How do CaO/CuO materials evolve in integrated calcium and chemical looping cycles?

Maintaining high CO2 uptake is critical for combined Ca-Cu looping applications, however, the long-term behaviour of combined Ca and Cu materials under repeated cycling conditions remains less understood. This study examined three materials with a fixed Cu/Ca mole ratio of 1.6 to analyse the material phase evolution and identify factors influencing CO2 uptake. The materials underwent 50 TGA cycles in two distinct looping applications: blast furnace gas (BFG) cycling (reduction-carbonation-oxidation) and flue gas cycling (carbonation-reduction-oxidation). Different preparation methods significantly affected the initial phase distribution. The multi-grain precipitate material (MGP), prepared to minimise the chemical contact between Ca and Cu, primarily contained separate CaO and CuO phases; while the multi-stage mechanically mixed materials (MM1 and MM2), in which there was extensive contact between the Ca and Cu, exhibited mixed Ca-Cu-O phases along with separate CuO. However, the initial phase distribution had little influence on the longer-term CO2 uptake with the accessibility of CaO and cycling conditions having a more significant impact. BFG cycling consistently resulted 70–100; % greater CO2 uptake than flue gas cycling, highlighting the strong influence of cycling conditions

Blast Furnace Gas Utilization with Calcium-Assisted Steel Mill Off-Gas Hydrogen Production (CASOH) Technology: Technical Evaluation

In pursuit of decarbonizing the iron and steel industry through the utilization of blast furnace gas (BFG), this study investigates the technical feasibility of a Ca–Cu looping technology known as calcium-assisted steel mill off-gas hydrogen production (CASOH). The process is modeled and analyzed using Aspen Plus software. The key technical performances of two versions of CASOH were evaluated and compared with more traditional solvent-based technology for the precombustion decarbonization of BFG using methyl diethanolamine (MDEA). The first case (base case, CASOH-B) uses part of the BFG to regenerate the sorbent; therefore, it concentrates CO2 up to 54%. In the second case (enhanced, CASOH-E), low-pressure steam is used for the calcination reaction. In the case of CASOH-B, the integration with a CO2 purification unit outperforms the other configurations regarding the CO2 capture efficiency, with values of up to 97% compared to 91% for CASOH-E and 83% for MDEA. However, CASOH-E demonstrated a significantly higher thermal output (224.5 MWLHV vs 77.6 MWLHV for CASOH-B), resulting in better cold gas efficiency and lower specific CO2 emissions (76% and 29.8 kgCO2/GJLHV for CASOH-E compared to 26.3% and 105.7 kgCO2/GJLHV for CASOH-B). Various scenarios were analyzed to meet the heat and power requirements of the process. When relying on an external energy source such as natural gas, biogas, or photovoltaic panels, the solvent-based case outperforms the CASOH configurations with a specific energy consumption per CO2 avoided (SPECCA) of 0.5–0.7 MJLHV/kgCO2, compared to 1.1–3.3 MJLHV/kgCO2 for CASOH configurations. However, if the hydrogen-rich stream produced in CASOH-E is used to meet energy demands, then CASOH-E becomes the most favorable option. These findings emphasize the importance of operational parameters in optimizing BFG decarbonization strategies by balancing thermal output, efficiency, and emissions capture.<br/

How do CaO/CuO materials evolve in integrated calcium and chemical looping cycles?

Maintaining high CO2 uptake is critical for combined Ca-Cu looping applications, however, the long-term behaviour of combined Ca and Cu materials under repeated cycling conditions remains less understood. This study examined three materials with a fixed Cu/Ca mole ratio of 1.6 to analyse the material phase evolution and identify factors influencing CO2 uptake. The materials underwent 50 TGA cycles in two distinct looping applications: blast furnace gas (BFG) cycling (reduction-carbonation-oxidation) and flue gas cycling (carbonation-reduction-oxidation).Different preparation methods significantly affected the initial phase distribution. The multi-grain precipitate material (MGP), prepared to minimise the chemical contact between Ca and Cu, primarily contained separate CaO and CuO phases; while the multi-stage mechanically mixed materials (MM1 and MM2), in which there was extensive contact between the Ca and Cu, exhibited mixed Ca-Cu-O phases along with separate CuO. However, the initial phase distribution had little influence on the longer-term CO2 uptake with the accessibility of CaO and cycling conditions having a more significant impact. BFG cycling consistently resulted 70–100; % greater CO2 uptake than flue gas cycling, highlighting the strong influence of cycling conditions

Carbon capture for decarbonisation of energy-intensive industries: a comparative review of techno-economic feasibility of solid looping cycles

Carbon capture and storage will play a crucial role in industrial decarbonisation. However, the current literature presents a large variability in the techno-economic feasibility of CO2 capture technologies. Consequently, reliable pathways for carbon capture deployment in energy-intensive industries are still missing. This work provides a comprehensive review of the state-of-the-art CO2 capture technologies for decarbonisation of the iron and steel, cement, petroleum refining, and pulp and paper industries. Amine scrubbing was shown to be the least feasible option, resulting in the average avoided CO2 cost of between 62.7C=⋅t−1CO2 for the pulp and paper and 104.6C=⋅t−1CO2 for the iron and steel industry. Its average equivalent energy requirement varied between 2.7 (iron and steel) and 5.1MJth⋅kg−1CO2 (cement). Retrofits of emerging calcium looping were shown to improve the overall viability of CO2 capture for industrial decarbonisation. Calcium looping was shown to result in the average avoided CO2 cost of between 32.7 (iron and steel) and 42.9C=⋅t−1CO2 (cement). Its average equivalent energy requirement varied between 2.0 (iron and steel) and 3.7MJth⋅kg−1CO2 (pulp and paper). Such performance demonstrated the superiority of calcium looping for industrial decarbonisation. Further work should focus on standardising the techno-economic assessment of technologies for industrial decarbonisation

Exploiting the potential of chemical looping processes for industrial decarbonization and waste to energy conversion. Process design and experimental evaluations

The impact of anthropogenic activities on the environment is leading to climate changes and exceptional meteorological phenomena all over the world. To address this negative trend, the scientific community agrees that the environmental impact from fossil fuels-based power production must be mitigated by the integration with alternative and sustainable technologies, such as renewable energy. However, the time required for the complete development and diffusion of such technology poses the urgency of finding a midterm solution to significantly reduce CO2 emissions. Carbon capture, utilization, and storage (CCUS) technologies represent an interesting option to mitigate CO2 emissions. CCUS involves (among other possible applications) the separation of the CO2 content from industrial off-gases, its transport and storage or its reconversion to a chemical/fuel. Chemical looping can be considered as an oxyfuel combustion where the oxygen supply comes from the lattice oxygen atoms of a solid. It is based on gas-solid reactions where a solid also known as oxygen carrier, generally a metal oxide, undergoes successive reduction and oxidation steps. In the reduction step, normally occurring at high temperatures (700-1000 °C), the oxygen carrier interacts with a reducing agent, such as coal, natural gas, syngas etc. and loses part of its oxygen atoms. By controlling the degree of reduction of the oxygen carrier is thus possible to achieve a complete oxidation of the reducing agent (the fuel) to CO2 and H2O (chemical looping combustion) or a partial oxidation to a syngas (chemical looping reforming and gasification). In these latter case, the introduction of external CO2 and H2O can be of help to support the reforming or gasification processes. The oxygen carrier in the reduced phase is then sent to an air reactor, where it reacquires the oxygen atoms by an exothermic reaction with air. This process presents several advantages according to the specific application. In chemical looping combustion, intrinsic separation of N2 and CO2 is achieved, because the two streams are involved in two different reaction steps. This largely simplifies the CO2 separation effort for storage or utilization purposes. On the other hand, in chemical looping reforming it is possible to achieve autothermal operation thanks to the exothermicity of the oxidation step in the air reactor, as well as high reforming efficiencies. Similarly, in chemical looping gasification the resulting syngas is characterized by no N2 dilution, lower tar release and possibility of autothermal operation. These benefits enhance the energy efficiency of the process, leading to a better energy utilisation. In this work, strategies for the decarbonisation and circularity of the industrial and power sector are proposed based on the synthesis of hydrogen and hydrogen-derived fuels. In particular, the potential of chemical looping technology is deeply studied aiming at exploiting its ability to reconvert or valorise CO2 or waste streams to a syngas and then to a liquid fuel/chemical, such as methanol or ammonia. This task is carried out through modelling and experimental evaluations. The modelling activities mainly concern design of process schemes involving the chemical looping section for waste or CO2 reconversion and the liquid fuel synthesis section. The experimental evaluations are focused on two crucial that have been limitedly discussed in the literature: the thermochemical syngas production step by oxidation with CO2 and H2O streams, the effect of high-pressure operation on the redox abilities of a typical iron and nickel-based oxygen carrier. In Chapter 1, a general overview on the main research developments on chemical looping technology is provided. A section is reserved for each chemical looping variant, i.e. combustion, reforming and gasification, and a general description of each process is provided along with the summary of the main research achievements. Subsequently, the technology is divided by application in power production and chemicals production. Main findings from techno-economic assessment and process designs are discussed in comparison with benchmark technologies and other clean pathways. In Chapter 2 steel mills are taken as an example of the hard-to-abate industry. A H2-based decarbonization strategy is proposed and assessed by Aspen Plus simulation. The strategy starts from an initial configuration that is characterized by a typical blast furnace-basic oxygen furnace steel mill and consider the introduction of direct reduction – electric arc furnace lines, that are more efficient and involve natural gas as reducing agent rather than coke. Sensitivity analyses are carried out to assess the effect of the introduction of H2/CH4 blendings in the direct reduction plant and of the utilization of scrap material in the electric arc furnace. The impact of each configuration on the CO2 emissions and the energy flows of the plant is assessed by mass and energy balances. The results indicate a promising decarbonization potential of the introduced technologies but require large investments to increase the renewable sources penetration in the energy mix and large availability of H2. Therefore, alternative pathways for an earlier decarbonization of hard-to-abate industries and for large scale syngas/H2 production need to be considered. In Chapter 3, a novel process scheme is proposed involving chemical looping for syngas production. The CO2 content in blast furnace gases is separated with a calcium looping cycle and subsequently injected with H2O into the oxidation reactor of a chemical looping cycle. Assuming an inlet stream of pure CO2, mass balances on the chemical looping plant are carried out to compare the performance of nickel ferrites and iron oxides in terms of required oxygen carrier flow rate to process 1 t/h of CO2. Computational fluid dynamics simulations with integrated reaction kinetics are then carried out to validate the assumptions on the oxygen carrier conversion and syngas compositions. In Chapter 4 and 5, experimental evaluations are carried out on two crucial aspects for the successful operation of a chemical looping plant aiming at syngas production. In Chapter 4, the syngas productivity by CO2 and H2O splitting over a Fe bed is investigated. This is a very important step, and the effect of various parameters was considered. Firstly, the CO2 splitting is analysed for different temperatures with an inlet flow rate of 1 NL/min to ensure a substantial dissociation of the CO2. Subsequently, combined streams of CO2 and H2O are evolved in the reactor. The effect of the total flow rate, reactants molar ratio and bed height is investigated and from the results, the optimal syngas composition is identified. SEM and XRD are used to assess the morphological evolution and the phase changes of the material during the test. On the contrary, in Chapter 5 the effect of high-pressure operation on the redox abilities of two NiFe aluminates is assessed. The aluminates present similar Fe loadings, but different Ni loadings. High pressure operation is crucial for the development of this technology because it facilitates downstream processing of the syngas to liquid fuels. For a comparative analysis, preliminary tests at low pressure are carried out at three temperatures. Subsequently, the effect of reactants flow rate, temperature, total pressure, gas composition is analysed at high pressure conditions. Finally, long term tests are performed both at ambient and high-pressure conditions. Material characterization by SEM, XRD and H2-TPR is used to support the comparative analysis. In Chapter 6, a techno-economic analysis on a process scheme encompassing methanol and ammonia production from chemical looping gases is carried out. Chemical looping hydrogen production is a very versatile technology and allows for the combined production of power and H2 or syngas. With proper calibration of the flow rates, a stream of high purity N2 can also be obtained at the air reactor outlet and used for ammonia synthesis. Back up with an alkaline electrolyser is considered for the supply of the required amount of hydrogen. Sensitivity analyses are carried out on the chemical looping plant to evaluate the effect of fuel flow rate, steam flow rate, and oxygen carrier inlet temperature to the fuel reactor. Subsequently, a techno-economic analysis is carried out evaluating several parameters among which: the specific CO2 emissions, the energy intensity, and the levelized cost of methanol and ammonia. Finally, a comparison with benchmark technologies and other clean alternatives is presented. In this way, the benefits as well as the drawbacks of chemical looping in terms of environmental and economic parameters are assessed and the missing elements to reach industrial competitivity are clarified

Developments in calcium/chemical looping and metal oxide redox cycles for high-temperature thermochemical energy storage: A review

Energy storage is one of the most critical factors for maximising the availability of renewable energy systems while delivering firm capacity on an as- and when-required basis, thus improving the balance of grid energy. Chemical and calcium looping are two technologies, which are promising from both the point of view of minimising greenhouse gas emissions and because of their suitability for integrating with energy storage. A particularly promising route is to combine these technologies with solar heating, thus minimising the use of fossil fuels during the materials regeneration steps. For chemical looping, the development of mixed oxide carrier systems remains the highest impact research and development goal, and for calcium looping, minimising the decay in CO2 carrying capacity with natural sorbents appears to be the most economical option. In particular, sorbent stabilisers such as those based on Mg are particularly promising. In both cases, energy can be stored thermally as hot solids or chemically as unreacted materials, but there is a need to build suitable pilot plant demonstration units if the technology is to advance

Calcium looping for pulp and paper industry decarbonisation and hydrogen production from biomass and waste

Manovic, Vasilije - Associate SupervisorGlobal CO₂ emissions from fossil fuels have been rising for more than a century. Nevertheless, to meet the ambitious targets set by the Paris Agreement, greenhouse gas emissions must be substantially reduced. The improvement of energy efficiency, implementation of carbon capture and reduction of fossil fuel dependency can play an important role. Of the CO₂ capture technologies, amine scrubbing is the most mature technology; however, calcium looping has shown to be a promising one. Thus, this research aimed to assess the techno-economic feasibility of calcium lopping as a carbon capture technology for combined heat, power and hydrogen production from biomass and/or waste. First, a new concept for the conversion of the pulp and paper industry to carbon-negative that relies on the inherent CO₂ capture capability of the Kraft process was proposed. This concept has shown that a pulp and paper plant can turn from importer to electricity exporter with the cost of CO₂ avoided of 39.0 €/tсо₂ . Second, in the pulp and paper industry, two carbon capture and storage routes were compared, calcium looping retrofitted to the pulp and paper plant and calcium looping coupled with black liquor gasification. The latter was assessed for H₂ production and for electricity generation with a gas turbine combined cycle or solid-oxide fuel cell. The last alternative has shown that the pulp and paper plant can also become a net electricity export asset at the expense of the cost of CO₂ avoided, 50.8 €/tсо₂ . On the contrary, the alternative for H₂ production presented the highest energy penalty but the lowest cost of CO₂ avoided (48.8 €/tсо₂ ). Third, the feasibility of calcium looping for H₂ production and in-situ CO₂ capture was assessed for waste-to-energy conversion in a greenfield scenario. However, this resulted in a significantly higher levelised cost of hydrogen (5.0 €/kgн₂ ) compared to that estimated for conventional gasification (2.7 €/kgн₂ ). Although calcium looping is more cost-efficient for carbon capture in a retrofitted scenario, this technology can become a competitive technology for hydrogen production in a greenfield scenario.PhD in Energy and Powe

Steel converter slag as an oxygen carrier

Thermal conversion of fuels can be used to produce heat and power in addition to chemicals. In order to be aligned with climate targets, it is necessary that such systems do not emit carbon dioxide to the atmosphere. Carbon capture and storage (CCS) can be used together with fuel conversion systems to prevent CO2 from entering the atmosphere. If CCS is used together with biomass-based fuels, it is possible to achieve a net-flow of carbon dioxide out of the atmosphere, so called negative emissions.Chemical looping technologies for combustion (CLC) and gasification (CLG) are technologies which can be used for heat, power and chemical production with no or low penalties for carbon capture. In any chemical looping applications, a functional oxygen carrier is essential. The oxygen carrier is normally a metal oxide based material that can transport oxygen from one reactor to another. However, when fuel is introduced into the system, ash can react with the oxygen carrier and decrease its operational lifespan, especially reactive ash from biomass and low-grade fuels. Therefore, there is growing interest in low-cost oxygen carriers that can contribute to making the process economically feasible. Low-cost oxygen carriers can be obtained from ores or as byproducts of the steel industry. Of particular interest is steel converter slag, which is also known as Linz-Donawitz (LD) slag. LD slag is generated in significant amounts, contains sufficient amount of iron oxide (that can act as an oxygen carrier) and available at a low cost.This work presents a comprehensive overview of the chemistry and behavior of LD slag when it is implemented as an oxygen carrier in chemical-looping applications. The material has been investigated in laboratory reactors, in addition to pilot and semi-industrial units, and LD slags interactions with different fuel components, ash, alkali salts, sulfur and tars have been investigated.It is concluded from this work that LD slag can be viable as material for both CLC and CLG processes with biomass. In contrast to other bed materials, such as silica sand or the commonly investigated iron-based oxygen carrier ilmenite, the slag has limited reactivity with reactive alkali components. This results in more alkali being available in the gas phase, which is beneficial for tar cracking and for the gasification rate of the solid char. The high content of calcium in the LD slag is also favorable in terms of gasification and ash interactions. Calcium oxide catalyzes both the water-gas shift reaction and is catalytic towards tar cracking. A high level of calcium also increases the melting points of both the K-Ca-P and K-Ca-Si matrixes. However, the structural integrity of the material is lower compared to, for example, ilmenite, resulting in more fines being generated during the process. Overall, LD slag is a potential oxygen carrier that is suitable for chemical-looping processes that utilize low-grade fuels

Emerging CO2 capture systems

In 2005, the IPCC SRCCS recognized the large potential for developing and scaling up a wide range of emerging CO2 capture technologies that promised to deliver lower energy penalties and cost. These included new energy conversion technologies such as chemical looping and novel capture systems based on the use of solid sorbents or membrane-based separation systems. In the last 10 years, a substantial body of scientific and technical literature on these topics has been produced from a large number of R&D projects worldwide, trying to demonstrate these concepts at increasing pilot scales, test and model the performance of key components at bench scale, investigate and develop improved functional materials, optimize the full process schemes with a view to a wide range of industrial applications, and to carry out more rigorous cost studies etc. This paper presents a general and critical review of the state of the art of these emerging CO2 capture technologies paying special attention to specific process routes that have undergone a substantial increase in technical readiness level toward the large scales required by any CO2 capture system

Advanced carbon capture and storage technologies

Tesi en cotutela Universitat Politècnica de Catalunya i AGH University of Science and TechnologyIn this work two research topics are presented: investigation of carbonation reactions of high – calcium waste materials and CO2 storage in coal. Firstly, sorption capacity of CO2 and CH4 of hard coal and associated sorption-induced expansion of the material was measured. This investigation was maintained in isothermal and non-isothermal conditions. Experiments were done on purpose-design apparatus allowing simultaneous measurement of sorption kinetics and sorption-induced swelling/contraction of coal. Chosen coal sample had higher sorption capacity for CO2 when compare to capacity for CH4.. Next to CO2 storage, the topic of CO2 utilization has been investigated. Carbonation of European high-calcium fly ashes is assessed. The experiments have been done on different fly ashes with content of 5-36% CaO. Complementary, characterization and analysis of fly ash samples has been performed. Acceleration of carbonation has been explored. Experiments has been done in temperature range between 25 and 290°C, 1-12 bar of CO2, CO2 + H2O and simulated flue gas over reaction times between 2 and 72 hours. Major conclusions of this work is that increasing the temperature and pressure strongly enhances the process of carbonation. Also, addition of water vapor substantially accelerates the process and increase its kinetics. This thesis reports that maintaining the carbonation process without steam addition leads to effective carbonation conversion. Chemical fixation of CO2 molecules with solid material of fly ash with high content of CaO to produce calcium carbonate is possible. The highest sequestration capacity achieved is 117.7 g CO2/kg fly ash and highest carbonation efficiency obtained is 48%. The microstructural analysis of fly ash samples showed the evolution of the cenosphere surface according to the carbonation experiments conditions. Different shapes and sizes of calcium carbonate has been detected after carbonation experiments. The compositional constraints of fly ashes that control reaction with CO2 has been described. It was found that not the bulk content of CaO is the factor controlling the carbonation reaction, but the content of free lime. Impact on carbonation of two pressure flow systems was assessed: batch and continuous flow, with and without addition of steam. Using he batch treatment with addition of steam gave the highest carbonation efficiency. Another set of carbonation experiments which has been done was with using simulated flue gas (84% N2, 15% CO2, 1 % H2O) instead of pure CO2 stream, in conditions: 160°C, 6 bar of gas and 2 hours of reaction time. It was concluded that using flue gas instead of pure stream of carbon dioxide lowers the carbonation rate of about 9%. Final part of this research was to determine the change of free lime content in fly ash samples before and after carbonation. Carbonation reactions lead to substantial decrease of free lime contents in fly ashes. In most cases, the amount of free lime in fly ash after carbonation was compatible with the current EU legislations regarding fly ash incorporation to cement as admixture.En este trabajo se presentan dos temas de investigación: almacenamiento de CO2 en carbón y carbonatación de residuos industriales con un alto contenido en calcio. En primer lugar, se midió la capacidad de sorción de CO2 y CH4 de la hulla y su asociada expansión. Esta investigación se mantuvo en condiciones isotérmicas y no isotérmicas. Los experimentos se realizaron en un aparato diseñado específicamente, el cual permite la medición simultánea de la cinética de sorción y su asociada expansión y contracción. La muestra de carbón elegido tenía una mayor capacidad de absorción de CO2 comparado a CH4. Además, la absorción de CO2 indujo una expansión de volumen en el carbón, duplicando la obtenida tras la absorción de CH4. La cinética de deformación lineal muestra que la expansión del carbón inducida por ambos gases es anisotrópica, y es mayor en la dirección perpendicular al plano de estratificación que en paralelo a este. El análisis dilatométrico hace referencia a la deformación del material en presencia de CH4 es casi dos veces más baja que la obtenida en presencia de CO2, en el mismo rango de presión. El aumento de temperatura da como resultado una expansión adicional del carbón cuando se expone a CH4. La absorción de CO2 en el carbón en condiciones iso-térmicas conduce a la contracción de la muestra. Esto podría estar asociado con la composición petrográfica del carbón. Los datos obtenidos de la cinética de absorción y expansión de carbón se ajustaron en una ecuación cinética. El modelo utilizado fue: ‘Ecuación Exponencial Estirada’. El modelado de la cinética de absorción y expansión es importante para determinar la respuesta del carbón como posible almacenamiento de gas y permite predecir los cambios en la absorción-transporte de carbón. Junto al almacenamiento de CO2, la utilización de este también ha sido investigado. Se evalúa la carbonatación de las cenizas volante de origen europeo con alto contenido en calcio. Los experimentos se han realizado en diferentes cenizas volantes con un contenido entre 5-36% de CaO. Un estudio detallado de la carbonatación acelerada de las cenizas volantes has sido llevado a cabo Los experimentos se han realizado en un rango de temperatura entre 25 y 290°C, 1 - 12 bares de CO2, CO2 + H2O y gases de combustión simulados durante tiempos de reacción entre 2 y 72 horas. La principal conclusión de este trabajo es: el aumento de temperatura, presión y la adición de vapor de agua acelera considerablemente el proceso de carbonatación en estos materiales. Evidencias experimentales sugieren que una carbonatación efectiva se puede obtener sin la adición de vapor de agua. La mayor capacidad de CO2 secuestrado es de 117.7 g CO2/kg de cenizas volantes y la mayor eficiencia de carbonatación obtenida equivale a 48%. El análisis microestructural de las cenizas volantes mostró una evolución de la superficie de la cenosferas según las condiciones de los experimentos de carbonatación. Se han detectado diferentes formas y tamaños de carbonato de calcio después de los experimentos de carbonatación Se han descrito las restricciones referidas a la composición de las cenizas volantes que controlan su reacción con CO2. Se encontró que el factor dominante que controla la reacción de carbonatación es el contenido mineralógico de cal libre, en lugar del contenido total de CaO. Se evaluó el impacto en la carbonatación de dos sistemas presurizados: batch y flujo continuo, con y sin adición de vapor. Las reacciones llevadas a cabo en sistemas tipo batch con la adición de vapor produjeron la mayor eficiencia de carbonatación. Otra serie de experimentos de carbonatación realizados consistieron en el uso de gas de combustión simulado (84% N2, 15% CO2, 1% H2O) en lugar de CO2 puro. Las condiciones experimentales fueron: 160°C, 6 bares de presión total y 2 horas de tiempo de reacción. Se concluyó que el uso de gas de combustión en lugar de dióxido de carbono puro reduce la tasa de carbonatación de aproximadamente el 9%. Finalizando, el contenido de cal libre ha sido determinado para cada muestra antes y después de las reacciones de carbonatación en una variedad de cenizas volantes. Las reacciones de carbonatación produjeron una disminución sustancial del contenido de cal libre en las cenizas volantes. En la mayoría de los casos, el contenido de cal libre después de la carbonatación fue compatible con las legislaciones actuales de la UE con respecto a la incorporación de cenizas volantes al cemento como aditivo.W niniejszej przedstawiono dwa tematy badawcze: badanie reakcji karbonatyzacji odpadów wysoko wapniowych i składowania CO2 w węglu. W pierwszej części badawczej dokonano analizy pojemności sorpcyjnej CO2 i CH4 węgla kamiennego oraz zmiany wolumetryczne węgla spowodowane procesem sorpcji. Eksperymenty prowadzono w warunkach izotermicznych i nieizotermicznych. Do pomiarów użyto specjalistycznego aparatu do jednoczesnego pomiaru sorpcji oraz ekspansji próbek wywołanej sorpcją. Wybrana próbka węgla charakteryzowała się większą pojemnością sorpcyjną dla CO2 niż dla CH4. Odkształcenia próbki węgla spowodowane sorpcją CO2 były dwa razy większe niż odkształcenia próbki wzbudzone sorpcją metanu. Ekspansja próbki jest anizotropowa w wyniku sorpcji obu gazów i większa w kierunku prostopadłym niż równoległym. Analiza dylatometryczna wskazuje, że ekspansja węgla w obecności CH4 jest prawie dwukrotnie mniejsza niż ekspasnsja węgla podczas sorpcji CO2, w tym samym zakresie ciśnień. Prowadzenie eksperymentów sorpcji w warunkach nieizotermicznych powoduje dodatkową ekspansję węgla podczaj reakcji z CH4. Sorpcja CO2 na węglu w tych warunkach prowadzi do kontrakcji próbki. Przedstawione różnice wolumetryczne mogą być związane ze składem petrograficznym węgla. Dane kinetyk sorpcji i rozszerzalności próbki węgla kamiennego zostały dopasowane do równania kinetycznego. Zastosowanym modelem było równanie ’Stretched Exponential Equation’. Modelowanie kinetyki sorpcji i rozszerzalności węgla jest ważne w celu określenia potencjalu zmagazynowania CO2 w węglu oraz pozwala przewidzieć zmiany wolumetryczne pokładów węglowych. W drugiej części niniejszej pracy zbadano temat utylizacji ditlenku węgla. Przedstawiono oraz zbadano temat karbonatyzacji europejskich popiołów lotnych o wysokiej zawartościści tlenku wapnia. Doświadczenia przeprowadzono na różnych popiołach lotnych o całkowitej zawartości CaO w przedziale 5-36%. Dokonano również charakteryzacji oraz analizy wybranych próbek popiołów lotnych. Przeprowadzono próby akceleracji kinetyki procesu karbonatyzacji. Eksperymenty wykonano w zakresie temperatur od 25 do 290°C, ciśnienia 1-12 barów CO2, CO2 + H2O lub mieszaniny gazów. Czas reakcji eskerymentów mieścił się w przedziale 2 a 72 godzin. Podwyższenie temperatury oraz ciśnienia CO2 zwiększa konwersję gazu i CaO do węglanu wapnia. Ponadto, dodanie pary wodnej do strumienia CO2 przyśpiesza proces karbonatyzacji. Uzyskane wyniki eskerymentów pozwalają wnioskować, że karbonatyzacja w warunkach gaz – ciało stałe, bez dostępu wody jest możliwa do przeprowadzenia. Opisane warunki doświadczeń pozwoliły na interakcję cząsteczek CO2 z tlenkiem wapnia zawartym w popiele lotnym i wytworzenie kalcytu. Najwyższa uzyskana pojemność sekwestracyjna CO2 wyniosła 117,7 g CO2/kg popiołu lotnego, a najwyższa uzyskana wydajność karbonatyzacji wyniosła 48%. Analiza mikrostrukturalna próbek popiołów lotnych ukazała ewolucję powierzchni cenosfer podczas zmieniających się warunków eskerymentalnych procesu karbonatyzacji. Podczas analizy próbek popiołu po karbonatyzacji wykryto w materiale różne kształty i rozmiary węglanu wapnia. Zdeterminowano wpływ składu chemicznego popiołów lotnych na reakcję z ditlenkiem węgla. Stwierdzono, że zawartość wolnego wapna jest czynnikiem kontrolującym reakcję, a nie całkowita zawartość CaO. Oceniono wpływ na reakcję karbonatyzacji dwóch układów przepływu ciśnieniowego: reaktor zamknięty oraz reaktor z ciągłym przepływem gazu, z dodatkiem pary wodnej lub bez. Zastosowanie reaktora zamkniętego z dodatkiem pary dało najwyższą wydajność karbonatyzacji. W finalnej partii eskerymentów karbonatyzacji użyto symulowanego gazu spalinowego (84% N2, 15% CO2, 1% H2O) zamiast czystego strumienia CO2, w warunkach: 160°C, 6 barów ciśnienia i 2 godzin czasu reakcji. Stwierdzono, że stosowanie gazu spalinowego zamiast czystego strumienia dwutlenku węgla obniża wydajność karbonatyzacji o około 9%. Końcową częścią badań procesu karbonatyzacji było określenie zmiany zawartości wolnego wapna w próbkach popiołu lotnego przed i po nasyceniu ditlenkiem węgla. Reakcje karbonatyzacji prowadzą do znacznego zmniejszenia zawartości wolnego wapna w popiele lotnym. W większości przypadków ilość wolnego wapna w popiele lotnym po nasycaniu ditlenkiem węgla była zgodna z obowiązującymi przepisami UE dotyczącymi utylizacji popiołów lotnych w cemencie, jako domieszki.Postprint (published version