Ilmenite as alternative bed material for the combustion of coal and biomass blends in a fluidised bed combustor to improve combustion performance and reduce agglomeration tendency

Garcia, Eduardo; Liu, Hao

doi:10.1016/j.energy.2021.121913

Cited by 31 publications

(5 citation statements)

References 55 publications

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“…The experiments in a field test environment confirmed a CO reduction of up to 75% during a steady-state operation with wood pellets. Recent experiments conducted by Hughes et al [6,16] and Garcia et al [17] confirmed the CO reduction potential using ilmenite as bed material for biomass-based fluidized bed combustion. Additionally, steadystate laboratory tests with methane demonstrated the local shift of oxygen within the BFB as well as an increased gaseous fuel conversion directly in the fluidized bed [18].…”

Section: Introductionmentioning

confidence: 90%

Effect of Natural Ilmenite on the Solid Biomass Conversion of Inhomogeneous Fuels in Small-Scale Bubbling Fluidized Beds

2022

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The application of oxygen carriers as alternative bed material in fluidized bed combustion originates from chemical lopping processes. They serve as oxygen transport agents undergoing consecutive redox cycles. Thereby, oxygen carriers can provide surplus oxygen in oxygen-lean areas of fluidized bed combustion processes. In turn, re-oxidation takes place in oxygen-rich reactor parts. A more homogeneous combustion and reduced CO emissions follow during steady-state operation. However, especially regarding solid biomass conversion, inhomogeneous fuel qualities result in transient combustion conditions. Therefore, this research deals with the influence of the oxygen carrier ilmenite on solid biomass conversion. Separated batch experiments with methane (volatile), char and wood pellets took place in a laboratory bubbling fluidized bed reactor. They reveal that ilmenite enhances the in-bed CO2 yield by up to 63% during methane combustion. Batch char experiments confirm that solid–solid reactions with ilmenite are negligible. However, heterogeneous gas–solid reactions reduce the O2 partial pressure and limit the char conversion rate. The batch wood pellet experiments show that the ilmenite oxygen buffering effect is mitigated due to high local oxygen demand around the pellets and limited pellet distribution in the bed. Finally, the continuous operation in a 100 kWth BFB with inhomogeneous fuel input indicates a higher in-bed fuel conversion and confirms lower CO emissions and less fluctuation in the flue gas during inhomogeneous fuel supply.

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Section: Introductionmentioning

confidence: 90%

Effect of Natural Ilmenite on the Solid Biomass Conversion of Inhomogeneous Fuels in Small-Scale Bubbling Fluidized Beds

2022

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“…6 d and 9 b indicate that the simultaneous application of ilmenite and silica sand particles in a fluidized bed combustor can help improve the bed material agglomeration resistance. Experimental findings indicated that considerably lower and smaller agglomerates were observed in a bubbling fluidized bed combustor of coal blended with wheat straw pellets when ilmenite was adopted as the bed material compared to silica sand [ 62 ].…”

Section: Resultsmentioning

confidence: 99%

A generalized analytical energy balance model for evaluating agglomeration from a binary collision of wet particles

Shabanian,

Duchesne,

Syamlal

et al. 2024

Heliyon

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“…Therefore, the higher observed reactivity between the Fe 2 O 3 particles and the released VM might be caused by Fe 2 O 3 reacting with the combustible gases directly, whereas reactions with CuO were slower because of the competing process of oxygen uncoupling, possible locally when CuO particles were in the vicinity of combustible gases and the homogeneous combustion of CO and O 2 was slow (i.e., at 1023 K). Despite not releasing gaseous O 2 in the whole volume of the bed, the presence of non-CLOU OCs (here, Fe 2 O 3 ) was postulated to even out the spatial distribution of O 2 in the bed by the redox reactions with the combustible gases (CO) and the incoming O 2 from the fluidizing gas, a process that aligns with OCAC. − Hence, Fe 2 O 3 is a good candidate for CLC or OCAC, while CuO is a good candidate for CLOU. A similar conclusion was drawn by Kajnas et al when using iron- and manganese-based OCs as bed materials to combust gaseous CO in an OCAC setup.…”

Section: Resultsmentioning

confidence: 99%

Chemical Looping Combustion of a Biomass Char in Fe₂O₃-, CuO-, and SrFeO_3−δ-Based Oxygen Carriers

et al. 2022

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This research focuses on the combustion of biomass char in fluidized beds of various particulate solids, which, under the conditions of the reaction, were either inert or capable of supplying oxygen to reactions. The latter were termed oxygen carriers. The solids used were SiO2, as an inert material, and three oxygen carriers: (1) Fe2O3 prepared from a natural pyrite ore, (2) CuO supported on mayenite, and (3) SrFeO3−δ strontium ferrite perovskite. Combustion experiments were undertaken by introducing a sample of partially devolatilized biomass (commercial “biochar”) to a hot bubbling bed (inner diameter of 30 mm), fluidized by a mixture of oxygen and nitrogen, then analyzing the composition of the off-gas and the burnout time of the char sample. In the temperature range investigated in this work (1023–1168 K), CuO and SrFeO3−δ but not Fe2O3 thermally decomposed, releasing gaseous O2 [so-called “chemical looping oxygen uncoupling” (CLOU)]. Hence, to make the combustion conditions comparable to various oxygen carriers, all experiments were performed using a fluidizing gas with a fixed partial pressure of O2 (pO2) of ∼0.015 bar. Despite the same nominal pO2, the occurrence of the oxygen uncoupling reaction increased the total net amount of O2(g) available in the process, affecting external mass transfer of O2 to the char particle and accelerating its rate of combustion. The time needed to totally combust 0.1 g of biochar particles in different beds at 1168 K followed the trend CuO < SrFeO3−δ < Fe2O3 ≈ silica sand. The difference in the performance of CuO and SrFeO3−δ was ascribed to the lower oxygen availability via CLOU in perovskite compared to copper oxide. Interestingly, combustion in the bed of Fe2O3 particles took a similar amount of time as combustion in the inert bed of SiO2, despite iron oxide playing an active role in the process. The finding is explained by Fe2O3 reacting with CO produced from incomplete char combustion, which results in the reduced oxide competing with char for O2(g) and effectively decreasing the local pO2.

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Ilmenite as alternative bed material for the combustion of coal and biomass blends in a fluidised bed combustor to improve combustion performance and reduce agglomeration tendency

Cited by 31 publications

References 55 publications

Effect of Natural Ilmenite on the Solid Biomass Conversion of Inhomogeneous Fuels in Small-Scale Bubbling Fluidized Beds

Effect of Natural Ilmenite on the Solid Biomass Conversion of Inhomogeneous Fuels in Small-Scale Bubbling Fluidized Beds

A generalized analytical energy balance model for evaluating agglomeration from a binary collision of wet particles

Chemical Looping Combustion of a Biomass Char in Fe₂O₃-, CuO-, and SrFeO_3−δ-Based Oxygen Carriers

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Ilmenite as alternative bed material for the combustion of coal and biomass blends in a fluidised bed combustor to improve combustion performance and reduce agglomeration tendency

Cited by 31 publications

References 55 publications

Effect of Natural Ilmenite on the Solid Biomass Conversion of Inhomogeneous Fuels in Small-Scale Bubbling Fluidized Beds

Effect of Natural Ilmenite on the Solid Biomass Conversion of Inhomogeneous Fuels in Small-Scale Bubbling Fluidized Beds

A generalized analytical energy balance model for evaluating agglomeration from a binary collision of wet particles

Chemical Looping Combustion of a Biomass Char in Fe2O3-, CuO-, and SrFeO3−δ-Based Oxygen Carriers

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Chemical Looping Combustion of a Biomass Char in Fe₂O₃-, CuO-, and SrFeO_3−δ-Based Oxygen Carriers