Oxygen Carrier Particles Research Articles

Experimental Evaluation Using Plastic Waste, Paper Waste, and Coal as Fuel in a Chemical Looping Combustion Batch Reactor

AbstractA comparative study of chemical looping combustion (CLC) with paper, plastic, and coal as fuel was carried out. Experiments were performed in a laboratory fluidized‐bed reactor by alternating between reduction and oxidation cycles. The results obtained indicated that a higher temperature leads to an increase in the CO2 yield and carbon conversion for all fuels. Paper had the highest fractional conversion of CO to CO2 followed by polyvinyl chloride (PVC) and coal. This was due to the higher fraction of volatiles in paper compared to PVC and coal. Scanning electron microscopy (SEM) analysis of the oxygen carrier particle after each of the solid fuel experiment was carried out. For the used ilmenite, there was a slight difference in the morphology for the three different fuels.

Perovskite-type LaMn1−xBxO3+δ (B = Fe, CO and Ni) as oxygen carriers for chemical looping steam methane reforming

• The doping of Fe, Co and Ni added surface active sites for methane activation. • The introduction of Fe, Co and Ni in LaMnO 3+δ accelerated migration of oxygen ion. • Fe, Co and Ni doped LaMnO 3+δ possessed higher yield of syngas and hydrogen. Chemical looping steam methane reforming (CLSMR) is capable of accomplishing both methane reforming and hydrogen generation, and the oxygen carrier is a key issue for CLSMR. In this work, LaMn 1−x B x O 3+δ (B = Fe, Co and Ni, x = 0.1, 0.2 and 0.3) perovskites were investigated as oxygen carriers for CLSMR in a fixed bed system. The test results showed that the doping of Fe, Co and Ni improved the oxygen release rate of LaMnO 3+δ and the improvement effect was in accordance with the order of Ni > Co > Fe, since the activation of methane molecule on the surface and the conduction of oxygen ion in the bulk of oxygen carrier particles were accelerated due to the evolution of perovskite structure, the addition of surface active sites and the formation of oxygen vacancies. The substitution of Fe, Co and Ni also increased the oxygen release amount, the CO selectivity and the hydrogen yield. No carbon formed on LaMnO 3+δ and LaMn 1−x Fe x O 3+δ in single tests and carbon deposition did not occur on LaMnO 3+δ , LaMn 0.7 Fe 0.3 O 3+δ and LaMn 0.8 Co 0.2 O 3+δ in the cyclic tests with short reduction stage, leading to the generation of high-quality syngas with the H 2 /CO ratio of 2 and pure hydrogen. Carbon deposition appeared on the LaMn 0.9 Ni 0.1 O 3+δ oxygen carrier in the cyclic tests due to the separation of part of Ni out of the perovskite structure. Considering the oxygen release rate, the yield of syngas and hydrogen as well as carbon deposition, it is deduced that LaMn 0.7 Fe 0.3 O 3+δ and LaMn 0.8 Co 0.2 O 3+δ could be used as desirable oxygen carriers for cyclic CLSMR.

Numerical Analyses of Heterogeneous CLC Reaction and Transport Processes in Large Oxygen Carrier Particles

Heterogeneous chemical looping combustion (CLC) reactions and conjugate transports in large oxygen carrier particles were numerically investigated with computational fluid dynamics (CFD) approaches, in which a simplified noncatalytic reaction model was implemented for reducing intraparticle modelling computation. Volumic gas-solid reactions were treated as surface reactions based on the equivalent internal surface in the particle model. In large porous particles such as fixed bed CLC reactors, the heterogeneous reactions are often limited by intraparticle diffusion. Comprehensive analyses were conducted on transports across the particle surface and their influences on reactions inside the single particles. A threshold Reynolds number of external convections was found for the enhancement of intraparticle reactions. The heterogeneous reactions, intraparticle diffusions and interstitial transports in a fixed bed CLC reactor randomly packed with 597 spheres were thoroughly analysed with the same numerical approaches. Comprehensive insights of the temporal evolution and spatial distribution of scalars in the packed bed reactor were presented.

Experimental Investigation of Oxygen Carrier Aided Combustion (OCAC) with Methane and PSA Off-Gas

Oxygen carrier aided combustion (OCAC) is utilized to promote the combustion of relatively stable fuels already in the dense bed of bubbling fluidized beds by adding a new mechanism of fuel conversion, i.e., direct gas–solid reaction between the metal oxide and the fuel. Methane and a fuel gas mixture (PSA off-gas) consisting of H2, CH4 and CO were used as fuel. Two oxygen carrier bed materials—ilmenite and synthetic particles of calcium manganate—were investigated and compared to silica sand, an in this context inert bed material. The results with methane show that the fuel conversion is significantly higher inside the bed when using oxygen carrier particles, where the calcium manganate material displayed the highest conversion. In total, 99.3–99.7% of the methane was converted at 900 °C with ilmenite and calcium manganate as a bed material at the measurement point 9 cm above the distribution plate, whereas the bed with sand resulted in a gas conversion of 86.7%. Operation with PSA off-gas as fuel showed an overall high gas conversion at moderate temperatures (600–750 °C) and only minor differences were observed for the different bed materials. NO emissions were generally low, apart from the cases where a significant part of the fuel conversion took place above the bed, essentially causing flame combustion. The NO concentration was low in the bed with both fuels and especially low with PSA off-gas as fuel. No more than 11 ppm was detected at any height in the reactor, with any of the bed materials, in the bed temperature range of 700–750 °C.

A multi-scale simulation of syngas combustion reactions by Ni-based oxygen carriers for chemical looping combustion

Density functional theory (DFT) calculations of syngas combustion with the Ni-based oxygen carriers were conducted to reveal new insights on the elementary reaction mechanisms. For the first time, the reaction mechanism of syngas combustion using NiO was revealed. The CO oxidation was proposed as a 1-step reaction, while the H2 oxidation was proposed as a 3-step reaction. Among all the reactions, H2 decomposition was proved to be the controlling step that dominated the overall syngas combustion process. A DFT-based mean-field (MF) model was established to investigate the impacts of the operating conditions on the oxygen carrier (OC) behaviors inside the channel of OC particles. The results show that a high ratio of H2 and a high temperature benefit OC conversion. Also, the increase in pressure resulted in the reduction of the OC conversion ratio. The predicted outcomes from the MF model are in agreement with experimental observations, which further validated the proposed reaction mechanism from DFT analysis. Furthermore, results from the MF model show that high temperatures and low pressures lead to high CO2/H2O product ratios. This computational study illustrates the key factors that affect the performance of this process at the atomistic scale and inside the channel of OC particles.

Chemical looping combustion with nanosize oxygen carrier: a review

This paper reports latest advancement on oxygen carriers (OCs) and effect of particle size from micro- to nanoscale in chemical looping combustion (CLC). CLC is basically a carbon capture and storage technology with the objective to reduce carbon dioxide emission from fossil fuel-based power plants, and it has the potential to reduce the global warming. Attention has been drawn toward utilization of nanosize-based oxygen carrier for bulk application. CLC is a novel technology for combustion of fossil fuels that avoids dilution of carbon dioxide (CO2) with flue gases. Performance of CLC system depends upon redox reactivity and stability of oxygen carrier particles at high operating temperature. Oxides of metals like nickel, iron, copper, and mixed metals have also been discussed. Tendency of discussed nano-OC to agglomerate and stability at high temperature can be addressed by the use of suitable inert support materials. Reactivity of oxygen carrier increases with decreasing particle sizes from micro- to nanosize. Recent developments in nanosized oxygen carriers can be exploited for application. The challenges associated with nanosize oxygen carriers are stabilization and agglomeration at temperature above 600 °C. Different techniques have been proposed and investigated to overcome challenges. Various metal/metal oxide pair has been evaluated for its oxygen bearing capacity, stability, and resistance to agglomeration. Stability and agglomeration of nanosize oxygen carrier at temperature above 700 °C is an open issue.

Numerical simulation of a chemical looping combustion of biomass: Hydrodynamic investigation

In the present work, the multi-phase particle-in-cell (MP-PIC) method, implemented in OpenFOAM, is used to simulate a biomass-fueled chemical looping combustion (CLC) process in a circulation mode. Hydrodynamics of the gas-particle flow are analyzed, mainly, through pressure drop along the reactor, solid volume fraction distribution, the solid circulation between the two connected reactors, and gas and solid fuel leakages. Preliminary simulations agree well with the experimental data reported in the literature. Additional simulations using various fluidization rates into both the fuel and air reactors and different solid inventories are then performed. Results show the relevance of the pressure balance between the reactors to decreasing the gas leakage. Increasing the solid mass in the system has a favorable impact on preventing gas mixing but it allows solid fuel particles to leak to the air reactor. This is due to the increase of the solid circulation between the reactors, thus causing biomass particles' entrainment by the oxygen carrier particles. Simulation results also reveal the higher impact of the air reactor fluidization rate on the solid circulation, with respect to that of the fuel reactor fluidization rate.

Effect of calcination/carbonation and oxidation/reduction on attrition of binary solid species in sorption-enhanced chemical looping reforming

The effects of chemical reactions on the attrition of oxygen carrier particles and CO2 sorbent based on a chemical looping reforming (CLR) process with intrinsic CO2 capture were analyzed. Iron/hematite as an oxygen carrier, and limestone/lime as a CO2 sorbent were tested in a jet attrition apparatus. Attrition tests were conducted with particles of a single species and with binary solid mixtures, for different temperatures, different gas species and ranges of gas concentrations, varied to the reactions. Material properties were measured to investigate how the chemical conversion of particle species affects the attrition in both single-species, and two-species environments. Iron oxidation decreased the particle crushing strength, forming a porous iron oxide layer on the surface. When hematite was reduced with CH4, the proportions of reduced iron oxides increased the intrinsic crushing strength on the surface. For limestone, calcination increased the attrition due to a decrease in the intrinsic particle crushing strength. Lime carbonation reduced attrition because of increasing ductility and sintering, as well as the formation of a limestone surface layer of carbonate. Particle attrition increased when two solid species were mixed together, due to the increasing frequency of inter-particle collisions.

A novel air reactor concept for chemical looping combustion systems operated at high pressure

We analyse the viability of a novel reactor concept for chemical looping combustion applications with CO2 capture. The reactor consists of a packed bed of reduced oxygen carrier particles traversed by a series of empty conducts oriented in the axial direction. These conducts are made of permeable but non-selective porous walls, through which air diffuses towards the region of reacting solids. The diffusion flux of air through the orifices, which is perpendicular to the main bulk flow of gas along the conducts, imposes very long oxidation times for all the reacting particles and a quasi-steady heating up of the air flow. The conducts designed to have a very high length/diameter ratio (i.e. above 50) allow a large bypass of pressurized air through the reactor without coming into direct contact with the solids, resulting in a modest pressure drop of the gas (i.e. below 5% at the reactor exit). A preliminary reactor design example is described for a case using Fe/Fe2O3 pellets as oxygen carrier, which are packed into a reactor (L = 100 m, I.D. = 2 m) traversed by air conducts (I.D. = 0.05 m) with a wall 2 mm thick and orifices occupying an area fraction of 0.12. The reactor can initially generate 100 MWth, with a gas flow at the exit at close to 1050 °C and 19 atm, and it could be used intermittently for more than 9 h as the main heater in a highly efficient Brayton cycle.

Techno-economic analysis of H2 production processes using fluidized bed heat exchangers with steam reforming – Part 1: Oxygen carrier aided combustion

This work presents the techno-economic assessment for a new process where a fluidized bed heat exchanger (FBHE) is used as heat source for steam reforming in a hydrogen production plant. This suggested process configuration is compared with a reference case representing a conventional steam methane reforming (SMR) large-scale hydrogen production plant. The use of a FBHE as a heat source for the endothermic reforming is an advantage because of the high heat transfer coefficient to the reformer tubes. The suggested process configuration utilizes oxygen carrier particles as bed material and a bubbling fluidized bed reactor with immersed reformer tubes to ensure sufficient heat production for the reforming and improved heat transfer to the reformer tubes compared a conventional plant. The results include a comparison of hydrogen production efficiency and levelized production costs (LCOH) of the two plants where the production efficiency is more than 11% higher and the LCOH is more than 7% lower for the suggested process configuration.

Ce-Fe-Zr-O/MgO coated monolithic oxygen carriers for chemical looping reforming of methane to co-produce syngas and H2

Chemical looping steam methane reforming (CL-SMR) is a promising technology for co-producing syngas and pure hydrogen without additional purification processes. As a typical gas-solid reaction, the size and geometry of oxygen carriers strongly influence the dynamic conditions of this process, especially for large-scale application. In the present work, we prepared the monolithic oxygen carrier using Ce-Fe-Zr-O(40 wt%)/MgO as active component and cordieritehoneycomb as structural support by a slurry coating method, and their activity for CL-SMR were compared with the pellet ones. The monolithic oxygen carrier shows higher activity for both methane oxidation and water splitting than pellet oxygen carriers, which results in much higher CH4 conversion (63.2% vs. 52.9%) and yields of syngas (2.85 mol·kg−1) and hydrogen (1.14 mol·kg−1). The honeycomb also enhances the resistance to carbon deposition during methane selective oxidation, which helps to prolong the running cycle of CL-SMR and improve the purity of produced H2. The comparison on the morphology of the cross section of the fresh and cycled monolithic oxygen carriers indicates that the oxygen carrier particles on the inner-surface of honeycomb channels are very stable during the long-term cycling. These results highlight the significance of designing a high-performance oxygen carrier by using a honeycomb support.

Chemical behavior of fluorine and phosphorus in chemical looping gasification using phosphogypsum as an oxygen carrier

In China, the amount of phosphogypsum (PG) has exceeded 250 million tons with more than 55 million tons of growth rates each year. As the micro constituent, fluorine and phosphorus restrict the resourceful disposal of PG. This paper focused on chemical looping gasification (CLG) which used PG as an oxygen carrier, systematically investigated the gasification performance and chemical behavior of fluorine and phosphorus contained in PG during CLG process. Main conclusions are as follows. The main pollutant of chemical looping gasification process was HF, which was transformed from NaF. Phosphorus transformed from water-soluble phosphorus (Ca(H2PO4)2, Ca(HPO4)) into insoluble Ca3(PO4)2.20 reducing-oxidizing cycles were investigated, and a less and less fluorine content in oxygen carrier was found because its phase transformation from solid NaF to gaseous HF, and the phosphorus content in oxygen carrier changed slightly under the current conditions. The Ca3(PO4)2 particle layers existed in both the middle of the reduced solid particles and the middle of the cycled oxygen carrier particles, confirmed to actually act as a glue between the particles. Furthermore, transformation routes of fluorine and phosphorus during the CLG process were discussed and the generation of syngas in CLG process needed to be purified.

Impact of fuel-derived chlorine on CuO-based oxygen carriers for chemical looping with oxygen uncoupling

During the chemical looping with oxygen uncoupling (CLOU) process for CO2 capture from solid fuels, CuO-based oxygen carriers are expected to efficiently transport oxygen from the air reactor and convert fuel in the fuel reactor by releasing gaseous oxygen. To maintain high fuel conversion and CO2 capture efficiency, it is important to understand the impact of the fuel-derived Cl, which is highly volatile and corrosive, on the CuO/Cu2O in a CLOU environment. In this work, thermodynamic modeling was carried out to predict the characteristics of Cu-Cl interaction and develop a Cu deactivation rate model. Combustion experiments were performed to examine the impact of the Cl-containing flue gas on the CuO-based oxygen carrier. The oxygen transport capacities of the oxygen carriers exposed to the Cl-containing flue gas were measured by TGA. XRD and SEM-EDS were employed to characterize the ashes and oxygen carrier particles, respectively. The modeling results suggest that Cu-Cl interaction leads to the formation of CuCl and Cu3Cl3, causing the loss of effective Cu. The fraction of HCl converted to CuCl/Cu3Cl3 (XHCl) was predicted to be almost linearly correlated with the Cl content, while H2O could hinder the Cu-Cl interaction. The Cu deactivation rate model was successfully developed. For the fuels containing 0.2–0.4 wt% Cl, the Cu loss rate was estimated to be 0.0025–0.01%/cycle with XHCl = 0.12–0.24. The results of combustion experiments and material characterization were consistent with the modeling predictions, clearly demonstrating the Cl-induced deactivation. Given the modeling predictions and experimental findings, potential countermeasures were proposed.

Oxygen transfer capacity of the copper component introduced into the defected-MgMnAlO4 spinel structure in CH4-CO2/air redox cycles

Oxygen carrier particles were fabricated by using defected-MgMnAlO4 as a support particle with crystal defects, and by the Cu2+ ions with a higher reduction potential substituted with Mg2+ ions, in order to use methane-chemical looping combustion (CH4-CLC) reaction. The oxygen transfer capacities of the particles were compared when conducting redox reactions under H2/air or CH4-CO2/air systems. As a result, the oxygen transfer capacity increased as the amount of Cu ions added increased. In particular, in the CH4-CO2/air system, Cu0.75Mg0.25MnAlO4 particle showed an excellent oxygen transfer capacity of 7.62%. The XPS result confirms that the Cu2+ (also partially Mn3+ ions) in the Cu0.75Mg0.25MnAlO4 particle oxidize CH4, and then they are restored to their original state by receiving oxygen from the Al3+ and Mg2+ ions in the support. The oxygen vacancies in the lattice due to the Cu2+ could easily induce oxygen delivery, and the reversible oxygen loss recovery by re-oxidation in the air reactor could be achieved. This is the most important factor in increasing oxygen transfer capacity. Ultimately, in this study, oxygen defects in the crystal lattices induced during the reaction seem to have a positive effect on the CH4 combustion reaction.

Dynamic modelling and optimal control strategies for chemical-looping combustion in an industrial-scale packed bed reactor

The transient operation of a Chemical-looping Combustion (CLC) process in a large-scale packed bed reactor (PBR) unit is presented in this study. This work adapts 1-D heterogeneous dynamic model that considers mass and heat transport resistances in the oxygen carrier particle and the bulk fluid phase. The proposed industrial-scale model was compared using data available in the open literature and was used to study optimal control strategies that can increase power production and reduce fuel slip during the oxidation and reduction stages of this process, respectively. Moreover, promising (optimistic) and pessimistic (worst-case) scenarios were considered for this process and used to demonstrate the operational flexibility of the packed bed reactor under different process operating conditions. Results from these scenarios show an extensive recovery heat process and a near full methane conversion into CO2 and H2O during the oxidation and reduction stages, respectively. Similarly, the purge stages were performed relatively fast using low amounts of purge gas. Therefore, the present study bolsters the importance of the CLC PBR process as an attractive carbon capture and sequestration (CCS) technology that can potentially reduce the energy penalty often entailed in CO2 capture and sequestration.

Numerical study of gas-solid flow behaviors in the air reactor of coal-direct chemical looping combustion with Geldart D particles

Chemical Looping Combustion (CLC) is a promising clean combustion technology alternative to conventional oxy-combustion because of its technical feasibility to achieve intrinsic separation of CO2. In a typical Coal-Direct Chemical Looping (CDCL) process, iron-based oxygen carriers belonging to Geldart D particles are used. Such system has been seldom studied. In this work, a two-fluid model (TFM) is adopted for describing the gas-solid flows in a bottom-enlarged air reactor of CDCL process. The model is qualitatively and quantitatively validated. The simulation results indicate that the oxygen carrier particles show a slugging flow pattern in the bottom section of the air reactor, an anti-core-annulus structure in the riser and a periodic fluctuation in the whole air reactor. Besides, the effects of several variables on the gas-solid flow in CDCL air reactor are also studied including gas velocity, specularity coefficient and different drag models. The simulation results indicate that the higher gas inlet velocity can increase the pressure drop over the air reactor and show a significant influence on solid allocation in the bottom section and the riser. Specularity coefficient of zero and Syamlal-O’Brien drag model give the closest mass flow rate by comparing with experimental values, indicating that they are suitable for the three-dimensional air reactor modelling. This model provides a cost-effective tool for better understanding of gas-solid flows in the air reactor of CDCL systems.

The melting characteristics of Vietnamese ilmenite and manganese ores used in chemical looping combustion

For chemical looping combustion (CLC) of solid fuel such as coal, char gasification kinetics is relatively slow and is the rate controlling step, so a high temperature is needed in order to enhance char conversion. However, the maximum allowable temperature in CLC depends on the property of oxygen carrier, and the melting state of the oxygen carrier is the upper limited temperature of the CLC reactors. Therefore, it is necessary to investigate the melting behaviors of oxygen carriers. In this work, a melting test setup with an optical camera-image system was used to experimentally study the melting characteristics of one vietnamese ilmenite and 7 kinds of manganese ores at inert and reducing condition. In inert atmosphere, the prototype temperature and flowing temperature are 1402℃ and 1500℃ for the oxidized ilmenite respectively, while reducing atmosphere can significantly decrease the melting temperatures of the oxygen carrier particles, the prototype temperature and flowing temperature of ilmenite in reducing atmosphere are decreased to 1337℃ and 1403℃, respectively. An important finding is that the melting temperatures of oxidized manganese ores are significantly lower than that of the oxidized ilmenite. Different manganese ores have different melting temperatures, and for some manganese ores, the prototype temperature can decrease to less than 1000℃. It was also found that the melting behaviors between the ilmenite and manganese ores have large differences. When heated up to the deformation temperature, the ilmenite melted rapidly within 8 °C–29 °C, whereas manganese ores melting had a wide temperature range from 38℃-301℃. It can be concluded that the maximum operational temperature of CLC reactors should be less than the prototype temperature of oxygen carrier particles in the actual environment. The operational temperature of CLC reactors when using ilmenite can be higher than that of using manganese ores as oxygen carriers. However, for manganese ores, it could be dangerous for fuel reactor when the operational temperature is higher than 950℃.

Combined manganese oxides as oxygen carriers for biomass combustion — Ash interactions

Carbon capture and storage (CCS) has been acknowledged as an important strategy for mitigation of climate change. Although highly applicable for fossil fuels, CCS with biomass could have the added advantage of resulting in negative emissions of carbon dioxide. One promising carbon capture technology is chemical-looping combustion (CLC). In CLC the reactors are filled with metal oxide bed material called oxygen carriers. Before CLC can be implemented for biomass combustion at a large scale, biomass ash components interaction with oxygen carriers needs to be further understood.Four combined manganese oxides Mn3O4-SiO2, Mn3O4-SiO2-TiO2, Mn3O4-Fe2O3 and Mn3O4-Fe2O3-Al2O3 were exposed to common biomass ash components K, Ca and P. The ash components can exist in many forms, but here the compounds CaCO3, K2CO3 and CaHPO4 were used. Exposures were performed at 900°C for six hours in oxidising, reducing and inert conditions. Crystalline phases were analysed by XRD and morphology examined with SEM-EDX.Results show that oxygen carrier particles containing silicon were more likely to form agglomerates, especially in combination with potassium, whereas the particles including iron were more stable. MnFeAl was the oxygen carrier that showed least agglomerating behaviour while simultaneously showing a propensity to absorb some ash components.Some inconsistencies between thermodynamic predictions and experimental results is observed. This may be explained by lack of relevant data in the used databases, were only a few of the oxygen carrier-ash systems and subsystems have been optimised. Further optimisation related to manganese rich systems should be performed to obtain reliable results.

Evaluation of calcined copper slag as an oxygen carrier for chemical looping gasification of sewage sludge

Chemical looping gasification (CLG) of sewage sludge (SS) using calcined copper slag as an oxygen carrier (OC) represents a novel approach for achieving the comprehensive use of two wastes (SS and copper slag), where the SS is converted into syngas through the oxidation of calcined copper slag. The effect of the calcined temperature on the reactivity of copper slag was first studied. The results show that the copper slag calcined at 1100 °C (1100CS) exhibits excellent performance for SS gasification. Using 1100CS as an OC, the effect of the mass ratio of OC and SS (OC/SS), steam content, oxygen source and cycle number on the SS CLG were investigated in detail in a fixed bed reactor. OC/SS and steam content are determined at 5 and 33.33% for obtaining a relatively high carbon conversion and an acceptable energy recovery during the SS CLG, respectively. The 1100CS is similar to steam, which can provide an oxygen source for SS conversion, and it can catalyze the cracking of tar. The conversion of SS undergoes a slight increase with the cycle number due to the prolongation of the gas-solid mean residence time (Rt) and the deposition of alkali or alkaline earth metals on the surface of the OC particles. Phosphorus eventually appears in the form of water-soluble phosphate during the SS CLG, benefiting its recovery. Thus, CLG with 1100CS as an OC is one of good option for sludge treatment.

Experimental Investigation on Mixing and Segregation Behavior of Oxygen Carrier and Biomass Particle in Fluidized Bed

In this work, lab-scale cold fluidization equipment is designed and constructed to investigate the mixing and segregating phenomena of binary fluidized beds. The focus of the investigation is carbon reduction with the fluidized bed technology-based Chemical Looping Combustion (CLC). Nowadays, aspiration to carbon reduction focuses on the solid fuels. Therefore, it is of great importance to integrate the benefits of CLC technology with the use of solid fuels. The measurements of fuel particles in the fluidized bed are extended from the homogeneous and spherical shape to the inhomogeneous, non-spherical shape. During the tests, an iron-based oxygen carrier (OC) for chemical looping combustors is examined with different particle sizes. In addition, the tests included the examination of three different fuel samples (crushed coal, agricultural pellet, and Solid Recovered Fuel (SRF)), which can be utilized in chemical looping combustion with In-situ gasification. The experiments are carried out using the bed-frozen method. With this method, the vertical concentration of active particles could be measured. The results show that the particle size of the oxygen carrier does fundamentally influence its vertical placement, and the non-spherical character of most alternative fuels must also be considered for optimal reactor design.