime and downtime that may occur in the chemical plant, the risk reduction to the worker or the surrounding environment, the product yield It can enable increased and improved quality, chemical plant maintenance and optimization of safety management systems.

The present invention includes a first step of establishing a material selection diagram (MSD) of a chemical plant facility; A second step of identifying a damage mechanism of the chemical plant equipment based on the material selectivity established in the first step; And

A method for preventing corrosion in a chemical plant comprising a third step of deriving key variables that affect the corrosion of a chemical plant plant based on the damage mechanism identified in the second stage.

Hereinafter, the corrosion prevention method of the present invention will be described in detail.

The method of the present invention can be applied to a management system of various chemical plants in which a large accident due to corrosion is concerned, and can improve the reliability of the plant equipment and the corrosive environment. Specifically, according to the method of the present invention, it is possible to accurately derive the main variables causing corrosion at each point of the chemical plant, and to quantify the failure of the equipment and the resulting accidents that may occur from the corrosion through the derived parameters In addition, risk assessments can be established to establish accurate inspection guidelines for facility inspection priorities, inspection methods, inspection intervals and scheduling. In addition, in the present invention, a comprehensive management system may be established by interworking the established guidelines with risk based inspection (RBI).

Specific examples of the chemical plant to which the method of the present invention may be applied include, but are not limited to, an oil refinery plant or a petrochemical plant, but may be applied to any plant where an accident due to corrosion is concerned.

The first step of the invention is the step of establishing the material selectivity associated with the plant to which the method of the invention is to be applied. The term "material selectivity" used in the present invention refers to the connection relationship between the main equipment or components (ex. Process piping, distillation column, stripper, pump, heat exchanger, valve, generator, probe and blower, etc.) in which a chemical plant process is performed. Means a document capable of providing comprehensive information on the flow of raw materials or discharges, process flows and materials of the equipment or parts. The main equipment or parts constituting a chemical plant such as an oil refinery or a petrochemical plant are made of different materials in consideration of corrosive substances or economical efficiency. For example, in the A-column of the Crude Distillation Unit (CDU), the main plant that constitutes the refinery, the upper part of the shell of the base carbon steel is Monel or Hastelloy. ) Lining, and the lower part is lining with SUS 405. The reason why A-columns are made of different materials as described above is that wet corrosion such as HCl corrosion and salt corrosion is likely to occur in the upper portion of the column, and sulfidation in the lower portion thereof. This is because high temperature corrosion, such as corrosion and naphthenic acid corrosion, is likely to occur. That is, in a chemical factory, various materials are applied in consideration of factors that may be particularly problematic in facilities such as plants or piping as described above. The first step of the present invention is the step of establishing a material selectivity in which materials are distinguished from such various equipments or parts, and displaying the connection relations and process flows.

The method of performing this first step of the present invention is not particularly limited. For example, in the first step, the material selectivity may include: (1) establishing a process flow diagram (PFD) for a process performed in a chemical plant; And

(2) It can be established by a method comprising the step of classifying and specifying the material of each facility in the process flow chart established in step (1).

In step (1), a process flow diagram relating to the whole process or the individual process performed in the chemical plant to which the method of the present invention is applied is established. In this case, the process flow chart includes a main valve including a process piping, a major equipment item, a control valve, a connection with other system, and a main bypass. Information such as major bypass streams, major recirculation streams, process data (e.g. temperature, pressure, mass flow rate or density) or process stream names It may include. In the present invention, a method of establishing the above-described process flow chart is not particularly limited, and is described in, for example, MS Ray, MG Sneesby, “Chemical Engineering Design Project: A Case Study Approach”, 2nd Edition, Gordan and Breach Science Publishers, ISBN 9056991361, 1998.) and the like can be used.

In step (2), each material is designated in consideration of the past or present material usage history, design data, and past history of the corresponding equipment or part in the process flow chart established in step (1). In step (2) it is also possible to further specify information relating to the probes which are installed in the individual process streams or which need to be additionally installed.

1 is a view showing the material selectivity of the refinery CDU process A-column portion established in accordance with an aspect of the present invention. The material selectivity of FIG. 1 is a process flow chart (PFD) related to the A-column of the CDU process of the refinery, and then the materials (ex. Chrome, duplex, 400SS, bottom) of each equipment used in the process. By establishing a probe that is installed or needs to be installed).

In the present invention, after establishing the material selectivity in the above manner, to determine the damage mechanism of the chemical plant process on the basis of this, in this step the corrosive substances and the resulting mechanism involved in the chemical plant overall process or individual processes Can be figured out.

The method of identifying the damage mechanism of the chemical plant in the second step of the present invention is not particularly limited, for example, (a) collecting design information and operation data information associated with the chemical plant process; (b) collecting corrosive material information contained within the process stream; And (c) identifying the damage mechanism (DM) of the process based on the information collected in steps (a) and (b) and on the American Petroleum Institute Refinery Process 571 (API 571). It may include a step.

Step (a) is a step of determining the temperature, pressure and heat treatment of the specific process based on the design information and operating data to collect, in order to identify the corrosive substances and mechanism of the corresponding equipment of the chemical plant process. The identified process temperature, pressure and heat treatment can be used as a basis for establishing a damage mechanism in the subsequent step (c).

Step (b) of the present invention is a step of collecting information related to the corrosive substances included in the process flow. Examples of corrosive substances to be collected at this time include sulfur, naphthenic acid, polythionic acid, chlorides, carbon dioxide, ammonia and cyanides. ), Hydrogen Chloride, Hydrogen Sulfide, Hydrofluoric Acid, Sulfuric Acid, Hydrogen, Phenolics, Oxygen and Carbon. And it is not particularly limited to being variously selected depending on the characteristics of the device.

The order in which steps (a) and (b) are performed in the method of the present invention is not particularly limited and may be performed sequentially or simultaneously.

Step (c) of the present invention is to identify the damage mechanism for each device and / or device site, based on the information collected in the above-mentioned step and the American Petroleum Institute standard 571. The American Petroleum Institute Standards provide basic information about the damage that can occur to equipment used in the refining process. Risk Based Inspection (RBI) (RP 580 and Publ. 581) and adequacy A specification to supplement the Fitness-for-Service (RP 579) technique.

American Petroleum Institute Standard 571 covers more than 60 damage mechanisms, and includes a general description of the damage, susceptible materials of construction, critical factors, and selection of test methods. Inspection method selection guidelines and control measures are presented. In addition, the specification provides drawings and references for each mechanism and additionally includes generic process flow diagrams that include a summary of the major damage mechanisms expected in a typical refinery process unit. It is.

Therefore, the average person skilled in the art can easily establish a damage mechanism for each process according to the data collected in steps (a) and (b) and the contents of the American Petroleum Institute Standard 571.

2 and 3 are a process flow diagram (PFD) showing the damage mechanism of the refinery A-column established in accordance with one aspect of the present invention. As can be seen from Figs. 2 and 3, in the case of the A-column, the damage mechanism of the upper portion is mainly HCl corrosion (red portion of Fig. 2), etc., and the damage mechanism of the lower portion is a high temperature sulfide corrosion (Fig. 2). Green part of 3). The damage mechanism of the entire chemical process, for example the CDU process, can also be established in this way, in which the creep / stress rupture, fuel ash corrosion, oxidation ), High temperature sulfidation, Naphthenic acid corrosion, Hydrochloric acid corrosion, Ammonium chloride (Salt) corrosion, Wet hydrogen sulfide corrosion (Wet H2S) Nine mechanisms can be chosen, such as corrosion and ammonia stress corrosion cracking.

In step (c) of the present invention, it is also possible to identify the damage mechanism on a detailed basis per unit device. For example, the upper part of the A-column of the CDU process may include HCl corrosion or salt corrosion; Interrupted parts are salt corrosion; And the lower portion may have different damage mechanisms such as naphthenic acid corrosion or high temperature sulphide corrosion.

The third step of the present invention is the step of selecting a critical reliability variable (CRV) that affects the corrosion of chemical plant equipment based on the damage mechanism identified in the second step.

The term "critical variable (CRV)" used in the present invention is derived based on the damage mechanism established in the second step, and is related to the main factors that may cause corrosion in each plant or a specific part of the plant. This could mean parameters related to substances that need to be inspected and monitored. Examples of such key variables include pH, Cl ^- content, Fe content, hydrogen sulfide content, ammonia content, TAN content, hydrogen partial pressure, temperature, pressure and corrosion rate, but these are variously selected for each process and device. It is not particularly limited to that.

In addition, the method of screening the main variables as described above in the third step of the present invention is not particularly limited, for example, the American Petroleum Association Standard (API) 571, the American Petroleum Association Standard (API) 580 and / or the United States Petroleum It may be selected based on Association Standard (API) 581 or the like. In the present invention, it is also possible to select key variables by referring to best practices and the like of general peers in the field. For example, one column A- key management and monitoring (Monitoring) variable in the upper part of the CDU showing a mechanism of damage HCL corrosion according to an aspect of the present invention is ^{pH (water pH), Cl -} (water Cl -), Fe (water Fe), hydrogen sulfide (water H ₂ S), ammonia (water NH ₃ ) and temperature may be selected.

In the present invention, further, following the above step, the step of establishing the inspection guideline of the chemical plant may be further performed based on the main variables calculated in the third step.

In other words, the main variables selected in the above manner in the present invention may serve as a basis for establishing inspection guidelines that can be effectively operated in the chemical plant. In the above, the inspection guideline is a system that provides comprehensive information on the inspection method, inspection position, maximum or minimum allowable value of the main variables inspected, and inspection period for each facility of the chemical plant. The method of establishing a guideline based on the main variables in the present invention is not particularly limited, for example, the American Petroleum Association Standard (API) 571, the American Petroleum Association Standard (API) 580 and / or the American Petroleum Association Standard (API) 581 et al. Can be established by reference. In the present invention, it is also possible to establish the guidelines with reference to the best practice or chemical vendor guideline of a general peer company in the field. 4 is a diagram showing the main parameters and inspection guidelines of the chemical process screened in the above manner. In addition, in the case of the A-column of the above-mentioned CDU, for example, in the main parameter of the HCl corrosion mechanism of the upper part, the pH is 6 to 7, Cl ⁻ less than 30 ppm, Fe is less than 1 ppm. Can be presented.

The invention also relates to a recording medium in which a program for performing the method according to the invention described above is recorded and readable by an electronic device.

That is, the method of the present invention can be written as a computer program, wherein each code or code segment constituting the program can be easily made by an average person skilled in the art without departing from the gist of the method of the present invention. Can be inferred.

The program can be stored in a computer reader media that can be read by a computer or the like, and can be read and executed by a computer or the like. In this case, examples of the information storage medium include, but are not limited to, a magnetic recording medium, an optical recording medium, and a carrier wave medium.

The present invention also includes a processing unit capable of presenting chemical plant inspection guidelines relating to key variables calculated according to the method of the present invention described above; A measurement unit linked to the processing unit and configured to monitor main variables of the facilities of the chemical plant according to the guidelines presented by the processing unit; And

A chemical plant, which is linked to the measuring unit and the processing unit and includes a control unit for adjusting an operating state of the chemical plant or a monitoring condition of the main variable when the main variable monitored by the measuring unit deviates from the guidelines presented by the processing unit. It relates to a management device of.

The management apparatus of the present invention, based on the guidelines obtained according to the method of the present invention, by monitoring the main parameters of each facility of the actual chemical plant on-line or off-line, and feedback the results appropriately to improve the reliability of the device or plant operating conditions It is an integrated management system that can be secured. Specifically, the main variable derived from the processing unit of the management device, the guideline or the DB containing the information can be used to determine the risk of the facility through the quantitative prediction of the failure of the facility and the resulting accident that may occur due to corrosion in the chemical plant. Information can be provided to the measurement unit for calculation and inspection guidelines such as facility inspection priorities, inspection methods, maximum or minimum allowances for key variables, inspection intervals and scheduling. In addition, the measurement unit monitors the main variables according to the above grounds, and when the monitored value exceeds or falls below the standard (allowed value) set forth in the guideline, the measurement unit transmits it to the controller. The control unit optimizes the operating state of the chemical plant or the monitoring method in the measuring unit, thereby performing damage management such as chemical plant corrosion with minimal effort and cost, thereby reducing the number of unexpected process interruptions, reducing downtime, It can reduce worker's risk, increase production, improve parts quality, realize the optimization of equipment maintenance, and innovate the safety management and maintenance system of equipment.

Specific details of the computer processing unit, the measuring unit and the control unit in the management device of the present invention are not particularly limited, and an average technician in this field may easily select an optimum configuration of the management device that can achieve the object of the present invention. Can be.

1 is a view showing the material selectivity of the refinery CDU process established in accordance with an aspect of the present invention.

2 and 3 are process flow diagrams illustrating the damage mechanism of the refinery CDU process established in accordance with one aspect of the present invention.

4 is a diagram illustrating key parameters and operational guidelines of a chemical process established in accordance with one aspect of the present invention.

Claims (14)

Establishing a material selectivity of the chemical plant equipment, comprising: (1) establishing a process flow diagram for a process performed at the chemical plant; And (2) classifying and specifying materials for each facility in the process flow chart established in step (1); On the basis of the material selectivity established in the first step, identifying the damage mechanism for each detailed part of the unit of the chemical plant, comprising: (a) collecting design information and operation data information related to the chemical plant process; (b) collecting corrosive material information contained within the process stream; And (c) defining a damage mechanism for each specific part of the unit based on the information collected in steps (a) and (b); And the main variables affecting the corrosion of chemical plant equipment based on the damage mechanism identified in the second stage, including pH, Cl ^- content, Fe content, hydrogen sulfide content, ammonia content, TAN content, hydrogen partial pressure, temperature, pressure and Derivation of one or more key variables selected from the group consisting of corrosion rates, based on which the inspection of the chemical plant includes information on the test method, location of inspection, maximum or minimum allowable values of the key variables or inspection intervals A method of preventing corrosion in a chemical plant, comprising a third step of establishing guidelines. The method of claim 1 wherein the chemical plant is an oil refinery or a petrochemical plant. delete The process flow diagram of claim 1, wherein the process flow diagram includes process pipes, process equipment items, process main valves, connection relationships between process systems, bypass flows, recirculation flows, process temperatures, process pressures, process mass flow rates, process densities, and process streams. A method comprising information about one or more selected from the group of names. delete The method of claim 1, further comprising determining whether the process temperature, process pressure, or process heat treatment is performed based on the design information and operation data collected in step (a). The method of claim 1, wherein the corrosive material is at least one selected from the group consisting of sulfur, naphthenic acid, polythionic acid, chloride, carbon dioxide, ammonia, cyanide, hydrogen chloride, hydrogen sulfide, hydrofluoric acid, sulfuric acid, hydrogen, phenols, oxygen and carbon . delete The method of claim 1 wherein the primary variable is calculated based on one or more selected from the group consisting of American Petroleum Institute Standard 571, American Petroleum Association Standard 580 and American Petroleum Association Standard 581. delete The method of claim 1 wherein the inspection guidelines are established based on one or more selected from the group consisting of American Petroleum Institute Standard 571, American Petroleum Association Standard 580 and American Petroleum Association Standard 581. 12. A recording medium having a program recorded thereon, which is readable by an electronic device, which carries out the method according to claim 1, 2, 4, 6, 7, 7, or 11. A processing unit capable of presenting chemical plant inspection guidelines relating to key variables calculated by the method according to claim 1, 2, 4, 6, 7, 9 or 11; A measurement unit linked to the processing unit and configured to monitor main variables of the facilities of the chemical plant according to the guidelines presented by the processing unit; And a control unit interlocked with the measuring unit and the processing unit, and configured to adjust an operating state of the chemical plant or a monitoring condition of the main variable when the main variable monitored by the measuring unit deviates from the guidelines suggested by the processing unit. Management device of the factory. 14. The inspection guideline of claim 13, wherein the inspection guideline includes information about one or more selected from the group consisting of facility inspection priorities, inspection methods, maximum allowable values for key variables, minimum allowable values for key variables, inspection intervals and inspection scheduling. Device characterized in that.

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