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A blend of 2-Amino-2-methyl-1-propanol (AMP)/ Piperazine (Pz), known as the CESAR 1 solvent, has been widely studied in different aspects like physical, transport and thermal properties; kinetic, mass transfer properties and equilibrium properties. The solvent has shown a potential to be better than the benchmarking solvent 30 mass% MEA. In this work, we report on an e-NRTL model for the system and compare with experimental data. Further, results from an aerosol growth model are presented. This is important to understand the performance of the solvent with regard to emissions.

Nonlinear model predictive control applications have been deployed on two large pilot plants for post combustion CO2 capture. The control objective is formulated in such a way that the CO2 capture ratio is controlled at a desired value, while the reboiler duty is formulated as an unreachable maximum constraint. With a correct tuning, it is demonstrated that the controllers automatically compensate for disturbances in flue gas rates and compositions to obtain the desired capture ratio while the reboiler duty is minimized. The applications are able to minimize the transient periods between two different capture rates with the use of minimum reboiler duty.

In the STEPWISE project, the Sorption Enhanced Water-Gas Shift (SEWGS) CO2 capture technology is brought to TRL6 by means of design, construction, operation and modelling a pilot installation in the Iron and Steel industry using actual Blast Furnace Gas (BFG). This advanced CO2 removal technology makes use of regenerative solid adsorbents. The STEPWISE project represents the essential demonstration step within the research, development and demonstration trajectory of the SEWGS technology. This project will further reduce the risks associated with scaling up of the technology. The pilot has been constructed and the initial pilot campaigns have been performed. Major achievements are the demonstration of sorbent production at tonnage scale, robust operation of the pre-shift section at lowered steam conditions, and SEWGS performance at >90% H2S removal efficiency and >90% CO2 capture rate at 90% product purity. Emphasis is currently on 2nd pilot campaign to complete the techno-economic analysis and the life-cycle- assessment studies, costing of a full-size installation and the business plan. The preliminary technical evaluation illustrates that the SPECCA coefficient, illustrating the energy requirement for capture, is below 2 which is around 30% lower than the amine-based case. The LCA indicates that all impact parameters are lower for the STEPWISE cases compared to post combustion amine scrubbing reference case.

This paper deals with the effect of solvent vapor liquid equilibrium (VLE) properties on the heat duty in a post-combustion CO2 capture process. The conceptual solvent properties include the absorption heat, absorption performance and cyclic capacity, modeled by a three-parameter VLE equation. There are four processes considered. A conventional process serves as a reference case. An ideal process is used to study the energy saving potential. As typical process improvements, an intercooling and a rich split process are used to analyze the heat duty reduction effect. The optimal solvent in each process is obtained by minimizing the total heat duty. By the sensitive analysis, the solvent with less favorable VLE properties owns a larger energy saving potential and energy saving effect. Results show that the rich split is a more energy-efficient process improvement method than the intercooling configuration for the typical amine solvents.

High cycle-to-cycle variations (CCV) in the spark ignition (SI) engine will not only lead to incomplete combustion and even misfire, but also affect the fuel economy and even influence the drivability and conformability of a vehicle, particularly at the lean-burn condition. However, the detail information about the root causes of CCV are still relatively limited, particularly the natural gas SI engine. In this paper, the impacts of the key operating and design parameters were investigated on the CCV of the high compression ratio SI natural gas engine under lean mixture condition. The results indicated that the in-cylinder pressure distribution tended to be concentrated, the number of partial burning or incomplete combustion cycles also reduced with increasing the engine speed. With increasing the load, the in-cylinder pressure distribution, peak combustion pressure and its location were tended to be concentrated. Furthermore, the number of the partial combustion or post combustion cycles declined from low-load to medium- and high-load zones. Moreover, the relationship between the peak combustion pressure and its location was almost linear with increasing the engine load. Unfortunately, with further increasing engine load, in-cylinder pressure traces started to disperse slightly. Under the low-load condition, in-cylinder pressure traces were tended to be concentrated with increasing compression ratio (CR). As CR continually increased, its influence on the in-cylinder pressure distribution decreased. In addition, the number of the partial combustion or post combustion cycles decreased with increasing CR. However, under the high-load condition, increasing the CR has slightly effects on the in-cylinder pressure distribution.

Linear/branched polyethyleneimines (PEI) and their modified structures have been widely used to prepare CO2 adsorbents due to their low material cost and high amine content. However, few studies have been carried out to comprehensively understand the effects of polymer structures on the properties of adsorbents, especially other than CO2 capacity. In this study, we rigorously investigated the effects of polymer structures on the CO2 adsorption capacity, kinetics, adsorbent stability, and regeneration heat of adsorbents using four amine polymers with different molecular weights, amine distributions, and ppm-level metal impurities. Linear tetraethylenepentamine (TEPA) exhibited the highest CO2 adsorption capacity due to its low tertiary amine content. However, unlike common intuition, the high CO2 capacity of TEPA did not lead to high energy efficiency of the CO2 capture process because of excessively strong CO2 adsorption and substantial H2O co-adsorption under typical flue gas adsorption conditions. Furthermore, the use of TEPA led to the slowest CO2 adsorption kinetics and the fastest thermochemical degradation, limiting its practical applicability. In contrast, epoxide-functionalized branched PEI exhibited the lowest CO2 capacity, but enabled the most energy-efficient CO2 capture due to its moderate CO2 adsorption strength and suppressed H2O co-adsorption. It also exhibited the fastest adsorption kinetics and the highest stability. Conventional branched PEIs showed intermediate behaviors. The present results indicated that the CO2 adsorption capacity of adsorbents, which was the major focus of previous studies, should not be overemphasized for CO2 adsorbent development and other important engineering aspects (e.g., adsorption kinetics, thermochemical stability, and regeneration heat) need to be considered collectively.

Pilot plant testing of amine solvents for post-combustion CO2 capture is an essential tool for fully understanding degradation behaviour and emission profiles under realistic process conditions. This review aims to summarise the lessons learned in different pilot campaigns, as well as to give recommendations how solvent stability and emissions can be monitored and assessed. A total of 18 different pilot plants and 29 individual campaigns were studied, of which the majority used ethanolamine and flue gas from coal-fired power plants. The findings of the review are that solvent stability data from different pilot plants show significantly higher operation time in which the solvent is stable, when extensive flue gas pretreatment is implemented. It was also found that no single degradation compound seems to suffice for the assessment of the degradation of a solvent, even for the widely studied ethanolamine process. Monitoring of the total liquid-phase heat stable salt concentration, as well as gas phase ammonia concentration may, however, give an informative picture of the state and degradation of the solvent. There seems to be a lack of universally applied analytical methods, which makes it difficult to compare one campaign or location to another. The implementation of validated and documented analytical standards in this regard will facilitate production of reproducible, reliable and comparable data for future solvent stability assessment. This is an open access article distributed under the terms of the Creative Commons CC-BY license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Polyethyleneimine (PEI)/silica adsorbents have been considered as a promising candidate for post-combustion CO2 capture, but the limited process study has been performed on a pilot-scale unit. Herein we report the 150 h continuous test results using a 100 kg sample of silica-PEI on a fluidized bed continuous unit. The CO2 removal efficiency and dynamic sorption capacity were evaluated continuously by changing a number of variables. For the sorption reactor, the changing variables were inlet H2O concentrations of 0–8.3 vol%, inlet CO2 concentrations of 12.0–21.5 vol%, bed temperatures of 50–70 °C and the bed differential pressures of 176–370 mmH2O. For the desorption reactor operated at the bed temperature of 129–130 °C, inlet H2O concentrations of 8.0–13.5 vol%, inlet CO2 concentrations of 14.6–81.2 vol% and bed differential pressures of 430–580 mmH2O were used. During continuous operation, CO2 removal efficiencies of over 90% were achieved with dynamic sorption capacities of 7.5 wt%. Solid sample collected during continuous operation were analyzed by TGA and 13C NMR to identity the decrease of CO2 adsorption capacity and the extent of thermo-oxidative side reactions. Slow oxidative degradation of the silica-PEI occurred because the transporting adsorbent was exposure to the non-humidified air in the solid transport system.

The abatement of anthropogenic CO2 gas and extensive demand for electricity has motivated cleaner power production from fossil fuels. Monoethanolamine (MEA) based post combustion CO2 capture plant (PCC) is a promising and mature technology to realize large scale cuts in carbon emissions at national and global levels. A carbon capture plant features non-linearity and multifaceted process interactions, therefore presents operational challenges requiring robust control strategies to ensure optimal but flexible operation of the plant as it responds to variable power plant output. This paper investigates two control strategies (viz, conventional feedback (PID) control and model predictive control (MPC)) with the control objective being formulated as economic functions around CO2 emissions (US$/t-CO2) and operational cost (US$/d). This presents a management capability to the power plant operator unlike the commonly used operational (technical only) objective of maximising CO2 capture (CO2%) at a given setpoint in conjunction with plant net energy performance (EPn). This economics-based formulation in the control strategy together with a demonstrated stability analysis fits well into plant-wide control implementation of MEA based PCC plants and supports cleaner production of electricity while helping such operation economically viable. It can be seen that embedment of MPC into PCC plant features attractive economic value (positive investment decision) based on the two above criteria. Whereas, CO2 emission cost and operational cost exhibit 30% and 60% of cost saving compared with the deployment of PID controller.

In a standard post-combustion carbon capture (PCC) process, the regeneration energy of the CO2 lean solvent dominates the overall energy consumption. The energy reduction achieved by stripper modifications, such as the cold-split bypass, interheated stripper, and integration of both configurations, have been reported in the literature. In the cold-split bypass, the cold rich stream is split to recover the energy contained in the overhead vapor that was directly fed into the condenser in the traditional stripper configuration. The interheated stripper draws the semi-rich solvent from the middle of the stripper and exchanges heat with the hightemperature lean solvent from the reboiler; thereby, the overall column temperature can be raised that favors CO2 desorption along the column. Therefore, the literature reported that the integrated modification, combining the cold-split bypass with the interheated stripper, takes both advantages of above modifications that can further reduce the energy requirement. However, the present work shows that energy-saving effect of integrated process is not as promising as the literature claimed. Once the feed stage of the warm-rich solvent is determined properly, the cold-split process can achieve the similar energy-saving performance as that achieved by the integrated process.

The ultra-low emission standard will be enforced on circulating fluidized bed (CFB) boilers in the near future in China. The coordinated control of NOx and CO emission was realized on a 0.5 MWth CFB test platform by new post-combustion technology with low NOx emission. When NOx reached ultra-low emission standard (≤50 mg/m3, at 6% O2), CO emissions of Fugu bituminous and its semi-coke were only 101.1 and 91.8 ppm, respectively. Moreover, the influence of coal variety on NOx emission and fly ash characteristics during the post-combustion was investigated. The experimental results indicated that the post-combustion technology had a better de-NOx effect on volatile-N. The speciation of residual nitrogen in fly ash was investigated by XPS, but it could not be linked to NOx emission by the present study. The post-combustion technology had various influences on the morphology of fly ash from different fuels. In addition, the fly ash of semi-coke had a more developed pore structure, which probably led to a more intense NOx reduction reaction in the post-combustion chamber.

Aqueous ammonia (NH3)-based capture process has the potential to simultaneously remove NOx/SO2/CO2 pollutants at low cost, but conventional NH3-based process suffers high NH3 slip, high energy consumption and high capital investment. The present study aims to advance the NH3-based scrubbing technology to overcome these technical issues. We used inter-cooled CO2 absorber to mitigate the NH3 emission and enhance CO2 absorption, while employed advanced flash stripper configuration to significantly decrease the absorbent regeneration duty. We also proposed an effective NOx/SO2 removal process by utilizing the slipped NH3 for multi-pollutant emission control. A validated model was used to gain insight into the techno-economic performance of this advanced NH3-based NOx/SO2/CO2 removal process, and important process parameters such as absorption temperature, NH3 concentration and flue gas NOx/SO2 concentrations were investigated in detail. The results indicate that the advanced NH3 process enabled great capital saving by 23% and energy saving by 42%, resulting in a low CO2-avoided cost of US$44.3/t CO2, which is 42.8% lower than the baseline NH3 process.

This paper presented a comparative study of monoethanolamine (MEA) and diethanolamine (DEA) for post-combustion CO2 capture (PCC) process with different process configurations to study the interaction effect between solvent and process. The steady state process model of the conventional MEA-based PCC process was developed in Pro/II® and was validated with the experimental data. Then ten different process configurations were simulated for both MEA and DEA. Their performances in energy consumption were compared in terms of reboiler duty and total equivalent work. The results show that DEA generally has better thermal performances than MEA for all these ten process configurations. Seven process configurations provide 0.38%–4.61% total energy saving compared with the conventional PCC process for MEA, and other two configurations are not favourable. For DEA, except one configuration, other process configurations have 0.27%–4.50% total energy saving. This work also analyzed the sensitivities of three key parameters (amine concentration, stripper pressure and lean solvent loading) in conventional process and five process modifications to show optimization strategy.

A systematic approach is proposed for the preliminary screening of binary amine mixtures as CO 2 capture candidates considering several important properties as selection criteria. The approach consists of several decision making stages which account for solvent–solvent and solvent–solvent–CO 2 interactions using standard group contribution models as well as equations of state and activity coefficient models for a wide range of molecular structures. A multi-criteria assessment methodology is combined with a systematic uncertainty quantification approach to unveil important trade-offs among several important properties and to propose the mixtures that appear to be promising as CO 2 capture candidates. The aim of the proposed approach is to support the identification of few valid amine combinations which may then be evaluated using rigorous prediction models or experiments, while quickly avoiding amine options of poor performance. The proposed method is applied in mixtures resulting from numerous binary combinations of amines which have been previously investigated in their pure aqueous form as CO 2 capture solvents. A mixture of 4-diethylamino-2-butanol (DEAB) and 2-amino-1-hexanol (2A1H) appears to be promising among other useful options.

In this paper, optimization of a post combustion carbon capture process based on two different objective functions of energy and utility requirements and associated costs is presented. CO2 residual mole fraction of the regenerated solution, solution circulation rates and lean solution temperature were selected as three most important variables of the process for optimization. One at a time method is adopted for optimization of the process variables. The results show that for a post combustion carbon capture process using monoethanolamine (MEA), lowest costs of the process are associated with the highest CO2 residual mole fraction of regenerated solution, lowest solution circulation rate and highest lean solution temperature. Based on the results of this research, having a general view of energy and utility requirements of the process leads to finding the lowest possible process costs. However, if a component oriented view is adopted for energy requirements, the worst possible choices of operational parameters are likely to be made.

The lowest energy consumption reported so far for CO 2 capture from dry flue gas (CO 2 /N 2 =15/85) with 95% purity and 90% recovery is 148 kWh/tonne of CO 2 captured ( Haghpanah et al., 2013b ). The process is a 4-step VSA cycle comprising light product pressurization (LPP), high pressure adsorption (HPA), co-current blowdown (CoBn) and countercurrent evacuation (CnEv) on 13X zeolite, and the evacuation pressure ( P L ) is 0.03 bar. The maximum productivity, although at a somewhat higher energy, is 0.6 mol/m 3 adsorbent. In this cycle, 95–90 purity-recovery is unachievable at P L above 0.04 bar. In contrast, we propose a 6-step dual-reflux VSA cycle with LPP, HPA, heavy reflux (HR) using the product from the light reflux (LR) step, CoBn, CnEv and LR that can achieve 95–90% purity-recovery targets set by the U.S. Department of Energy without requiring deep vacuum. Optimum performances of the two cycles are compared for 13X Zeolite, the current industrial benchmark for CO 2 capture, and UTSA-16, a promising MOF structure. Minimum energy and maximum productivity for the two cycles are presented as function of the P L for both the adsorbents. The optimum P L for both VSA cycles is found to be ~0.02 atm with respect to both objectives. The 6-step cycle can deliver 95–90% purity-recovery of the captured CO 2 up to a P L of 0.20 atm (~0.2 bar). The increase in energy consumption is modest up to P L of 0.1 atm (~0.1 bar). In the comparable P L range, the 6-step cycle also delivers significantly higher productivity than the 4-step cycle. Between UTSA-16 and 13X zeolite, the former performs at 19–24% lower energy and 51–75% higher productivity in the 4-step cycle, and 14–19% lower energy and 107–154% higher productivity in the 6-step cycle in the range of P L investigated.

A detailed optimization-orientated model of monoethanolamine-based CO 2 capture plant and compression train in which all the technical and economic assumptions are defined and/or optimized was developed and used to simultaneously determine the cost optimal control and design variables including feed fraction ratio at different degrees of capture (DOC), which represents the amount of CO 2 removed, for plant designs that partially bypass the CO 2 capture process so as to achieve low to moderate reductions of CO 2 , but at lower overall cost. The effects of varying carbon prices on the levelized cost of CO 2 capture and compression were also studied. The capture bypass option was observed to be the cost optimal choice for lower than 60% overall DOC. Carbon prices were observed to have a clear impact on the cost optimal DOC, with the cost-optimal DOC shifting from 70%⿿80% to 85%⿿90% at carbon prices of $4/t CO 2 to $23/t CO 2 respectively. The study highlighted that if a suitably high carbon price does not materialize through a market mechanism, appropriate policies need to be put in place to achieve decarbonisation targets.

In this work, the absorption performance, regeneration performance, and cyclic absorption capacity of three kinds of mixed monoethanolamine (MEA) solvents were studied compared to those of using MEA solvents alone in self-made apparatuses, including MEA-piperazine (PZ), MEA-potassium carbonate (K2CO3), and MEA-ammonia (NH3). The mixed solvent of 10 wt% MEA/5 wt% PZ has a similar absorption performance and a higher regeneration temperature compared with the 20 wt% MEA solvent. And the mixed solvent of 10 wt% MEA/5 wt% K2CO3 has the lowest initial absorption rate, but it has a better cyclic absorption performance and a longer effective reaction time. The mixed solvent of 10 wt% MEA/5 wt% NH3 has both a faster absorption rate and a lower regeneration temperature. These results prove that the mixed MEA solvent mixed with K2CO3 or NH3 has good potential to replace the MEA solvent alone with a lower energy consumption.

Potassium carbonate supported on alumina is used as a solid sorbent for CO2 capture at low temperatures. However, its CO2 capture capacity decreases immediately after the first cycle. This regeneration problem is due to the formation of the by-product [KAl(CO3)(OH)2] during CO2 sorption. To overcome this problem, a new regenerable potassium-based sorbent was fabricated by CO2 thermal treatment of sorbents prepared by the impregnation of δ-alumina with K2CO3 in the presence of 10 vol% CO2 and 10 vol% H2O. The CO2 capture capacities of the new regenerable sorbents were maintained over multiple CO2 sorption tests. These results can be explained by the fact that the sorbent prepared by CO2 thermal treatment did not form any by-product during CO2 sorption. Based on these results, we suggest that the regeneration properties of potassium-based sorbents using δ-alumina could be significantly improved by the use of the CO2 thermal treatment developed in this study.

Research on CO2 capture has mainly been focused on improving the effectiveness and enhancing the efficiency of CO2 absorption process, while little attention has been paid to the stripping performance of rich solutions. The available literature in the area of detailed desorption methods and desorber operation is relatively scarce as compared to absorption research. This paper gives a brief summary of the methods used for the regeneration of rich solutions in chemical absorption of carbon dioxide. The performances of different absorbents in the conventional heating process were compared and the newly developed methods, including acid addition, membrane technology, dual alkali method and etc., are discussed and compared with the conventional heating process. The comparison of these methods is focused on the regeneration ratio, cyclic performance and energy consumption.

Thiourea was selected as representative of combined S- and N-inhibitors and injected after the post-combustion zone of two full-scale municipal solid waste incinerators (MSWIs) using a dedicated feeder. Firstly, the operating conditions were scrutinised by monitoring the concentrations of SO2, NH3 and HCl in the clean flue gas. The suppression experiment showed that in MSWI A thiourea could reduce the total I-TEQ value in flue gas by 73.4% from 1.41 ng I-TEQ/Nm3 to 0.37 I-TEQ/Nm3, those in fly ash by 87.1% from 14.3 ng I-TEQ/g to 1.84 I-TEQ/g and the total dioxins emission factor by 87.0 wt.%, with a (S + N)/Cl molar ratio of 9.4. The suppression efficiencies of PCDD/Fs in flue gas and fly ash in MSWI B could be up to 69.2% and 83.0% when the (S + N)/Cl molar ratio attained 7.51. Furthermore, the congener distributions of dioxins were also analysed in the flue gas and fly ash, before and after addition of thiourea, to find cues to some suppression mechanism. In addition, the filtered fly ash was explored by the Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS) analysis of fly ash. These results suggest that poisoning the metal catalyst and blocking the chlorination are most probably responsible for suppression.

There are currently no studies in the literature on the use of natural waste marble powder (WMP) resources as inexpensive sorbents for looping cycle CO2 capture. The high volume of marble production is associated with considerable amounts of WMP generated as byproduct during cutting and polishing procedures, which negatively impacts the surrounding environment. The main goal and innovative idea addressed in this study consists of investigating if solid wastes WMP from marble producer sources can be used as possible inexpensive and effective solid materials to be used as precursors of CaO-based sorbents in Ca-looping cycle CO2 post-combustion capture process. The cyclic carbonation–calcination reactions were experimentally studied in a laboratory-scale fixed-bed reactor unit for 10 and 20 cycles. The innovative and interesting results obtained show that Portuguese WMP represents a category of promising natural inexpensive solid sorbents to be used as effective CaO-based sorbents for looping cycle CO2 post-...

Ca-Looping technology has experienced a substantial development in the technical readiness level in the last years, especially in its application as post-combustion CO 2 capture technology in power plants. Experimental results from MW-scale power plants worldwide have confirmed post-combustion Ca-Looping process using interconnected circulating fluidised bed reactors as a promising technology for CO 2 capture. Among the different fields of research having contributed to this breakthrough, modelling activity aiming at assessing sorbent properties, interpreting results from experimental reactors or assessing technology scale-up through large-scale reactors and process integration have played a crucial role. This paper aims at reviewing and discussing findings obtained by different research groups worldwide about post-combustion Ca-Looping process modelling. Assumptions made with respect to sorbent performance, reactor operating conditions and process integration between different components are crucial when evaluating the performance of the Ca-Looping process as a post-combustion technology for CO 2 capture. With the aim of understanding the importance of these assumptions, this paper covers particle reaction and reactor models for carbonation and calcination steps, assessing the impact of the conditions used for their determination into their reactivity predictions, as well as process modelling works that assess performance obtained when integrating a Ca-Looping process into a power plant. Indications on the research needs detected among the reviewed works have also been highlighted in this work to contribute to the advancement of the knowledge on the Ca-Looping technology.

Some features of heating and melting iron-rich pellets (IRP) by the method of charging the pellets through the axial ducts of electrodes are considered. When using this system of supplying iron ore raw materials through the holes in the electrodes, loose pellets fall into the impact zone of the electric arcs on the melt that ensures a high speed of their fusion. At the same time the technical-and-economic indices of the electrosmelting in the electric arc furnace (EAF) are improved. The use of the fuel-oxygen burners allow optimizing the IRP melting process improving the slagging conditions, heating, metal decarburization with post-combustion of final burning gases (CO, H2, etc.) in the arc furnace.

The more and more restrictive environment requirements in the field of pollutant emissions of co-generative plants are imposing researches related to the more efficient work of those related to the post combustion facility. The paper presents the results of a post combustion burner achieved on a test bench, when it idling operates on natural gas mixed with air or with burned gases of a gas turbine. The modeling of the measured emissions, led to NOx concentrations in ambient air that are below the limits imposed by the in force regulations related to air quality and are correlated to the real time measured data.

The market of solar-assisted post-combustion CO2 capture (SPCC) is emerging globally in recent years. It is considered as a promising technology to apply the ammonia as the absorbent to implement the SPCC technology in view of its low regeneration temperature and low regeneration heat duty. However, few literatures indicate which type of solar thermal collectors (STCs) involved in the ammonia-based SPCC power plant is more applicable. Therefore, in this paper, the maximum theoretical potential price of STCs which make the value of the levelized costs of electricity (LCOE) and the cost of CO2 removed (COR) lower than that of the reference post-combustion CO2 capture (PCC) power plant is estimated. The potential of ammonia-based SPCC technology in the selected locations is also estimated, based on the detailed solar radiation resource assessment (i.e. DNI, sunshine time) and the STCs performance. It would be more attractive to adopt the vacuum tube (VT) as the STC involved into the ammonia-based PCC power plant to capture CO2 than parabolic trough collector (PTC). In order to achieve lower LCOE and COR than that of the reference PCC system, the price of the vacuum tube (VT) has to be reduced to 131.02 $/m2, 91.76 $/m2 and 57.10 $/m2 for the location of M1(Lhasa), M2(Tianjin) and M3(Xi’an), respectively. And the price of the parabolic trough collector (PTC) has to be reduced to 139.09 $/m2, 89.83 $/m2 and 50.84 $/m2, respectively.

A precise understanding of phase behavior for a variety of both artificial and natural processes is essential to achieving scientific and technological goals. There has been growing research interest in gas hydrates confined in nanoporous media aiming to simulate and analyze the unique behavior of natural gas hydrates in sediments. Moreover, the appearance of peculiar properties due to the confinement effect stimulates research on gas hydrate technology for gas separation, such as CO2 capture from versatile pre/post combustion emissions. In spite of their importance, reliable phase equilibrium data on gas hydrates confined at a nanoscale are scattered throughout the literature, while those in bulk state are abundant. Accordingly, we surveyed the previous studies on the phase behavior of gas hydrates in various nanoporous materials to include and provide valuable information and knowledge for start-up researchers in various gas hydrate fields.

There is a necessity to reduce GHG emission because climate change may have critical consequences in many places around the world. The main gas which causes climate change is CO2 which is released into atmosphere mainly by industries and vehicles. This research aims to compare two technologies for CO2 capture: chemical absorption with membranes, and to present hybrid processes using both of these. A review of the state of art for CO2 capture is used in this research. The capture by absorption with amines is the state of the art for post-combustion because it produces CO2 with higher purity and is cheaper. However, the energy and installation cost are high which does do not encourage its applicability. Membrane for CO2 capture from natural gas is promissory because of this. Thus, researchers have studied other technologies for CO2 capture to replace or add through including hybrid processes. Capture by membrane is a promising technology for this, provided that since it presents appropriate selectivity and permeability. This paper presents a comparison between CO2 capture by absorption with amines and by membranes. The goal is to discuss hybrid processes with these two technologies in series.

Among the current technologies for post-combustion CO2 capture, amine-based chemical absorption appears to be the most technologically mature and commercially viable method. This review highlights the opportunities and challenges in post-combustion CO2 capture using amine-based chemical absorption technologies. In addition, this review provides current types and emerging trends for chemical solvents. The issues and performance of amine solvents are reviewed and addressed in terms of thermodynamics, kinetics, mass transfer, regeneration and solvent management. This review also looks at emerging and future trends in post-combustion CO2 capture using chemical solvents in the near to mid-term.

A present challenge in the mitigation of anthropogenic CO2 emissions involves the design of less energy- and water-intensive capture technologies. Sorbent-based capture represents a promising solution, as these materials have negligible water requirements and do not incur the heavy energy penalties associated with solvent regeneration. However, to be considered competitive with traditional technologies (i.e., MEA capture), these sorbents must exhibit a high CO2 loading capacity and high CO2/N2 selectivity. It has been reported that ultramicroporous character and surface nitrogen functionality are of great importance to the enhancement of CO2 capacity and CO2/N2 selectivity. However, the role of pore size in combination with surface functionality in the enhancement of these properties remains unclear. To investigate these effects, grand canonical Monte Carlo (GCMC) simulations were carried out on pure and N-functionalized 3-layer graphitic slit-pore models and compared to experimental results for two high performing materials reported elsewhere. We show that the quaternary, pyridinic, and especially the oxidized pyridinic group lend to enhanced performance, with the latter providing exceptional CO2 loading (4.31 mmol g−1) and CO2/N2 selectivity (138.3:1). Increasing surface nitrogen content resulted in enhanced loading and excellent CO2/N2 selectivity (45.8:1–55.9:1), provided that the sorbent has significant ultramicroporous character. Additionally, we elucidate a threshold pore width, under which N-functionalization becomes increasingly influential on performance parameters, and show how this threshold changes with application (PC vs. NGCC capture). Finally, we propose that an alternative functionality – the nitroso group – may be responsible for the enhanced performance of some recent materials reported in the literature.

The ultimate benefit of flexible operation of the post-combustion CO 2 capture (PCC) plant depends on the ability to optimally balance between many competing factors, including the additional capital investment and operating cost savings. In this work, a large number of scenarios are constructed by considering combinations of possible realizations of the uncertain economic factors such as energy cost profile, emission penalty and value of captured CO 2 . Then, the design choices like the size of the storage tanks and the regeneration capacity are optimized by minimizing an overall cost averaged over all the scenarios. The optimal design problem is naturally formulated as a two-stage stochastic program. This multi-scenario optimal design is compared with the design that minimizes the overall cost for just a single nominal scenario as well as the design that minimizes the cost averaged over the worst-case scenarios.

Post-combustion capture of CO 2 from the flue gas of power plants by calcium looping, in which lime is used to capture CO 2 , is currently a promising technology. The decay in CO 2 uptake capacity of natural limestone is an intrinsic disadvantage of this technology, and the design of more stable sorbents has become an important goal. Techno-economic calculations that examine calcium looping must take into account this decay in capacity, and this has to date been accomplished using a formula for the population distribution of particles in the cycling system. However, the formula has some limitations that make it less suited to very stable sorbents, making it difficult to incorporate newer materials in such calculations. We developed a more general formula for the population distribution of solid particles in processes involving recirculations, and compared it with the widely used equation in the calculation of several process metrics. Particular consideration was given to conditions relevant to enhanced or tailored sorbents, for which our modified formula was well suited. In addition, the impacts of calcium looping process configuration on this generalized population distribution of solid particles were studied from mathematical and operational perspectives.

Hollow fiber membrane contactors (HFMCs) can effectively separate CO22 from post-combustion flue gas by providing a high contact surface area between the flue gas and a liquid solvent. Accurate models of carbon capture HFMCs are necessary to understand the underlying transport processes and optimize HFMC designs. There are various methods for modeling HFMCs in 1D, 2D, or 3D. These methods include (but are not limited to): resistance-in-series, solution-diffusion, pore flow, Happel’s free surface model, and porous media modeling. This review paper discusses the state-of-the-art methods for modeling carbon capture HFMCs in 1D, 2D, and 3D. State-of-the-art 1D, 2D, and 3D carbon capture HFMC models are then compared in depth, based on their underlying assumptions. Numerical methods are also discussed, along with modeling to scale up HFMCs from the lab scale to the commercial scale.

For post-combustion CO2 capture technology, integration of CO2 capture will lead to considerable efficiency penalty of the power plant. This paper quantitatively compares the thermal performance of the integrated system with CO2 capture by three different solid sorbents, namely the solid amine Pentaethylenehexamine (PEHA), Na2CO3 and K2CO3. Due to different regeneration temperature, the retrofit schemes of the integrated system differ for three different sorbents. The back-pressure turbines are used to retrieve the surplus energy of the extracted steam for PEHA and Na2CO3, whereas multi-stage compressors are used to increase the extracted parameters for K2CO3. The thermodynamic and exergy analysis results show that the thermal consumption of regeneration and the regeneration temperature are the two key parameters influencing the efficiency penalty. Efficiency penalty is increased by 1.4% per 1.0 GJ/tCO2 increment and 0.67% per 10 °C temperature increment of regeneration. Due to a low thermal consumption of regeneration and regeneration temperature, the solid amine sorbent (PEHA) performs the best out of the three solid sorbents with the lowest efficiency penalty of 9.59%. Besides, comparison with monoethanolamine (MEA) based solvent systems (efficiency penalty of 9.66%–13.73%) shows that, the solid amine sorbent (PEHA) exhibits promising competitiveness in terms of energy consumption.

This study provides a description of a new benchmark post-combustion CO2 capture (PCC) technology reflecting the publicly reported performances by various technology suppliers. To achieve this several amines and amine formulations have been considered using a process model developed in ProTreat®. A 40 wt% formulation of PZ (piperazine)/AMP (amino-methyl-propanol) in a 1:2 M ratio was selected as the most representative of the current state of the art. A PCC process configuration with absorber intercooling and rich split flow was selected to reflect the fact that the technology suppliers use a variety of process designs to optimize the process performance. The techno-economic performances were further detailed for the PCC process integrated with an ultra-supercritical coal fired power station and a natural gas fired combined-cycle. The techno-economic evaluation of the PCC process indicated that the costs of capture with respect to 30 wt% MEA for the coal-fired power station were reduced by 22% and for the natural gas fired combined-cycle by 15%.

To explore the influences of different feeding position and post-combustion air (PCA) arrangement on combustion and original NOx emission characteristics of Shenmu semi-coke, the experiments were carried out on a new circulating fluidized bed (CFB) test platform, which was composed of a CFB and a post-combustion chamber (PCC). The experimental results showed that the feeding position of loop seal could effectively reduce original NOx emission and CO emission concentration in comparison to the conventional coal feeding position of furnace. The NOx emission concentration was 60.3 mg/m3 with single stage PCA. As the grading number of PCA increased, NOx emission can be gradually reduced, eventually falling to 49.6 mg/m3 with triple stages PCA. However, for CO emission, the double stages PCA were able to minimize CO emission. In addition to grading number of PCA, an appropriate injection position of PCA was also helpful for CO burnout. For double stages PCA, the two PCA nozzles should be arranged in the middle of the PCC. According to the above research results, the best feeding position and PCA distribution mode to achieve ultra-low original NOx emission (

The human-induced increase in average global temperature since pre-industrial times (1850–1900 average) has already reached 1.0 °C in 2017 so there is a strong call for effective carbon capture and storage/utilization technology especially in the energy sector where the CO2 emissions are the largest. Membrane technologies are often declared to be a good option. This work tries to find how the commercially available modules are doing from the economical and practical point of view and if there are some new membrane materials which could be feasible and practically applicable in the power plat post-combustion CO2 separation. The main conclusion is that membrane technology is potentially suitable for fuel gas purification in the future but there are still some issues to be solved such as for example membrane resistance for humid feed stream, fouling and long-term stability of thin selective layer.

Global greenhouse gas emanations from fossil-fuel combusting for power-generation alone contribute 9.795 gigatonnes (Gt) in 2014. There is a tremendous focus on global carbon capture researchers to cut down these emissions significantly. Chemical absorption is widely used and the use of monoethanolamine (MEA) was generally preferred. However, MEA solutions were not without problems. For example, equipment deterioration due to O2 presence, high energy for solvent-regeneration, solvent degradation and formation of undesired harmful by-products inhibits the solvent's cyclic capacity. To address these issues megasonics-assisted (1 MHz - tank-type) solvent regeneration process had been investigated experimentally. The results revealed that low regeneration temperature (

This study presents the design of a robust nonlinear model predictive controller (NMPC) for the absorber unit of a post-combustion CO2 capture process operating downstream from a coal-fired power plant. The controller employs a dynamic mechanistic model for this process, which allows for a precise treatment of the sources of uncertainty. In the case of the absorber, the model enables explicit consideration of uncertainty in the process operating conditions dictated by upstream units and in physical property parameters associated with phenomenological descriptions of the process. Using the multi-scenario approach, discrete realizations of the uncertain parameters inside a given uncertainty region can be incorporated into the controller to produce control actions that result in a robust operation in closed-loop. The multi-scenario controller was tested under several disturbance rejection scenarios of varying complexity and their performance was assessed against that of single-scenario NMPCs. The benefits of the robust NMPC approach were most evident for longer simulations and, considering the continuous nature of a power plant and its emissions, make the robust NMPC approach suitable for the operation of this process in the presence of uncertainty and disturbances.