Simulation of Two-Stage Fuel Reactor Chemical Looping Hydrogen Process Using Solid Fuel

2014 ◽  
Vol 908 ◽  
pp. 349-352 ◽  
Author(s):  
Long Fei Wang ◽  
Shu Zhong Wang ◽  
Ming Luo
Keyword(s):  
Carbon Dioxide ◽  
Solid Fuel ◽  
Flue Gas ◽  
Oxygen Carrier ◽  
Molar Ratio ◽  
Chemical Looping ◽  
Two Stage ◽  
Fuel Reactor ◽  
Simulation Results ◽  
Reactor Temperature

Chemical looping hydrogen (CLH) has become a promising technology for hydrogen production with inherent separation of carbon dioxide. Aspen Plus was used to simulate a two-stage fuel reactor CLH process of coal as solid fuel. Simulation results show that the two-stage reactor can fully convert the fuel and generate the maximum Fe0.947O component to react with the steam in steam reactor. The optimum OC/coal molar ratio in the two-stage fuel reactor was 2.8. The CO2 fraction of the flue gas in the fuel reactor reached 99% when the vapor was condensed at the temperature of 950 °C. The fraction of dry-based H2 in the steam reactor was nearly 100% when the steam reactor temperature was 700 °C and the steam/oxygen carrier molar ratio was 0.48.

Simulation of Chemical Looping Hydrogen Production Using Solid Fuel

2013 ◽  
Vol 724-725 ◽  
pp. 1254-1257 ◽  
Author(s):  
Long Fei Wang ◽  
Shu Zhong Wang ◽  
Ming Luo
Keyword(s):  
Hydrogen Production ◽  
Solid Fuel ◽  
Flue Gas ◽  
Carbon Capture ◽  
Oxygen Carrier ◽  
Chemical Looping ◽  
Gas Composition ◽  
Reactor Performance ◽  
Simulation Results ◽  
Effects Of Temperature

Chemical looping hydrogen production (CLH) has become a promising technology for hydrogen production with inherent separation of carbon dioxide. This paper simulated the three reactors of CLH process of coal as solid fuel using Aspen Plus. The effects of temperature, oxygen carrier/coal ratio, steam/coal ratio, and the air/coal ratio on the gas composition in specific reactor were discussed. Simulation results showed that the temperature had a great effect on the reactor performance. The optimized OC/coal ratio in the OC/coal ratio in this paper was 19.1. The CO2 fraction in the flue gas of FR reached 87.5% when the vapor was condensed at the temperature of 950 °C. The fraction of dry-based H2 in the SR was almost 100% when the SR temperature was 815 °C and the steam/coal ratio was 18.8. The simulation confirmed that the CLH process showed high potential in hydrogen production and the carbon capture.

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

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.

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

2016 ◽  
Vol 14 (2) ◽  
pp. 637-652 ◽  
Author(s):  
Zheng Min ◽  
Shen Laihong
Keyword(s):  
Coal Gasification ◽  
Oxygen Carrier ◽  
Molar Ratio ◽  
Chemical Looping Combustion ◽  
Chemical Looping ◽  
Transfer Capability ◽  
Fuel Reactor ◽  
Optimum Reaction ◽  
The Stability

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.

scholarly journals Materials for Chemical-Looping with Oxygen Uncoupling

2013 ◽  
Vol 2013 ◽  
pp. 1-19 ◽  
Author(s):  
Tobias Mattisson
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Carrier ◽  
Fluidized Bed Reactors ◽  
Chemical Looping ◽  
Thermodynamic Evaluation ◽  
Oxygen Carriers ◽  
Fuel Reactor ◽  
Combustion Technology ◽  
Continuous Chemical ◽  
Full Conversion

Chemical-looping with oxygen uncoupling (CLOU) is a novel combustion technology with inherent separation of carbon dioxide. The process is a three-step process which utilizes a circulating oxygen carrier to transfer oxygen from the combustion air to the fuel. The process utilizes two interconnected fluidized bed reactors, an air reactor and a fuel reactor. In the fuel reactor, the metal oxide decomposes with the release of gas phase oxygen (step 1), which reacts directly with the fuel through normal combustion (step 2). The reduced oxygen carrier is then transported to the air reactor where it reacts with the oxygen in the air (step 3). The outlet from the fuel reactor consists of only CO2 and H2O, and pure carbon dioxide can be obtained by simple condensation of the steam. This paper gives an overview of the research conducted around the CLOU process, including (i) a thermodynamic evaluation, (ii) a complete review of tested oxygen carriers, (iii) review of kinetic data of reduction and oxidation, and (iv) evaluation of design criteria. From the tests of various fuels in continuous chemical-looping units utilizing CLOU materials, it can be established that almost full conversion of the fuel can be obtained for gaseous, liquid, and solid fuels.

A Pb/Zn Based Chemical Looping System for Hydrogen and Power Production With Carbon Capture

2011 ◽  
Author(s):  
Niall R. McGlashan ◽  
Peter R. N. Childs ◽  
Andrew L. Heyes
Keyword(s):  
Power System ◽  
Flue Gas ◽  
Power Output ◽  
Carbon Capture ◽  
Oxygen Carrier ◽  
Fluid Phase ◽  
Chemical Looping Combustion ◽  
Inlet Temperature ◽  
Chemical Looping ◽  
Lower Efficiency

This paper describes an extension of a novel, carbon-burning, fluid phase chemical looping combustion system proposed previously. The system generates both power and H2 with ‘inherent’ carbon capture using chemical looping combustion (CLC) to perform the main energy release from the fuel. A mixed Pb and Zn based oxygen carrier is used, and due to the thermodynamics of the carbothermic reduction of PbO and ZnO respectively, the system generates a flue gas which consists of a mixture of CO2 and CO. By product H2 is generated from this flue gas using the water-gas shift reaction (WGSR). By varying the proportion of Pb to Zn circulating in the chemical loop, the ratio of CO2 to CO can be controlled, which in turn enables the ratio between the amount of H2 produced to the amount of power generated to be adjusted. By this means, the power output from the system can be ‘turned down’ in periods of low electricity demand without requiring plant shutdown. To facilitate the adjustment of the Pb/Zn ratio, use is made of the two metal’s mutual insolubility, as this means they form in to two liquid layers at the base of the reduction reactor. The amount of Pb and Zn rich liquid drawn from the two layers and subsequently circulated around the system is controlled thereby varying the Pb/Zn ratio. To drive the endothermic reduction of ZnO formed in the oxidiser, hot Zn vapour is ‘blown’ into the reducer where it condenses, releasing latent heat. The Zn vapour to produce this ‘blast’ of hot gas is generated in a flash vessel fed with hot liquid metal extracted from the oxidiser. A mass and energy balance has been conducted for a power system, operating on the Pb/Zn cycle. In the analysis, reactions are assumed to reach equilibrium and losses associated with turbomachinery are considered; however, pressure losses in equipment and pipework are assumed to be negligible. The analysis reveals that a power system with a second law efficiency of between 62% and 68% can be constructed with a peak turbine inlet temperature of only ca. 1850 K. The efficiency varies as the ratio between power and H2 production varies, with the lower efficiency occurring at the maximum power output condition.

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

Energies ◽  
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.

Chemical Looping Gasification of Coal in a 5 kWth Interconnected Fluidized Bed with a Two-Stage Fuel Reactor

2017 ◽  
Vol 32 (4) ◽  
pp. 4291-4299 ◽  
Author(s):  
Tianxu Shen ◽  
Jian Wu ◽  
Laihong Shen ◽  
Jingchun Yan ◽  
Shouxi Jiang
Keyword(s):  
Fluidized Bed ◽  
Chemical Looping ◽  
Two Stage ◽  
Fuel Reactor

Review of Computational Fluid Dynamics Studies on Chemical Looping Combustion

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.

scholarly journals Enhanced performance of chemical looping combustion of methane with Fe2O3/Al2O3/TiO2oxygen carrier

RSC Advances ◽  
2018 ◽  
Vol 8 (70) ◽  
pp. 39902-39912 ◽  
Author(s):  
Hsuan-Chih Wu ◽  
Young Ku
Keyword(s):  
Oxygen Carrier ◽  
Methane Combustion ◽  
Molar Ratio ◽  
Chemical Looping Combustion ◽  
Chemical Looping ◽  
Moving Bed

The effect of Fe2O3/CH4molar ratio on fuel and oxygen carrier conversion for methane combustion in the moving bed.

Review of Hydrogen Production from the Steam-Iron Process by Chemical-Looping Combustion

2014 ◽  
Vol 953-954 ◽  
pp. 966-969 ◽  
Author(s):  
Long Fei Wang ◽  
Shu Zhong Wang ◽  
Ming Luo
Keyword(s):  
Hydrogen Production ◽  
Solid Fuel ◽  
Process Development ◽  
Oxygen Carrier ◽  
Energy Conversion Efficiency ◽  
High Reactivity ◽  
Future Research ◽  
Pure Hydrogen ◽  
Chemical Looping ◽  
Oxygen Carriers

Chemical looping hydrogen production (CLH) is a promising method for pure hydrogen production, which not only can improve energy conversion efficiency and reduce environmental pollution, but also can separate carbon dioxide. This paper try to review the present chemical looping hydrogen process development on the screening of oxygen carrier particles of gaseous fuel and solid fuel, the design of proper reactors, and the system simulation. The design of solid fuel CLH system and the development of oxygen carriers with high reactivity and abrasion resistance for solid fuel at high temperature and pressure will be future research focuses.

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