Paitoon Tontiwachwuthikul

Part 1: Design, modeling and simulation of post-combustion CO2 capture systems using reactive solvents

The simulation and modeling of post-combustion CO2 capture systems are considered to be an important strategy to obtain process integrity and gain design confidence for the construction and commissioning of commercial post-combustion CO2 capture plants. It is therefore essential to obtain an understanding of the fundamental concepts of designing and modeling. This article reviews the concepts of designing a CO2 capture system with specific emphasis on the absorber for diameter and height. It covers several steps (i.e., empirical design method, theoretical design method, laboratory method and pilot plant techniques) used to design the absorber. A conceptual design of an overall CO2 capture process is also given in the article. Process validations of the modeling using ProMax with four existing pilot plants. (the International Test Centre of CO2 Capture pilot plant, the Esbjerg CASTOR pilot plant, the Institute of Thermodynamics and Thermal Process Engineering, Stuttgart pilot plant and the SINTEF/NTNU pilot plant) are presented. Moreover, a discussion of process integration of the CO2 capture plant into a fossil fuel-fired power plant is included in this paper.

Part 5b: Solvent chemistry: reaction kinetics of CO2 absorption into reactive amine solutions

Reaction kinetics is one of the most important parameters for the amine-based CO2 capture process because it indicates how fast CO2 reacts with amine, and it is one of the key parameters required for simulating and designing the absorption column. Reaction kinetics has been studied for several decades to aid the understanding of the reaction mechanism, obtaining the kinetics data and understanding the kinetics behavior. This article will comprehensively review these research activities from past to present and look at the future perspective of the study of CO2 absorption kinetics.

Part 5c: Solvent chemistry: solubility of CO2 in reactive solvents for post-combustion CO2

Concerns about climate change have propelled research efforts to develop affordable and environmentally benign technologies to capture CO2 from large emission sources, which can subsequently be used either for enhanced oil recovery or stored in other geological storage sites. The study of the solubility of CO2 in solvents is therefore of great interest, both from the theoretical and practical points of view. To screen solvents or to design CO2 capture processes, knowledge of the equilibrium solubility of CO2 in the solvents is necessary. A large body of solubility data of CO2 in aqueous and non-aqueous solutions of prominent industrial amines are available in literature. We present such data along with a description of the experimental techniques and thermodynamic models used. Innovations made to obtain an optimum solubility of CO2 and to minimize the energy cost of a desired CO2 capture system by adopting different kinds of solvents are also reviewed.

Recent progress and new development of post-combustion carbon-capture technology using reactive solvents

†Author for correspondence: 1International Test Centre for CO2 Capture (ITC), Faculty of Engineering and Applied Science, University of Regina, 3737 Wascana Parkway, Regina, Saskatchewan S4S0A2, Canada; 2Joint International Center for CO2 Capture and Storage (iCCS), Department of Chemical Engineering, Hunan University, Changsha, 410082, People’s Republic of China Tel.: +1 306 585 4160; E-mail: paitoon@uregina.ca *Full affiliations provided at the end of the article. The capture of CO 2 from industrial flue gases has become an important issue in recent years. The threat of climate change from increased levels of greenhouse gases (GHGs) in the atmosphere is significant. Mean global temperatures are on the rise and various regions of the world have been experiencing adverse climate issues. For example, polar ice caps are melting at an alarming rate, heat waves and droughts are becoming commonplace and the occurrence of violent weather has increased around the globe. Therefore, the need for research and development of cost-effective CO 2 capture technologies is urgent. Energy-related activities accounted for 81% of total GHG emissions in Canada in 2008 and large stationary sources accounted for over 46% of total GHG emissions (as indicated in Canada’s 2008 Greenhouse Gas Inventory [101]. It is worthy to note that CO 2 accounts for 78.2% of Canada’s total GHG emissions. In addition, according to the International Energy Agency (IEA) World Energy Outlook (2009) predictions, worldwide energy-related CO 2 emissions will reach 40.2 gigatons by 2030 (which is correlated with a 6°C increase in global temperature) unless strong efforts are made to achieve the newly agreed upon target of stabilizing greenhouse gas concentrations at 450 ppm CO 2 equivalent. In the IEA’s 450 Scenario, which represents the projected outcomes if GHG emissions are limited to 450 ppm CO 2 equivalent, implementation of technologies such as carbon capture and storage before 2015 is critical to meeting the necessary emissions targets. Since coal is relatively inexpensive and exists in abundant quantities around the world, it is likely that it will remain the fuel of choice at thermal power stations for decades to come. If CO 2 emission rates at these facilities can be reduced in a cost-effective manner, the anthropogenic contribution to global warming will be minimized. Carbon-capture and storage (CCS) is expected to contribute nearly 20% of global GHG emission reductions by mid-century. The technologies and research results described in this submission represent some of Paitoon Tontiwachwuthikul†,1,2, Raphael Idem , Don Gelowitz et al.

Part 3: Corrosion and prevention in post-combustion CO2 capture systems

This article is part 3 of the review series on ‘Recent progress and new development of post-combustion carbon capture technology using reactive solvents’. This review focuses on alkanolamine absorption during post-combustion CO2 capture from coal-fired flue gas, looking at a range of absorbents, including those that are commonly used, as well as blended and new solvents. The effects on corrosion of blended and new absorbents and process parameters (e.g., amine concentration, CO2 loading, oxygen concentration, SO2 concentration and temperature) are reviewed. Also reviewed is the effect of corrosion on the formation of heat-stable salts in the absorbent stream, as well as the presence of impurities in flue gas. Finally, corrosion mechanisms are discussed and corrosion inhibition approaches are reviewed.

Part 6: Solvent recycling and reclaiming issues

Purification of solvents is required to maintain quality and absorption capacity for better performance and economics for CO2 capture plants. An effective technique is needed to separate degradation products from their parent amines to prevent operational problems such as corrosion, foaming, fouling and change of solvent physicochemical properties. To overcome these problems, an amine reclamation process is used to clean up the solvent. Over 30 years ago, only five amine clean-up methods – solvent changeover, solvent purging/feeding, mechanical filtration, activated carbon filtration and neutralization of organic/inorganic acids – existed, which are reviewed in this article. More specific and advanced approaches developed later to achieve more effective removal of impurities and degradation products from the solvents are also summarized. This article also gives future trends for reclamation techniques in amine-based CO2 capture processes including hybrid processes or improvement of the current technologies such as extraction, ion exchange, thermal distillation and electrodialysis.

Part 2: Solvent management: solvent stability and amine degradation in CO2 capture processes

Solvent stability in CO2 capture from industrial flue gases is one of the most significant parameters that needs to be closely monitored to maintain the highest efficiency in the carbon CO2 absorption operation. Amines used in the capture process are known to degrade, resulting in the most serious degree of solvent loss in CO2 capture from flue gases. Reactive constituents in flue gas, specifically O2, SO2, nitrogen oxides (NOx) and inorganic oxide fly ash, competitively react with amines, leading to irreversible decomposition of amine into various degradation products. Because of degradation, the absorption efficiency deteriorates and corrosion problems occur. In this article, we review research activities in amine degradation from past to present for CO2 and sulfur compound-induced degradation. Research conducted on oxidative degradation of amines before and after 2000 is also reviewed, including our works undertaken at the International Test Centre for CO2 Capture and works by other researchers.

Applications of three data analysis techniques for modeling the carbon dioxide capture process

The objective of this paper is to study the relationships among the significant parameters impacting CO2 production. An enhanced understanding of the intricate relationships among the process parameters enables prediction and optimization, thereby improving efficiency of the CO2 capture process. Our modeling study used the operational data collected over a 3-year period from the amine-based post combustion CO2 capture process at the International Test Centre of CO2 Capture (ITC) located in Regina, Saskatchewan of Canada. This paper describes the data modeling process using the approaches of: (1) statistical study, (2) artificial neural network (ANN) modeling combined with sensitivity analysis (SA), and (3) neuro-fuzzy technique. It was observed that the neuro-fuzzy modeling technique generated the most accurate predictive models and best support explication of the nature of the relationships among the key parameters in the CO2 capture process.

Inferential modelling technique for constructing second generation knowledge based systems

A novel inferential modeling technique (IMT) which aims to first clarify the domain ontology and inferences before proceeding onto the dynamic processing aspects of expertise is presented. The proposed model consists of the four levels of strategy, task, inference, and domain layers. The former two levels constitute the dynamic component and the latter two the static component. The static representation consists of the domain primitives and their interrelations, while the dynamic component represents a variety of tasks or activities which manipulate the domain entities in order to accomplish objectives. It is argued that the technique is useful as a tool in the elicitation and analysis phases of the development of a knowledge-based system. A preliminary application of the technique for constructing a knowledge-based system in the chemical engineering domain is described.<<ETX>>

Life cycle assessment of a hypothetical Canadian pre-combustion carbon dioxide capture process system

The methodology of life cycle assessment was applied for evaluating the environmental performance of a Saskatchewan lignite integrated gasification combined cycle (IGCC)-based electricity generation plant with and without the pre-combustion CO2 capture process. A comparison between the IGCC systems (with and without CO2 capture) and the competing lignite pulverized coal electricity generating station was conducted to reveal which technology offers more positive environmental effects. The results showed significant reduction of GHG emissions where both post- and pre-combustion CO2 capture processes are applied. With the application of the CO2 removal technology, GHG emissions were reduced by 27–86%. The performances of the IGCC systems were superior to those of the pulverized coal systems. However, in terms of other environmental impacts, multiple environmental trade-offs are involved depending on the capture technology. For the post-combustion CO2 capture process system, it was observed that the environmental impact was shifted from the air compartment to the soil and water compartments. The IGCC systems showed the same tendency of shifting from air pollution to soil and water pollution, but the amount of pollution is less significant. This is likely because the IGCC system operates at higher efficiencies; hence, it requires less fuel and produces fewer emissions.