Prediction and Assessment of Corrosion in Amine Systems
Joint Industry Program Proposal
Presented herein is a proposal prepared by InterCorr International, Inc. for a technical investigation on "Prediction and Assessment of Corrosion in Amine Systems". This proposal has been developed in association with Flint Hill Responses, L.P. to address important technical needs of the petroleum refining industry which substantially impact issues related to unit throughput, treatment capacity, reliability and related plant productivity.
Many studies have been conducted that have focused mainly on empirical findings heavily relying on evaluations of operational experience. There is currently a need for more precise and quantitative data on amine unit corrosion for a variety of materials under simulated service conditions. These data are needed as a technical basis for improved prediction of corrosion in amine systems for use in materials selection, control of process unit operation, and assessment of chemical treatments. Furthermore, there is a major economic impact of amine unit corrosion on overall plant profitability that more than justifies the sponsorship commitment and the level of funding proposed for this program.
The program involves the following tasks:
Task 1 - Development of Baseline Data Base for Sour MEA,
DGA, DEA , Systems
As a result of joint industry sponsorship of this program, each participating sponsor company will be required to pay only a small portion (<10 percent) of the total program cost. Maximum benefit is being given to the Original Sponsors that join at the start of the program. Furthermore, the results and the associated software from this program will be held in confidence among the sponsoring companies for a period of at least two years from their release to the program sponsors. Late-sponsor and Non-sponsor companies desiring to obtain the program results and software during this confidentiality period will have to pay a fee up to 50 percent higher than that paid by the Original Sponsors. This arrangement gives program sponsors maximum leveraging of their sponsorship fee.
Presented herein is a proposal prepared by InterCorr International, Inc. for a technical investigation on "Prediction and Assessment of Corrosion in Amine Systems". This proposal has been developed in association with Flint Hill Responses, L.P. to address important technical needs of the petroleum refining industry which substantially impact issues related to unit throughput, treatment capacity, reliability and related plant productivity. It has been developed to solicit support to sustain a significant joint industry sponsored investigation in this technical area.
A focus group meeting was held with potential sponsors in June 2001, to review the program concept. The results of this meeting were used to direct the program to meet specific industry needs and to identify program deliverables that be of value to sponsor companies. The program now includes a strong focus on the investigation of corrosion in amine systems focusing on aspects that impact reliability and profitability of refinery operations.
The subject of amine unit corrosion in petroleum refineries, similar to sour water corrosion, has been addressed over the past 40 years has been addressed in the literature . However, despite the prevalence of amine corrosion problems in refining operations, there is very little quantitative corrosion data that can be directly utilized in quantitative guidelines for corrosion control. Importantly, most of these studies do not take into account velocity (which appears to be a critical variable) and have not investigated a wide range of unit conditions. The approach used in many studies has been to focus on empirical findings heavily relying on evaluations of operational experience. There is currently a need for more precise and quantitative data on amine corrosion developed under rigorously simulated service conditions. These data are needed as a technical basis for improved prediction of amine corrosion for use in control of process unit operation and assessment of chemical treatments.
In an experience survey conducted by the American Petroleum Institute conducted in the late 1950's, corrosion of carbon steel by amines in gas treatment and sulfur recovery was identified as a major concern. [1,2] Major causes of amine corrosion identified included poor plant design and operating practices, and solution contamination. In general terms it was identified that amine systems used for removal of only CO2 were generally more corrosive than those involving only H2S, and MEA systems were generally more corrosive than DEA. Mechanistic treatments of the subject have identified that amine corrosion is usually most severe where the gases are absorbed or deabsorbed from rich amine solutions where temperature, flow and turbulence are important considerations. 
The most common material of construction for amine units is carbon steel. Amine stress corrosion cracking (SCC) is also a consideration that has been extensively discussed in the literature. However, experience has proven that more failures in amine units have actually resulted from corrosion than SCC. Limits (for corrosion control) including amine concentration (around 20%), acid gas loading (0.3 to 0.6 mole/mole), flow rate (rich amine - 6 fps; lean amine - 6 to 20 fps) rich circuit temperatures (210-220 F) and reboiler temperatures (260 - 300 F) have been developed by evaluating services experience in various plants with sometimes vastly different designs, throughput and operating conditions. [4-5]. Also, limits for impurities such as heat stable salts are typically based entirely on "rules of thumb" and may range from 1 to 2 percent. Consequently, there is a wide operating envelope with little technical basis to help designers and operators optimize unit reliability and performance. There has been only limited use of test data and none has approached this area using rigorously controlled environment and flow conditions as proposed in this study.
With increased interest by plant designers and operators to maximize amine unit reliability, along with demands for increased throughput, and circulation and treatment capacity, improved corrosion prediction capabilities are required. It has not been uncommon for amine units, designed to handle a given acid gas loading, to be exposed to higher loadings when refinery operations demand it. This usually results in increased possibilities of corrosion and in some cases unit reliability problems and unscheduled shutdowns, thus affecting overall refinery profitability. Some of these situations have resulted in installation of additional treatment capacity and system upgrades to stainless alloys which may or may not been justified. The economic impact of such problems is major and more than justifies the commitment and the level of funding proposed for this program.
InterCorr International, Inc., in collaboration with Flint Hill Responses, L.P. Petroleum Group L.P. has been actively investigating a more rigorous basis for predicting and assessing amine corrosion. InterCorr proposes a joint industry sponsored program that has been specifically designed to generate useful engineering data and expand the understanding of corrosion in amine treatment systems. This information will be used as a basis for the development of a more accurate and comprehensive predictive tool including assessment methodologies for control of amine unit corrosion to help attain safe, efficient and reliable refinery operations.
As a result of joint industry sponsorship of this program, each participating sponsor company will be required to pay only a small portion (<10 percent) of the total program cost. Furthermore, the results and the associated software from this program will be held in confidence among the sponsoring companies for a period of at least two years from their release to the program sponsors. Non-sponsor companies desiring to obtain the program results and software during this confidentiality period will have to pay a fee 50 percent higher than that paid by the Original Sponsors. This arrangement gives program sponsors maximum leveraging of their sponsorship fee.
An important benefit to joining sponsors will be the immediate access to a substantial quantity of test results already available that have been generated in an amine flow loop that currently exists at InterCorr developed under the auspices of Koch Petroleum. These results will be presented in the first program status report and discussed at the program kick-off meeting. They will show the corrosion performance of carbon steel and AISI 304 over a range of relevant amine service conditions. These initial investigations have focused on defining corrosive conditions in MEA and DGA systems. See Task 1.
Furthermore, the results generated during the balance of the program will provide an engineering and technical basis for expanded assessment methodologies and a predictive tool on which to evaluate materials selection decisions, operational controls and chemical treatment in refinery amine units. This information should have significant economic benefits in terms of increased reliability, reduced failures and more efficient materials selection and chemical treatment. Finally, program sponsors will benefit by being able to have access to the same flow loop apparatus at InterCorr for conducting proprietary tests.
Over the past year, an engineering/research study has been in progress at InterCorr International focusing on developing corrosion data in amine environments using a laboratory flow loop run under simulated service conditions. This work, while only partially complete, has demonstrated substantial success in terms of being able to simulate corrosion in environments common to refinery amine units. The results from these tests have been utilized to evaluate and improve plant operations. However, the range of amine treatment conditions in refinery operations is broad. An expanded program is needed to better address a significant set of amine conditions from which more accurate predictive tools and practical assessment methodologies can be developed.
The experimental method used in the program has been to define sets of test conditions that are relevant to amine units in refinery operations. Once a baseline database has been established, several tests have followed which explored the role of a specific variable (e.g. acid gas loading or velocity) in separate tests. This approach is in specific contrast to a statistical experimental design where a mathematically determinant matrix of tests is defined which involve changing multiple variables with each test. While, in some cases the statistical approach has certain merits, the single variable approach is being employed in this study to define the specific regions of corrosion performance for each alloy while paying close attention to conditions where large incremental changes in corrosion rate are occurring (i.e. threshold conditions). This latter approach is admittedly slower but it (1) allows for more direct interim evaluation of the test results, (2) utilizes the interim results to define the selection of subsequent test conditions, (3) provides the ability to focus the studies under test conditions that relate to specific operating conditions of high interest, and (4) facilitate input of data into a parametric corrosion model embodied in a software tool for prediction and assessment of amine corrosion.
Thus far, a major accomplishment in the initial effort has been the demonstrated ability to evaluate specific test variables in a controlled rheological environment. This has proven to yield the ability to generate data relevant to specific plant conditions. Additionally, both practical experience and the experimental data produced thus far show that velocity is a critical parameter in amine corrosion process. Consequently, the flow loop approach currently in use at InterCorr has been shown to handle the full range of test conditions anticipated in this program. This will allow for the major portion of the program efforts to go toward the development of engineering data and not test method development.
The present study will involve a series of tasks containing sets of tests developed to address specific questions related to amine corrosion. This proposal specifically addresses involves the development of corrosion rate data for carbon steel for a range of environments and velocities related to treatment of H2S-containing refinery streams where H2S loading and velocity are the principal variables for regularly used amine solvents and concentrations. The proposed work will also include parametric studies of the effects of temperature, salt content, and CO2 loading. It will culminate in the development of an engineering data base and predictive tool embodied in a software format similar to Predict® developed by InterCorr in past programs and currently utilized by major companies worldwide.
Baseline Engineering Data Development
Task 1 - Development of Baseline Data Base for Sour MEA, DGA, DEA , Systems
This work will focus on the development of corrosion rate data in sour amine systems in the range of low and high H2S loading (up to 0.5 to 0.8 mole/mole) and a temperature of 130 F (55 C). A range of velocities will be investigated ranging from 0 to 80 ft/sec to produce desired levels of wall shear stress. The primary material to be included in this task will be carbon steel. However, AISI 304 will be included for comparison. These materials will be included in triplicate in each test. Three amine-based solvents will be included in this task. They include: 18% MEA, 45% DGA and 25% DEA.
The results from the initial tests on MEA and DGA (total of 12 tests) from this task are complete and will be available to sponsors in the first status report to be presented at the program kick-off meeting. This will occur when the necessary minimum number of companies establish their participation in the program to initiate activities. It is anticipated that this task will involve a total of about 40 tests. However, the exact number of tests may vary depending on the level of effort required for accurate simulation.
Parametric Data Development
Task 1 has been designed based on relatively simple matrices. This allows for maximum experimental control to clearly establish trends in corrosion rate as an independent function of a limited number of variables, namely H2S loading and velocity. This approach will produce specific baseline conditions for three amine solvents with low and high levels of H2S loading. Once Task 1 is substantially complete and the fundamental trends identified at the baseline conditions, effort will be placed on defining the influences of other key variables that are expected to impact amine corrosion. Based on the sponsor survey conducted in advance of this proposal [See website for meeting minutes at: http://www.intercorr.com/amine_prosp.htm ], the key parametric effects that will be addressed in this program for amine systems are: (1) service temperature and (2) CO2/H2S Ratio, (3) heat stable salts, and (4) organic acids.
Task 2 - Parametric Evaluation of Service Temperature
This Task will examine the influence of amine solution temperature on the corrosion rate of carbon steel and AISI 304 as influenced by velocity in combination with H2S loading and temperature. A total of 12 tests are estimated based on 3 amine solvents (MEA, DGA and DEA), 2 H2S loadings and 2 test temperatures at a fixed condition of wall shear stress. The two proposed temperatures to be used in Task 2 are 200 F and a second temperature to be selected once the data from the Task 1 and early Task 2 tests are available. Combined with the data from Task 1 conducted at 130 F (55C), these tests will effectively yield three conditions from which the temperature relationship can be identified. However, the specific test conditions for Task 2 will be finalized based on examination of the experimental results obtained in Task 1.
Task 3 - Parametric Evaluation of CO2/H2S Ratio
Task 3 will examine the influence of CO2 on the corrosion rate of carbon steel and AISI 304. This series of tests will produce corrosion data to define the contribution of CO2 at a fixed acid gas loading in combination with a fixed wall shear stress at 130 F. A total of 6 tests are estimated based on 2 CO2/H2S ratios and 3 amine solvents at a fixed condition of wall shear stress and temperature. Combined with the data from Task 1 where no CO2 was added, these tests will effectively yield three conditions from which the CO2 effect can be identified. The two H2S ratios will be selected based on examination of the experimental results obtained in Tasks 1 and 2.
Task 4 - Parametric Evaluation of Heat Stable Amine Salts (HSAS)
These series of tests will examine the influence of HSAS on the corrosion rate of carbon steel and AISI 304. A mix of salts to be used in these tests will be selected to be specific to each of the three amine solvents included in this task (MEA, DGA, DEA). This series of tests will produce corrosion data to define the influence of salt concentration at a fixed acid gas loading in combination with a fixed wall shear stress at 130 F. A total of 6 tests are estimated based on 2 HSAS concentrations and 3 amine solvents at a fixed condition of wall shear stress. Combined with the data from Task 1 where no salt was added, these tests will effectively yield three conditions from which the influence of HSAS can be identified. The two salt concentrations are expected to include a low and high concentration up to a maximum of 2 wt. percent. However, the exact conditions will be selected based on examination of the experimental results obtained in Task 1 through 3 and input from the sponsors.
Task 5 - Parametric Evaluation of Organic Acids
Task 5 will examine the influence of organic acids (e.g. formic, oxalic and acetic acids) on the corrosion rate of carbon steel and AISI 304. A mix of organic acid salts (e.g. formate, oxalate and acetate) will be used in these tests. These will be selected specifically for each of the three amine solvents included in this task (MEA, DGA, DEA). This series of tests will produce corrosion data to define the influence of concentration at a fixed H2S loading and velocity at 130 F (55 C). A total of 6 tests are estimated based on 2 concentrations of organic acid salts and 3 amine solvents at a fixed condition of wall shear stress. Combined with the data from Task 1 where no organic acid salts were added, these tests will effectively yield three conditions from which the influence of organic acid salts can be identified. The two organic acid salt concentrations will be selected based on examination of the experimental results obtained in Task 1 through 4.
Task 6 - Parametric Matrix Optimization
An additional 10 tests have been identified that will be used to fill-in needed areas in any of the matrices in Tasks 1 through 5. These "Wild-Card" tests will be used after review of the data with the sponsors and once a consensus has been reached as to the need for additional data to better define certain parametric relationships. These tests can also be used to confirm existing data or to examine combinations of variables not included in the program as currently defined.
Development of A Predictive Software Tool
Task 6 - Development of Predict-Amine
Once a significant portion of the data from this program is available, InterCorr will incorporate the data and related rules developed from the experimental effort into a new software program. This will be similar in nature and functionality to its currently available Predictâ program (See Appendix I) and the software being developed under joint industry sponsorship for refinery ammonium bisulfide (sour water) corrosion (Predict-SW).
Predict is a user-friendly Windows-based corrosion prediction tool that was originally developed in 1994. It was originally used to take inputs of typical operating parameters to assess corrosion rates of steels in multiphase oilfield production environments containing H2S and CO2. Predict-SW has been developed to handle assessment of various sour water parameters to predict the rate of ammonium bisulfide corrosion for materials commonly used in refinery units. The new software tool originating from this program (Predict-Amine) will incorporate this program data, related rules and any other appropriate data and experience (1) available in the published literature on amine corrosion, (2) submitted from sponsor companies on a voluntary basis and (3) provided in applicable industry standards. During the development, the sponsors will review the technical basis of the software and have access to a Beta-version of the program for review and comment. At the conclusion of the Phase I program, sponsors will obtain a single user license for the Predict-Amine software. The Predict-Amine software will not be made available to non-sponsors for a period of two years after its offering to the sponsors of this program.
The technical effort described in this Phase I program proposal will involve testing capabilities and technical specialists from InterCorr International, Inc. InterCorr will provide both technical capabilities and expertise and important business functions that will include responsibilities for overall program management, contractual matters and development of and liaison with the sponsoring group.
The Program Manager for this JIP effort will be Dr. Michael S. Cayard, President of InterCorr International, Inc. Dr. Cayard has over 12 years of experience in materials and corrosion engineering and research activities. Specifically, he has led numerous contract efforts for client companies and has served as Program Manager and/or Principal Investigator to several major joint industry sponsored programs including those in the areas of refinery sour water corrosion, wet H2S cracking and API funded research efforts in large-scale evaluation of these phenomena. He will be assisted by Mr. Sridhar Srinivasan, Manager of the InterCorr Software and Internet Services Division, for software programming expertise and Dr. Russell D. Kane, Vice President of InterCorr, as technical advisor in the areas of corrosion simulation and laboratory testing.
InterCorr International Inc. will conduct the experimental program described herein. It has the unique technical expertise, specialized laboratory testing and computer programming capabilities vital to the success of this multidisciplinary program.
InterCorr has a track record of successful completion of major joint industry sponsored research and engineering data development programs with specific emphasis on the needs of the petroleum industry. This includes work in the areas of wet H2S cracking, high temperature naphthenic acid and sulfidic corrosion, and amine and sour water corrosion. InterCorr has developed and operated sophisticated flow loop systems for simulation of petroleum service environments under conditions of high pressure, high temperature and high flow rate also involving exposure to H2S, CO2, crude oil and a variety of aqueous solutions.
Program Administration, Schedule, Cost and Reporting
The program presented herein will be funded by joint industry support. Each participating sponsor company will be required to pay only a small portion (<10 percent) of the total program cost. This benefit provides substantial cost savings and leveraging of valuable corporate funds while providing access to the results from a major technical effort in amine corrosion.
To qualify as a sponsor of the program, each company must sign a participation agreement and make timely payments of the program sponsorship fee. The greatest economic leveraging will be given to the Original Sponsors of the program that establish their participation at the beginning of the Phase I program. Sponsors that join later will be classified as Late Sponsors and will incur an additional late fee of 25 percent after the first three months of the program. This late fee will be increased to 40 percent for those Late Sponsors that join after the first 12 months of the effort.
Furthermore, the results and the associated software from this program will be held in confidence among the sponsoring companies for a period of at least two years from its release to the program sponsors. Non-sponsor companies desiring to obtain the program results and software during this confidentiality period will have to pay a fee 50 percent higher than that paid by the Original Sponsors. This arrangement gives program sponsors maximum leveraging of their sponsorship fee.
The program is anticipated to run over a period of approximately twenty-four (24) months. The program will start when three (3) companies establish their participation. At this level of participation, The companies will receive the initial Task 1 data developed for Koch Petroleum and the additional Task 1 data to be developed in this program. Once the number of sponsoring companies increases to six (6), Tasks 2 and 3 will be completed and a preliminary Beta version of the Predict software will be made available to sponsor representatives for evaluation purposes. Tasks 4 through 6 will be completed when a total of at least ten (10) companies have established their participation in this program.
Please contact Dr. R.D. Kane for current participation fee structure at firstname.lastname@example.org or tele: 281-444-2282.
At the completion of each task, the data will be organized into a topical report and supporting database summarizing the results and major findings. These reports will include analysis of the data and interpretation relative to important aspects of the results (i.e. key findings). These data will be provided in both tabular and graphic form. Where possible, plots will be made showing regions of corrosion behavior using isocorrosion lines for the alloys evaluated to the extent possible from data obtained in the various tests. All program data, documents, reports, and sponsor discussion thread will be archived on a secure, password protected web site (See: http://www.intercorr.com/multi/amine/index.htm) to be maintained by InterCorr for the sponsors for at least the duration of the program. This feature will provide ease of access to the program results to authorized sponsor company representatives.
InterCorr International, Inc.
InterCorr International, Inc., (located in Houston, Texas) is an independent technology company that specializes in the technology needs of industry in the area of materials and corrosion research and engineering. It has three operating divisions that provide
Headquartered in Houston, InterCorr provides industry with quick response, results-oriented solutions to problems involving corrosion in a multitude of industries. InterCorr provides testing, consulting and related technical services in facilities located in Houston and has a Technology Center in the U.K. InterCorr also can provide custom test equipment for sale to companies for their own laboratories. In the field, the company provides equipment (SmartCet and CHx) for monitoring corrosion on-line and in real-time, coupled with sophisticated corrosion management and prediction software. InterCorr personnel have a depth of experience and expertise unparalleled in corrosion, working with more than 850 clients in 31 countries, including major companies -- from the China to the North Sea and Calgary to Brazil.
We look forward to your company's participation in this exciting, new technical program that is in support of the research and engineering needs of the petroleum refining industry. If you would like to receive agreements to establish your company's sponsorship or if you would like further information, please contact the following:
Dr. Russell D. Kane
Original Predictâ Software Description
Predict was conceived in 1994 as a new generation software tool that addresses one of the most significant issues in corrosion evaluation, i.e., assessment and prediction of corrosion rates for materials exposed to corrosive environments. The Original Predict, a result of years of H2S/CO2 corrosion research and modeling, puts to good use application of state-of-the-art software technology to provide access to a comprehensive knowledge on corrosion rate prediction and decision-making. It's easy-to-use graphical interface integrates the effects of a complex set of environmental parameters to provide a corrosion rate assessment based on extensive literature data, lab testing and field/plant experience. The Predict concept has been expanded to include domain expertise related to areas of interest in plant operations including sour water corrosion and amine corrosion.
Predict performs a rigorous evaluation of corrosive environments and provides a prediction of maximum potential corrosion rate of steels. Incorporates comprehensive and accurate corrosion modeling to account for the effects of a number of critical parameters. It also provides decision-making rules for corrosion characterization on the basis of a corrosion model that accounts for the interaction of many critical parameters utilizing heuristics, operating experience and laboratory data. Determines annualized and present worth cost as a means to conducting cost analyses to compare different material choices.
Predict is aMicrosoft® Windows based tool that can run on most common personal computers (single user version) and network systems (multi-user systems). Its easy to use graphical interface makes using the system a simple task. Predict incorporates extensive on-line help and assists the user in understanding the significance of different corrosion evaluation parameters. Its Cost analysis module facilitates comparison of project cost when using different materials. Predict can be easily installed on any stand-alone or network system compatible with Windows/Windows NT/Windows for Work groups/Windows-95, 98 operating system. It has been shown to result in significant reduction in time spent assessing corrosion and can be a means for obtaining cost-effective automated solutions and interface with other computer assisted engineering operations such as risk based inspection and fitness-for-service applications. Predict users can also have access to extensive consulting and development support from InterCorr in using/customizing Predict for their specific (and proprietary) uses.
Original Predict User Interface
Further information is available online at:
InterCorr International, Inc.
14503 Bammel-N. Houston, Suite 300
Houston, Texas USA 77014
Tel: 281 444-2282, Fax: 281 444-0246
copyright 2000 InterCorr International, Inc.