Simulation Of CO2 Capture Process Research Articles

Simulation of CO2 capture process in gas-solid bubbling fluidized bed by computational mass transfer

In this paper, a recently developed two-equation turbulent (TET) model based on the methodology of computational mass transfer (CMT) [1] is adopted to simulate the capture process of carbon dioxide by potassium carbonate particles in a gas-solid bubbling fluidized bed (BFB). The TET model uses two auxiliary equations, namely the concentration variance equation and its dissipation rate equation to determine the turbulent mass diffusion of species, which enables the simulation on mass transfer process be more rigorous than that based on empirical turbulent Schmidt number model. Comparison between the simulated results and experimental data in literature is made, which shows a satisfactory agreement (AARD% are 2.47 % and 8.45 % respectively for two cases of simulation) and thus verifies the validity of the model. Furthermore, the turbulent mass diffusion in the BFB is characterized and discussed. The calculated turbulent Schmidt number by the present model varies along axial and radial directions (with averaged value of 0.32), revealing that the use of constant turbulent Schmidt number (i.e., 0.7) is only an approximate.

Simulation of CO2 Capture Process in Flue Gas from Oxy-Fuel Combustion Plant and Effects of Properties of Absorbent

Oxy-fuel combustion technology is an effective way to reduce CO2 emissions. An ionic liquid [emim][Tf2N] was used to capture the CO2 in flue gas from oxy-fuel combustion plant. The process of the CO2 capture was simulated using Aspen Plus. The results show that when the liquid–gas ratio is 1.55, the volume fraction of CO2 in the exhaust gas is controlled to about 2%. When the desorption pressure is 0.01 MPa, desorption efficiency is 98.2%. Additionally, based on the designability of ionic liquids, a hypothesis on the physical properties of ionic liquids is proposed to evaluate their influence on the absorption process and heat exchanger design. The process evaluation results show that an ionic liquid having a large density, a large thermal conductivity, and a high heat capacity at constant pressure is advantageous. This paper shows that from capture energy consumption and lean circulation, oxy-fuel combustion is a more economical method. Furthermore, it provides a feasible path for the treatment of CO2 in the waste gas of oxy-fuel combustion. Meanwhile, Aspen simulation helps speed up the application of ionic liquids and oxy-fuel combustion. Process evaluation helps in equipment design and selection.

Simulation of CO2 Capture Process for Coal based Power Plant in South Sumatra Indonesia

Indonesia committed to reduce greenhouse gas emission by 29% in 2030. Carbon dioxide (CO2) emissions from flue gas in coal power plant must be captured to reduce greenhouse gas emissions. Technology to decrease greenhouse gases on a large scale and in a relatively short period is Carbon Capture and Storage (CCS). Chemical absorption method is a more advantageous CCS technology than other methods owing to high efficiency, low cost, and mature technology. Solvents in chemical absorption include amine-based solvent such as monoethanolamine (MEA) was frequently utilized to absorb CO2 from low-pressure flue gas streams, especially fossil fuel-based power plant, owing to rapid reaction rate with CO2 and low cost of raw amines compared to other amines. In this study, Aspen Hysys was used to simulate the CO2 capture process and 30 wt% of MEA was selected as a solvent which is mainly handy for CO2 capture from flue gas. The results show that lean amine temperature, flue gas temperature, and regenerator feed temperature has effects on the CO2 capture and energy consumption. The rich-split stream configuration was developed to examine energy reduction in various split fractions. The minimum in energy consumption and reboiler duty occurs when 30% of the solvent is split to the top of the column.

Experiment and simulation for CO2 capture using low transition temperature mixtures as solvents

CO2 capture and storage technology, which is used to control the rate of global warming, is the most promising and feasible solution to reduce the concentration of CO2 in the atmosphere. In this work, experiment and simulation of CO2 capture process using low transition temperature mixtures (LTTMs) as solvents are studied. First, LTTMs were synthesized by using levulinic acid as hydrogen bond donor (HBD) and tetraethylammonium chloride as hydrogen bond acceptor (HBA). The solubility of CO2 in LTTMs was measured and effects of the mole ratio of HBD to HBA on solubility were also examined. It demonstrated that the solubility of CO2 in LTTMs increased with the increasing pressure or the decreasing temperature. Henry’s constants and thermodynamic properties such as Gibbs energy, enthalpy and entropy of dissolution were deduced by correlating the solubility data. Second, in order to explain the absorption mechanism, σ-profiles were adopted to study the molecular interactions between HBD/HBA/LTTMs and CO2. The analysis for geometry, interaction energy, independent gradient model and atoms in molecules were performed to explain the interaction mechanisms between CO2 and HBD/HBA/LTTMs. Moreover, CO2 capture process with LTTMs as solvents was simulated using Aspen Plus software. The design variables of CO2 capture process were optimized using multi-objective generic algorithm, and the optimal operating parameters were obtained. At last, the dynamic controllability of CO2 capture process was studied and an effective control structure was proposed, which worked quite well for the disturbances in both feed flow rate and feed composition.

Two-dimensional full-loop simulation of CO2 capture process in a novel dual fluidized bed system

The integrated bubbling-transport fluidized bed can realize both sufficient gas-solid contact time and adjustable solid circulation rate. This paper performed a full-loop simulation of continuous CO2 capture process in a dual fluidized-bed system, using the bubbling-transport bed as the adsorber and K2CO3/γ-Al2O3 as the sorbents. Two-dimensional Eulerian-Eulerian models coupling with reaction kinetics were applied in the simulation. The results show that the adsorption reaction mainly takes place in the bubbling section of the adsorber, but rarely in the central riser and transport section. The increase of the sorbent circulation rate and the water vapor concentration in flue gas benefit the CO2 capture performance, and the latter is more preferable. Together with the sorbents, part of flue gas is entrained from the bubbling section to the central riser, causing an apparent fluctuation of sorbent circulation, as well as a low global CO2 capture efficiency due to the insufficient gas-sorbent contact.

Computational simulation of CO2 capture process in a fluidized-bed reactor

A dry sorbent in a fluidized bed reactor system is nominated as an efficient method to remove CO2 from flue gases. In this study, a two-dimensional CFD simulation with the Euler–Euler two-phase fluid flow model incorporating the kinetic theory of solid particles is used to validate a specific reported experimental data. The non-uniform distribution of the solid-phase volume fraction and CO2 concentration is captured in the carbonation reactor. CO2 removal increases by decreasing dry gas flow and enhancing solid sorbent flux. Furthermore, it has an ascending-descending behavior including a maximum point by increase in water vapor content of the feed gas. The CFD model is also implemented to optimize the reactor height based on operating conditions. By using optimized volume fraction of water vapor in the feed gas and enhancing solid sorbent rate to a minimum required value, the reactor height can be decreased to improve the cost and system size condition.

Assessment of CO2 capture using potassium-based sorbents in circulating fluidized bed reactor by multiscale modeling

Potassium-based carbonate looping in a circulating fluidized bed system including an absorber and a regenerator is a potential CO2 capture technology, which has attracted great focus in recent years. In the current work, the simulation of CO2 capture process is carried out by considering the influence of clusters on the hydrodynamic and reaction, where the multiscale reaction model is employed to reflect the change of CO2 absorption rate caused by clusters. The non-uniform flow structure in the absorber can be predicted very well. The distributions of solid sorbents and temperature field are also predicted. The results reveal that there exists heterogeneous feature for temperature and solid sorbents owing to the cluster formation. The prediction considering the cluster effect is more consistent with experimental data. Meanwhile, the impact of gas inlet velocities on the hydrodynamic and CO2 removal process is evaluated.

Modeling and Simulation of CO2 Capture Process for Coal- based Power Plant Using Amine Solvent in South Korea

The interest in carbon capture technology is continuously rising since worldwide climate-change problems have intensified the concern regarding efficient removal of carbon dioxide. Amine-based capture technology is a conventional technology to remove carbon dioxide in natural gas processing, and also can be used for carbon dioxide removal from flue gas in coal-based power plants. In particular, monoethanolamine is a conventional commercial absorbent to remove carbon dioxide and considered as a standard amine absorbent. Due to the high non-ideality of amine, rate-based models have been suggested to describe absorption and desorption of amine absorbent. However, most suggested models were validated against large-scale pilot plant results, and there were few models to consider both absorber and stripper with rate-based model. In this study, we applied two rate-based models introduced by previous literature to the actual pilot plant operation data in 0.1MW-scale Boryeong pilot plant, South Korea and developed a modified model with increased accuracy. The developed model showed good agreements with pilot plant results for both absorber and stripper. However, under low liquid-to-vapor ratio operation with high rich loading value, all model showed worse estimations.

A comparative study of carbon dioxide capture capabilities between methanol solvent and aqueous monoethanol amine solution

Simulations have been performed to compare the performance of CO2 capture power between 98.5 wt% methanol solvent and 30 wt% MEA aqueous solution. A general purpose chemical process simulator, PRO/II with PROVISION release 8.3 was used for the modeling of CO2 capture process. For the simulation of CO2 capture process using methanol as a solvent, NRTL liquid activity coefficient model was used for the estimation of the liquid phase non-idealities, Peng-Robinson equation of state model was selected for the prediction of vapor phase non-idealities, and Henry’s law option was chosen for the prediction of the solubilities of light gases in methanol and water solvents. Amine special thermodynamic package built-in PRO/II with PROVISION release 8.3 was used for the modeling of CO2 capture process using MEA aqueous solution. We could conclude that the 30 wt% of MEA aqueous solution showed better performance than the 98.5 wt% methanol solvent in CO2 capture capability. Through this study, we tried to compare the differences between the two processes from the aspects of capital and operating costs using a commercial process simulator. This will guide the optimal process design in the carbon dioxide capture process.