In Situ Gasification Chemical Looping Combustion of Coal Using the Mixed Oxygen Carrier of Natural Anhydrite Ore and Calcined Limestone

Abstract The utilization of CaSO4-based oxygen carrier suffers the deactivation problem caused by sulphur loss. To capture the gas sulphides and to improve the stability of CaSO4 oxygen carrier, calcined limestone was introduced into the fuel reactor of Chemical Looping Combustion (CLC). Kinetic behaviors and thermodynamics of the combined process of coal gasification and oxygen carrier reduction using the mixed oxygen carrier CaSO4-CaO under different atmospheres were investigated. The effects of reaction temperature, gasification intermediate, and molar ratio of CaO to CaSO4 on gas sulphide emissions, CO2 generation, and distribution of other gas emissions and characterization of solid products are taken into account. It is found the CaO-based additive evidently suppressed the sulphur emissions, and improved both chemical reaction rate and CO2 generation efficiency. The sulfation products, both CaS and CaSO4, can be used as oxygen carrier later. The optimum reaction parameters are evaluated and obtained in terms of gas sulphide emissions, CO2 capture, other gas releases and maintenance of oxygen transfer capability.

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Multicycle Study on Chemical Looping Combustion with a CaSO4-CaO Mixed Oxygen Carrier

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2018-0114 ◽

2019 ◽

Vol 17 (10) ◽

Author(s):

Pu Sixu ◽

Zheng Min ◽

Liu Yulou ◽

Zhao Zhitong ◽

Sarma Pisupati

Keyword(s):

Environmental Factor ◽

Carbon Capture ◽

Oxygen Carrier ◽

Total Carbon ◽

Molar Ratio ◽

Chemical Looping Combustion ◽

Chemical Looping ◽

Molar Ratios ◽

Fuel Reactor ◽

High Concentrations

Abstract Chemical looping combustion (CLC) is a carbon capture technology which enables CO2 capture with low net efficiency penalty. Calcium sulfate (CaSO4) is an optional oxygen carrier for commercial use, but its usage is limited due to sulfur dioxide (SO2) emission. This study approaches this issue by adding CaO species into the CaSO4 oxygen carrier to inhibit the release of SO2 from CaSO4 oxygen carrier. In this study, the cyclical tests of a CaSO4-based oxygen carrier under alternating reducing and oxidizing conditions were performed at 900 °C and 800 °C respectively in a tubular furnace reactor at atmospheric pressure. The effects of reducing gas concentration and molar ratio of CaO/CaSO4 on the performance of CaSO4-CaO oxygen carrier were studied in terms of CO2 yields, Environmental factors of SO2 and COS, molar ratios of gas sulfides to CO2 generated in fuel reactor, and molar ratios of SO2 and COS to total carbon inlet. The use of CaO additive increased the yields of CO2 obviously. The release of COS in the fuel reactor and SO2 in the air reactor decreased, but while the overall release of SO2 in the fuel reactor increased. However, for per mole CO2 generation, less gas sulfides released from the fuel reactor. High concentrations of CO were beneficial for CO2 production and a low SO2 environmental factor, and meanwhile, the molar ratios of SO2 released to inlet CO {{\text{n}}_{{\text{S}}{{\text{O}}_2}}}/{{\text{n}}_{{\text{CO}}}} decreased. However, it led to a drop in CO2 yield and an increase in COS environmental factor. As a whole, the use of CaO additive and higher CO concentration both accelerated the parallel CaSO4 reductions in fuel reactor, especially the selectivity of CaSO4 reduction to CaS.

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Macroscopic fuel reactor modelling of a 5 kWth interconnected fluidized bed for in-situ gasification chemical looping combustion of coal

Chemical Engineering Journal ◽

10.1016/j.cej.2018.05.025 ◽

2018 ◽

Vol 348 ◽

pp. 978-991 ◽

Cited By ~ 7

Author(s):

Hongpeng Xu ◽

Jinchen Ma ◽

Haibo Zhao

Keyword(s):

Fluidized Bed ◽

Chemical Looping Combustion ◽

Chemical Looping ◽

Fuel Reactor

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Modeling of the Chemical Looping Combustion of Hard Coal and Biomass Using Ilmenite as the Oxygen Carrier

Energies ◽

10.3390/en13205394 ◽

2020 ◽

Vol 13 (20) ◽

pp. 5394

Author(s):

Anna Zylka ◽

Jaroslaw Krzywanski ◽

Tomasz Czakiert ◽

Kamil Idziak ◽

Marcin Sosnowski ◽

...

Keyword(s):

Fluidized Bed ◽

Oxygen Carrier ◽

Experimental Tests ◽

Chemical Looping Combustion ◽

Hard Coal ◽

Chemical Looping ◽

Simulation Accuracy ◽

Energy Technologies ◽

Fuel Reactor ◽

Relative Errors

This paper presents a 1.5D model of a fluidized bed chemical looping combustion (CLC) built with the use of a comprehensive simulator of fluidized and moving bed equipment (CeSFaMB) simulator. The model is capable of calculating the effect of gas velocity in the fuel reactor on the hydrodynamics of the fluidized bed and the kinetics of the CLC process. Mass of solids in re actors, solid circulating rates, particle residence time, and the number of particle cycles in the air and fuel reactor are considered within the study. Moreover, the presented model calculates essential emissions such as CO2, SOX, NOX, and O2. The model was successfully validated on experimental tests that were carried out on the Fluidized-Bed Chemical-Looping-Combustion of Solid-Fuels unit located at the Institute of Advanced Energy Technologies, Czestochowa University of Technology, Poland. The model’s validation showed that the maximum relative errors between simulations and experiment results do not exceed 10%. The CeSFaMB model is an optimum compromise among simulation accuracy, computational resources, and processing time.

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Review of Computational Fluid Dynamics Studies on Chemical Looping Combustion

Journal of Energy Resources Technology ◽

10.1115/1.4048680 ◽

2020 ◽

Vol 143 (8) ◽

Author(s):

Yali Shao ◽

Ramesh K. Agarwal ◽

Xudong Wang ◽

Baosheng Jin

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Oxygen Carrier ◽

Combustion Process ◽

Chemical Looping Combustion ◽

Chemical Looping ◽

Flow Process ◽

Gas Leakage ◽

Fuel Reactor ◽

Energy Penalty

Abstract Chemical looping combustion (CLC) is an attractive technology to achieve inherent CO2 separation with low energy penalty. In CLC, the conventional one-step combustion process is replaced by two successive reactions in two reactors, a fuel reactor (FR) and an air reactor (AR). In addition to experimental techniques, computational fluid dynamics (CFD) is a powerful tool to simulate the flow and reaction characteristics in a CLC system. This review attempts to analyze and summarize the CFD simulations of CLC process. Various numerical approaches for prediction of CLC flow process are first introduced and compared. The simulations of CLC are presented for different types of reactors and fuels, and some key characteristics including flow regimes, combustion process, and gas-solid distributions are described in detail. The full-loop CLC simulations are then presented to reveal the coupling mechanisms of reactors in the whole system such as the gas leakage, solid circulation, redox reactions of the oxygen carrier, fuel conversion, etc. Examples of partial-loop CLC simulation are finally introduced to give a summary of different ways to simplify a CLC system by using appropriate boundary conditions.

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