Post-combustion Capture Process Research Articles

Operability-economics trade-offs in adsorption-based CO2 capture processes

Dispatchable low-carbon power underpins the transition to a sustainable energy system, providing balancing load for the integration of intermittent renewable power. In such load-following operation, the post-combustion carbon capture process must be capable of highly transient operation. Here we have developed a computational framework that integrates process design, operability and techno-economic assessment of a pressure-vacuum swing adsorption process for CO2 capture. We demonstrate that the cost-optimal design has limited process flexibility, challenging reactiveness to disturbances in the flue gas conditions. Flexibility can be introduced by relaxing the CO2 recovery constraint on the operation, albeit at the expense of the capture efficiency of the process. We discover that adsorption-based processes can be designed to enhance flexibility, while improving performance with respect to the operational constraints on CO2 recovery and purity. The results herein demonstrate a trade-off between process economics and process operability, which must be rationalised to integrate CO2 capture units in low-carbon energy systems.

Post-combustion carbon capture process modeling, simulation, and assessment of synergistic effect of solvents

Post-combustion carbon capture appears to be a promising solution to reduce the emission of carbon dioxide (CO2) from power plants that generate electricity using either coal or natural gas. In addition, carbon capture process efficiency, capacity, and energy consumption have become challenging against the performance of the capture process. However, synergistic effect due to solvents blend has gained attention to reduce the process energy consumption and enhance process efficiency. In this study, blends of methyldiethanolamine (MDEA) and piperazine (PZ) at different concentrations were investigated using a validated post-combustion capture process model using Aspen HYSYS. Results were compared with 30 wt% monoethanolamine (MEA) as reference case. The effective process variables are concentration of solvents, the amount of water and solvent in the makeup section, viscosity of solvent, energy consumed in different process stages, and the amount of lean solvent flow rate. These variables were studied against fixed process variables using rate-based model. The study shows that using (43 wt% MDEA/7 wt% PZ) for post-combustion carbon capture needs 2.53 MJ/kgCO2 regeneration energy for 88.5% process efficiency compared to 4.003 MJ/kgco2 for 30 wt% MEA without the need for any process modifications. In addition, it was found that solvents synergistic effect contributes to resolving the drawbacks of post-combustion capture that will enable the high utilization of the process and contribution to reduce the consequences effect of climate change. Therefore, the study will help policymakers, industries and encourage researchers towards the large-scale commissioning of blended solvent -based post-combustion capture process.

Technical and economic performance assessment of blue hydrogen production using new configuration through modelling and simulation

Steam methane reforming (SMR) is the dominant process for hydrogen production, which produce large amount of carbon dioxide (CO2) as a by-product. To address concerns about carbon emissions, there is an increasing focus on blue hydrogen to mitigate carbon emissions during hydrogen production. However, the commercialization of blue hydrogen production (BHP) is hindered by the challenges of high cost and energy consumption. This study proposes a new configuration to address these challenges, which is characterized by: (a) the use of piperazine (PZ) as a solvent, which has a high CO2 absorption efficiency; (b) a more efficient heat exchange configuration which recovers the waste exergy from flue gas; (c) the advanced flash stripper (AFS) was adopted to reduce the capital cost due to its simpler stripper configuration. In addition, the technical and economic performance of the proposed energy and cost-saving blue hydrogen production (ECSB) process is investigated and compared with the standard SMR process. The detailed models of the SMR process and the post-combustion carbon capture (PCC) process were developed and integrated in Aspen plus® V11. The results of the technical analysis showed that the ECSB process with 30 wt.% PZ achieves a 36.3 % reduction in energy penalty when compared to the standard process with 30 wt.% Monoethanolamine (MEA). The results of the economic analysis showed that the lowest levelized cost of blue hydrogen (LCBH) was achieved by the ECSB process with 30 wt.% PZ. Compared to the BHP process with 30 wt.% MEA, the LCBH was reduced by 19.7 %.

High accuracy prediction of the post-combustion carbon capture process parameters using the Decision Forest approach

This paper investigates the relationships among the important process parameters that impact Post-combustion Carbon Capture (PCC) carbon dioxide (CO2) separation. A better understanding of the complex relationships among those parameters can support optimization and performance enhancement of the separation process. Being able to precisely predict the process parameters will enable the operator to determine the current state of the process, forecast any potential changes or events, and adjust process parameters to enhance the plant's performance. With the objective of studying the process parameters' correlations in the amine-based PCC process, we modeled the multi-year historical production data of the Clean Energy Technologies Research Institute (CETRi) (formerly known as the International Test Center for PCC or ITC) in Regina, Saskatchewan, Canada, using a Decision Forest approach. The model validation process revealed that the Decision Forest model produced higher predictive accuracy than previous efforts. The Decision Forest models we developed also represent knowledge about the importance of parameters involved in the capture process, and such knowledge is useful for further optimization of the capture process in the future.

A technical and environmental comparison of novel silica PEI adsorbent-based and conventional MEA-based CO2 capture technologies in the selected cement plant

The cement industry accounts for almost 7 % of anthropogenic carbon dioxide emissions globally. Therefore, it is imperative to identify innovative solutions to mitigate carbon dioxide emissions from the cement industry.This study aims to evaluate and compare the technical and environmental aspects of integrating two post-combustion carbon capture processes (CCS) into a cement plant: the conventional monoethanolamine (MEA)-based CCS process and the novel silica-alkoxylated polyethyleneimine (SPEI)-based CCS process. Three scenarios were considered: (i) a reference cement plant without CCS, (ii) the conventional MEA-based CCS system integrated into a cement plant and (iii) the novel SPEI-based CCS system integrated into a cement plant. The technical evaluation results showed that the regeneration energy requirements for the conventional MEA and novel SPEI-based CCS processes were 3.53 GJ/tonne CO2 and 2.36 GJ/tonne CO2, respectively, to achieve a capture rate of 90 %. However, the performance of MEA-based carbon capture processes can be improved by using advanced amine formulations that offer lower regeneration heat requirements at 3.3 GJ/tonne CO2, although this is still higher than the SPEI-based carbon capture processes.The novel SPEI-based CCS process showed superior environmental performance compared to the conventional MEA-based CCS process. The endpoint single score was conducted which showed that the SPEI-based CCS process had a lower impact on human health, ecosystems, and resources (7 %, 9 %, and 26 % lower, respectively) compared to the MEA-based CCS process.

Cost optimization methodology based on carbon-techno-economic analysis: An application to post-combustion carbon capture process

Recently, a carbon tax has been introduced to encourage emissions reduction, and it has become an additional cost burden. To evaluate the carbon emissions and process costs simultaneously in a single indicator, a carbon-techno-economic analysis (CTEA) methodology that combines carbon tax and process cost was developed in this study. The proposed CTEA model was used to optimize the post-combustion carbon capture (PCC) process, which is an energy- and cost-intensive process. In CTEA optimization, as the carbon tax price increases from $12.5/tonne CO2 to $250/tonne CO2, more energy is provided to the PCC process to increase the carbon capture level from 58.92 % to 99.64 %. This results in a decrease in power generation of the natural gas combined cycle power plant from 462.33 MW to 436.07 MW, and an increase in the incremental cost of electricity from $14.05/MWh to $17.74/MWh. The decrease in profit from CTEA optimization is only 8.75 %, which is relatively smaller than the 11.68 % and 32.32 % decrease in profit from energy and TEA optimization, respectively. The results demonstrate that CTEA-based process optimization is beneficial and highlight the trade-off relationship among carbon tax, process cost, and profit. The results of this study can guide commercial companies in setting operational strategies for their processes as carbon tax prices change and can also assist governments in establishing carbon tax policies to encourage carbon emission reductions in industries.

Heat integration, process design and techno-economic assessment of post-combustion carbon capture using piperazine for large-scale ethylene plant

With the development of increasingly larger ethylene plants and the associated requirement to reduce carbon emissions effectively, there is a growing need to explore approaches that reduce the cost and energy consumption in carbon capture from ethylene plants. In this study, the flue gas heat recovery (FHR) strategy was proposed and implemented for different configurations of piperazine (PZ)-based post-combustion carbon capture (PCC) process applied to an ethylene plant with a capacity of 60,000 t/year. Four different cases of the PZ-based PCC process with or without FHR were simulated in Aspen Plus® V11 to explore the cost reductions and energy saving potential. The advanced flash stripper (AFS) configuration with FHR and absorber inter-cooling achieves a minimum regeneration energy requirement of 2.28 GJ/tonCO2, a reduction of 37.71 % compared to standard PCC configuration using MEA solvent. The economic evaluation was carried out using Aspen Process Economic Analyzer® (APEA). The results show that the carbon capture cost using AFS configuration with FHR and inter-cooling can reduce to 47.27 $/tonCO2, a reduction of 36.76 % against the standard PCC process using MEA. The proposed technology presents significant technical and economic benefits for the large-scale deployment of carbon capture for ethylene plants.

New improvement of amine-based CO2 capture processes using heat integration and optimization

The post-combustion capture process (PCCP) using amine-based solvent was the most mature and adequately researched carbon capture and storage (CCS) technology. Monoethanolamine (MEA) solvent regeneration in the stripper (desorption process) usually takes high energy consumption and a MEA make-up is required before re-entering the absorber (absorption process). To improve the CO2 capture efficiency and reduce the overall energy consumption of PCCP, four configurations (Design-1, Design-2, Design-3, Design-4) are presented, where Design-1 is denoted as the base case design. Design-2 is an extension of Design-1 by adding the side intercooler in the absorber. Design-3 is an extension of Design-2 by using internal heat integration in the stripper. Design-4 is an extension of Design-3 by adding the side interheater in the absorber. By using response surface methodology (RSM) in conjunction with central composite design (CCD), operating parameters (MEA solvent flowrate, MEA concentration, pressure) including side intercooler/side interheater locations of Design-2 to Design-4 are optimized. It is successfully validated that the side intercooler absorber could increase the CO2 capture ability by MEA solvent and the side interheater stripper with internal heat integration could effectively reduce energy consumption about 36% to 62%.

Application of post-combustion carbon capture process in marine diesel engine

ABSTRACT This study has investigated the effect of using a waste heat recovery system and carbon capture process on carbon reduction efficiency and the Energy Efficiency Design Index (EEDI) to reduce carbon emissions from ships. Organic Rankine Cycle (ORC) was used as waste heat recovery and ORC system turbine power was determined at variable engine loads. The effect of system parameters such as exhaust absorber inlet temperature, MEA concentration and flow rate, number of columns on carbon capture performance has been revealed in the carbon capture process. Furthermore, the EEDI was estimated using the existing system, the ORC system configuration, and the utilization of the carbon capture system. It has been determined that the optimal exhaust absorber inlet temperature is 50°C and the carbon capture performance is 95% on average. In the applied system, the EEDI is reduced by 14% with the ORC system and by 90% with the carbon capture system. ORC system turbine output power ranges from approximately 414 kW to 606 kW for variable CCS inlet temperatures for 100% load condition. Thus, the study predicts that the carbon capture system can effectively meet the regulations in case of using fossil fuels in the future.

Integration of adsorption based post-combustion carbon dioxide capture for a natural gas-fired combined heat and power plant

This paper proposes a continuous CO2 capture system for natural gas combined heat and power (CHP) facility and explores the potential of low-temperature vacuum-swing adsorption (VSA) process for post-combustion CO2 capture (PCC) in the context of carbon capture and storage (CCS). Although VSA has strong potential for efficient CO2 capture in district-scale energy systems, previous case studies have largely focused on high-emission coal combustion sources, making VSA application challenging for these conditions. We address this issue by theoretically designing a ready-to-operate flue gas cleaning process with CCS for a medium-sized 4.3 MW natural gas CHP operating in the local industry. Our in-depth analysis examines the most critical parts such as dehydration, involving condenser and temperature-swing adsorption (TSA), and CO2 capture via VSA. The conceptual design and performance of VSA are approached by developing a mathematical model to estimate the technology size and performance. This work shows that utilising a small fraction of heat recovered from CHP-generated flue gas is sufficient to supply the necessary heat for auxiliary units, and that using natural cooling water for dehydration effectively reduces moisture (87 vol%) and energy demand for final dehydration via TSA. Furthermore, it demonstrates that 4-step VSA consisting of 15 columns using zeolite 13X can separate CO2 with a desired purity of 90.4%, meeting the requirements for CO2 storage and transportation onshore, at a 15.6% recovery rate. The cost of achieving high CO2 purity without pre-pressurising the CO2-rich flue gas, while maintaining cycle simplicity, is discussed. Overall, our paper provides a comprehensive approach to retrofitting distract-scale power plants with CO2-lean emissions, presenting a ready-to-operate flue gas cleaning technology based on real operating conditions and technical restrictions, which can contribute towards decarbonisation.

Machine learning based modelling and optimization of post-combustion carbon capture process using MEA supporting carbon neutrality

The role of carbon capture technology using monoethanolamine (MEA) is critical for achieving the carbon-neutrality goal. However, maintaining the efficient operation of the post-combustion carbon capture is challenging considering the hyperdimensional design space and nonlinear characteristics of the process. In this work, CO2 capture level from the flue gas in the absorption column is investigated for the post-combustion carbon capture process using MEA. Artificial neural network (ANN) and support vector machine (SVM) models are constructed to model CO2 capture level under extensive hyperparameters tuning. The comparative performance analysis based on external validation test confirmed the superior modelling and generalization ability of ANN for the carbon capture process. Later, partial derivative-based sensitivity analysis is carried out and it is the found that absorbent-based input variables like lean solvent temperature and lean solvent flow rate are the two most significant input variables on CO2 capture level in the absorption column. The optimization problem with the ANN model embedded in the nonlinear programming-based optimization environment is solved under different operating scenarios to determine the optimum operating ranges for the input variables corresponding to the maximum CO2 capture level. This research presents the optimum operating conditions for CO2 removal from the flue gas for the post-combustion carbon capture process using MEA that contributes to achieving the carbon neutrality goal.

Analysis of CO2 capture process from flue-gases in combined cycle gas turbine power plant using post-combustion capture technology

Combined cycle gas turbine power plants (CCGTs) are a combined cycle consisting of a gas turbine and a steam turbine to generate electricity. Sometimes CCGTs incorporate cogeneration to produce both heat and power. After the gas fuel combustion in the gas turbine combustion chamber, the flue gases are passed through the Heat Recovery Steam Generator (HRSG) to extract heat and generate additional electrical power using the steam turbine. The CCGT technology is recognized for its highest efficiency of 58% in electricity production among the power production technology. A highly efficient CCGT power plant with 60% efficiency produces even 2.5 times less CO2 than a modern coal power plant with an efficiency of 45% because of the use of gas fuel and electrical efficiency. The CO2 emission can be reduced further when the post-combustion CO2 capture methods are applied. To perform CO2 capture and to reduce the CO2 emission from power plants, the CO2 mass fraction in flue gas is the crucial parameter for the operation of the Post-combustion Carbon Capture and Storage (PCCS) technology. The PCCS technology uses solvents, which is the aqueous solution of amine that reacts with flue gas and absorbs the CO2, which is treated and separated later. The paper presents the results of the energy analysis of a post-combustion carbon capture process when integrated with a combined cycle gas power plant. The study considered two different gas fuels such as methane and syngas. Syngas composition was determined from the sewage sludge gasification process and can be treated as zero-emission CO2 gas fuel. When the flue gas produced from the syngas is used in PCCS at more than 50% of load conditions, the negative CO2 emission level in large-scale CCGT power plants can be reached. The paper presents the results of mass and energy balance analysis of HRSG of a CCGT integrated with PCCS to perform CO2 capture. The analysis of HRSG using flue gases from methane and syngas is performed by calculating the enthalpy of flue gas, rate of heat exchange, and temperature distribution of each component of HRSG. The comparison of the result shows slight differences due to the different composition and flow rates of flue gases. The flue gas at the outlet of two HRSG is used in the PCCS at different load conditions. An aqueous solution of 30 wt% Monoethanolamine (MEA) with rich loading of 0.5 mol-CO2/mol-MEA and a mixture of 16 wt% 2-amino-2-methyl-1-propanol (AMP) – 14 wt% Piperazine (PZ) with rich loading of 0.62 and 0.86 mol-CO2/mol-amine respectively are used in the PCCS. Due to the reboiler duty of amines, the steam consumed by the PCCS for AMP-PZ regeneration is less compared to MEA. Depending upon the flue gas and solvent used in the PCCS, the power consumed by the PCCS from CCGT power plant is measured from 9.6% to 11.6%. For the given operating condition of the CCGT and PCCS at more than 50% load condition, the negative CO2 emission level can be achieved.

Experimental investigation of novel ternary amine-based deep eutectic solvents for CO2 capture.

This study investigates the effect of using water as a low-viscosity component in ternary amine-based deep eutectic solvents (DESs) on the physicochemical properties, thermal stability, and CO2 absorption capacity of the resulting DESs. It should be emphasized that water is a component of the ternary DES. The effect of water content in the DES, type of hydrogen bond acceptors (HBAs), hydrogen bond donors (HBDs), and HBA:HBD ratio on the above parameters was investigated. Moreover, the effect of temperature and pressure on the CO2 absorption capacity of DESs was predicted using the predictive model COSMO-RS. This model was also used to predict the CO2 solubility in the DESs and the results were compared with the experimental values. The results showed that the addition of small amounts of water, e.g., 5 and 10 wt% during preparation, can significantly decrease the viscosity of the resulting DESs, up to 25% at room temperature, while maintaining the high CO2 absorption capacity and high thermal stability. The ternary DESs based on MEA exhibited a high CO2 absorption capacity of 0.155-0.170 g CO2 / g DES. The ternary DESs were found to be thermally stable with a decomposition temperature of 125°C, which promotes the use of such solvents in post-combustion capture processes. Finally, COSMO-RS proved to be a suitable tool for qualitative prediction of CO2 solubility in DESs and demonstration of trends related to the effects of temperature, pressure, molar ratio, water content, HBD and HBA on CO2 solubility.

Impact of high capture rates and solvent and emission management strategies on the costs of full-scale post-combustion CO2 capture plants using long-term pilot plant data

Pilot plant campaigns are critical to our understanding of the performance of solvent-based post-combustion capture processes. During the ALIGN-CCUS project, long-term pilot plant runs in the Niederaussem lignite-fired power plant were conducted, that aimed to investigate solvent degradation and emissions management and capture rates beyond 90%. Based on these pilot runs, we here investigated the cost effect of amine degradation and emissions for two solvent systems, MEA and CESAR1, as well as the effect of incorporating degradation and emission mitigation strategies and the effect of higher carbon capture rates. We found that for lignite-fired power plants, CESAR1 is not per se a cheaper solvent system than MEA when actual solvent losses (or their mitigation measures) are considered, contrary to what earlier studies have suggested. It may, therefore, be just as good a benchmark as MEA would be, as long as all degradation and emission (mitigation) costs are included in their cost estimates. Second, MEA reclaiming with ion exchange resins and CESAR1 emission mitigation measures (dry-bed and/or turbulent flue gas pre-treatment) do not increase the cost of CO2 capture or electricity. If anything, our work suggests these measures reduce costs marginally, owing to lower solvent make up, offsetting the additional capital and operational costs. Finally, the cost effect of capture rates beyond 90% proves minimal (the cost of CO2 capture and the levelized cost of electricity increase by 3% and 5%, respectively, when moving from 90% to 98% CO2 capture rate), indicating solvent-based CO2 capture may also be a useful mitigation strategy in societies transitioning towards net-zero-CO2 emissions.

Thermodynamic analysis of a post-combustion carbon dioxide capture process in a pilot plant equipped with a heat integrated stripper

This paper presents a thermodynamic analysis of a carbon dioxide absorption process from flue gases, focusing on the Heat Integrated Stripper (HIS) as a promising modification to the conventional process. The primary objective is to compare the performance of the HIS-modified process with that of the standard process. Experimental research was conducted on a mobile pilot plant using aqueous solutions of MEA 30% for treating 200 m3/h of the flue gas.An advanced data validation and reconciliation method was used to reconcile measurements in the mass balancing of the carbon dioxide absorption process. The results demonstrate that heat integration has a positive impact on the temperature profile of the stripper, leading to an increase in carbon dioxide capture without requiring additional heat consumption. Specifically, the reboiler heat duty in the process was reduced from 3.22 to 3.00 MJ/kgCO2, indicating the effectiveness of the HIS-modified process in reducing energy consumption. The use of the advanced data validation and reconciliation method also increases the reliability of the obtained results, which can be beneficial for process modeling and design. These findings contribute to the development of more efficient carbon capture technologies.

Environmental and Economic Analysis of a Natural Gas Combined Cycle Power Plant Using CO2 Utilization Technologies and Ecosystem Services

Power plants are major contributors to CO2 emissions. Post-combustion carbon capture (PCC) processes are commonly integrated, but the capture effectiveness is limited. In this work, four conversion technologies for CO2 utilization from a power plant plus PCC to produce formic acid, methanol, and syngas as value-added chemicals are analyzed. We also analyze the implications of implementing forest ecosystems, for which trees with three types of maturity are considered. The results show that the environmental implications of process utilization technologies may lack desired effectiveness, since the emissions of the utilization plant may still be significant with respect to the amount of captured CO2. Ecological systems are more effective from environmental considerations, but the number of trees and land use may be too high to process the amount of CO2 produced by power plants. A hybrid scheme that integrates a suitable transformation technology with forest ecosystems shows that they may have benefits from both economic and sustainability considerations.

A techno-economic assessment of the reutilisation of municipal solid waste incineration ash for CO2 capture from incineration flue gases by calcium looping

Waste-to-Energy (WtE) through municipal solid waste (MSW) incineration is a key waste management strategy to reduce the mass and volume of landfilled wastes, especially for land-constrained areas such as urban centres. However, this process releases large amounts of CO2 into the atmosphere and the ash that remains after burning, which contains a variety of metals and minerals, is often sent to the landfill after some metal recovery. In this study, the CaO containing ash is used to derive sorbents for the calcium looping (CaL) process for post-combustion CO2 capture and storage (CCS), and a techno-economic assessment was performed to preliminarily probe the feasibility of retrofitting a CaL plant using ash-derived sorbents to capture CO2 from a 200MWth WtE plant, as a possible means to decarbonise WtE plants. The analysis was performed through process modelling of the CaL plant using 4 different supplementary fuels in the calciner, namely, biomass charcoal (BC), solid recovered fuel (SRF), coal, and natural gas (NG). At the base purge ratio of 5%, all the cases show increases in the levelised cost of electricity (LCOE) over the base WtE, ranging from 184 (NG) to 246 (BC) USD/MWhe. The sale of additional electricity generated from the heat recovery steam cycle could slightly mitigates the capital intensiveness of the process, resulting in a levelised cost of carbon abatement (LCCA) range of USD 89 (SRF) to 184 (coal)/tCO2, which is competitive with other bioenergy with CO2 capture and storage (BECCS) technologies. The biogenic fuels also result in lower specific primary energy consumption per CO2 avoided (SPECCA) of 5.6 (BC) and 6.8 (SRF) MJLHV/tCO2, which are comparable to values from other CCS technologies and CaL implementation studies. Sensitivity analysis of 14 economic and process parameters reveals that further improvements can be achieved through optimisation of the energy intensive sub-processes, such as cryogenic air separation and CO2 compression and purification. Tighter solid heat integration (SHI) concepts were also modelled and are shown to effectively reduce fuel and O2 requirements by up to 22.2%, thereby lowering annualised costs by up to 11.9%. In addition, this paper highlights the importance of regulatory support through favourable policies such as higher carbon pricing and CO2 credit trading to push the development and adoption of negative emission technologies to meet global decarbonisation targets.

Reduction of energy consumption in post-combustion carbon capture process via amine-functionalized metal-organic frameworks

In this study, CO2 capture performance of ethylenediamine-functionalized Mg-MOF-74 (EDMOF-74) suspended in 30 wt% monoethanolamine (MEA) aqueous solution is analyzed. A CO2 absorption experiment was performed in a bubble column reactor based on EDMOF-74 concentrations of 0.005, 0.01, 0.05, and 0.1 wt% for different ethylenediamine loadings. It shows that EDMOF-74/30 wt% MEA mixtures improve CO2 absorption performance by a maximum of 7.18 % as compared with the base fluid. Subsequent experiment based on large-volume feed gas reveals a less volatile CO2 absorption rate. By adding EDMOF-74 to the 30 wt% MEA aqueous solution in a cyclic CO2 absorption experiment to evaluate its industrial application, an increase in durability is indicated, which implies a reduction in energy consumption during CO2 regeneration. A feasibility study on the reduction of CO2 regeneration energy was investigated in terms of the results of cyclic experiment and the facility status of Boryeong power plant. The CO2 regeneration energy can be reduced by 13.64 %, which corresponds to a decrease of 484,233 MWht/year for 1 unit of the Boryeong power plant. The abovementioned approach is expected to compensate for the disadvantages of MEA in the industrial CO2 capture process, i.e., low CO2 capacity and high CO2 regeneration energy input.

Design and multi-objective optimization of a CO2 capture plant using deep eutectic solvents

The United Nation’s 2030 Agenda for Sustainable Development has called for taking of urgent action to combat climate change and its impacts, where CO2 capture processes have gained relevance for achieving emission objectives. Traditionally, monoethanolamine (MEA) is used in post-combustion capture (PCC) as a solvent because of its high absorption capacity. However, the use of amines is related to several environmental problems. In this work a novel post-combustion carbon capture plant is designed in Aspen Plus, under a sustainable design scheme considering environmental and economic indexes, using novel green liquids: deep eutectic solvent (DES) choline chloride/urea (1:2). Four case studies are considered for the most used fossil fuels in the power plant: coal, natural gas, associated gas, and biogas. This work represents a base case for multi-objective optimization of the PCC process coupled with a power plant for combustion. An optimization problem was defined considering the following objective functions: minimization of the environmental impact (EcoIndicator 99), minimization of the total solvent recovery energy (TSRE) and greenhouse gas emissions (GHGE); the economic objectives were set to minimize the total annual cost of the plant (TAC) and maximize return over investment (ROI). A metaheuristic optimization method, differential evolution with tabu list was chosen, and Pareto fronts for the objective functions were obtained for all case studies. It was found that the PCC process for coal-based power generation exhibits the best overall performance among all evaluated fuels. A comparison with a similarly optimized MEA-based carbon capture process shows that the use of DES leads to a 171.8% reduction in environmental impact when treating flue gas from a coal-based power process. To showcase the feasibility of the DES as a green solvent, an energy consumption of 6.62 MJ/kgCO2 is needed, compared with 6.40 MJ/kgCO2 for the MEA-based process.

Vapor Liquid Equilibrium of Aqueous Diethanolamine Solution for Carbon Dioxide Capture Processes

Objectives : Acid gases such as carbon dioxide (CO<sub>2</sub>) and hydrogen sulfide (H<sub>2</sub>S) that cause global warming are mainly generated in chemical processes. As a technology for reducing acid gas, the post-combustion capture process is representative. Aqueous alkanolamine solution, which is mainly used in the carbon dioxide absorption process, is used as the most representative chemical absorbent. Thermodynamic data of vapor-liquid equilibrium are important for the economics of process design and operation. In this study, vapor-liquid equilibrium data of water + DEA are measured so that DEA, a secondary amine, can be used in the carbon dioxide absorption process, so that it can be used for designing a new carbon dioxide absorption process.Methods : Vapor-liquid equilibrium data of a mixture of water + DEA (diethanolamine) were measured under isothermal conditions of 393.15 K using HSGC (Headspace Gas Chromatography).Results and Discussion : The measured vapor-liquid equilibrium data were correlated using NRTL, an activity coefficient model. In addition, as additional thermodynamic data of the absorbent mixture, the density of the DEA aqueous mixture was measured at a temperature of 303.15 K to 333.15 K using a density meter (Anton Paar DMA4500). The measured density data of the mixture was converted into excess volume, and the excess volume data was correlated using the Redilchi-Kister-Muggianu equation. Using the measured water+DEA vapor-liquid equilibrium data, it is expected to reducing the design cost and operating cost of the carbon dioxide absorption processes.