Post-combustion Carbon Capture Process Research Articles

A novel pinch-based method for process integration and optimization of Kalina cycle

Low-and-medium waste heat utilization is crucial for alleviating energy dilemma and carbon dioxide emissions in industrial plants. Although Organic Rankine Cycle (ORC) has made significant advances in waste heat recovery, other equally important thermodynamic ways to recover waste heat such as Kalina Cycle (KC) have not been fully explored. In this study, a novel pinch-based mathematical model is developed for process integration and optimization of Kalina Cycle. The model performs heat integration with variable heat capacities and enables the modifications of KC simultaneously, in a bid for generating maximum net power output without increasing the amount of hot utility. The proposed model allows for non-isothermal phase transition of working fluid and can be extended to handle multiple Kalina Cycles combined with process integration, thus enhancing waste heat recovery efficiency. The effectiveness of the proposed method is verified by a well-studied example from literature, in which the net power output is increased by 12.2% compared to the results using existing literature approaches. Furthermore, the developed model has been successfully applied to the post-combustion carbon capture process, where proper integration of process and Kalina Cycle leads to a 15.8% increase in net power output and a 4.13 percentage point decrease in the efficiency penalty.

Sodium carbonate-based post combustion carbon capture utilising trona as main sorbent feed stock

In the pursuit of shifting technology towards sustainable, environmentally benign processes, post-combustion carbon capture technology is recognised to be a timely mitigation option. This paper presents the development of a novel sodium carbonate-based post combustion carbon capture process utilising the carbonate mineral trona (trisodium hydrogendicarbonate dihydrate) as main sorbent feedstock source. The energy penalty, the fraction of energy sacrificed to capture CO2 relative to the net energy produced serves as main performance indicator. Investigations on the correlative relationship between energy penalty as a function of capture efficiency are carried out by retrofitting the process to a 600 MW reference coal-fired power plant. The energy penalty of the global system features a distinct local minimum of 3.99%, corresponding to a CO2 capture efficiency of 90.00% and a CO2 outlet purity of 99.90%. The Specific Primary Energy Consumption for CO2 Avoided (SPECCA) index corresponding to this minimum is evaluated to be SPECCA = 0.514MJkgCO2-1. Sensitivity analyses on the effect of increasingly high SO2 flue gas volume fractions ySO2 show that the capture efficiency is virtually unimpaired for calcination temperatures of 190 ⩽T⩽280 °C and ySO2 ranging from 0.50 to 0.70%. Whilst commercially available CO2 capture technology is energy intense and prone to sorbent degradation, the process developed retains high capture efficiencies of calcium oxide-based looping cycles at low operating temperatures and eliminates the predisposition of amine-based sorbents utilised in scrubbing capture schemes to deplete due to the presence of SO2 in the inlet flue gas stream. It can be concluded that sodium carbonate based post-combustion capture processes are a competitive alternative to existing CO2 capture technologies.

Investigation into an energy-saving mechanism for advanced stripper configurations in post-combustion carbon capture

Abstract In a standard post-combustion carbon capture (PCC) process, the regeneration energy of CO2 lean solvent constitutes the majority of overall energy consumption. The energy reduction achieved by advanced stripper configurations, such as the cold-split bypass (CSB), interheated (IH) stripper, and lean vapor compression (LVC), have been reported in relevant literature. Energy-saving performance may be enhanced by combining the different modifications. In this study, the energy-saving mechanism for advanced stripper configurations was investigated using a standard amine-based process, in which 30 wt% monoethanolamine (MEA) aqueous solution was applied. Contrary to the literature reviewed, the energy-saving performance attained by combining the different modifications was limited. This was due to the major contribution of energy reduction in the various modifications sharing the similar mechanism. In addition, this study demonstrated that the overall energy required, as needed by the heat recovery in the cross-flow heat exchanger (HX) and the reboiler duty, is dominated by overhead vapor generation. Reducing the amount of vapor generated may effectively relieve the overall energy burden. Thus, when energy reduction is reliant on a HX with a poor heat recovery system, the energy-saving purpose is not fulfilled. Therefore, a successful energy-saving design may significantly reduce the amount of vapor generated, whilst maintaining a reliable heat recovery.

A new method for scale-up of solvent-based post-combustion carbon capture process with packed columns

Solvent-based post-combustion carbon capture (PCC) with packed column is the most commercially ready CO2 capture technology. To study commercial-scale PCC processes, validated pilot scale models are often scaled up to commercial-scale using the generalized pressure drop correlation (GPDC) chart which requires assuming the column pressure drop. The GPDC method may lead to either over-estimation or under-estimation of the column diameter. In this paper, a new method for estimating the packed column diameter without assuming the pressure drop has been proposed and used for model scale-up. The method was validated by scaling between two existing pilot plant sizes. The CO2 capture process was simulated in Aspen Plus® and validated at pilot scale. The validated model was scaled up to commercial CO2 capture plant capable of serving a 250 MWe combined cycle gas turbine power plant using the new method proposed in this study. The results obtained from the scale-up study were compared to those obtained when the GPDC method was used to design the same commercial CO2 capture plant. The results showed that the GPDC method overestimated the absorber and stripper diameter by 1.6 % and 8.5 % respectively. Process simulation results for the commercial-scale plant showed about 2.12 % and 5.63 % lower solvent flow rate and reboiler duty with the proposed method. Therefore, the capital and operating costs for the process using the newly proposed scale-up method could be lower based on our estimates of the column dimensions, solvent flow rate and specific reboiler duty.

Control of Solvent-Based Post-Combustion Carbon Capture Process with Optimal Operation Conditions

Solvent-based post-combustion carbon capture (PCC) is a mature and essential technology to solve the global warming problem. The high energy consuming issue and the flexible operation required by the power plants inquire about the development of effective control systems for PCC plants. This study proposes the optimal-based control approach that utilizes optimal set-point values for the quality controllers. The five optimal-based control schemes studied all employed L/G (liquid to gas ratio in absorber) as one quality control variable. Performance comparisons with a typical conventional control scheme are conducted employing a rate-based dynamic model for the MEA (monoethanolamine) solvent PCC process developed on a commercial process simulator. Compared to the typical control scheme, the optimal-based control schemes provide faster responses to the disturbance changes from the flue gas conditions and the set-point change of the CO2 capture efficiency, as well as better results in terms of IAEs (integral of absolute errors) of capture efficiency and reboiler heat duty during the stabilization period. LG-Tstr and LG-Tabs-Cascade are the best schemes. In addition to L/G, these two schemes employ the control of Tstr (the temperature of a stage of stripper) and a cascade control of Tabs (the temperature of a stage of absorber) (outer loop) and Tstr (inner loop), respectively.

CO2/SO2 emission reduction in CO2 shipping infrastructure

There is an increased focus on the reduction of anthropogenic emissions of CO2 by means of CO2 capture processes and storage in geological formations or for enhanced oil recovery. The necessary link between the capture and storage processes is the transport system. Ship-based transport of CO2 is a better option when distances exceed 350 km compared to an offshore pipeline and offers more flexibility for transportation, unlike pipelines which require a continuous flow of compressed gas. Several feasibility studies have been undertaken to ascertain the viability of large-scale transportation of CO2 by shipping in terms of the liquefaction process, and gas conditioning, but limited work has been done on reducing emissions from the ship’s engine combustion.From 2020, ships operating worldwide will be required to use fuels with 0.5% or lower sulphur content (versus 3.5% now) or adopt adequate measures to reduce these emissions. This study explores the use of the solvent-based post-combustion carbon capture and storage (CCS) process for CO2 and SO2 capture from a typical CO2 carrier. A rate-based aqueous ammonia process model was developed, validated, then scaled up and modified to process flue gas from a Wartsila 9L46 F marine diesel engine. Different modes of operation of the carrier were analysed and the most efficient mode to operate the CCS system is during sailing. The heat recovered from the flue gas was used for solvent regeneration. A sensitivity study revealed that the 4 MWth supplied by the “waste heat recovery” system was enough to achieve a CO2 capture level of 70% at a solvent recirculation flowrate of 90–100 kg/s. The removal of SO2 by the ammonia water solution was above 95% and this led to the possibility of producing a value-added product, ammonium sulphate. The boil-off gas and captured emitted CO2 were recovered using a two-stage re-liquefaction cycle and re-injected into the cargo tanks, thereby reducing extra space requirements on the ship.

In-situ experimental investigation on the growth of aerosols along the absorption column in post combustion carbon capture

The amine-based post combustion carbon capture process is one of the most advanced and preferred technologies to reduce CO2 emissions from point sources like power plants. The emissions of amine from capture plants is one of the biggest challenges faced by this technology. These emissions typically occur by means of aerosol/mist formation. To develop effective countermeasures, it is crucial to understand the dynamic behavior of aerosols within the column, which is currently not well understood. This manuscript presents the results from a study aiming to understand the mechanism of aerosol growth and its behavior along the absorber column in terms of particles number concentration, particle size distribution, and amine emissions. For that, a series of experiments were performed in TNO’s bench scale CO2 capture plant using 30 wt% monoethnolamine (MEA) as solvent. For a SO3 and CO2 concentrations of 5.25 ppm and 12.5 vol.% in the flue gas, MEA emissions at the top exit of the column were recorded as 1051 mg/Nm3 (with vapour emissions of 381 mg/Nm3). In the absence of SO3 in the flue gas, inlet particle concentration was 2.71 × 107/cm3 and resulting MEA emissions reduced by 63.5%–383 mg/Nm3.From the bottom of the column until the point of maximum temperature, the MEA content in the vapour phase was consistent with the volatility of the solvent. After this point it drastically increases to 1051 mg/Nm3. Both the number of particles and the total particle mass has lowered from the bottom to the top of the column. For the benchmark test, inlet and outlet total particle concentration were found to be 6.24 × 107/cm3 and 2.3 × 107/cm3 respectively, while total particle mass is 2.22 mg/m3 at inlet and 1.32 mg/m3 at outlet. Particles with a dimeter below 0.006 μm contribute the most to total particle concentration both at the inlet (50%) and outlet (32%), while particles with diameter of 0.087 μm contributes the most to the total particle mass at inlet (47%) and outlet (55%). The measured total mass of particles was in the order of magnitude of 1 mg/m3. This is much lower than the expected aerosol mass emissions, in the order of magnitude of 1 g/Nm3 based on FTIR emissions.No particles larger than 0.147 μm were recorded, which might explain the low total mass recorded. The cause for this is still under investigation, but it suggests that the sampling procedure may induce systematic errors to the measurements. Nonetheless, the observations from this study have given further insight into the aerosol dynamics in the absorber column and corresponding emissions.

Flexible operation of coal-fired power plant integrated with post-combustion CO2 capture

For environmental protection, solvent-based post-combustion carbon capture (PCC) process has been applied to the coal-fired power plant as an end-of-pipe approach. Power plant needs to provide steam for PCC process and this will significantly influence the net power output. In this regard, this paper aims to: 1) provide an integrated model of small-scale PCC process with small-scale coal-fired power plant; 2) propose feed-back control structures for the integrated system and 3) develop a feed-forward controller to manipulate the steam draw-off flowrate in order to satisfy the rapid response to grid demand. Case studies were presented to investigate the system performance in the face of setpoints tracking and response to load change. The simulations were carried out in gCCS toolkit. Results demonstrate that the feed-forward controller can satisfactorily lower the time needed for power output target tracking.

Thermostability enhancement of the α-carbonic anhydrase from Sulfurihydrogenibium yellowstonense by using the anchoring-and-self-labelling-protein-tag system (ASLtag)

Carbonic anhydrases (CAs, EC 4.2.1.1) are a superfamily of ubiquitous metalloenzymes present in all living organisms on the planet. They are classified into seven genetically distinct families and catalyse the hydration reaction of carbon dioxide to bicarbonate and protons, as well as the opposite reaction. CAs were proposed to be used for biotechnological applications, such as the post-combustion carbon capture processes. In this context, there is a great interest in searching CAs with robust chemical and physical properties. Here, we describe the enhancement of thermostability of the α-CA from Sulfurihydrogenibium yellowstonense (SspCA) by using the anchoring-and-self-labelling-protein-tag system (ASLtag). The anchored chimeric H5-SspCA was active for the CO2 hydration reaction and its thermostability increased when the cells were heated for a prolonged period at high temperatures (e.g. 70 °C). The ASLtag can be considered as a useful method for enhancing the thermostability of a protein useful for biotechnological applications, which often need harsh operating conditions.

Investigation of Energy-Saving Designs for an Aqueous Ammonia-Based Carbon Capture Process

In an aqueous ammonia-based postcombustion carbon capture (PCC) process, the regeneration energy of the CO2 lean solvent dominates the overall energy consumption. The energy reduction in the CO2 stripper can be achieved by either formulating new solvents or optimizing the process configurations. The ammonia concentration in the lean solvent is an important design parameter. A high concentration of ammonia results in a lesser lean solvent required at a constant CO2 removal efficiency, e.g., 90%; however, it encourages the formation of ammonium bicarbonate in the reflux, which brings the desorbed CO2 back into the stripper. To achieve constant CO2 removal, extra solvent in the stripper needs to be vaporized, which results in higher energy consumption than that required in applying a lean solvent with a low ammonia concentration. In this study, an index, which is the vaporization ratio of the solvent to the captured CO2, is used to evaluate the energy required for regenerating the lean solvent. A higher value of the index indicates that extra solvent needs to be vaporized, as compared to the captured amount of CO2. This index unifies the energy-saving concepts of the pressurized stripper and advanced stripper configurations. The former increases the stripper temperature, which favors CO2 desorbed from the rich solvent, while the latter lowers the top temperature of the stripper, which enhances the CO2 purity at the top. Both methods, which are the pressurized stripper and advanced stripper configuration, can achieve the energy-saving purpose by reducing the vaporization ratio, because a higher CO2 purity at the top leads to lesser solvent required to be vaporized for constant CO2 removal. In addition, the energy reduction achieved by stripper modifications, which include the rich-split process, the interheating process, and the integration of both configurations, is investigated. The results indicate that the energy-saving effect of the rich-split process integrated with interheaters (IHs) is not as promising as the literature claims. Once the design parameters of the rich-split process are selected properly, the rich-split process without IHs can achieve the same energy-saving effect as that achieved by process of integration with IHs.

Global warming potential and net power output analysis of natural gas combined cycle power plants coupled with CO2 capture systems and organic Rankine cycles

The objective of this study was to analyze the environmental and energetic analysis of a natural gas combined cycle (NGCC) power plant integrated with post-combustion carbon capture (PCC) and an organic Rankine cycle (ORC) as an alternative to increase net power output using thermal integration between the three processes. This study consisted of the calculation of the global warming potential (GWP) and the net power output as a function of the amount of CO2 captured. For the analysis, the base was taken as the simulation of a 453-MWe NGCC power plant with a monoethanolamine-based PCC process and an ORC. The base case shows that the ORC could generate a considerable amount of energy using a stream of hot water to evaporate the working fluid; this stream was previously extracted from the low pressure turbine and used in the stripper reboiler. Then three study cases were considered. For case 1 (NGCC + PCC + ORC), the power output is 381.2 MW with a capture of 42.43 kg/s of CO2 and a production of 2.02 MW in the ORC with a GWP of 94.75 g CO2e/kWh. For case 2, exhaust gas recirculation (EGR) was considered. For this case, the energy production is 386.52 MW, with 1.905 MW produced in the ORC. For case 3 with PCC and NGCC thermal integration, the net power output is 391.42 MW. These three cases were analyzed and the amount of combustive gases were varied to determine the effect on the power output, CO2 captured, and the GWP of these processes. The results show the tradeoffs between the considered goals and set an objective framework for policymakers to better operate these types of systems.

CO2/SO2 Emission Reduction in CO2 Shipping Infrastructure

There is an increased focus on the reduction of anthropogenic emissions of CO2 by means of CO2 capture processesand storage in geological formations or for enhanced oil recovery. The necessary link between the capture andstorage process is the transport system. Ship-based transport of CO2 is a better option when distances exceeds 350 km compared to an offshore pipeline and offers more flexibility for transportation unlike pipelines which require a continuous flow of compressed gas. Several feasibility studies have been undertaken to ascertain the viability of large scale transportation of CO2 by shipping in terms of the liquefaction process, and gas conditioning, but limited work has been done on reducing emissions from the ship’s engine combustion. From 2020, ships operating worldwide will be required to use fuels with 0.5% or less sulphur content (versus 3.5% now) or adapt adequate measures to reduce these emissions. This study explores the use of the solvent-based post-combustion carbon capture and storage (CCS) process for CO2 and SO2 capture from a typical CO2 carrier. A rate based aqueous ammonia process model was developed, validated, then scaled up and modified to process flue gas from a Wartsila 9L46F marine diesel engine.Different modes of operation of the carrier were analysed and the most efficient mode to operate the CCS system is while it is sailing. The heat recovered from the flue gas was used for solvent regeneration. A sensitivity study revealed that the 4 MWth supplied by the “waste heat recovery” system was enough to achieve a CO2 capture level of 70% at a solvent recirculation flowrate of 90-100 kg/s. The removal of SO2 by the ammonia water solution was above 95% and this led to the possibility of formating a value-added product, ammonium sulphate. The boil-off gas and captured emitted CO2 were recovered using a two stage re-liquefaction cycle and re-injected into the cargo tanks; thereby reducing extra space requirements on the ship.

Application of piece-wise linear system identification to solvent-based post-combustion carbon capture

Solvent-based post-combustion carbon capture (PCC) is currently the most promising method to reduce CO2 emission. To achieve a plant-wide controller for flexible operation, it is necessary to develop a data-driven model to understand the dynamic characteristics of PCC plant. This paper aims to: (i) carry out system identification to develop a data-driven model and (ii) provide insights into the nonlinear dynamics among the key variables from the PCC process in a wide operating range. These key variables include: CO2 capture rate, reboiler temperature, condenser temperature and lean solvent temperature. Pilot-scale PCC process implemented in gCCS was used to generate simulation data for system identification and model comparison. Linear single-input-single-output (SISO) transfer function models were firstly developed at different capture rates. Open loop step tests on identified models were then introduced to report the dynamics of key variables in various operating conditions and to indicate the level of system nonlinearity graphically. The nonlinearity analysis was carried out to investigate the system nonlinearity distribution in a quantitative manner. Based on the nonlinearity analysis, a multi-input-multi-output (MIMO) piece-wise model was proposed to simulate the nonlinear characteristics of PCC plant. The piece-wise model shows a satisfactory agreement with gCCS simulation data. Results of this study successfully demonstrate the nonlinear behavior of the solvent-based PCC process, which can be applied in the design of flexible plant-wide controllers.

Model-free adaptive control for MEA-based post-combustion carbon capture processes

For the flexible operation of mono-ethanol-amine-based post-combustion carbon capture processes, recent studies concentrate on model-based protocols which require underline model parameters of carbon capture processes for controller design. In this paper, a novel application of the model-free adaptive control algorithm is proposed that only uses measured input-output data for carbon capture processes. Compared with proportional-integral control, the stability of the closed-loop system can be easily guaranteed by increasing a stabilizing parameter. By updating the pseudo-partial derivative vector to estimate a dynamic model of the controlled plant on-line, this new protocol is robust to plant uncertainties. Compared with model predictive control, tuning tests of the protocol can be conducted on-line without non-trivial repetitive off-line sensitivity or identification tests. Performances of the model-free adaptive control are demonstrated within a neural network carbon capture plant model, identified and validated with data generated by a first-principle carbon capture model.

Design of energy efficient reactive solvents for post combustion CO2 capture using computer aided approach

The reduction of CO2 emissions has become a challenge due to rapid economic growth all over the world. Growing concerns on this issue have led the researcher to develop and implement several strategies including one very promising strategy involving CO2 capture from power plants. This paper presents a Computer Aided Molecular Design (CAMD) technique to design new alternative solvents as replacements for commonly used solvents during the post combustion carbon capture process in power plants, which is often costly and energy intensive. The CAMD technique can quickly identify the most suitable solvents and avoid spending resources on infeasible solvent replacements. In this study, the reverse design approach is used where, first, the criteria of the targeted solvents are identified and then the desired solvent candidates generated. The methods for this work consists of five steps: 1) Problem formulation, 2) Generation of single reactive solvent candidate using ProCAMD tools in ICAS software, 3) Prediction of the reaction mechanism between the potential amine solvent candidate and CO2 using the zwitterion mechanism and base-catalysed hydration mechanism, 4) Evaluation of process performance by calculating the heat required for the solvent regeneration process, and 5) Selection of the best solvent candidate based on its desired process performance. The result of this study reveals that 25 amine-based solvents for the chemical absorption process were successfully generated from the amine and alcohol functional groups. By using the proposed solvent, significant savings on regeneration energy, up to 31.4%, could be achieved compared to the conventional solvent, MEA. The percentage average absolute deviation (AAD) of the property prediction model that this study used to estimate the value of heat of formation is 4.67%. This finding is important to further reduce the regeneration energy, which makes the CO2 capture process costly, and achieve a more sustainable and cleaner environment.

Review of dynamic modelling, system identification and control scheme in solvent-based post-combustion carbon capture process

Solvent-based post-combustion carbon capture (PCC) process is widely viewed as the most viable option for reducing CO2 emission. This technology has been deployed globally and many researches have been conducted in this area. In this paper, current status of dynamic modelling, system identification and control scheme of solvent-based PCC process is reviewed. Different research directions of these areas are discussed to conclude the existing challenges. Based on this, this paper is also trying to provide potential solutions as possible pathways for flexible and economical operation.

Thermal integration of natural gas combined cycle power plants with CO2 capture systems and organic Rankine cycles

In this paper, the thermal integration of a natural gas combined cycle (NGCC) power plant integrated with post-combustion carbon capture (PCC) and CO2 compression is proposed. With the objective of finding a heat exchanger network (HEN) that decrease the energy impact of the PCC process, which reduce the power output of the turbines as it requires a large amount of steam for its operation and it uses part of the power generated by the NGCC power plant. Also, the possibility of implementing an Organic Rankine Cycle (ORC) to generate electricity with the wasted energy of the process is analyzed. This study consists of a 453MWe NGCC power plant with an MEA-based PCC process, and the option to consider a fixed 260kWe ORC or an ORC with variable power output, which are simulated in ASPEN PLUS® to obtain all the process inventories. Then the thermal integration is performed using the SYNHEAT model. Result show that the proposed HENs can reduce the use of steam in the striper reboiler to 65.43Kg/s and it can also reduce the use of hot water to heat the input of natural gas producing a 126.571MWe power output of the steam turbines increasing the thermal efficiency to 50.94% whereas the implementation of the ORC can increase the power output up to 1.651MWe using the wasted energy of the plant and also the global warming potential (GWP) decrease 78% due to the reduction in CO2 emission and the generation of more power in comparison with the stand alone NGCC.

Operation and Bidding Strategies of Power Plants with Carbon Capture

For the post-combustion carbon capture (PCC) process with MEA solvent, most of the relevant literature discussed the optimal operation under a cost-minimum target. A power plant integrated with the PCC process, however, prefer to maximize its lifetime cumulative profits. To maximize the profits, we may identify the following issues. For the power plant operation, trade-offs should be made between electricity output and the energy-intensive carbon capture process; for the CO2 allowance bidding, a fossil-fuel power plant should bid and win adequate allowances from the market to balance its demand of CO2 emission. We apply the Sarsa temporal difference (TD) learning algorithm to search for a strategy that maximizes profits during the power plant lifetime with the above issues. This strategy includes both the operation and the bidding of the power plant. Our results show it is better than the independently-designed bidding and operation strategy with a fixed CO2 capture level. In addition, the Sarsa TD algorithm can find a better strategy than Sarsa(λ) if training data can be generated cheaply.

Improvement of Post-combustion Carbon Capture Process in Retrofit Case

Carbon dioxide emission, one of the core cause of global warming and other threats of nonreversible environmental effects, is in focus today. Among the several methods of CO2 emission mitigation, post-combustion carbon capture (PCC), based on absorberdesorber systems with amine absorbents, is one of the promising alternatives. The major anthropogenic CO2 point sources are power plants, natural gas extraction units, oil refineries, cement factories, biogas plants, etc. As these CO2 sources can be treated with a PCC absorber-desorber system, then these two units should cope with various conditions. To maintain a desired high removal efficiency, the capture unit must work in flexible conditions. The aim of this study is to evaluate the influence of the extent of the absorption of carbon dioxide on the overall performance of the acid gas removal process, considering that, generally, as the amount of removed CO2 increases, the separation becomes more challenging. In this work a verified computer based process model for the absorber-desorber system is used. Aspen Plus® professional flowsheet simulator is used for this purpose. Attention is paid on the proper operating parameters of a PCC absorber-desorber system for the case of increasing the CO2 capture efficiency up to 99%. As alternative solutions for these cases different scenarios are considered:•the increase of the capacity of a classic configuration of an absorber-desorber system;•the introduction of a second absorber column as extending the absorption column height;•the possible use of two absorbers and two desorbers working in series.This work deals with the detailed study on maximizing CO2 removal efficiency while maintaining the minimal energy consumption for the absorbent regeneration section.

Enhancements in mass transfer for carbon capture solvents part I: Homogeneous catalyst

The novel small molecule carbonic anhydrase (CA) mimic [CoIII(Salphen-COO−)Cl]HNEt3 (1), was synthesized as an additive for increasing CO2 absorption rates in amine-based post-combustion carbon capture processes (CCS), and its efficacy was verified. 1 was designed for use in a kinetically slow but thermally stable blended solvent, containing the primary amines 1-amino-2-propanol (A2P) and 2-amino-2-methyl-1-propanol (AMP). Together, the A2P/AMP solvent and 1 reduce the overall energy penalty associated with CO2 capture from coal-derived flue gas, relative to the baseline solvent MEA. 1 is also effective at increasing absorption kinetics of kinetically fast solvents, such as MEA, which can reduce capital costs by requiring a smaller absorber tower. The transition from catalyst testing under idealized laboratory conditions, to process relevant lab- and bench-scale testing adds many additional variables that are not well understood and rarely discussed. The stepwise testing of both 1 and the novel A2P/AMP solvent blend is described through a transition process that identifies many of these process and evaluation challenges not often addressed when designing a chemical or catalytic additive for industrial CCS systems, where consideration of solvent chemistry is typically the primary goal.