The Preparation Methods of Fe2O3/Al2O3 Oxygen Carriers and their Chemical Looping Combustion Performance

2013 ◽  
Vol 724-725 ◽  
pp. 1145-1149 ◽  
Author(s):  
Zi Song Liu ◽  
Yong Gang Wei ◽  
Kong Zhai Li ◽  
Hua Wang ◽  
Xing Zhu ◽  
...  
Keyword(s):  
High Selectivity ◽  
Oxygen Carrier ◽  
Combustion Process ◽  
Chemical Looping Combustion ◽  
Chemical Looping ◽  
Oxygen Carriers ◽  
Preparation Methods ◽  
Air Atmosphere ◽  
Infrared Gas Analyzer ◽  
Structure And Activity

60wt%Fe2O3/Al2O3oxygen carriers were prepared by different methods and characterized by means of XRD, H2-TPR, infrared gas analyzer. The effects of preparation methods on the structure and activity of Fe2O3/Al2O3oxygen carriers for chemical looping combustion of methane were also investigated. The factors on the selectivity of CO2in the chemical looping combustion process at different reaction temperatures were discussed. Methane can be quickly converted to CO2and H2O with high selectivity at 850°C for 15 min. After redox cycling in alternant methane/air atmosphere for 30 times, the formation of CO2was enhanced, indicating higher activity of oxygen carrier after the redox experiment.

The Performance Research on Reaction of Fe2O3/Al2O3 Oxygen Carrier and CO in Chemical-Looping Combustion Process

2012 ◽  
Vol 550-553 ◽  
pp. 974-978
Author(s):  
Wen Yan Li ◽  
Xing Lei Liu ◽  
Qiu Luan Chen ◽  
Feng Ming Chu
Keyword(s):  
Oxygen Carrier ◽  
Combustion Process ◽  
Kinetic Mechanism ◽  
Chemical Looping Combustion ◽  
Chemical Looping ◽  
Oxygen Carriers ◽  
Novel Technology ◽  
Mechanism Function ◽  
Tg And Dtg ◽  
Performance Research

Chemical-looping combustion (CLC) is a novel technology, which has inherent property of separating the greenhouse gas CO2, which uses oxygen carriers to transfer oxygen for combustion from air to fuel. The reactivity of Fe2O3/Al2O3 oxygen carrier was assessed by measuring their ability to oxidize CO. The kinetics and mechanism of oxygen carrier have been studied by TG and DTG techniques. The kinetic mechanism function of the reaction between Fe2O3/Al2O3 and CO has been built using the Coats-Redfern equation.

Study and Improvement of the Regeneration of Metallic Oxides Used as Oxygen Carriers for a New Combustion Process

2006 ◽  
Vol 4 (1) ◽  
Author(s):  
Sebastien Roux ◽  
Ammar Bensakhria ◽  
Gerard Antonini
Keyword(s):  
Oxygen Carrier ◽  
Combustion Process ◽  
Reactive Oxygen ◽  
Chemical Looping Combustion ◽  
Regeneration Ability ◽  
Chemical Looping ◽  
Oxygen Carriers ◽  
Air Oxidation ◽  
Metallic Oxide ◽  
Metallic Oxides

A new combustion process called chemical-looping combustion, has been suggested as an energetically efficient method for separation and capture of the carbon dioxide, generated by the combustion of fossil's fuels. This process consists of a reversible combustion, based on successive fuel oxidation via the reduction of metallic oxide followed by its regeneration by air oxidation. The generated products are: the reduced oxygen carrier, which is regenerated in a second reactor by air and recycled, and a flue gas, mainly composed of CO2 and H2O, which could be separated by condensation.In chemical-looping combustion process, it is important that the metallic oxide, used as an oxygen carrier, has a high reactivity with the fuel and good regeneration ability. It should have also good mechanical characteristics, in order to avoid its attrition and agglomeration during the successive cyclic reactions.In this work, the reactivity study of various oxygen carriers was carried out, during ten successive oxidation and reduction cycles, using a thermal gravimetrical analysis apparatus. From the results obtained, two types of oxygen carriers were identified: very reactive oxygen carriers, with a decreasing of their reactivity during the successive cycles of reduction and oxidation, and oxygen carriers with low and constant reactivity during the successive cycles.In order to improve the capacity of regeneration of the reactive oxygen carrier, several mixtures were prepared by adding stable and non-reactive metallic oxide, which acts as binder or doping agent by the mechanical properties of the mixed oxygen carrier improvement.The results obtained showed that, for all mixtures prepared and tested, the addition of binders to the reactive metallic oxides improve their regeneration ability. The best results, concerning the reactivity and the regeneration performances, were obtained with Fe2O3 mixed with CaO, TiO2 or MgO, followed by NiO mixed with CaO or TiO2 and finally CuO mixed with TiO2 or MgO.

Comparison of Chemical-Looping with Oxygen Uncoupling and Chemical-Looping Combustion Technology Reaction Mechanism

2014 ◽  
Vol 955-959 ◽  
pp. 2261-2266
Author(s):  
Xiao Ning Gao ◽  
Hui Min Xue ◽  
Yuan Li ◽  
Xue Feng Yin
Keyword(s):  
New Technologies ◽  
Oxygen Carrier ◽  
Combustion Process ◽  
Chemical Looping Combustion ◽  
Chemical Looping ◽  
Oxygen Carriers ◽  
High Efficient ◽  
Direct Separation ◽  
Fuel Reactor ◽  
Combustion Technology

In order to reduce the emission of CO2and control the global greenhouse effect, the paper introduces and compares two new technologies named chemical-looping combustion (CLC) and chemical-looping with oxygen uncoupling (CLOU) that are both high-efficient and clean. Through comparative analysis, CLC has been widely studied because of its direct separation of CO2, reduction loss of the heat, improvement of energy efficiency and avoiding of the generation of fuel type NOxin the combustion process. Besides the current research for metal oxygen carrier, there are some scholars find various non-metal oxygen carriers that have the better performance in CLC. But the study on reactors of CLC is still not mature, especially the solid fuel reactor, which is different from CLOU. In a certain sense, CLOU is an improved technology based CLC, besides the bove advantages, it also can react with coal directly. Many scholars use coal as fuel in the fluidized bed by the technology of CLOU, and the results of them are feasible. So from this perspective, CLOU technology has more broad prospects than CLC in the China.

Simulation of a New Chemical-Looping Combustion Process without Sulfur Evolution Based on Ca-Based Oxygen Carrier

2014 ◽  
Vol 12 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Hongjing Tian ◽  
Xiude Hu ◽  
Jing Chang ◽  
Mingdong Han ◽  
Guanglin Sun ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Oxygen Carrier ◽  
Combustion Process ◽  
Operating Regime ◽  
Steam Gasification ◽  
Chemical Looping Combustion ◽  
Chemical Looping ◽  
Oxygen Carriers ◽  
Combustion System ◽  
Reactor Temperature

Abstract Calcium sulfate (CaSO4) is a promising oxygen carrier for chemical-looping combustion system. The release of sulfurous gas in the circulating of Ca-based oxygen carrier is a crucial problem. In this paper, it is found that the released amount of sulfurous gas is greatly affected by the partial pressure of reductive gas. If the partial pressure of the mixed reductive gases, composed of H2 and CO, maintains higher than 40 kPa, the sulfurous gas can be completely eliminated even at the reacting temperature higher than 1,000°C. Therefore, a new chemical-looping combustion system based on CaSO4 and NiO oxygen carrier, without any sulfur evolution, is simulated using Aspen Plus software. In the system, the syngas is generated from the steam gasification of coal and reacts with CaSO4 and NiO consecutively. The sulfur release occurred in the circulating of Ca-based oxygen carriers can be prevented because the concentrations of CO and H2 keep higher than 45% in the presence of Ca-based oxygen carriers. The suitable operating regime, in which auto-thermally operating of the system, zero-sulfur release and easy sequestration of CO2 from the flue gas are realized, is proposed in this paper. The effects of fuel reactor temperature, air reactor temperature and the recycle rate of oxygen carrier on the released heat from the system and the concentration of CO2 and H2O are also studied in the paper.

scholarly journals The effect of Niobium oxide as a promoter on -Al2O3 based oxygen carrier for chemical looping combustion

2021 ◽  
Vol 12 (3) ◽  
pp. 3833-3839
Author(s):  
Nur Adibah Mohd Ghazalia Et.al
Keyword(s):  
Low Cost ◽  
Oxygen Carrier ◽  
Combustion Process ◽  
Reduction Reaction ◽  
Vital Role ◽  
Chemical Looping Combustion ◽  
Chemical Looping ◽  
Potential Candidate ◽  
Oxygen Carriers ◽  
Oxygen Transport Capacity

Chemical looping combustion (CLC) is known as a low-cost strategy for the capture of carbon dioxide for fuel combustion. In CLC process, oxygen carriers (OCs) are the cornerstone and play a vital role in defining reaction process. The aim of the present work was to investigate the potential of niobium (Nb) as a promoter on the -Al2O3 and its behavior as an oxygen carrier for chemical looping combustion process. In this work, the Nb loading was varied between 5 – 15 wt. %.  Their behavior in CLC was analyzed by TPR, TPO, SEM and TGA. From the TPR results, the reduction temperature for 5 wt.%, 10 wt.% and 15 wt.% Nb loading were 560 ℃, 529 ℃ and 545 ℃, respectively which indicated that reduction reaction occurs around 500 ℃ and above. SEM analysis showed that increasing of Nb loading resulted in some agglomeration and thus lowering the ability of metal oxide to gain and release oxygen. The redox characteristics were carried out using TGA with 5% CH4/N2 was used as the reducing gas, while air was used as oxidizing gas. The highest oxygen transfer capacity was 3.0% which is presented by 5 wt.% of Nb loading. Since the addition of Nb successfully improved the oxygen transport capacity, it can be concluded that Nb is the potential candidate for oxygen carrier in CLC.

Chemical-looping combustion — a thermodynamic study

2008 ◽  
Vol 222 (6) ◽  
pp. 1005-1019 ◽  
Author(s):  
N R McGlashan
Keyword(s):  
Heat Exchange ◽  
Redox Reactions ◽  
Oxygen Carrier ◽  
Combustion Process ◽  
Reduction Process ◽  
Equilibrium Temperature ◽  
Working Fluid ◽  
Chemical Looping Combustion ◽  
Chemical Looping ◽  
Ic Engine

The poor performance of internal combustion (IC) engines can be attributed to the departure from equilibrium in the combustion process. This departure is expressed numerically, as the difference between the working fluid's temperature and an ideal ‘combustion temperature’, calculated using a simple expression. It is shown that for combustion of hydrocarbons to be performed reversibly in a single reaction, impractically high working fluid temperatures are required — typically at least 3500 K. Chemical-looping combustion (CLC) is an alternative to traditional, single-stage combustion that performs the oxidation of fuels using two reactions, in separate vessels: the oxidizer and reducer. An additional species circulates between the oxidizer and reducer carrying oxygen atoms. Careful selection of this oxygen carrier can reduce the equilibrium temperature of the two redox reactions to below current metallurgical limits. Consequently, using CLC it is theoretically possible to approach a reversible IC engine without resorting to impractical temperatures. CLC also lends itself to carbon capture, as at no point is N2 from the air allowed to mix with the CO2 produced in the reduction process and therefore a post-combustion scrubbing plant is not required. Two thermodynamic criteria for selecting the oxygen carrier are established: the equilibrium temperature of both redox reactions should lie below present metallurgical limits. Equally, both reactions must be sufficiently hot to ensure that their reaction velocity is high. The key parameter determining the two reaction temperatures is the change in standard state entropy for each reaction. An analysis is conducted for an irreversible CLC system using two Rankine cycles to produce shaft work, giving an overall efficiency of 86.5 per cent. The analysis allows for irreversibilites in turbine, boiler, and condensers, but assumes reactions take place at equilibrium. However, using Rankine cycles in a CLC system is considered impractical because of the need for high-temperature, indirect heat exchange. An alternative arrangement, avoiding indirect heat exchange, is discussed briefly.

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 Characterization for Disposal of the Residues Produced by Materials Used as Solid Oxygen Carriers in an Advanced Chemical Looping Combustion Process

2018 ◽  
Vol 8 (10) ◽  
pp. 1787
Author(s):  
Adriana Carrillo ◽  
Carmen Forero
Keyword(s):  
Manganese Oxides ◽  
Negative Impact ◽  
Low Cost ◽  
Combustion Process ◽  
Chemical Looping Combustion ◽  
Chemical Looping ◽  
Oxygen Carriers ◽  
Additional Energy ◽  
General Terms ◽  
Solid Oxygen

Chemical looping combustion (CLC) is a technology that is part of the capture and storage of CO2 through the combustion with solid oxygen carriers (OCs). It is considered an energy-efficient alternative to other methods, since it is a technology that inherently separates CO2 and has the advantage of not requiring additional energy for this separation. The key to the performance of CLC systems is the OC material. Low-cost materials, i.e., natural minerals rich in metal oxides (chromite, ilmenite, iron, and manganese oxides) were used in this investigation. These may contain traces of toxic elements, making the carrier residues hazardous. Therefore, the oxidized and reduced-phase residues of six OCs, evaluated in a discontinuous batch fluidized bed reactor (bFB) using methane and hydrogen as the reducing gas, were characterized by several techniques (crushing strength, SEM, XRD, and XRF). The researchers found that, in general terms, the residues present a composition very similar to that reported in the fresh samples, and although they contain traces of Ba, Cu, Cr, Ni or Zn, these compounds do not migrate to the leachate. It was mainly found that, according to the current regulations, none of the residues are classified as toxic, as they do not exceed the permissible limits of metals (100 and 5 mg/L for Ba and Cr, respectively), with 3.5 mg/L the highest value found for Ba. Thus, they would not have a negative impact on the environment when disposed of in a landfill.

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