Simulation of amine units for carbon capture and gas treating in AVEVA™ Process Simulation

Posted: April 04, 2025

Traditional process simulators for amine treating can typically model only the amine unit and its related systems. However, modern process engineers need a software tool that can simulate the entire process¾which may include the downstream liquefied natural gas (LNG) plant or the steam-methane reformer (SMR) unit, as well as associated systems of flare, cooling water, steam and fuel gas, along with pipeline gathering and distribution networks—in a single platform. This single platform for comprehensive process design reduces design risk and cost, optimizes energy and sustainability, and enhances collaboration and decision support between cross-functional teams.

AVEVA Process Simulation is this single simulation platform. It has numerous advantages for simulation users:

1. Electrolytic NRTL-based framework with rigorous rate-limited, mass transfer modeling of amine units for carbon capture and gas treating, with primary, secondary and tertiary amines, as well as amine blends and activated amine solvents
2. Seamless transition between Steady State, Fluid Flow/Rating and Dynamic modes, all in the same interface
3. Equation-oriented (EO) solver means that models do not need controllers/adjusts, and any specifications can be swapped and used as inputs
4. Regress custom/proprietary amine solvents (including properties and reaction data) easily
5. Open equation modeling foundation where users can easily modify a unit operation’s underlying equations or write new equations
6. Simulation models run approximately 10-20x faster than traditional sequential modular (SM) simulators with large models and a lot of recycles
7. Built-in integration with live data from AVEVA™ PI System or AVEVA™ Historian, including data reconciliation (error minimization), to create an online digital twin
8. Native multi-variable optimizer to maximize or minimize a variable or function
9. Integration with AVEVA™ Unified Engineering, for data exchange between process simulation and engineering drawing and design tools (including 1D, 2D and 3D plant models)

Why mass transfer models improve amine unit simulations

Initially, process simulators for amine units used equilibrium stages with reaction rate effects.  However, equilibrium stage models do not capture the effects of rate-limited mass transfer characteristics and performance of the actual column’s physical hardware. Equilibrium stage models consider the number of ideal/theoretical stages in a tower, while equipment vendors, solvent providers, engineering companies and owner operators need actual tray counts, types and passes (for trayed columns), or packing depth and volume of specified size, type and material (for packed columns). With ideal stages, translation between the ideal and real is an open question and oftentimes requires user-supplied or internally generated empirical corrections.^[1]

On the other hand, mass transfer rate models use the actual number of real trays supplied by the tray vendor, or the actual depth of the physical packing fabricated by the packing vendor. For example, one expects a column containing 40 feet of 1Y-style structured packing to give different mass transfer performance from the same column packed with 40 feet of IMTP-25 random packing, or 20 conventional valve trays.^[2]

In summary, a mass transfer, rate-based simulation model combines material balances, phase equilibrium, chemical kinetics, and the mass transfer characteristics of tower internals into a comprehensive, reliable, predictive method. This simulation methodology is needed for carbon capture and gas treating in the industry today, as it allows engineers to design and predict the performance of new facilities where no operating data or field experience exists, while enabling them to meet global decarbonization targets. This is the methodology used for amine modeling in AVEVA Process Simulation.

To learn more about how to use AVEVA Process Simulation for carbon capture modeling, watch our on-demand webinar below.

^{[1] Behradi, R, Kh. Mohamadbigy, M. Bazmi, R. Binesh. Research Institite of Petroleum Industry, Tehran, Iran. (November 11, 2005). Amine Absorption Column Design Using Mass Transfer Rate Simulation. chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www.vurup.sk/wp-content/uploads/dlm_uploads/2017/07/PC_2_2005_Mohamadbighy.pdf
[2] Seagraves, Jenny and Ralph Weiland. Digital Refining. (February 2007). Troubleshooting amine plants using mass transfer rate-based simulation tools. https://www.digitalrefining.com/article/1000877/troubleshooting-amine-plants-using-mass-transfer-rate-based-simulation-tools}