Amine Sweetening

For over two decades, TSWEET was known as the industry standard for simulating amine sweetening facilities. In an effort to better serve our clients, BR&E has now incorporated TSWEET into ProMax. This union has significantly enhanced the capabilities of our software, especially in the area of amine sweetening. Benefits include more complete thermodynamic models, calculation of more thermo-physical properties and better integration with hydrocarbon packages and unit operations. These benefits allow you to model many more processes such as complex absorber / stripper configurations, three-phase flashes and oils in amine units. The following amines are available either individually or as blends: MEA, DEA, DGA, MDEA, DIPA, TEA, and AMP. ProMax also introduces BR&E’s new Electrolytic-ELR model. This new model is a significant improvement to the NRTL acid gas model in TSWEET. The sweetening package also continues TSWEET’s unprecedented ability to model selective absorption using CO₂ kinetics.

Benefits:

Model virtually any amine unit configuration
Best available predictions of amine solutions-acid gas VLE as well as actual plant data
Model real or ideal stages in absorbers and strippers
Optimize the type of amine, amine flow rate and reboiler duty
Determine hydrocarbon / BTEX absorption in amine solutions

Applications

Almost any amine unit flow scheme may be simulated, including multiple absorbers in series or parallel, multiple strippers, split flow units, multiple feeds to absorbers and strippers, water wash, multiple semi-lean product withdrawals from the stripper, steam or natural gas injection into the stripper reboiler, flash gas absorbers, etc. Liquid hydrocarbon treating can also be performed.

Ionic Information for a Process Stream

Ionic Information reports the overall Ionic Strength of an aqueous stream, and the following properties for each species: Molar Flow, Mole Fraction, Mass Flow, Mass Fraction, Molarity, and p[Molarity].
Ionic Strength is one-half the summation of the product mole fraction times ionic charge squared for all the ionic species present in the solution:

where x is the mole fraction of species i and z is the ionic charge for species i.

Display of ionic species for liquid streams

TSWEET Kinetics Model

A kinetic model for the CO₂-amine reaction which predicts the selective absorption of H₂S from streams containing both CO₂ and H₂S is included in ProMax. If CO₂ is present in the sour gas stream, the TSWEET Kinetics model must be used, except for liquid hydrocarbon treating. (The TSWEET Kinetics Model is not applicable to liquid treating).

Specifier/Solver Applications

Set the Reboiler Steam Rate Relative to the Amine Circulation Rate - If circulation rate changes, the steam rate will change to maintain the same lb/gal steam. In the Specifier dialog, the Independent Variable is the lean amine circulation rate, and the Specified Variable is the steam rate providing heat to the reboiler.

Rich Amine Loading - A Simple Solver may be used to manipulate the amine solution circulation rate to achieve a specified rich amine acid gas loading. In the Simple Solver dialog, the Measured Variable is the acid gas loading in the Amine Analysis for the rich stream. The Calculated Variable is the amine circulation rate specified in a lean amine stream.

Sweet Gas Specification - A Simple Solver can manipulate some parameter such as amine solution circulation rate, stripper steam rate, hardware parameter (e.g. Diameter, Weir Height), etc. to meet a sweet gas specification. In the Simple Solver dialog, the Measured Variable is the concentration of H₂S or CO₂ in the sweet gas. The Calculated Variable is the parameter such as circulation rate or steam rate which is being manipulated.

Lean Amine Loading - Manipulate reboiler duty or reboiler steam rate to achieve a specified lean amine loading. In the Solver dialog, the Measured Variable is the acid gas loading in the Amine Analysis for the lean stream. The Calculated Variable is the reboiler duty or steam rate.

Lean Loading (Stand Alone Absorber) - Add acid gas to an amine solution stream via a mixer to achieve a certain lean loading. In the Solver dialog, the Measured Variable is the lean loading calculated for the mixed steam via an Amine Analysis, and the Calculated Variable is the flow rate of acid gas mixed with the amine solution.

Amine Analysis

Rich and/or lean acid gas loadings can be checked easily by adding an Amine Analysis to an aqueous amine stream. See Amine Analysis for details.

Determining the Lean and Rich End Pinch for an Absorber

In amine sweetening applications, the Lean Approach and Rich Approach absorber specifications allow the user to view useful information indicating how close the system is to equilibrium conditions, usually at the top or bottom of the absorber. For example, if the Lean Approach for H₂S in the overhead vapor is 10%, and the Rich Approach for H₂S at the bottom is 99% of Maximum Loading, the absorber is "rich end pinched" and the circulation rate should be increased to assure stable operations.

Lean End Pinch

In amine sweetening applications, the "lean end pinch" in an absorber is an indication of how close the composition of acid gas in the vapor exiting overhead is to equilibrium relative to the inlet lean amine fed to the absorber. Thus it is the equilibrium composition divided by the actual composition.
If a significant amount of CO₂ is slipped overhead in the absorber, as in most MDEA cases, the lean approach may be a very low number (e.g. 0.1%).
When current operations are not satisfactory, lean approaches of 90+% indicate that neither additional stages nor additional circulation can be expected to produce a cleaner overhead product. Lower values for the Lean Approach indicate what changes to the unit can significantly improve the performance. If the Rich Approach is high (75+%), improved performance can be achieved by increasing circulation rate (provided that lean solvent purity can be maintained), while if the Rich Approach is low, improved performance can be achieved by adding ideal stages to the absorber (more trays, greater depth of packing, or more efficient trays or packing).

Rich End Pinch

The "rich end pinch" in an absorber is an indication of how close the rich amine is to equilibrium or maximum loading with respect to the sour gas feed. Thus it is the actual loading divided by the equilibrium loading.
The Rich Approach value decreases as the ratio of solvent circulation to gas feed rate increases.
If a significant amount of CO₂ is slipped overhead in the absorber, as in most MDEA cases, the rich loading may not ever be high enough to get very close to equilibrium loading.
The percent equilibrium loading is the percentage of maximum loading with respect to the entering acid gas. If the program calculates 75% of max load (.75 rich approach) and the rich loading is 0.3, then the circulation rate is decreased such that the rich load is 0.4, the rich approach should be 100%.

Hydrocarbon Solubility in Ethanolamine Solutions

Hydrocarbons exhibit greater affinity for aqueous amine solutions than for water. Recent interest in measuring hydrocarbon solubility in aqueous ethanolamine solutions has led to a number of published data sets for hydrocarbon-ethanolamine solubility.
A hydrocarbon solubility model is included in Electrolytic ELR and Electrolytic Kent-Eisenberg property packages with parameters which have been fitted using experimental data treating the hydrocarbons as Henry’s law components.
Solubility for methyl mercaptan, ethyl mercaptan, isomers of n-propyl mercaptan, and isomers of n-butyl mercaptan in ethanolamine solutions has also been added to Electrolytic ELR and Electrolytic Kent-Eisenberg Property Packages.
In general, hydrocarbon solubility increases with increasing amine concentration, and decreases as the amine solutions become more heavily loaded. Hydrocarbons also show greater solubility as the temperature increases. In the VLE region, as the pressure increases the hydrocarbon solubility increases. However, in the LLE region, pressure has little effect on hydrocarbon solubility. Aromatic hydrocarbons are more soluble in amine solutions than paraffinic hydrocarbons.


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Free SixxacMenu module license Capabilities Amine Sweetening Glycol Dehydration Heat Exchanger Rating Crude Oil Refining LPG Recovery NGL Fractionation Caustic Treating Sulfur and TGCU Reactors Sour Water Stripper Pipelines Vessel Sizing Other Processes Interface Flowsheet Drawing Multiple Flowsheets Project Viewer Reporting Property Packages Extensibility TSWEET PROSIM Client List Sales Information Testimonials	Amine Sweetening For over two decades, TSWEET was known as the industry standard for simulating amine sweetening facilities. In an effort to better serve our clients, BR&E has now incorporated TSWEET into ProMax. This union has significantly enhanced the capabilities of our software, especially in the area of amine sweetening. Benefits include more complete thermodynamic models, calculation of more thermo-physical properties and better integration with hydrocarbon packages and unit operations. These benefits allow you to model many more processes such as complex absorber / stripper configurations, three-phase flashes and oils in amine units. The following amines are available either individually or as blends: MEA, DEA, DGA, MDEA, DIPA, TEA, and AMP. ProMax also introduces BR&E’s new Electrolytic-ELR model. This new model is a significant improvement to the NRTL acid gas model in TSWEET. The sweetening package also continues TSWEET’s unprecedented ability to model selective absorption using CO₂ kinetics. Benefits: Model virtually any amine unit configuration Best available predictions of amine solutions-acid gas VLE as well as actual plant data Model real or ideal stages in absorbers and strippers Optimize the type of amine, amine flow rate and reboiler duty Determine hydrocarbon / BTEX absorption in amine solutions Applications Almost any amine unit flow scheme may be simulated, including multiple absorbers in series or parallel, multiple strippers, split flow units, multiple feeds to absorbers and strippers, water wash, multiple semi-lean product withdrawals from the stripper, steam or natural gas injection into the stripper reboiler, flash gas absorbers, etc. Liquid hydrocarbon treating can also be performed. Ionic Information for a Process Stream Ionic Information reports the overall Ionic Strength of an aqueous stream, and the following properties for each species: Molar Flow, Mole Fraction, Mass Flow, Mass Fraction, Molarity, and p[Molarity]. Ionic Strength is one-half the summation of the product mole fraction times ionic charge squared for all the ionic species present in the solution: where x is the mole fraction of species i and z is the ionic charge for species i. Display of ionic species for liquid streams TSWEET Kinetics Model A kinetic model for the CO₂-amine reaction which predicts the selective absorption of H₂S from streams containing both CO₂ and H₂S is included in ProMax. If CO₂ is present in the sour gas stream, the TSWEET Kinetics model must be used, except for liquid hydrocarbon treating. (The TSWEET Kinetics Model is not applicable to liquid treating). Specifier/Solver Applications Set the Reboiler Steam Rate Relative to the Amine Circulation Rate - If circulation rate changes, the steam rate will change to maintain the same lb/gal steam. In the Specifier dialog, the Independent Variable is the lean amine circulation rate, and the Specified Variable is the steam rate providing heat to the reboiler. Rich Amine Loading - A Simple Solver may be used to manipulate the amine solution circulation rate to achieve a specified rich amine acid gas loading. In the Simple Solver dialog, the Measured Variable is the acid gas loading in the Amine Analysis for the rich stream. The Calculated Variable is the amine circulation rate specified in a lean amine stream. Sweet Gas Specification - A Simple Solver can manipulate some parameter such as amine solution circulation rate, stripper steam rate, hardware parameter (e.g. Diameter, Weir Height), etc. to meet a sweet gas specification. In the Simple Solver dialog, the Measured Variable is the concentration of H₂S or CO₂ in the sweet gas. The Calculated Variable is the parameter such as circulation rate or steam rate which is being manipulated. Lean Amine Loading - Manipulate reboiler duty or reboiler steam rate to achieve a specified lean amine loading. In the Solver dialog, the Measured Variable is the acid gas loading in the Amine Analysis for the lean stream. The Calculated Variable is the reboiler duty or steam rate. Lean Loading (Stand Alone Absorber) - Add acid gas to an amine solution stream via a mixer to achieve a certain lean loading. In the Solver dialog, the Measured Variable is the lean loading calculated for the mixed steam via an Amine Analysis, and the Calculated Variable is the flow rate of acid gas mixed with the amine solution. Amine Analysis Rich and/or lean acid gas loadings can be checked easily by adding an Amine Analysis to an aqueous amine stream. See Amine Analysis for details. Determining the Lean and Rich End Pinch for an Absorber In amine sweetening applications, the Lean Approach and Rich Approach absorber specifications allow the user to view useful information indicating how close the system is to equilibrium conditions, usually at the top or bottom of the absorber. For example, if the Lean Approach for H₂S in the overhead vapor is 10%, and the Rich Approach for H₂S at the bottom is 99% of Maximum Loading, the absorber is "rich end pinched" and the circulation rate should be increased to assure stable operations. Lean End Pinch In amine sweetening applications, the "lean end pinch" in an absorber is an indication of how close the composition of acid gas in the vapor exiting overhead is to equilibrium relative to the inlet lean amine fed to the absorber. Thus it is the equilibrium composition divided by the actual composition. If a significant amount of CO₂ is slipped overhead in the absorber, as in most MDEA cases, the lean approach may be a very low number (e.g. 0.1%). When current operations are not satisfactory, lean approaches of 90+% indicate that neither additional stages nor additional circulation can be expected to produce a cleaner overhead product. Lower values for the Lean Approach indicate what changes to the unit can significantly improve the performance. If the Rich Approach is high (75+%), improved performance can be achieved by increasing circulation rate (provided that lean solvent purity can be maintained), while if the Rich Approach is low, improved performance can be achieved by adding ideal stages to the absorber (more trays, greater depth of packing, or more efficient trays or packing). Rich End Pinch The "rich end pinch" in an absorber is an indication of how close the rich amine is to equilibrium or maximum loading with respect to the sour gas feed. Thus it is the actual loading divided by the equilibrium loading. The Rich Approach value decreases as the ratio of solvent circulation to gas feed rate increases. If a significant amount of CO₂ is slipped overhead in the absorber, as in most MDEA cases, the rich loading may not ever be high enough to get very close to equilibrium loading. The percent equilibrium loading is the percentage of maximum loading with respect to the entering acid gas. If the program calculates 75% of max load (.75 rich approach) and the rich loading is 0.3, then the circulation rate is decreased such that the rich load is 0.4, the rich approach should be 100%. Hydrocarbon Solubility in Ethanolamine Solutions Hydrocarbons exhibit greater affinity for aqueous amine solutions than for water. Recent interest in measuring hydrocarbon solubility in aqueous ethanolamine solutions has led to a number of published data sets for hydrocarbon-ethanolamine solubility. A hydrocarbon solubility model is included in Electrolytic ELR and Electrolytic Kent-Eisenberg property packages with parameters which have been fitted using experimental data treating the hydrocarbons as Henry’s law components. Solubility for methyl mercaptan, ethyl mercaptan, isomers of n-propyl mercaptan, and isomers of n-butyl mercaptan in ethanolamine solutions has also been added to Electrolytic ELR and Electrolytic Kent-Eisenberg Property Packages. In general, hydrocarbon solubility increases with increasing amine concentration, and decreases as the amine solutions become more heavily loaded. Hydrocarbons also show greater solubility as the temperature increases. In the VLE region, as the pressure increases the hydrocarbon solubility increases. However, in the LLE region, pressure has little effect on hydrocarbon solubility. Aromatic hydrocarbons are more soluble in amine solutions than paraffinic hydrocarbons.