Browsing by Author "Supap, Teeradet"

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Open Access
A commercial pathway for evaluating the performance of a novel amine solvent blend in a mini-pilot plant for carbon capture
(Faculty of Graduate Studies and Research, University of Regina, 2024-08) Bekoe, Patience Tiorkor; Idem, Raphael; Supap, Teeradet; Tontiwachwuthikul, Paitoon (P.T.)
This study investigates the performance of a novel solvent bi-blend, 4M (2:2) AMP:1-(2HE) PRLD, for CO2 capture through absorption and desorption, providing a potential alternative to the conventional 5M Monoethanolamine (MEA). The pathway utilized to assess the performance of the amine bi-blend for commercial application involved conducting carbon capture experiments in a laboratory bench-scale mini-pilot plant. This approach aimed to validate the solvent's performance under conditions that mimic a full-scale commercial industrial CO2 capture plant. The research also addresses the urgent need for more efficient and cost-effective carbon capture solutions to combat increasing greenhouse gas emissions and global warming. Experiments were conducted with varying feed gas compositions, with CO2 concentrations ranging from 4.5% to 30%, to simulate different industrial emission scenarios. Key performance metrics, including CO2 absorption efficiency, cyclic capacity, mass transfer rates, and energy consumption for solvent regeneration, were meticulously evaluated. For a CO2 partial pressure of 4.5%, the novel solvent blend demonstrated significant performance enhancements compared to 5M MEA. Specifically, the 4M (2:2) AMP:1-(2HE) PRLD blend exhibited an enhancement in absorption efficiency by up to 25% at a reboiler temperature of 110 °C, 41% at 100 °C, and over 700% at 90 °C. Additionally, there was a reduction in regeneration energy requirements by approximately 30% at 110 °C, 43% at 100 °C, and 84% at 90 °C. The novel blend showed robust performance across a wide range of these parameters, indicating its versatility and suitability for diverse industrial applications. The study also revealed an average increase of 150% in the overall gas phase volumetric mass transfer coefficient (KGav) and 110% for the overall liquid-phase volumetric mass transfer coefficient (KLav). These significant improvements emphasize the novel blend's superior mass transfer performance, which is crucial for maximizing CO2 capture efficiency and column design. Parametric studies were conducted to understand the influence of various operational parameters on mass transfer performance. It was observed that the absorption efficiency and mass transfer rates were significantly influenced by CO2 loading, gas flow rate, desorption temperature and pressure. Results from this exercise showed that there is a strong positive correlation between the reboiler temperature and the efficiency as well as the overall mass transfer coefficient. It was also noted that the mass transfer was mainly controlled by the liquid phase while increasing the desorber pressure had an inverse effect on the lean amine loading which was attributed to the higher gas solubility at the higher pressure. The effect of CO2 partial pressure was also studied and a negative correlation was observed between CO2 partial pressure and the absorber efficiency, overall gas phase mass transfer coefficient. Heat duty analysis revealed that the novel solvent blend required less energy for regeneration, thus offering a more energy-efficient solution. The specific energy consumption for the AMP-PRLD blend was found to be significantly lower than that for 5M MEA, highlighting its potential to reduce operational costs and environmental impacts. The study concludes that the novel solvent blend not only provides a more efficient CO2 capture solution but also aligns with the goals of reducing greenhouse gas emissions and achieving net-zero emissions from the indirect co-combustion of natural gas and biomass for energy generation even at relatively lower desorption temperature (100-110 °C) thus significantly contributing to energy savings.
Open Access
Achieving net-zero CO2 emissions from indirect co-combustion of biomass and natural gas with carbon capture using a novel amine blend
(Faculty of Graduate Studies and Research, University of Regina, 2022-09) Avor, Esther Praise; Idem, Raphael; Jia, Na; Supap, Teeradet; Narku-Tetteh, Jessica; Torabi, Farshid
Due to the aggravating effect of climate change as a result of unprecedented levels of greenhouse gases, particularly CO2, in the atmosphere, the need to minimize CO2 emissions into the atmosphere has become very crucial. The energy sector remains the largest source of CO2 emissions, therefore, a technology which allows for achieving netzero CO2 emissions in this sector is imperative. This research work evaluated the possibility of achieving net-zero emissions (on the minimum) through the application of co-combustion of natural gas and biomass for electricity generation. Based on the study, it is was identified that indirect co-combustion of natural gas with biomass (in the form of producer gas) with carbon capture technology is the way to go towards achieving net-zero CO2 emissions. To effectively describe the process as being a net-zero CO2 emissions approach, Life Cycle Assessment data was applied to the various processes involved in the indirect co-combustion of biomass and natural gas coupled with carbon capture technology. In the first phase of this work, 5M MEA, which is the benchmark solvent for CO2 capture was used as the worst-case scenario to determine the ratio of producer gas-to natural gas (on energy basis) sufficient for achieving net-zero CO2 emissions. Using the SaskPower forecasted electricity generation capacity for 2025/2026 as a case study and applying LCA data to 5M MEA as the solvent for CO2 capture, it was determined that on energy basis, 14.5% of producer gas (balance natural gas) is sufficient for achieving netzero CO2 emissions while satisfying the set electricity generation target. The next phase of the work was to develop an amine blend with an improved CO2 removal efficiency compared to the bench-scale 5M MEA. Four different blends were screened to assess their respective performance against 5M MEA. These included 2:2 AMP: 1-(2HE) PRLD, 2:2 AMP: DEA-1,2-PD, 3:1 1-(2HE) PRLD: AMP and 3:1 1-(2HE) PRLD: DEA-1,2-PD bi-blends. Among these solvents, 2:2 AMP: 1-(2HE) PRLD was the optimum solvent as it demonstrated a high CO2 absorption-desorption parameter compared to the other blends. The absorption parameter for 2:2 AMP:1-(2HE) PRLD was 4.5% higher than that for 5M MEA and the desorption parameter 1,667% higher than 5M MEA. In the last phase, the increased CO2 removal efficiency of the solvent was applied to LCA data to determine the ratio of electricity generation from natural gas and producer gas towards achieving net-zero CO2 emissions when the optimum solvent developed is used in place of 5M MEA. It was determined that at a desorption temperature of 110℃, nearly all the CO2 in the rich amine for the optimum was removed. The CO2 removal efficiency of this solvent is about 31% higher than that for 5M MEA, implying this solvent allows for the removal of higher amount of CO2 in the flue gas stream. From the life cycle massessment, using 2:2 AMP: 1-(2HE) PRLD as the absorbent for CO2 capture in place of 5M MEA, it was determined that the producer gas requirements on energy basis, for cocombusting indirectly with natural gas towards achieving net-zero CO2 emissions is just about 8%. The findings from this work demonstrates that co-combusting biomass with natural gas (which is a lesser emitter of CO2 compared to other fossil fuels) allows for satisfying the energy demands while achieving net-zero CO2 emissions when CO2 capture is applied. The major limitation that has faced the application of bioenergy with carbon capture technology has been concerns over its competition with farmlands for food production. The results obtained from this work has showed that lower amount of biomass would be needed for energy generation via co-combustion with natural gas towards achieve net-zero emissions when a solvent with an improved CO2 removal ability is used as the absorbent in the CO2 capture process.
Open Access
Amine and Catalyst Stability Studies in the Catalyst-Aided CO2 Capture Process
(Faculty of Graduate Studies and Research, University of Regina, 2021-08) Amoako, Benjamin; Idem, Raphael; Supap, Teeradet; Narku-Tetteh, Jessica; Tontiwachwuthikul, Paitoon; Torabi, Farshid
The application of sol id base and sol id acid catalysts to improve CO2 capture has been one of the most notable technological advancements in amine-based post -combust ion capture. Despite the inherent benefits of the catalysts, the amine solvent is st i l l prone to degradation, which is a major operational problem associated with the capture process. The nature of solvent degradation in catalyst -aided CO2 capture has not been reported before, and thus, the effect of catalyst on solvent or vice versa is unknown. This work evaluates the effect of catalyst on solvent degradation and vice versa using BEA-AMP bi -blend solvent and recent absorber and desorber catalysts , which have produced remarkable CO2 capture performance. The absorber and desorber catalysts are CNTs/K-MgO and Ce(SO4 )2 /ZrO2 , respectively. A preliminary stability study was conducted under typical absorption conditions in a semi -batch mode. The results revealed that CNTs/K-MgO increases solvent degradation. Degradation was direct ly proportional to temperature in the region of 313-333K. It was also found that the catalyst reduces the activat ion energy of degradation by 11%. In addition, NH3 emissions from the degradation cell s increased wi th temperature . However, emissions were lower with the addition of catalyst due to the presence of colloidal silica used in binding the catalyst . The absorber catalyst was further investigated using normal conditions of the absorber during capture . The results showed 41 and 30% increments in degradation rates of BEA and AMP, respectively, with the catalyst . The effect of Ce(SO4 )2 /ZrO2 on the solvent was investigated in a bench-scale CO2 capture plant . The catalyst increased degradation by 23% for BEA and 20% for AMP. The effect of catalytic degradation on performance was evaluated by comparing the CO2 cyclic capacities of the catalytic and non-catalytic runs on the f irst and last days of the experiment . The results showed that the cyclic capacity of the catalytic run was 25% higher than the non-catalytic run on the last day, which is 18% lower than that obtained on the first day. Again, the decline in cyclic capacity of the catalytic system was faster by 10% due to the additional effect of catalyst on speeding amine degradation. The Ce(SO4 )2 /ZrO2 -aided degraded solvent was further tested with CNTs/K-MgO in the semi -batch mode. Further degradation was observed, showing that the combined ef fect of both catalysts would be higher in a typical capture plant . The fresh and spent catalysts from the test runs were characterized and compared to assess the stability of the catalysts. From the results, there were changes to the physical and chemical properties of the catalysts, which are known to be essential for CO2 capture. Increased degradation translates to a higher solvent replacement cost . Therefore, the findings of this work would represent the first step in developing better catalysts that would have a significantly reduced effect on the stability of the solvent to lower the cost of capture.
Open Access
Beyond Net-Zero Carbon Emissions in Industrial Process through Catalyst-Aided Amine Solvents for the Indirect Co-Combustion of Natural Gas and Biomass
(2024-11-06) Nii-Adjei Adjetey, Samuel; Appiah, Foster; Natewong, Paweesuda; Narku-Tetteh, Jessica; Supap, Teeradet; Idem, Raphael
This poster demonstrate research efforts undertaken to explore innovative approaches to achieving net-zero carbon emissions in industrial processes by integrating catalyst-enhanced amine solvents for the indirect co-combustion of natural gas and biomass. The research focuses on the development and optimization of heterogeneous solid-base catalysts to enhance CO₂ absorption rates, improve solvent loading, and increase overall process efficiency. Various catalysts, including PEI-modified catalysts, K/MgO, K/MgO-CaO, and activated carbon blends, were synthesized and evaluated. Results indicated significant improvements in CO₂ capture rates, with the K/MgO-CaO catalyst demonstrating notable chemical, thermal, and mechanical stability. Furthermore, a life cycle assessment (LCA) based on the ReCiPe methodology highlighted the environmental benefits of this novel catalyst-solvent system compared to conventional MEA-based carbon capture and the novel solvent AMP:PRLD. This work presents a promising pathway for power and energy sectors to enhance sustainability, reduce emissions, and move beyond net-zero targets.
Open Access
Catalyst-aided CO2 capture from exhaust gases of industrial point sources for utilization in cement-based industry
(Faculty of Graduate Studies and Research, University of Regina, 2024-01) Brakwah, Emma Kwarteng; Idem, Raphael; Supap, Teeradet; Ibrahim, Hussameldlin; Tontiwachwuthikul, Paitoon(P.T)
The utilization of solid-base catalysts to improve CO2 capture in amine-based postcombustion processes represents a significant technological advance. However, addressing both cost and catalytic efficiency remains crucial. Given the inherently expensive nature of amine-based post-combustion, there is an urgent need to explore innovative strategies to alleviate financial burdens. Research has shown that costs can be reduced by eliminating the desorption tower and utilizing enriched solvent directly from the absorber column. Accelerating the capture process via catalyst introduction reduces column height and further cuts costs. The primary focus of our study was to develop an alkaline catalyst to enhance CO2 loading in Potassium Glycinate salt solution. Our ultimate goal was to apply this enriched solution in the cement-based industry for producing concrete, mortar, and grout. In the course of this research, a total of twelve super basic catalysts were synthesized and rigorously assessed using a semi-batch apparatus. Their initial absorption rates were meticulously scrutinized and juxtaposed against the baseline scenario devoid of any catalyst. Notably, the introduction of most catalysts yielded a marked acceleration in CO2 absorption, resulting in remarkably increased absorption rates. These initial absorption rates were observed to follow a discernible ascending order Ce/CaO < K/MgO < Blank < AGO* < K/MgO + AGO < K/MgO + GO < Ce/MgO < AC (H) < AC (H) + MgO < GO < AGO + AC (H) < K-MgO/AC (C) < AGO. Outstandingly, AGO exhibited the highest initial absorption rate at 5.12×10-2 (mol CO2/l.min), closely traced by KMgO/ AC (C) at 4.77×10-2 (mol CO2/l.min), while Ce/CaO and K/MgO displayed relatively lower performance at 3.56×10-2 and 3.63×10-2, respectively. Intriguingly, it was noted that Ce/CaO and K/MgO, rather than facilitating CO2 absorption by the Potassium Glycinate salt solution, reverted to their starting materials, Ca(OH)2 and Mg(OH)2 respectively, in the presence of water which formed carbonates with the CO2, diminishing the readily available CO2 for the Potassium Glycinate salt solution to capture. Considering the intricate and potentially hazardous nature of the AGO preparation process, along with environmental and safety concerns related to the chemicals used, KMgO/ AC (C) was selected as the preferred catalyst for this study. It exhibited a 25.2% enhancement in the absorption process, in contrast to the 34.4% improvement achieved by AGO. K-MgO/AC (C) underwent comprehensive characterization to determine both its chemical and physical properties, and the findings are meticulously documented in this study. Moreover, the results derived from the characterization of K-MgO/AC (C) were juxtaposed with existing data on AC (H) and K/MgO from literature, providing insights into and comparisons of the performance of these three catalysts based on their respective characteristics. In an effort to assess the stability of the K-MgO/AC (C) catalyst, two distinct approaches were employed. In the first approach, the same catalyst was utilized for three consecutive runs, with fresh solvent introduced between each run. In the second approach, the catalyst underwent washing, drying, and high-temperature calcination to eliminate any residual deposits before being reused. The stability analysis outcomes corroborated the robust stability of the K-MgO/AC (C) catalyst for up to three successive cycles of usage, a conclusion reinforced by the results obtained from thermal gravimetric analysis (TGA). Worth noting is the fact that all experiments conducted during the course of this study remained well within the acceptable margin of error, not exceeding 8%.
Open Access
CO2 emissions reduction through catalytic production & use of fuels derived from biomass
(Faculty of Graduate Studies and Research, University of Regina, 2023-03) Anokye-Poku, Terza; Idem, Raphael; Ibrahim, Hussameldin; Supap, Teeradet; Jia, Na
This study focused on the preparation of environmentally friendly heterogenous catalyst from biomass specifically waste egg shells, cow bones and fish scales for use in the production of biodiesel from waste cooking oil (WCO) which is also a biomass-based waste feedstock collected from households that will be an alternative fuel source and contribute to reducing CO2 emissions into the environment as well as the cost of biodiesel production To begin, the biodiesel feedstock properties needed to be checked for its suitability in making fuel because the feedstock properties were going to impart the properties of biodiesel. The first property of the oil checked was the fatty acid composition. The need for a further purification step apart from filtration was confirmed and other properties of the feedstock such as viscosity, density, acid value and water content of the WCO were also checked. Based on these, the WCO fell in the range within which it could be used in making biodiesel, there was no need for further physical purification steps because the properties of both the crude and purified WCO were very close. In addition, the properties showed that a catalyst basic in nature was suitable for the transesterification process. The next phase involved carrying out reactions with the conventional basic catalyst (KOH) to serve as a baseline for the work to which heterogenous catalytic reactions would be compared. The heterogenous catalysts were then synthesized from waste egg shells (ES), cow bones (CB) and fish scales (FS) separately before bi-blend (CBES, FSCB, FSES) and tri-blend mixtures (M3) of these components were made in a ratio of 1:1 and 1:1:1 respectively and characterized. The focus of the catalyst was on the performance of M3 and how CB, FS and ES contributed to that as well as its performance in comparison to biii blend mixtures that have been the kind of blends prepared in literature for biodiesel catalysts. All seven heterogenous catalysts were utilized in transesterification reaction of the WCO at the same process conditions to evaluate their performance with respect to biodiesel yield. The biodiesel yield of these catalysts followed a trend of decreasing order as follows: M3 > FSES > CBES > ES > FSCB > FS >CB mainly due to the basicity resulting from the type of active components present in these catalysts. Regression analysis was performed to further validate which characteristics affected the performance and it was confirmed that the most important characteristic of the catalysts in this work was basicity. Furthermore, since M3 was the focus and the best performing catalyst amongst the heterogenous catalysts as well, it was compared to the yield of the homogenous reactions that was used as the baseline and a difference of averagely 27% was observed. M3 was then used in reactions to study the effect of the process variables on the biodiesel yield and the optimum conditions were found to be a temperature of 60°C, 6 hours of reaction time, stirring speed of 600 rpm, ethanol-to-oil molar ratio of 15:1 and catalyst concentration of 2wt% of the oil.
Open Access
A Comparison Study of Carbon Dioxide Absorption Performance in MEA and Blended Amine Solvents for Post-combustion Process: Experiment, Modeling and Simulation
(Faculty of Graduate Studies and Research, University of Regina, 2020-04) Li, Tianci; Tontiwachwuthikul, Paitoon; Idem, Raphael; Supap, Teeradet; Na, Jia
In recent years, industrialization causes excess carbon dioxide emissions. Carbon dioxide (CO2) is one of the main greenhouse gases due to human activities. However, high costs remain the main challenge to control the carbon dioxide from industry. Due to this issue, the carbon capture technique is developing slowly in most developing countries. This work is going to compare and explore a more effective blended amine solvent comparing with current common single amine solvents for the CO2 chemical absorption process for improving absorption performance and reducing the investment and operating costs. In this research, the CO2 absorption performance of aqueous MDEA/PZ blends and aqueous MEA/MDEA/PZ blends were comprehensively investigated experimentally and compared with the benchmark aqueous solution 5M MEA in terms of CO2 absorption rate, CO2 absorption efficiency, mass transfer efficiency and CO2 equilibrium solubility using a bench-scale packed column and a CO2 solubility apparatus. The simulation results have been validated with the experimental date from this research work other published experimental data. Different scenarios were assessed to evaluate the absorption performance using experiment method and simulation method. The overall mass transfer coefficient of the aqueous solvents and the CO2 absorption rate under ambient pressure is ranked as 2M MDEA+3M PZ>1M MEA+2M MDEA+2M PZ > 3M MDEA+2M PZ > 5M MEA. The measurements of the CO2 solubility experiments were performed over the CO2 partial pressure range of 8-51 kPa at 40oC. A new set of experimental data for the CO2 solubility in an aqueous solution of 1M MEA+2M MDEA+2M PZ blended solvent and aqueous MDEA/PZ blends were investigated and compared with the prediction results from the Artificial Neural Network model and the simulation results using MATLAB and ProMax, respectively. The prediction results from ANN model confirmed that the CO2 equilibrium solubility of 2M MDEA+3M PZ was higher than other blend amine solvents and the conventional amine (5M MEA). Also, the comparison results indicate that the neural network modeling provides more accurate prediction results of CO2 solubility test than the simulation results when compared with new experimental results in this research.
Open Access
Development of a diagnostic approach for early detection and control of amine degradation in an amine-based CO2 capture process
(Faculty of Graduate Studies and Research, University of Regina, 2022-12) Mensah, Ebenezer Kofi; Idem, Raphael; Ibrahim, Hussameldin; Supap, Teeradet; Zeng, Fanhua
Chemical absorption of CO2 with aqueous amine-based solvents is considered as one of the current benchmark post-combustion capture technologies mainly because of its high process efficiency. When amines are used to capture CO2 from flue gases, changes in the physical and chemical properties of the solvent may take place over time. The changes in these properties of the amines are manifestations of physical changes such as the differential evaporation of components of the aqueous amine solvents and chemical changes resulting from degradation of the amines. Therefore, if changes of these properties relative to the original solvent properties are monitored during the capture process, they could be used to determine whether a physical change such as water evaporation has taken place or a chemical change such as degradation has occurred or both. The amine concentration can be restored by adding the right amount of the right component to restore the amine solution to its original form. This work uses a diagnostic approach to determine the occurrence of physical or chemical changes in amine-based solvents by means of simple solvent property measurements as a way of monitoring solvent quality during the CO2 capture process to maximize the capture efficiency and improve the capture performance of amine-based solvents. In the first phase of the work, amine was prepared at different concentrations to closely imitate the physical changes that could take place in a conventional CO2 capture plant as a result of the differential evaporation of the components of the amine. CO2 loading and temperature were also varied to take into account the different conditions that might exist in the capture plant at the time a sample was taken for analysis. The amine properties at these different concentrations and conditions were measured and then compared to the properties of the original or desired solvent. For the chemical change experiment, the amine was synthetically degraded by intentionally adding different concentrations of primary degradation products and measuring the corresponding properties of the degraded amine. The experimental data obtained from the first phase of the work was then used to develop predictive models that were capable of predicting physical or chemical changes or both based on the change in properties of the amine sample. Three predictive models were developed for physical change using MS Excel, Minitab software and Artificial Neural Network (ANN) with MATLAB software. The standard error for the model developed using MS Excel was determined to be 0.097 with R2 value of 0.97 and average absolute deviation (AAD) of 1.56% between model predicted and actual response values of the validation dataset. The model trained using Minitab reserved a fraction of 0.3 of the data for internal testing and returned standard error of 0.09 and 0.11 for training and test set with R2 values of 0.977 and 0.953 respectively. The AAD between model predicted and actual response values of additional test data was determined to be 1.39%. The trained ANN also returned root mean squared error (RMSE) of the training, validation and test dataset as 0.035, 0.046 and 0.068 respectively with R2 value of 0.995 for the test set. AAD for validation and test set was computed to be 0.91% and 1.47% respectively. An optimizable Gaussian Process Regression (GPR) model was developed for chemical change using Regression Learner tool in MATLAB. The trained model with the best hyperparameters returned R2 values of 0.99 and 0.95 for the validation and test set with RMSE of 0.042 and 0.090 respectively. The AAD for the test set parity plot was computed to be 3.45%. The models with satisfactory performance and accuracy were then selected and employed in the development of an interactive graphical user interface (GUI) to make predictions, interpret predicted values for the user and suggest actions that would enable the user offset any disturbance or deviation from set values.
Open Access
Development of a System of MEA Solutions Activated by Novel Poyamines for Natural Gas Sweetening Mass Transfer in Absorber and Desorber Columns
(Faculty of Graduate Studies and Research, University of Regina, 2020-03) Jaafari, Laila Ibrahim; Idem, Raphael; Torabi, Farshid; Tontiwachwuthikul, Paitoon; Supap, Teeradet; Raina-Fulton, Renata; Adesina, Adesoji
This study focused on finding new and efficient activators to be blended with methyldiethanolamine (MDEA) for natural gas processing. Polyamines were highlighted in the open literature to have high CO2 loading as well as high absorption rate. As branched polyethyleneimine (PEI-B) (MW ≈ 800 with almost 16 amino groups) showed a superior performance in adsorption applications for capturing CO2, it was important to test its performance in absorption process. Tetraethylenepentamine (TEPA) is another polyamine (five amino groups) that was indicated in both adsorption and absorption as an excellent solvent; therefore, it was included in this study. PEI-B and TEPA were tested individually and as activators in MDEA blends. Furthermore, the performance of PEI-B and TEPA was evaluated against the performance of the standard activator of MDEA which is piperazine (PZ). Theses activators were screened using a simple absorption and desorption set up. In the screening experiments, the absorption and desorption temperatures were 40 and 100 ○C respectively. A dilute concentration for single polyamine (0.01 M) was applied at 100 mol% CO2 to investigate the maximum absorption rate at low viscosity and resistance in liquid and gas phases respectively. Also, higher amine concentrations of 0.1, 0.3, and 0.5 M were tested at 50 mol% CO2 to investigate their performance when both the solution viscosity and the gas resistance increased. Furthermore, in the screening step, these activators were tested in MDEA blends. The concentration of MDEA was kept constant at 3 M (30 wt%) while the concentration of the activators (PZ, TEPA, PEI-B) was varied at 0.1, 0.2 and 0.3 M. The performance of these activators individually and in MDEA blends was evaluated in terms of rich loading, lean loading, cyclic capacity, absorption rate and desorption rate. The results showed that PEI-B gave the highest performance individually and in MDEA blends followed by TEPA while PZ exhibited the lowest efficiency in all absorption and desorption parameters. Moreover, MDEA blends with PZ, TEPA and PEI-B were also investigated in a small pilot plant. Two blending ratios (0.1 and 0.3 M activator to 3 M MDEA) were selected to be tested in the pilot plant. Four CO2 contents of 20, 50, 70 % (the balance is N2) as well as 100 mol% were used in the gas feed. Again, PEI-B blends showed the highest absorption and desorption efficiencies followed by TEPA blends and then PZ blends. Also, the overall gas mass transfer coefficient (KGav) as well as the overall liquid mass transfer coefficient (KLav) were calculated to represent the mass transfer of CO2 in absorber and in desorber respectively. In both trends of KGav and KLav, PEI-B blends were recorded the best followed by TEPA blends and then PZ blends while non-activated MDEA gave the lowest mass transfer coefficients. Two models were applied for KLav and for KGav to predict their experimental values. The experimental values of KLav and KGav showed good fit with the models with acceptable average absolute deviations of 4.1 and 14.5 %, respectively.
Open Access
Development of solvent for CO2 capture for utilization in concrete and storage in geological formations
(Faculty of Graduate Studies and Research, University of Regina, 2023-03) Sam, Yusif Rhule; Idem, Raphael; Tontiwachwuthikul, Paitoon; Supap, Teeradet; Veawab, Amornvadee
This study focused on developing an environmentally benign solvent for CO2 capture for utilization in concrete and the potential permanent storage in geological formations. Initial solvent screening and the selection included 2M aqueous solvents of KOH, NaOH, K2CO3, Na2CO3, sodium and potassium salts of glycine and lysine at 40oC and 20% CO2 balance nitrogen. The performance of the solvents was evaluated in terms of initial absorption rate, solvent precipitation and CO2 equilibrium loading. To present the best performing solvents as commercial products, the selected solvents were further optimized concerning solvent concentration, precipitation, CO2 partial pressure and absorption temperature. The absorption performance parameter values were 10.99, 11.95 and 13.47 (mol CO2 absorbed)2/(L soln.)2.min) x10-2 for potassium lysinate salt, KOH, and potassium glycinate salts respectively. Moreover, the optimum absorption condition for the best-performing solvents were experimentally determined to be 3M and 40oC, 5M and 60oC, and 6M and 60oC for aqueous potassium lysinate salt, KOH and potassium glycinate salt respectively. In the utilization section, best performing solvents from the optimization studies were loaded with CO2 and used for carbonation reactions. The presence of CaCO3, the main product formed when CO2 reacts with concrete, was confirmed by XRD phase identification analysis. Also, by the TGA thermogram, the calcium carbonates in the precipitate of the K2CO3-Ca(OH)2 reaction was 44.1wt.%, whiles that from CO2-loaded potassium glycinate-Ca(OH)2 was 55.4wt.%, demonstrating the ease with which potassium glycinate easily releases CO2 to concrete compared to carbonates and hydroxide systems. Moreover, these findings proved the concept of utilizing the CO2-loaded solvents in concrete. Finally, kinetic studies were conducted for the best performing solvent concerning both CO2 capture and utilization in concrete, potassium glycinate salt. The kinetic performance was measured in terms of the initial absorption rate. To fit the kinetic data, the power law model was used. With the aid of NL-Reg software, the activation energy obtained was Ea = -5.5x103 J/mol. This was expected because, the rate of absorption decreased with increasing temperature. For reversible reaction such as this, the backward reaction might have been favoured at high temperatures leading to this observation. Also, CO2 and potassium glycinate had reaction orders of 1 and 0.11, respectively. The AAD% obtained was 5.15%, demonstrating how well the model predicts the experimentally observed rates.
Open Access
Effects of flue gas impurities on amine stability in C02 capture process
(Faculty of Graduate Studies and Research, University of Regina, 2023-03) Nyarko, Collins; Idem, Raphael; Tontiwachwuthikul, Paitoon; Supap, Teeradet; Young, Stephanie
Amine stability in a post-combustion carbon capture plant is considered one of the most essential parameters tracked to keep the process running at peak efficiency. The presence of impurities in exhaust gases (O2, SOx, NOx) is known to undergo undesired irreversible reactions with the amine to form products leading to solvent loss which impedes the optimum operation of the plant. Metal oxides (the main constituents of industrial exhaust gas fly ash) influence on solvent degradation however have not been reported extensively and hence this study aims at investigating the effects of different metal oxides common in the blast furnace exhaust gas of iron and steel mills on the degradation of the amine solvent. In this study, oxygen-induced degradation of 0.28 CO2 loaded 5M MEA-DMAE (3M:2M) solvent under 0.12g of different metal oxides was quantified by NH3 emissions measured using an ammonia-nitrate analyzer. The effect of oxygen concentrations, temperatures, and the different metal oxides on the solvent stability were studied. The experiment was performed with four different systems each containing amine solution unique with a metal oxide constituent of ZnO, Fe2O3, and Al2O3 and a reference system containing no metal oxides(blank). The solubility of the metal oxides in the amine solution obtained using ICP-MS analysis from the experimental run conducted 10% O2 at 60oC showed that the solubility of ZnO > Fe2O3 > Al2O3 in the amine solution. ZnO and Fe2O3 systems showed catalytic effects in increasing the rate of NH3 emissions whereas the Al2O3 showed a relatively low NH3 emissions to the blank system. However, the specific rates of emissions with respect to the mass of dissolved metals showed that the Fe2O3 system had the highest catalytic effect compared to the ZnO system in increasing the rate of NH3 emissions. The time weighted NH3 emissions rates observed in this study ranged from 0.21-5.99 ppmV/hr. The studies showed that, the rate of NH3 emissions increased with increasing oxygen partial pressure and temperature. The relationship between solubility of various metal oxides in amine and the degradation of amine under typical conditions common to real life post combustion capture plants have been established.
Open Access
Evaluating and optimizing the performance of single and blended amines based on their chemical structures for carbon dioxide capture from industrial gas streams
(Faculty of Graduate Studies and Research, University of Regina, 2023-03) Fraij, Heba; Idem, Raphael; Ibrahim, Hussameldin; Supap, Teeradet; Mobed, Nader; Suriyapraphadilok, Uthaiporn
With the well-known fact on negatively impact of the human activities and the tremendously growth of industrial sectors and the increase in the global energy demand, the increase of the Green House Gas (GHG) including CO2 is very central because almost all fossil fuel activities lead to generation of this environmentally harmful GHG which found to cause increasing on the average global temperature which causing several major issues such as extreme weather conditions, heat waves, sea level rise, wild fires, health problems and many more. Actions are required immediately to reduce the emission such as using alternative energy source with less GHG emission and use Carbon Capture and Sequestration (CCS). Post combustion capture by using a liquid absorbent solution is successful method specially the ability to regenerate the solution which makes this method cost sufficient for industrial applications. The scientists are still looking for perfect fit solution in both performance and management’s levels. This research is focused on finding a good solution that has high absorption-desorption performance and has lower corrosion rate, foaming and degradation. The relation between the performance and the chemical structure, finding the optimum condition of the single amine solutions and the blend ratio for best performance were also studied. However, two sets of amines studied mono amines and diamines. In the diamine set, the ethanol was added to the nitrogen atom in the structure while in the monoamine, the alkyl group was added to the structure. The desorption and absorption parameters criteria were used for selecting components of amine blend. The concentration and the ratio of the blend components varied in order to find the optimum ratio and concentration. The optimum blend and its single components were then studied for corrosion, foaming and degradation. The results of screening of 4AB and 4A2MB showed that adding methyl group to the straight chain enhance the absorption and the desorption performance while reduce the heat duty. The study of the diamines 22AEE and BMEM showed adding 3 methyl group sto the nitrogen atoms in the structure reduced the absorption and desorption performance and increased the heat duty, while in 22AEE and EDA; adding the -OH group to EDA as seen in 22AEE increased the rich loading, desorption rate and cyclic capacity while absorption rate, pKa, and heat duty reduced by adding the ethanol group to the structure. Considering –OH group in the structure increases the solubility of the amine and makes it less volatile which is preferred. However, the mass transfer limitations on all amines in this research had no impact on the performance at the concentrations used in the research. On the other hand, increasing the number of amine groups from mono to diamine caused to generate larger amounts of bicarbonate ions which lead to higher CO2 desorption rates and cyclic capacity, but lower heat duty. Also, the higher alkyl group found to have high viscosity. Adding ethanol groups to the diamine increased the viscosity in general but it had no impact on the performance. The developed criteria of blend selection of the diamine in terms of absorption parameter was based on taking the average pKa1 and pKa2 which resulted at the end in selection of the best performance fit of 22AEE:EDA (3:1) of overall 1M blend after screening several ratios and concentration. This had an outstanding desorption characteristics/heat duty as well as very good absorption characteristics. 22AEE to EDA 3:1 blend, implying that it is a good potential solvent for post combustion CO2 capture. Then, carried 3:1 blend for further management testing like (corrosion, foaming and degradation/emission). 22AEE found to have lower foaming than EDA and thus due to the existing three hydrophilic groups and higher surface tension compared to two groups in EDA structure. Corrosion found to be higher in EDA than 22AEE. The degradation rate found higher in 22AEE while the accumulated emission found higher in EDA.
Open Access
Heat Duty, Cyclic Capacity and Rate of Desorption for MDEA Activated by Novel Polyamines for Natural Gas Sweetening
(Faculty of Graduate Studies and Research, University of Regina, 2020-03) Jaffary, Bander Ebraheem; Idem, Raph; Wee, Andrew; Zeng, Fanhua; Ibrahim, Hussameldin; Supap, Teeradet; Nithitanakul, Manit
This study focused on finding suitable activators to be blended with aqueous MDEA for use in natural gas sweetening. Polyamines are promising amines for capture of CO2 efficiently as they contain more than one amino group in their structures. Polyethylenimine (PEI-B) and Tetraethylenepentamine (TEPA) were chosen and screened to investigate their performance as efficient activators for MDEA. PEI-B and TEPA were compared with piperazine (PZ) which is currently used as the standard activator of MDEA. The screening experiments were carried out using a simple absorption and desorption setup at atmospheric pressure. This setup was validated using 5 M MEA with 100 mol% CO2 and the equilibrium rich loading was in a good agreement with the literature (Shen and Li, 1992) with a deviation of 5%. Single polyamines (PZ, TEPA and PEI-B) were tested at dilute concentration (0.01 M) using 100 mol% CO2 to investigate their performance at low viscosity in liquid phase as well as at zero resistance in the gas phase. The absorption and desorption temperatures were 40 and 100 ◦C respectively. Also, the individual single polyamines were tested at higher concentrations (0.1, 0.3 and 0.5 M) using a feed gas with 50% CO2 content (balance is N2) to investigate their capacity at higher viscosity and higher gas resistance in the liquid and gas phases, respectively. Moreover, the activators (PZ, TEPA and PEI-B) were blended with MDEA and screened using 100 mol% CO2. In MDEA blends, the concentration of MDEA was kept constant at 3 M (34 wt%) whereas the concentration of the activators was varied as 0.1, 0.2 and 0.3 M. The reproducibility of the results in the screening set up was within 1%. The screening experiments focused on absorption and desorption parameters which include rich loading, lean loading, cyclic capacity, desorption rate and heat duty. In the results of screening experiments, PEI-B performed the best as an individual amine as well as in blends with MDEA as compared with TEPA or PZ in all absorption and desorption parameters. Also, PEI-B gave the lowest heat duty using individual single solutions and in blends with MDEA as compared with TEPA or PZ. Furthermore, MDEA blends with PZ, TEPA and PEI-B were also investigated in a bench-scale pilot plant. The pilot plant was validated using 5 M MEA at 15 mol% CO2 and the rich loading was compared with the standard rich loading of 5 M MEA. The deviation obtained was 3%. Two blending ratios of 0.1 M/3 M and 0.3 M/3 M (activator/MDEA) were chosen to be used in the small pilot plant studies. The CO2 contents of 20, 50, 70 and 100% were applied in the pilot plant. The absorber column was operated at a pressure of 1 bar while the regenerator as well as the reboiler were operated at 2 bar. The results also showed a superior performance of PEI-B blends in all absorption and desorption parameters followed by TEPA blends and then PZ blends. The reproducibility of the experimental results obtained from the pilot plant was within 8%. PEI-B blends displayed the lowest heat duty among all tested blends. Furthermore, the NMR analysis was used to investigate the possible products at different CO2 loadings in 0.1 M PEI-B and 0.1 M PZ single amines as well as in blends with 3 M MDEA. Also, a heat duty model was developed based on the results obtained from the pilot plant and the structural properties of the amines. The model showed an acceptable average absolute deviation (7%). Moreover, a preliminary cost analysis was performed to evaluate the total cost (capital and operating costs) for PZ blends and PEI-B blends at 20, 50 and 70 mol% CO2. This economic analysis showed that PEI-B blends exhibited lower total costs than PZ blends.
Open Access
Kinetic Studies on Catalyst-Aided Absorption and Desorption in a Bench-Scale Post-Combustion CO2 Capture Pilot Plant Using a Novel Solvent Blend
(Faculty of Graduate Studies and Research, University of Regina, 2018-08) Afari, Daniel Boafo; Idem, Raphael; Ibrahim, Hussameldin; Supap, Teeradet; Volodin, Andrei
A total of seven solid base/alkaline catalysts comprising BaCO3, CaCO3, Ca(OH)2, Cs2O/α-Al2O3, Cs2O/γ-Al2O3, K/MgO and Hydrotalcite were screened on a semi-batch scale to select the most suitable for CO2 absorption into a novel aqueous solvent, BEA/AMP. The selected catalyst was incorporated into the absorber section of a benchscale pilot plant and its kinetic performance was evaluated. Intrinsic kinetic data were extracted and kinetic parameters were determined. Both cases of reversible and irreversible reactions of CO2 with the aqueous BEA/AMP solvent were analysed. An activation energy, Ea of 5.67E+04 J/mol and 3.40E+04 J/mol were obtained for the reversible and irreversible cases respectively. A reaction order of 2 with respect to CO2 for the irreversible case shows a higher dependency of the reaction rate on CO2 with the introduction of a heterogeneous catalyst and is a further indication of the complexity of the reaction as a third phase (solid) is introduced. A parity plot showing the degree of correlation between the experimental and predicted rate gave an AAD of 14.1%. Also, the performance of the novel solvent was compared with conventional Monoethanolamine (MEA) and blended Monoethanolamine (MEA)/n-Methyldiethanolamine (MDEA) in the presence and absence of a solid acid catalyst (HZSM-5). The results showed that the novel solvent (4M BEA-AMP) outperformed conventional 5M MEA and the 7M MEA-MDEA blend despite its lower molarity. For the novel solvent, Parametric Sensitivity Analysis (PSA) was conducted to investigate the impact of each independent process parameter on the CO2 conversion. It was observed that the most influential parameter was the absorber catalyst composition, followed by the gas flowrate and lean amine loading. The least influential was seen to be the desorber catalyst composition. Preliminary economic ii analysis showed that the novel solvent, BEA-AMP recorded the least annual operating cost when compared with conventional MEA and MEA-MDEA solvents. A separate analysis on the BEA-AMP system revealed that the introduction of absorber catalyst resulted in lowering the operating costs by about 40% using the base case of no absorber catalyst as reference. Employing catalysts in Post-combustion capture helps in truncating the associated operating costs and greatly contributes to making it a long term viable technology.
Open Access
Kinetic study of oxidative degradation in gas treating unit using aqueous monoethanolamine solution.
(Faculty of Graduate Studies and Research, University of Regina, 2000) Supap, Teeradet; Tontiwachwuthikul, P.; Kybett, B.
Open Access
Kinetic Study of the Catalytic Desorption of Carbon Dioxide (CO2) from CO2-Loaded Monoethanolamine (MEA) and Blended Monoethanolamine-Methyldiethanolamine (MEA-MDEA) during Post Combustion CO2 Capture from Industrial Flue Gases
(Faculty of Graduate Studies and Research, University of Regina, 2016-12) Akachuku, Ananda Udochi; Idem, Raphael; Ibrahim, Hussameldin; Supap, Teeradet; Tontiwachwuthikul, Paitoon
The objective of this research was to elucidate the kinetics of the catalyst-aided desorption of CO2 from CO2-loaded aqueous solutions of single monoethanolamine (MEA), and monoethanolamine blended with methyldiethanolamine (MEA-MDEA) during the post-combustion capture of CO2 from industrial flue gases. The experiments were performed over γ-Al2O3 and HZSM-5 catalysts in a complete absorber – desorber CO2 capture pilot plant unit with the absorber and desorber columns having an internal diameter of 2-inches (0.051 m) and a total height of 3.5 ft (1.067 m). The experimental kinetic data for CO2 desorption were obtained in the catalytic packed bed tubular desorber at three temperatures (348, 358, and 358 K), using MEA and MEA-MDEA concentrations respectively of 5M and 5:2M (molar ratio and total molarity of 7M) and CO2 loading ranging from ∼ 0.331-0.5 mol CO2/mol amine for different ratios of weight of catalyst/flow rate of amine (W/FAo). The kinetic performance was evaluated in terms of conversion (i.e. %CO2 desorbed), activation energy, frequency factor and rate constants. A comprehensive first order power law rate model and Langmuir-Hinshelwood-Hougen-Watson (LHHW), mechanistic models for the heterogeneous reactions, were developed. The results showed that HZSM-5 catalyst with higher Brønsted/Lewis acid site ratio exhibited dual site adsorption mechanism and provided faster kinetics and higher conversions with lower activation energy in comparison with γ-Al2O3 for both solvents. Also, a statistical analysis using four catalysts, namely, HZSM-5, γ-Al2O3, silica-alumina and HY (of widely varying characteristics in terms of BET surface area, pore size and distribution, pore volume, total acid sites, acid site strength and Brønsted/Lewis acid site ratio), as well as an inert parking scenario to determine the contributions of each characteristic to catalyst performance in CO2 desorption from CO2-loaded aqueous amines. The results showed that catalyst performance on CO2 desorption from CO2-rich MEA solution depended strongly on both the combined high acid strength with high B/L ratio as well as the high ratio of pore size to pore volume.
Open Access
Mass Transfer and Emission Studies on a Catalyset-Aided CO2 Absorption and Desorption in a Post Combustion CO2 Capture
(Faculty of Graduate Studies and Research, University of Regina, 2018-08) Coker, James; Idem, Raphael; deMontigny, David; Supap, Teeradet; Torabi, Farshid
The mass transfer study of a catalyst aided absorption and desorption with the intent of minimizing the energy requirement for the solvent regeneration as well as improving the absorption efficiency of the solvent was carried out. This included the selection and screening for suitable amine solvents for the absorption and desorption process using a bench scale pilot plant. The solvent screening process was evaluated in terms of absorption efficiency, cyclic capacity of amine, height requirement of the column and the overall mass transfer coefficient of both the absorber and desorber. Solvents used were 5M monoethanolamine (MEA), 5M MEA-2M methyl diethanolamine (MDEA) and 2M 2-Butylaminoethanol (BEA)-2M 2- amino 2 methyl 1 propanol (AMP). For process improvement, the selection and screening of a number of solid base catalyst to improve the absorption of CO2 was also carried out. The improvement of CO2 absorption with the selected solid base catalyst, K/MgO, for the absorption process and a solid acid catalyst, HZSM-5 for the desorption process was evaluated using the bench scale pilot plant. The result reveals the tremendous improvement with the addition of the catalyst in terms the overall mass transfer coefficient which translates into a shorter absorption and desorption column. A 46% increase in cyclic capacity, 95% and 45% increase in the overall volumetric mass transfer coefficient for the absorption (KGaV) and desorption columns (KLaV) respectively was obtained for the application of both catalyst. A parametric study including effect of desorption bed temperature, absorber catalyst weight, solvent inlet temperature to the absorber, solvent flowrate, solvent blend ratio and hybrid desorption catalyst (HZSM-5 and ɣ-Al2O3) effect were studied. Results also showed the effect of gas flowrate, solvent flowrate and the %K on MgO as the most controlling parameters in the capture process. An emissions study on volatile organic matter from amine degradation showed the emission of ethanol, acetone, acetaldehyde and ammonia as components of the emissions from the absorber. An economic analysis on the operating cost of CO2 capture showed the introduction of the absorber catalyst as more economical with energy penalty of 232 Watts per kg of CO2 produced.
Open Access
Mass Transfer Studies on Catalyst-Aided CO2 Desorption in a Post Combustion CO2 Capture Plant
(Faculty of Graduate Studies and Research, University of Regina, 2016-12) Osei, Priscilla Anima; Idem, Raphael; Supap, Teeradet; Tontiwachwuthikul, Paitoon; Ibrahim, Hussameldin
Two solid acid catalysts of contrasting characteristics were studied on their effects on the liquid-side mass transfer performance for the desorption of CO2 from CO2-loaded 5M monoethanolamine (MEA) solvent. The characteristics of the catalysts were both physical (surface area of catalyst which increases the interfacial area for mass transfer) and chemical (the catalyst acid sites to catalyze the desorption of CO2). Protonated zeolite socony mobile-5 (HZSM-5) representing a higher Brφnsted/Lewis acid site ratio in a catalyst and γ-Al2O3 representing lower Brφnsted/Lewis acid site ratio were used. The experiments were conducted in a 1.07 m height x 0.051m diameter packed column in full cycle operation. The packing structure consisted of a 0.51 m bed height of 6 mm inert marble randomly mixed with a specific mass of catalyst and a 50.8 mm Sulzer LDX structured packing acting as top and bottom support beds. 5M monoethanolamine (MEA) was selected as the baseline solvent for the study and further tested on an optimum 7M MEA + 2M Methyl diethanolamine (MDEA) blend. The effect of several other operating variables on desorption performance was also analyzed. The catalyst physical characteristics in terms of the added interfacial area which enhances desorption was higher for HZSM-5 compared to γ-Al2O3. The mass transfer coefficient increased by an average of 16% and 22% using γ-Al2O3 and HZSM-5 catalyst respectively with the baseline solvent at a CO2 desorption temperature of 85oC. These results are consistent with the ability of HZSM-5 as a proton acceptor to facilitate 𝑀𝐸𝐴𝐶𝑂𝑂− breakdown throughout the loading range of desorption as compared with γ- Al2O3, an amphoteric oxide, which substitutes the role of 𝐻𝐶𝑂3 − to release CO2 with lower energy penalties at leaner CO2 loadings. The results using the blended solvent showed a better performance compared to the baseline. The tertiary solvent, MDEA, introduces other preferential desorption ions that further facilitate 𝑀𝐸𝐴𝐶𝑂𝑂−and 𝐻𝐶𝑂3 − breakdown. This constitutes a 12% and 14.5% increase in the mass transfer coefficient using H-ZSM-5 and γ-Al2O3, respectively compared to the baseline solvent. The percentage increase implies a reduction in the size of the desorber column which further translates to lower capital cost.
Open Access
Modeling, Simulation and Experimental Validation of a New Rigorous Desorber Model for Low Temperature Catalytic Desorption of CO2-Loaded Amine Solvents over Solid Acid Catalysts
(Faculty of Graduate Studies and Research, University of Regina, 2016-12) Decardi-Nelson, Benjamin; Idem, Raphael; Supap, Teeradet; Ibrahim, Hussameldin; Tontiwachwuthikul, Paitoon
Carbon Capture and Storage (CCS) have gained tremendous attention amongst policy makers, researchers and engineers in response to the increasing fears for climate change which is caused by increased amounts of greenhouse gases (GHGs) being emitted into the atmosphere. This is in an effort to decarbonize fossil fuels, especially coal, in order to make them environmentally sustainable while allowing these fuels to contribute to the global energy mix. Due to its maturity, post-combustion capture by chemical absorption, has been the technology focus to capture carbon dioxide (CO2) from combustion flue gases emanating from fossil fuel-based power plants. In this work, a numerical model for catalyst-aided CO2 desorption from CO2-loaded aqueous amines solution has been developed. The model includes a hot water-heater and considers phase separation at the top of the desorption column. The model was validated with experimental data obtained from an integrated post-combustion CO2 capture pilot plant which used 5 M monoethanolamine (MEA), and 5 M MEA mixed with 2 M N-Methyldiethanolamine (MDEA) solutions with two industrial catalysts, namely, HZSM-5 and γ-Al2O3. The model considers the presence of electrolytes and multi-component mass transfer as well as both the physical and chemical contribution of the catalyst in aiding the process. The data obtained from model simulation were in good agreement with the experimental data in terms of CO2 production rates with an absolute average deviation of approximately ±8.9 % for MEA and ±7.7 % for MDEA. The simulation slightly over-predicted the CO2 production rate at the low temperature regime (75 °C) and under-predicted the CO2 production rate at the high temperature regime (95 °C) in both cases. Also, the temperature profiles predicted by the model was in close agreement with the experimental temperature profiles even though it under-predicted them. Based on the simulation as well as the experimental data, HZSM-5 was seen to have greater effect in aiding CO2 desorption than γ-Al2O3 for both solvents. However, the extent of aiding desorption of CO2 from loaded MEA was higher than that of MEA-MDEA. Also, the concentration of CO2 in the gas phase was seen to be quite high and can greatly decrease the driving force for mass transfer. Furthermore, it was interesting to observe that that the presence of maldistribution in the column be shown based on the simulation results.
Open Access
Optimization of CO2 Flooding Strategy to Enhance Heavy Oil Recovery
(Faculty of Graduate Studies and Research, University of Regina, 2015-07) Huang, Tuo; Zeng, Fanhua; Zhao, Gang; Supap, Teeradet; Aroonwilas, Adisorn
Heavy oil is a significant energy resource around the world. In Canada, there are tremendous heavy oil reserves lying in the north of the provinces of Alberta and Saskatchewan. The key point for heavy oil recovery is to increase the mobility of heavy oil in the reservoir condition. The most effective methods of heavy oil recovery are thermal methods such as steam flooding, cyclic steam stimulation (CSS), steam-assisted gravity drainage (SAGD) and in-situ combustion for the great heavy oil viscosity reduction by heat. However, thermal methods are proving to be unsuitable for most of the heavy oil reservoirs in Canada because of the thin net-pay zones, large depths and other rock, fluid and geological conditions. Therefore, cold production methods are mostly considered. In recent years there has been more development of solvent injection methods. CO2 is considered one of the most promising solvents used in both light and heavy oil for its high solubility. In light oil recovery, the production pressure in CO2 flooding is kept above the minimum miscible pressure in order to maintain the miscibility. Although in heavy oil recovery, CO2 miscibility can hardly be reached because of the high oil viscosity, but the oil recovery can still be stimulated to a great extent by CO2 injection. Different CO2 flooding strategies can significantly affect the recovery factor. In this study, different injection and pressure control schemes were tested by 1-D core-flooding experiments to obtain an optimized one. Field data, oil samples and brine from a heavy oil field in north China were used for the core-flooding experiments. Experimental results indicated that a lower CO2 injection rate led to a higher recovery factor from 31.1% to 36.7%. In terms of the effects of different production strategies, a constant production pressure at the production port yielded a recovery factor of 31.1%, while a pressure depletion at the production port yielded 7% more oil recovery; and the best pressure control scheme was that in which the production pressure was kept constant during the CO2 injection period, then the model pressure was depleted with the injector shut-in, yielding a recovery factor of 42.5% of the initial OOIP. Numerical simulations were conducted to history match the experimental results. The same oil relative permeability curve was used to match the experimental results to all tests. Different gas relative permeability curves were obtained when the production pressure schemes were different. A much lower gas relative permeability curve and higher critical gas saturation were achieved in the best pressure control scheme case compared to other cases. The lower gas relative permeability curve indicated that foamy oil was formed in the pressure depletion processes. A 3-D reservoir model was built by Computer Modeling Group (CMG) software based on field data and relative permeability curves from history match of the tests. Different strategies, including different injection and production schemes and different injection materials were used, and the better results were chosen for analysis.