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Some of the relevant post‐combustion CCS research trends includes the reduction of the energy consumption required for regeneration. It is a priority to find novel solvents that show high affinity for CO2 together with an ease of regeneration and reuse. Recently, impregnated solid sorbents have been suggested to tackle with these issues. In particular amine‐impregnated solid sorbents require less regeneration energy due to the reduction in water content and the higher heat capacity of solids. As a consequence, they may have the ability to reduce the efficiency penalty of CCS in power plants. Several studies have quantified the efficiency penalty of CO2 capture in commercial power plants with amine absorption. It is generally assumed a reduction of 7–10 efficiency points. Nevertheless, there is not a clear quantification of the effect of solid sorbent capture plants on efficiency penalty. This paper tries to shed some light on this issue. The objective of this work is to demonstrate and quantify the effect on net power and efficiency penalty of using amine‐impregnated solid sorbents when applied as an option to carbon capture. A full process integration of the system and an overall optimisation for power generation have been carried out. Interesting results have been achieved; it is possible to reduce the efficiency penalty down to 6.7 efficiency points. This figure could make feasible the impregnated amine solid sorbent as a future and promising option for CO2 capture. Amine‐impregnated solid sorbents (AISS) for CO2 capture require less regeneration energy than other options. This characteristic makes them suitable for reducing the efficiency penalty of CCS in power plants. This work demonstrates and quantifies the effect on net power and efficiency of using AISS for carbon capture. Full process integration shows that it is possible to reduce the efficiency penalty down to 6.7 efficiency points. [ABSTRACT FROM AUTHOR]

O2GEN project was running during more than three years and it was successfully finished in January 2016. The main target was to develop the 2 nd generation oxyfuel circulating fluidized bed (CFB) power plants based on higher oxygen concentrations with the aim of decreasing flue gas recirculation and the energy penalty. Remarkable advances have been achieved in Air Separation (ASU) and Compression and Purification Units (CPU) reducing significantly their energy consumption. CFB boiler concept was proposed by scaling-up from past designs. No special drawbacks were found regarding combustion, heat transfer and emissions. Finally, a process integration methodology was applied and overall efficiency was increased by heat integration. Energy penalty was reduced from 10.5 to 7.3 efficiency points. The new power plant lay-out avoids technical restrictions in the use of complex heat exchangers and facilitates the operational flexibility of the system. [ABSTRACT FROM AUTHOR]

The share of renewable energy production is growing quickly. The output and variability of renewable power will force to fossil fuel power plants to adapt its electricity production to variable demand. In a future scenario, with CO 2 capture systems installed in power plants, the variable performance will affect not only to fossil fuel power plant but also to the CO 2 capture behavior. The knowledge of part load performance of fossil fuel power plants with CO 2 capture systems will be essential in a near future. This paper analyzes the integration between Ca-looping cycles and power plants to foresee the requirements derived from a flexible operation. With this goal, the performance of the integrated system under different load scenarios is studied. An integration scheme designed for nominal load is proposed under different load scenarios at steady state, to study their performance. Then, for each load scenario, the optimum integration is designed, to quantify the minimum energy penalty of each specific load level. Finally, a comparative analysis of the general integration against the optimum one for each scenario is performed. [ABSTRACT FROM AUTHOR]

Abstract: Despite the interest of carbon capture and storage research on the calcium looping cycle due to the potentially low CO2 avoided cost this technology offers, there is a need to keep on reducing both cost and system size to ensure the economic advantage of this technology. This work presents three novel calcium looping configurations designed with the objective of decreasing the fuel consumption in the regeneration reactor and the energy requirements in the air separation unit. Available heat from the solid and gaseous streams leaving the calciner is used to heat up the particles before entering this reactor. These systems are thermodynamically modelled and their thermal efficiencies and available energy flows analyzed to establish which configuration has the higher coal and oxygen consumption saving potential. The configuration that includes an extra heat recovery bed to exchange heat between the CO2 stream and the solid particles entering the calciner presents the lowest coal and fresh sorbent consumption in the regeneration step. As a consequence, smaller system size and operational cost may be achieved with this configuration. Since fuel requirements are reduced, so does the oxygen demand from the air separation unit which will introduce less energy penalties associated to its high specific electrical consumption. [Copyright &y& Elsevier]

Abstract: Oxyfuel combustion is a promising alternative for CO2 capture. While this has been proven in pulverized fuel (PF) burners, research in fluidized bed (FB) reactors is still scarce. Our work aims to increase the knowledge about this technology. To this purpose, a 95kWth FB oxyfuel combustion test rig has been erected. Its main characteristics are described in this paper, giving detailed information on the subsystems: the FB reactor, the fuel and oxidant supplies, and ancillaries. Plant flexibility is emphasized. It allows to operate under different CO2/O2 ratios, and to recycle CO2 from the flue gases. Both the processes design and monitoring are supported by simulations that have been validated against experimental data, regarding fluid dynamics, combustion, and heat transfer. Finally, the performance of the facility has been tested both with coal alone and blended with biomass. CO2 concentrations over 90% (dry basis) in the flue gases have been obtained. Comparison of air and oxygen combustion tests and operational recommendations are discussed, confirming the feasibility of the FB oxyfuel technology for CO2 capture purposes. [ABSTRACT FROM AUTHOR]

Abstract: High temperature looping cycles, such as carbonation-calcination cycles based on calcium sorbents or chemical looping combustion are being developed and play an essential role in CO2 capture technologies. Among proposed configurations, outstanding schemes make use of a number of interconnected fluidized beds and may operate at bubbling or circulating regime. Fluidized bed behaviour is well-known since they are included in many industrial applications, such as power plants and chemical industries. However, there is a lack of knowledge about their operation when more than one fluidized bed are coupled in the same system. One promising configuration for Ca-based sorption looping systems relies on the use of two circulating beds as carbonator and calciner and two bubbling beds acting as loop-seal valves. Many theoretical and lab experimental studies point out the need of large solid circulation in the system to reach high carbonation efficiencies. The control of this flow in complex CFB looping systems, where also internal recirculation exists in the risers, becomes a difficult task and deserves further studies to characterize them. The challenge to solve, through experimental tests and mathematical modelling, is finding a comprehensive control method to operate two circulating beds in turbulent regime and two bubbling sealing devices. Experimental results supporting high carbonation efficiency or feasibility in scaling-up solid circulation rates and inventories are needed to make the system more reliable. A lab-scale cold flow facility has been designed based on Glicksman’s scaling rules and constructed in order to conduct experimental tests. The mechanical design of the facility and the choice of solid material, fluidizing gas and operating conditions should be such as to ensure the circulation of solids between reactors and the presence of solids inventory in the carbonator which are necessary to achieve high capture efficiencies. Operation of the system has been tested for a long number of hours under very different conditions. Measurements of circulation rate, static pressure, voidage profiles and standpipe height of solids have been used to identify trends in the hydrodynamic behaviour of the whole system while varying gas velocities in the risers, loop-seals, inventories in the reactors or size distribution of the particles. The circulation rates attained in the cold flow plant are comparable, after scaling-up, to solid flows in the loop which lead to high enough carbonation efficiencies of the system. [Copyright &y& Elsevier]

Abstract: A common characteristic of carbon capture and storage systems is the important energy consumption associated with the CO2 capture process. This important drawback can be solved with the analysis, synthesis and optimization of this type of energy systems. The second law of thermodynamics has proved to be an essential tool in power and chemical plant optimization. The exergy analysis method has demonstrated good results in the synthesis of complex systems and efficiency improvements in energy applications. In this paper, a synthesis of pinch analysis and second law analysis is used to show the optimum window design of the integration of a calcium looping cycle into an existing coal power plant for CO2 capture. Results demonstrate that exergy analysis is an essential aid to reduce energy penalties in CO2 capture energy systems. In particular, for the case of carbonation/calcination CO2 systems integrated in existing coal power plants, almost 40% of the additional exergy consumption is available in the form of heat. Accordingly, the efficiency of the capture cycle depends strongly on the possibility of using this heat to produce extra steam (live, reheat and medium pressure) to generate extra power at steam turbine. The synthesis of pinch and second law analysis could reduce the additional coal consumption due to CO2 capture 2.5 times, from 217 to 85MW. [Copyright &y& Elsevier]

Abstract: CO2 capture systems based on the carbonation/calcination loop have gained rapid interest due to promising carbonator CO2 capture efficiency, low sorbent cost and no flue gases treatment is required before entering the system. These features together result in a competitively low cost CO2 capture system. Among the key variables that influence the performance of these systems and their integration with power plants, the carbonation conversion of the sorbent and the heat requirement at calciner are the most relevant. Both variables are mainly influenced by CaO/CO2 ratio and make-up flow of solids. New sorbents are under development to reduce the decay of their carbonation conversion with cycles. The aim of this study is to assess the competitiveness of new limestones with enhanced sorption behaviour applied to carbonation/calcination cycle integrated with a power plant, compared to raw limestone. The existence of an upper limit for the maximum average capture capacity of CaO has been considered. Above this limit, improving sorbent capture capacity does not lead to the corresponding increase in capture efficiency and, thus, reduction of CO2 avoided cost is not observed. Simulations calculate the maximum price for enhanced sorbents to achieve a reduction in CO2 removal cost under different process conditions (solid circulation and make-up flow). The present study may be used as an assessment tool of new sorbents to understand what prices would be competitive compare with raw limestone in the CO2 looping capture systems. [Copyright &y& Elsevier]

Abstract: CO2 capture system based on the carbonation/calcination loop, still in its infancy, has gained rapid interest due to promising carbonator CO2 capture efficiency, low sorbent cost and the fact that no flue gases desulphurization unit is needed before entering the system. The sum of these features results in a competitively low cost CO2 capture system. There are different options to design the carbonation loop. In this work, a basic configuration that makes use of two interconnected circulating fluidized beds (carbonator and calciner) has been studied. Among the key variables that influence the performance of these systems, the carbonation conversion of the sorbent and the heat requirement at calciner are the most relevant. Both variables are mainly influenced by CaO/CO2 ratio and make-up flow (purge) of solids. A purge is necessary in order to reduce the sorbent deactivation and to compensate the formation of CaSO4 from the SO x content in the flue gas. Large CaO/CO2 ratios improve the carbonation conversion but also increase the cost of the system due to a more intensive solid circulation. High make-up flow also improves the carbonation conversion and hence the CO2 capture, but increases the heat demand at calciner and the fresh sorbent cost. The aim of this paper is to calculate the optimum make-up flow and CaO/CO2 ratio in order to minimize the capture cost of the system. Independent variables are make-up flow of fresh CaCO3 and CaO/CO2 ratio. The constraint equations are experimental data on carbonation reaction, mass and energy balances, oxygen requirement and fuel composition. [Copyright &y& Elsevier]

Abstract: One of the most promising options for CO2 capture in large power generation facilities is the system based on the CO2 sorption loop. This method has gained rapid importance due to promising carbonator CO2 capture efficiency, the existence of low cost sorbents and the fact that no gas pre-treatment unit is needed before entering the system. The sum of these features results in a competitively low cost CO2 capture system when using low cost natural sorbents. Different regenerable sorbents are being investigated for large-scale CO2 capture purposes and high temperature Mg-based, Li-based and Ca-based sorbents are considered as suitable candidates. This study considers the applicability of lithium orthosilicatum, hydrated limestone and raw natural limestone. A basic configuration that makes use of two interconnected circulating fluidized beds (carbonator and calciner) has been studied. Among the key variables that influence the performance of these systems, the carbonation conversion of the sorbent and the heat requirement at calciner are the most relevant. Both variables are mainly influenced by sorbent/CO2 ratio and make-up flow (purge) of solids. Purge is necessary to mitigate the sorbent deactivation. Large sorbent/CO2 ratios improve the carbonation conversion but also increase the cost of the system due to a more intensive solid circulation. Large make-up flow also improves the extent of sorption phenomena and hence the CO2 capture, but increases the heat demand at calciner and the fresh sorbent cost. The aim of this paper is to calculate the optimum make-up flow of fresh sorbent and sorbent/CO2 ratio for a set of these regenerable sorbents in order to minimize the capture cost of the system integrated into a power plant. Resulting optimal values are compared to assess the energetic performance and CO2 capture cost of the cycle for each sorbent material. [Copyright &y& Elsevier]

Abstract: For clean utilization of coal, enhanced gasification by in situ CO2 capture has the advantage that hydrogen production efficiency is increased while no energy is required for CO2 separation. The unmixed fuel process uses a sorbent material as CO2 carrier and consists of three coupled reactors: a coal gasifier where CO2 is captured generating a H2-rich gas that can be utilized in fuel cells, a sorbent regenerator where CO2 is released by sorbent calcination and it is ready for capture and a reactor to oxidize the oxygen transfer material which produces a high temperature/pressure vitiated air. This technology has the potential to eliminate the need for the air separation unit using an oxygen transfer material. Reactors'' temperatures range from 750°C to 1550°C and the process operates at pressure around 7.0bar. This paper presents a global thermodynamic model of the fuel processing concept for hydrogen production and CO2 capture combined with fuel and residual heat usage. Hydrogen is directly fed to a solid oxide fuel cell and exhaust streams are used in a gas turbine expander and in a heat recovery steam generator. This paper analyzes the influence of steam to carbon ratio in gasifier and regeneration reactor, pressure of the system, temperature for oxygen transfer material oxidation, purge percentage in calciner, average sorbent activity and oxidant utilization in fuel cell. Electrical efficiency up to 73% is reached under optimal conditions and CO2 capture efficiencies near 96% ensure a good performance for GHG''s climate change mitigation targets. [Copyright &y& Elsevier]

Postcombustion CO2 capture is the best suitable capture technology for existing coal power plants. This paper focuses on an emerging technology that involves the separation of CO2 using the reversible carbonation reaction of CaO to capture CO2 from the flue gas, and the calcination of CaCO3 to regenerate the sorbent and produce concentrated CO2 for storage. We describe the application to this concept to an existing (with today’s technology) power plant. The added capture system incorporates a new supercritical steam cycle to take advantage of the large amount of heat coming out from the high temperature capture process (oxyfired combustion of coal is needed in the CaCO3 calciner). In these conditions, the capture system is able to generate additional power (26.7% efficiency respect to LHV coal input to the calciner after accounting for all the penalties in the overall system), without disturbing the steam cycle of the reference plant (that retains its 44.9 efficiency). A preliminary cost study of the overall system, using well established analogues in the open literature for the main components, yields capture cost around 16€/ton CO2 avoided and incremental cost of electricity of just over 1€/MWhe. [Copyright &y& Elsevier]

Abstract: Absorption by chemical solvents combined with CO2 long-term storage appears to offer interesting and commercial applicable CO2 capture technology. However one of the main disadvantages is related to the large quantities of heat required to regenerate the amine solvent that means an important power plant efficiency penalty. Different studies have analyzed alternatives to reduce the heat duty on the reboiler and the thermal integration requirements on existing power cycles. In these studies integration principles have been well set up, but there is a lack of information about how to achieve an integrated design and the thermal balances of the modified cycle flowsheet. This paper proposes and provides details about a set of modifications of a supercritical steam cycle to overcome the energy requirements through energetic integration with the aim of reducing the efficiency and power output penalty associated with CO2 capture process. Modifications include a new designed low-pressure heater flowsheet to take advantage of the CO2 compression cooling for postcombustion systems and integration of amine reboiler into a steam cycle. It has been carried out several simulations in order to obtain power plant performance depending on sorbent regeneration requirements. [Copyright &y& Elsevier]

Carbon capture and utilization (CCU) may offer a response to climate change mitigation from major industrial emitters. CCU can turn waste CO2 emissions into valuable products such as chemicals and fuels. Consequently, attention has been paid to petrochemical industries as one of the best options for CCU. The largest industrial CO2 removal monoethanol amine-based plant in Iran has been simulated with the aid of a chemical process simulator, i.e., Aspen HYSYS® v.10. The thermodynamic properties are calculated with the acid gas property package models, which are available in Aspen HYSYS®. The results of simulation are validated by the actual data provided by Kermanshah Petrochemical Industries Co. Results show that there is a good agreement between simulated results and real performance of the plant under different operational conditions. The main parameters such as capture efficiency in percent, the heat consumption in MJ/kg CO2 removed, and the working capacity of the plant are calculated as a function of inlet pressure and temperature of absorber column. The best case occurred at the approximate temperature of 40 to 42 °C and atmospheric pressure with CO2 removal of 80.8 to 81.2%; working capacity of 0.232 to 0.233; and heat consumption of 4.78 MJ/kg CO2. [ABSTRACT FROM AUTHOR]

Abstract: High temperature looping cycles involving solid circulation, such as carbonation–calcination, play an essential role among the CO2 capture technologies under development. The low cost and high availability of Ca-based sorbents together with the feasibility of integration between these capture systems and existing power plants lead to very competitive potential costs of avoided CO2, below 20€/tonne. Optimal configurations make use of several interconnected fluidized beds. One promising configuration for Ca-based sorbents looping systems relies on the use of two circulating beds (carbonator and calciner) and two bubbling beds acting as non-mechanical valves. Fluidized beds are well characterized when operating independently since they are extensively used in industrial applications, power and chemical plants. However, the operation when two or more fluidized beds exchange solid material through non-mechanical valves is still uncertain because of the more complex pressure balance of the system. Theoretical studies based on thermo-chemical simulations and experimental studies show that minimum CO2 capture cost is attained with large solid circulation flow between reactors. The challenge is to reach the required particle circulation in a system with a complex configuration and be able to control it. Solid internal recirculation in any of these fluidized beds would provide flexibility in its control but it will also make harder the characterization of the whole system. The aim of this work is to analyse the hydrodynamics of the system and to generate a comprehensive mathematical model to better understand the interaction between the elements of the system. Measurements of circulation rate, static pressure, voidage profiles and standpipe height of solids have been used to identify trends in the hydrodynamic behaviour of the whole system while varying fluidizing gas velocities in the risers, loop-seals, solid inventories in the reactors or size distribution of the particles. These measurements are also used to adjust and validate the mathematical model presented in this study. [Copyright &y& Elsevier]

Abstract: Hydrogen is expected to be one of the most important energy carriers in the future. Gasification process may be used to produce hydrogen when joined with carbon capture technologies. Furthermore, the combination of biomass gasification and carbon capture presents a significant technical potential in net negative greenhouse gas emissions. Lime enhanced biomass gasification process makes use of CaO as a high temperature CO2 carrier between the steam biomass gasifier and an oxy-fired regenerator. Important energy penalties derive from the temperature difference between the reactors (around 250–300 °C). A cyclonic preheater similar to those used in the cement industry may improve the energetic efficiency of the process if the particles entering the regenerator reactor are heated up by the gas leaving this reactor. A lime enhanced biomass gasification system was modelled and simulated. A cyclonic preheater was included to evaluate the improvement. Results show an increase of the gasification chemical efficiency and a reduction of the energy consumption in the regenerator. [Copyright &y& Elsevier]

The iron and steel industry is one of the most energy-intensive industries, emitting 5% of the total anthropogenic carbon dioxide (CO 2). The control of CO 2 emissions has become increasingly stringent in the European Union (EU), resulting in EU allowance above 90 €/t CO2. Carbon capture will be required to achieve CO 2 emissions control, and carbon utilization via power-to-gas could significantly increase interest in carbon capture in the iron and steel sector. This paper presents a new concept that combines amine scrubbing with power-to-gas to reduce emissions in blast furnace-basic oxygen furnace steelmaking plants. Synthetic natural gas (SNG) is produced using green hydrogen from water electrolysis and CO 2 from steelmaking. The synthetic natural gas is later used as a reducing agent in the blast furnace, constantly recycling carbon in a closed loop and avoiding geological storage. The oxygen by-produced via electrolysis eliminates the necessity of an air separation unit. By applying these innovations to steelmaking, a reduction in CO 2 emissions of 9.4% is obtained with an energy penalty of 16.2 MJ/kg CO2 , and economic costs of 52 €/t HM or 283 €/t CO2. A sensitivity analysis with respect to electricity and the CO 2 allowances prices is also performed. • Novel power-to-gas and amine scrubbing integration proposed for BF-BOF steel making. • Detailed steel plant process model developed and validated. • Technical viability of the novel process concept demonstrated. • A reduction of 9.4% in CO 2 emissions has been achieved. • The novel concept would be profitable under 35 €/MWh and 177 €/tCO 2. [ABSTRACT FROM AUTHOR]

Highlights: [•] A procedure for integrating high temperature CO2 capture systems is developed. [•] Two sorption–desorption cycles for CO2 capture are assessed applying this methodology. [•] The most economical HEN for each case was obtained by following the procedure. [ABSTRACT FROM AUTHOR]

Highlights: [•] Heat integration is essential to minimize energy penalties in calcium looping cycles. [•] A design and analysis of four heat exchanger networks is stated. [•] New design with higher power, lower costs and lower destroyed exergy than base case. [Copyright &y& Elsevier]

Abstract: This paper addresses the mathematical development and the experimental validation of a semi-empirical model designed to characterize the fluid-dynamic response of a fluidized bed reactor under oxy-fuel operation. The objective is to survey the main differences between a conventional air operation and a novel O2/CO2 operation, as for the interactions of solid-phase and gas-phase. The model provides all the relevant variables describing the fluid-dynamics, and it is conceived to simulate the performance of a lab-scale facility. Data gathered from the cold- and hot-operation of a 90kWth oxy-fired fluidized bed are used for validation purposes. Bed porosity, minimum fluidization velocity and bubbles’ size are detected to change under oxy-firing conditions. Once validated, the tool will be used to predict the performance under new fluidizing atmospheres and will be integrated within an entire model coupling fluid-dynamics, combustion and heat transfer phenomena. [Copyright &y& Elsevier]