Post-combustion CO2 Absorption Research Articles

Bi-objective optimization of post-combustion CO2 capture using methyldiethanolamine

Process simulation and analyzes based on multiple evaluation indexes are crucial for accelerating the practical use of the post-combustion CO2 capture process. This study presents a bi-objective optimization of the post-combustion CO2 absorption process using methyldiethanolamine (MDEA) via machine-learning and genetic algorithm to evaluate CO2 emissions from the absorption process using life cycle assessment and cost from operating and capital expenditures. An initial dataset was generated by changing eight design variables, and machine-learning models were built using random forest classifier and Gaussian process regression. Pareto solutions were predicted using a genetic algorithm (NSGA-II) with the constraints of purity, recovery, and temperature, and were verified via process simulation. Verified data were added to the dataset, and model building, prediction, and verification were repeated. Eventually, 56 Pareto solutions were obtained after 11 iterations. In the final Pareto solutions, CO2 emissions increased from 0.56 to 0.6 t-CO2/t-CO2 with a decrease in cost from 74 to 66 USD/t-CO2. The trends and composition of each objective variable were examined, and the optimal structure of the equipment and operation conditions was clarified. The approach of bi-objective optimization in this study is promising for evaluating the CO2 capture process and individual processes of carbon capture, utilization, and storage.

Optimization of post combustion CO2 absorption system monoethanolamine (MEA) based for 320 MW coal-fired power plant application – Exergy and exergoenvironmental analysis

Carbon Capture and Storage (CCS) technology which has been widely used, such as CO2 absorption system, still has environmental and energy issues. Further investigations should be carried out by understanding the causes of inefficiency in the system. Exergy and exergoenvironmental analysis are the method to describe the associated of each component in the system so that it can be optimized to produce optimum operating condition. A comprehensive study of coal fired power plant using CO2 absorption with MEA (monoethanolamine) solution is presented. This paper aims to optimize the CO2 absorption system by maximizing exergy and minimizing exergoenvironmental. Exhaust gas temperature, MEA molar flow rate, and reboiler duty on the regenerator are chosen as the decision variables. The results showed that, the optimum operating conditions of the three variables respectively are 90 °C, 2,500 kmol/h, and 9.14 MW. From the exergy and exergoenvironmental calculation results, the components which should be improved are heat exchangers, regenerators, and absorbers since they have minimum exergetic efficiency and have many byproducts given to the environment. This study can be the basis for maximizing the efficiency of the CO2 absorption system which has implications for reducing environmental impacts through optimization of components in the CCS system.

The Role of Nanotechnology for Energy Storage, Conservation and Post Combustion CO<sub>2</sub> Capture in Industry: A Review

Nanotechnology is referred to as the science of nanoscale which is objects that range in nanometers in size. The use of nanomaterials in energy conversion and storage represents an opportunity to improve the performance, density and ease of transportation in renewable resources. Energy is an unavoidable theme in contemporary society, ranging from basic daily life to superior science and technology. Over increasing energy demand and always deteriorating environmental issues, electricity has turn out to be bottleneck and is hindering the development of society. The use of nanotechnology to increase a suite of sustainable power manufacturing schemes is one of the most necessary scientific challenges of the 21st century. The challenge is to design, to synthesize, and to represent new useful nanomaterials with controllable sizes, shapes, and structures. And also now a day’s a serious interset is required to reduce the level of CO2 the use of advanced and environment friendly CO2 seize technologies. Carbon dioxide seize and storage (CCS) applied sciences can also play an necessary function in this direction. Nanotechnology is used to seize CO2 formore than a few industrial processes. This review is ordinarily centered on the role of nanotechnology in the electricity storage, conservation and post-combustion CO2 absorption process. The features of nanomaterials and nanoparticles have been studied in the current work.

Parametric Process Design and Economic Analysis of Post-Combustion CO2 Capture and Compression for Coal- and Natural Gas-Fired Power Plants

For the envisaged large number of commercial-scale carbon capture and storage (CCS) projects that are to be implemented in the near future, a number of issues still need to be resolved, the most prominent being the large capital and operational costs incurred for the CO2 capture and compression process. An economic assessment of the capture and compression system based on optimal design data is important for CCS deployment. In this paper, the parametric process design approach is used to optimally design coal and natural gas monoethanolamine (MEA)-based post-combustion CO2 absorption–desorption capture (PCC) and compression plants that can be integrated into large-scale 550 MW coal-fired and 555 MW natural gas combined cycle (NGCC) power plants, respectively, for capturing CO2 from their flue gases. The study then comparatively assesses the energy performance and economic viabilities of both plants to ascertain their operational feasibilities and relative costs. The parametric processes are presented and discussed. The results indicate that, at 90% CO2 capture efficiency, for the coal PCC plant, with 13.5 mol.% CO2 in the inlet flue gas, at an optimum liquid/gas ratio of 2.87 kg/kg and CO2 lean loading of 0.2082 mol CO2/mol MEA, the CO2 avoidance cost is about $72/tCO2, and, for the NGCC PCC plant, with 4.04 mol.% CO2 in the inlet flue gas, at an optimum liquid/gas ratio of 0.98 kg/kg and CO2 lean loading of 0.2307 mol CO2/mol MEA, the CO2 avoidance cost is about $94/tCO2.

The role of nanotechnology on post-combustion CO2 absorption in process industries

Abstract At present, higher greenhouse gas (GHG) have triggered global efforts to reduce their level as much as possible for sustainable development. Carbon dioxide is one of the imperative anthropogenic emissions due to its increased excessive accumulation in the environment. Thus, serious attention is required to reduce the level of CO2 using advanced and efficient CO2 capture technologies. Carbon dioxide capture and storage (CCS) technologies may play an important role in this direction. At present, solvent-based sorbents are being utilized in CO2 capture for various industrial processes. In this category, the characters of non-materials are playing a crucial role to improve the CO2 absorption capacity of the process. This study is mainly focused on the role of nanotechnology in the post-combustion CO2 absorption process. The functions of nanomaterials and nanoparticles have been studied in the present work. Additionally, various challenges related to absorption efficiency using nanomaterials have been discussed. The study concludes that the higher thermal stability and exceptional properties of nanomaterials popularized them for use in CO2 capture processes.

Experimental and e-NRTL model predicted VLE of CO2 in aqueous solutions of 2-((2-aminoethyl)-amino)-ethanol and speciation study

Recently, 2-((2-Aminoethyl) amino) ethanol (AEEA), containing a primary and a secondary amino group, is focused as a new solvent for post-combustion CO2 absorption. In this work, vapour-liquid equilibrium (VLE) of CO2 absorption in the aqueous AEEA is studied over a wide temperature range of 303.15–343.15 K and pressure up to 243 kPa in the amine concentration range of 0.51–4.11 mol AEEA.kg−1 water using a stirred cell thermostatic setup. A rigorous thermodynamically consistent model based on Electrolyte Non-Random Two-Liquid (ENRTL) theory is developed using Aspen V9.0 to correlate and predict the vapour liquid equilibrium of CO2 in aqueous AEEA solutions. The model predicted CO2 solubility showing 28% of average absolute deviation (AAD) from experimental data. The model predicted pair parameters, binary interaction parameters, equilibrium constant, dielectric constant, pure component physical properties and coefficients of extended Antoine vapour pressure correlation are presented in this study. Equilibrium liquid phase speciation for all solvents is predicted using ENRTL-model. The ENRTL model is also used to predict the heat of reactions for the individual equilibrium reactions as function of temperature and the heat of absorption of CO2 in aqueous AEEA solutions as a function of CO2 loading.

Gas phase amine depletion created by aerosol formation and growth

Aerosols are systems of droplets or wet particles suspended in gases. In post combustion CO2 absorption systems aerosols can be formed by spontaneous phase transitions in supersaturated gas phases or by droplets or particles entering the absorber with the gas to be treated. Micron and sub-micron mist droplets and fog formed in these processes cannot be removed by conventional demisting devices and because amine may be absorbed in the droplets this may increase dramatically the amine emissions from absorption columns as reported previously (Khakharia et al., 2015; Schaber et al., 2002). Thus, it is important to understand the mechanisms governing droplet growth and amine uptake through absorber as well as the effect large numbers of aerosol droplets can have on the bulk gas phase composition.A model developed and implemented in Matlab, predicts how the gas phase composition and temperature change along the absorber taking into account mass and heat transfer to and from both the bulk liquid and the droplet phase. The objective of this work, compared to earlier work, Majeed et al. (2017), is to study the possible effect of gas phase component depletion on the droplet growth and droplet internal variable profiles and how this varies with initial droplet size and composition, droplet number concentration and amine volatility.For MEA, as a relatively volatile solvent it is seen that gas phase depletion already takes place at number concentrations above 105 droplets/cm3 with an initial droplet radius of 1.5μ and 5M MEA initial concentration. For initial droplet radius 0.15μ and 0.0001M MEA initial concentration, which may be a more realistic case, hardly any depletion effect is seen up to 107 droplets/cm3. With change in amine volatility it is seen that the gas phase depletion effect is significantly stronger in the case of low volatility than for MEA at high droplet number concentrations. It is found that gas phase amine depletion has a strong effect on droplet growth.

Prospects of Implementing CO2 Capture and Sequestration (CCS) in the Proposed Supercritical Coal Power Plants in India

Abstract India is heavily dependent on coal for electricity generation with 60% of the installed capacity was coal fired plants. Many more coal power plants are expected to be built in the next few years and most of them would be super-critical or ultra-super-critical plants. The coal plants are responsible for large emissions of CO2 – a major greenhouse gas (GHG) considered to be responsible for climate change. India being the 3rd largest CO2 emitter in the world, there is a need for exploring various carbon mitigation techniques with ever increasing concerns about climate change. Carbon Capture and Sequestration (CCS) is one such mitigation option wherein CO2 emitted by the power plants and other industries is captured and transported to a storage site where it is isolated from the atmosphere permanently. This study is to understand the economic & environmental impacts of implementing CCS in the Supercritical Coal power plants with the help of Integrated Environment Control Model (IECM-cs). Two technology options, viz. post-combustion CO2 absorption from flue gas and oxy-fuel combustion with CO2 capture, have been analyzed.

Dominating dynamics of the post-combustion CO2 absorption process

A dynamic model of the post-combustion CO2 capture process based on chemical absorption is used to investigate the transient behavior and dynamic responses of the process and to detect stabilization time when various disturbances are introduced. Plant dimensions and parameter settings are based on the SINTEF CO2 capture pilot plant at Tiller in Norway, and the overall process model is validated using two sets of steady state pilot plant data. A deviation between model and pilot plant results of −0.8% and −4.5% in absorbed CO2 and 2.6% and 1.2% in desorbed CO2 is seen for the two cases used in validation, respectively, which is within the observed pilot plant CO2 mass balance error of ±6%. The simulated absorber and desorber temperature profiles show also adequate agreement to the pilot plant measurements. The process model is further used to simulate set-point changes in flue gas flow rate, reboiler duty and solvent flow rate in order to investigate typical stabilization times at various locations in the process. As expected, mixing models such as the absorber sump and reboiler will introduce time constants that affect the dynamic response profiles, while plug flow models such as the cross heat exchanger and lean cooler causes pure transport delays and no additional settling time. Mass transfer and chemical reaction rates causes some process inertia, but it is relatively small compared to the inertia of larger mixing vessels such as the absorber sump, reboiler and buffer tank and transport delay caused by plug flow. Changes to the solvent flow rate are also seen as a larger disturbance to the process compared to changes in flue gas flow rate and reboiler duty, reflected by longer process stabilization time to reach new steady state conditions. The estimated 90% settling times for the response in CO2 capture rate in the Tiller pilot plant are less than 1h, 3.5–6h and 3.5–4h for step changes in flue gas flow rate, solvent flow rate and reboiler duty, respectively.

Dynamic model validation of the post-combustion CO2 absorption process

A general dynamic process model of the post-combustion carbon dioxide (CO2) absorption process based on aqueous monoethanolamine (MEA) is developed and implemented in MATLAB. The overall process model contains several unit models developed from first principle conservation laws for mass and energy, each representing individual process equipment. An equation based numerical integration method is used to solve the overall equation system simultaneously in MATLAB. Pilot plant data from specifically designed dynamic experiments with 30wt% MEA is collected from a pilot plant at NTNU and SINTEF laboratories. This includes steady state data for eight different conditions along with six dynamic data sets with relevant step changes in lean solvent flow rate and reboiler duty. The pilot plant data show a very good steady state mass balance which indicates that the generated data sets are reliable. Two of the dynamic data sets are used for model validation and the results shows adequate agreement between model and pilot plant data. An average of 0.3% and −2.8% deviation in absorbed CO2 is seen for the two simulated cases compared to pilot plant results and it is concluded that the model is able to capture the main dynamics of the experiments. The main cause of deviation is believed to concern uncertainties in mass transfer and effective mass transfer area correlations.

Experimental analyses of mass transfer and heat transfer of post-combustion CO2 absorption using hybrid solvent MEA–MeOH in an absorber

• Mass transfer of MEA–MeOH was comprehensively investigated. • The K G a v of MEA–MeOH is higher than that of MEA–H 2 O. • MeOH is vulnerable to evaporate and should be operated at a low temperature. • Optimizing operating conditions can reduce solvent evaporation. The performance of CO 2 absorption into a hybrid solvent such as monoethanolamine (MEA) in methanol (MeOH) was experimentally investigated in a lab-scale absorber packed with Sulzer DX-type structured packing, and compared with that of aqueous MEA solution. The experiments were performed at various key operating conditions over a MEA concentration range of 2.5–5.0 kmol/m 3 , a CO 2 lean loading range of 0–0.373 mol/mol, a liquid flow rate range of 2.92–16.09 m 3 /m 2 h, an inert gas flow rate range of 24.37–63.54 kmol/m 2 h, a CO 2 partial pressure range of 6.7–13.8 kPa, and an inlet liquid temperature of 10 °C. The absorption performance was presented in terms of the overall gas phase mass transfer coefficient ( K G a v ), CO 2 concentration and system temperature profiles along the height of the absorber, and the system temperatures at the bottom and the top of the absorber, T bot and T top , respectively. It was found that the K G a v for MEA–MeOH was higher than that of MEA–H 2 O. In addition, the experimental results showed that key operating parameters such as MEA concentration, CO 2 loading, liquid flow rate and inert gas flow rate have large effect on the performance of CO 2 absorption into the MEA–MeOH.

Thermal Degradation Comparison of Amino Acid Salts, Alkanolamines and Diamines in CO2 Capture

Abstract In the selection of candidates for post-combustion CO2 absorption, solvent degradation has become a general concern due to the significant impact on operational cost and the intention to use thermal compression from high temperature stripping to minimize the overall process energy. In this research, structural analogs of amino acid salts, alkanolamines and diamines were thermally degraded in order to explore their thermal stability from a structural standpoint. Functional groups, amine orders and steric effect were investigated for their impact on amine thermal degradation. Primary amines with chain structures showed a thermal stability trend as diamine > alkanolamine > amino acid salt. For alknolamine and diamine structural isomers, the primary amines are more stable than the secondary amines. Steric hindrance around the amine group was shown to play a positive role in protecting amines against thermal degradation.

Turning CO2 Capture On and Off in Response to Electric Grid Demand: A Baseline Analysis of Emissions and Economics

Coal consumption accounted for 36% of America’s CO2 emissions in 2005, yet because coal is a relatively inexpensive, widely available, and politically secure fuel, its use is projected to grow in the coming decades (USEIA, 2007, “World Carbon Dioxide Emissions From the Use of Fossil Fuels,” International Energy Annual 2005, http://www.eia.doe.gov/emeu/iea/carbon.html). In order for coal to contribute to the U.S. energy mix without detriment to an environmentally acceptable future, implementation of carbon capture and sequestration (CCS) technology is critical. Techno-economic studies establish the large expense of CCS due to substantial energy requirements and capital costs. However, such analyses typically ignore operating dynamics in response to diurnal and seasonal variations in electricity demand and pricing, and they assume that CO2 capture systems operate continuously at high CO2 removal and permanently consume a large portion of gross plant generation capacity. In contrast, this study uses an electric grid-level dynamic framework to consider the possibility of turning CO2 capture systems off during peak electricity demands to regain generation capacity lost to CO2 capture energy requirements. This practice eliminates the need to build additional generation capacity to make up for CO2 capture energy requirements, and it might allow plant operators to benefit from selling more electricity during high price time periods. Post-combustion CO2 absorption and stripping is a leading capture technology that, unlike many other capture methods, is particularly suited for flexible or on/off operation. This study presents a case study on the Electric Reliability Council of Texas (ERCOT) electric grid that estimates CO2 capture utilization, system-level costs, and CO2 emissions associated with different strategies of using on/off CO2 capture on all coal-fired plants in the ERCOT grid in order to satisfy peak electricity demand. It compares base cases of no CO2 capture and “always on” capture with scenarios where capture is turned off during: (1) peak demand hours every day of the year, (2) the entire season of peak system demand, and (3) system peak demand hours only on seasonal peak demand days. By eliminating the need for new capacity to replace output lost to CO2 capture energy requirements, flexible CO2 capture could save billions of dollars in capital costs. Since capture systems remain on for most of the year, flexible capture still achieves substantial CO2 emissions reductions.