Michael M. Moser, Christoph Voser, C. Onder, L. Guzzella
Idling losses constitute a significant amount of the fuel consumption of internal combustion engines. Therefore, shutting down the engine during idling phases can improve its overall efficiency. For driver acceptance a fast restart of the engine must be guaranteed. A fast engine start can be performed using a powerful electric starter and an appropriate battery which are found in hybrid electric vehicles, for example. However, these devices involve additional cost and weight. An alternative method is to use a tank with pressurized air that can be injected directly into the cylinders to start the engine pneumatically. In this paper, pneumatic engine starts using camshaft driven charge valves are discussed. A general methodology for an air-optimal charge valve design is presented which can deal with various requirements. The proposed design methodology is based on a process model representing pneumatic engine operation. A design example for a two-cylinder engine is shown, and the resulting optimized pneumatic start is experimentally verified on a test bench engine. The engine’s idling speed of 1200 rpm can be reached within 350 ms for an initial pressure in the air tank of 10 bar. A detailed system analysis highlights the characteristics of the optimal design found.
{"title":"Design Methodology of Camshaft Driven Charge Valves for Pneumatic Engine Starts","authors":"Michael M. Moser, Christoph Voser, C. Onder, L. Guzzella","doi":"10.2516/OGST/2013207","DOIUrl":"https://doi.org/10.2516/OGST/2013207","url":null,"abstract":"Idling losses constitute a significant amount of the fuel consumption of internal combustion engines. Therefore, shutting down the engine during idling phases can improve its overall efficiency. For driver acceptance a fast restart of the engine must be guaranteed. A fast engine start can be performed using a powerful electric starter and an appropriate battery which are found in hybrid electric vehicles, for example. However, these devices involve additional cost and weight. An alternative method is to use a tank with pressurized air that can be injected directly into the cylinders to start the engine pneumatically. In this paper, pneumatic engine starts using camshaft driven charge valves are discussed. A general methodology for an air-optimal charge valve design is presented which can deal with various requirements. The proposed design methodology is based on a process model representing pneumatic engine operation. A design example for a two-cylinder engine is shown, and the resulting optimized pneumatic start is experimentally verified on a test bench engine. The engine’s idling speed of 1200 rpm can be reached within 350 ms for an initial pressure in the air tank of 10 bar. A detailed system analysis highlights the characteristics of the optimal design found.","PeriodicalId":19444,"journal":{"name":"Oil & Gas Science and Technology-revue De L Institut Francais Du Petrole","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76988087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper derives an LQR anti-jerk controller for an automotive driveline. The time derivative of the drive shaft torque, which is closely related to the vehicle jerk, is used as a virtual system output and regulated to zero. Thereby, the controller does not need a reference model for generation of reference trajectories for the control law evaluation. The controller acts as a torque compensator for the driver’s torque demand which the controller output asymptotically follows. The properties of the controller are discussed and the behavior is illustrated by simulation examples and verified with experiments on a heavy duty truck.
{"title":"A Powertrain LQR-Torque Compensator with Backlash Handling","authors":"Peter Templin, B. Egardt","doi":"10.2516/OGST/2011147","DOIUrl":"https://doi.org/10.2516/OGST/2011147","url":null,"abstract":"This paper derives an LQR anti-jerk controller for an automotive driveline. The time derivative of the drive shaft torque, which is closely related to the vehicle jerk, is used as a virtual system output and regulated to zero. Thereby, the controller does not need a reference model for generation of reference trajectories for the control law evaluation. The controller acts as a torque compensator for the driver’s torque demand which the controller output asymptotically follows. The properties of the controller are discussed and the behavior is illustrated by simulation examples and verified with experiments on a heavy duty truck.","PeriodicalId":19444,"journal":{"name":"Oil & Gas Science and Technology-revue De L Institut Francais Du Petrole","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80375583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dynamic kinetic data collected over commercial V2 O5 -WO3 /TiO2 and Fe-zeolite catalysts analyzing the standard NH3 -SCR of NO for the abatement of NOx from vehicle exhausts showed transient effects at low temperatures related to the inhibiting action of excess ammonia. In order to describe such transient effects, a specific rate expression accounting for NH3 inhibition of the standard SCR reaction is needed in mathematical models of real SCR converters. We present herein a dual-site Mars-Ven Krevelen-type rate equation suitable to describe dynamic features associated with ammonia injection and shut-off over both V-based and Fe-zeolite catalysts.
{"title":"Kinetic Modeling of Dynamic Aspects of the Standard NH3-SCR Reaction Over V2O5-WO3/TiO2 and Fe-Zeolite Commercial Catalysts for the Aftertreatment of Diesel Engines Exhausts","authors":"I. Nova, M. Colombo, E. Tronconi","doi":"10.2516/OGST/2011132","DOIUrl":"https://doi.org/10.2516/OGST/2011132","url":null,"abstract":"Dynamic kinetic data collected over commercial V2 O5 -WO3 /TiO2 and Fe-zeolite catalysts analyzing the standard NH3 -SCR of NO for the abatement of NOx from vehicle exhausts showed transient effects at low temperatures related to the inhibiting action of excess ammonia. In order to describe such transient effects, a specific rate expression accounting for NH3 inhibition of the standard SCR reaction is needed in mathematical models of real SCR converters. We present herein a dual-site Mars-Ven Krevelen-type rate equation suitable to describe dynamic features associated with ammonia injection and shut-off over both V-based and Fe-zeolite catalysts.","PeriodicalId":19444,"journal":{"name":"Oil & Gas Science and Technology-revue De L Institut Francais Du Petrole","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86948395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Model-Based Throttle Control using Static Compensators and Pole Placement - In modern spark ignited engines, the throttle is controlled by the Electronic Control Unit (ECU), which gives the ECU dir ...
{"title":"Model-Based Throttle Control using Static Compensators and Pole Placement","authors":"Andreas Thomasson, L. Eriksson","doi":"10.2516/OGST/2011137","DOIUrl":"https://doi.org/10.2516/OGST/2011137","url":null,"abstract":"Model-Based Throttle Control using Static Compensators and Pole Placement - In modern spark ignited engines, the throttle is controlled by the Electronic Control Unit (ECU), which gives the ECU dir ...","PeriodicalId":19444,"journal":{"name":"Oil & Gas Science and Technology-revue De L Institut Francais Du Petrole","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91459259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In order to make modern Diesel engines cleaner and more fuel efficient, their air systems architecture become more and more complex. The control strategies of these systems must take account of the multiple components interactions with minimal calibration effort required. In this context, model based techniques are very attractive. In this paper, we propose a control oriented model of a variable geometry turbocharger in an architecture with two Exhaust Gas Recirculation (EGR) loops: High Pressure (HP) and Low Pressure (LP). This model is implemented in a basic control strategy and evaluated experimentally during tests with LP or HP EGR. The results show that the choice of EGR circuit has a high influence on the turbocharger actuator position, but that this effect is well taken into account in the proposed model.
{"title":"Control Oriented Model of a Variable Geometry Turbocharger in an Engine with Two EGR Loops Modélisation de compresseur à géométrie variable dédiée au contrôle pour un moteur avec deux boucles EGR","authors":"J.-C. Chauvin, Olivier Grondin, P. Moulin","doi":"10.2516/OGST/2011103","DOIUrl":"https://doi.org/10.2516/OGST/2011103","url":null,"abstract":"In order to make modern Diesel engines cleaner and more fuel efficient, their air systems architecture become more and more complex. The control strategies of these systems must take account of the multiple components interactions with minimal calibration effort required. In this context, model based techniques are very attractive. In this paper, we propose a control oriented model of a variable geometry turbocharger in an architecture with two Exhaust Gas Recirculation (EGR) loops: High Pressure (HP) and Low Pressure (LP). This model is implemented in a basic control strategy and evaluated experimentally during tests with LP or HP EGR. The results show that the choice of EGR circuit has a high influence on the turbocharger actuator position, but that this effect is well taken into account in the proposed model.","PeriodicalId":19444,"journal":{"name":"Oil & Gas Science and Technology-revue De L Institut Francais Du Petrole","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90398697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Finding the correct Top Dead Center (TDC) offset for an internal combustion engine is harder than it seems. This study introduces a novel method to find the TDC offset based on the simple assumption that the heat loss power through the combustion chamber walls is constant for motored cycles in a narrow Crank Angle interval around TDC. The proposed method uses nonlinear least squares optimization to find the combination of specific heat ratio and TDC offset that makes the heat loss power as constant as possible. An important subproblem is to determine the peak pressure location with high accuracy. Fitting a third order Fourier series to the motored cylinder pressure allows the pressure maximum to be estimated with a standard deviation of 0.005° Crank Angle (CA) and it can also be used instead of the measured pressure to reduce the uncertainty of the TDC estimate by approximately 50%. The standard deviation of a single-cycle TDC estimate is approximately 0.025° CA when using a crank resolution of 0.2° CA for the measurements. The bias of the TDC estimate is in the 0-0.02° CA range both when comparing to measurements with a TDC sensor and with simulated motored cycles. The method can be used both for calibration and on-board diagnostics purposes e.g. during cranking, fuel cut-off or engine switch-off. The third order Fourier series fit comes with a significant computational penalty but since it is only applied very intermittently this does not have to be a serious issue.
{"title":"TDC Offset Estimation from Motored Cylinder Pressure Data based on Heat Release Shaping","authors":"P. Tunestål","doi":"10.2516/OGST/2011144","DOIUrl":"https://doi.org/10.2516/OGST/2011144","url":null,"abstract":"Finding the correct Top Dead Center (TDC) offset for an internal combustion engine is harder than it seems. This study introduces a novel method to find the TDC offset based on the simple assumption that the heat loss power through the combustion chamber walls is constant for motored cycles in a narrow Crank Angle interval around TDC. The proposed method uses nonlinear least squares optimization to find the combination of specific heat ratio and TDC offset that makes the heat loss power as constant as possible. An important subproblem is to determine the peak pressure location with high accuracy. Fitting a third order Fourier series to the motored cylinder pressure allows the pressure maximum to be estimated with a standard deviation of 0.005° Crank Angle (CA) and it can also be used instead of the measured pressure to reduce the uncertainty of the TDC estimate by approximately 50%. The standard deviation of a single-cycle TDC estimate is approximately 0.025° CA when using a crank resolution of 0.2° CA for the measurements. The bias of the TDC estimate is in the 0-0.02° CA range both when comparing to measurements with a TDC sensor and with simulated motored cycles. The method can be used both for calibration and on-board diagnostics purposes e.g. during cranking, fuel cut-off or engine switch-off. The third order Fourier series fit comes with a significant computational penalty but since it is only applied very intermittently this does not have to be a serious issue.","PeriodicalId":19444,"journal":{"name":"Oil & Gas Science and Technology-revue De L Institut Francais Du Petrole","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82331409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
O. Zadakbar, R. Abbassi, F. Khan, K. Karimpour, M. Golshani, A. Vatani
Flaring is a common method of disposal of flammable waste gases in the downstream industries. Flare flame out (flame lift-off or blow-outs) often occurs causing toxic vapors to discharge. The toxic gases released may have hazardous effects on the surrounding environment. To study the effect of inhalation exposure of these toxic gases on human health, the four steps of the EPA (Environmental Protection Agency ) framework with the field data to quantify the cancer and non-cancer health risks are integrated in this paper. As a part of exposure assessment, gas dispersion modeling using AERMOD and UDM-PHAST is applied in two different conditions of normal flaring and flare flame out during a particular climate condition in Khangiran region. Recommendations to avoid flare flame out conditions are also presented here.
{"title":"Risk Analysis of Flare Flame-out Condition in a Gas Process Facility Analyse des risques des conditions d’extinction de torche au sein d’une installation de traitement de gaz","authors":"O. Zadakbar, R. Abbassi, F. Khan, K. Karimpour, M. Golshani, A. Vatani","doi":"10.2516/OGST/2010027","DOIUrl":"https://doi.org/10.2516/OGST/2010027","url":null,"abstract":"Flaring is a common method of disposal of flammable waste gases in the downstream industries. Flare flame out (flame lift-off or blow-outs) often occurs causing toxic vapors to discharge. The toxic gases released may have hazardous effects on the surrounding environment. To study the effect of inhalation exposure of these toxic gases on human health, the four steps of the EPA (Environmental Protection Agency ) framework with the field data to quantify the cancer and non-cancer health risks are integrated in this paper. As a part of exposure assessment, gas dispersion modeling using AERMOD and UDM-PHAST is applied in two different conditions of normal flaring and flare flame out during a particular climate condition in Khangiran region. Recommendations to avoid flare flame out conditions are also presented here.","PeriodicalId":19444,"journal":{"name":"Oil & Gas Science and Technology-revue De L Institut Francais Du Petrole","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75623289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Pröll, Philipp Kolbitsch, Johannes Bolhar-Nordenkampf, H. Hofbauer
A chemical looping pilot plant was designed, built and operated with a design fuel power of 120 kW (lower heating value, natural gas). The system consists of two Circulating Fluidized Bed (CFB) reactors. Operating results are presented and evaluated for a highly reactive nickel-based oxygen carrier, total system inventory 65 kg. The performance in fuel conversion achieved is in the range of 99.8% (CH4 conversion) and 92% (CO2 yield). In chemical looping reforming operation, it can be reported that thermodynamic equilibrium is reached in the fuel reactor and that all oxygen is absorbed in the air reactor as soon as the global stoichiometric air/fuel ratio is below 1 and the air reactor temperature is 900°C or more. Even though pure natural gas (98.6 vol.% CH4 ) without steam addition was fed to the fuel reactor, no carbon formation has been found as long as the global stoichiometric air/fuel ratio was larger than 0.4. Based on the experimental findings and on the general state of the art, it is concluded that niche applications such as industrial steam generation from natural gas or CO2 -ready coupled production of H2 and N2 can be interesting pathways for immediate scale-up of the technology.
{"title":"Chemical Looping Pilot Plant Results Using a Nickel-Based Oxygen Carrier","authors":"T. Pröll, Philipp Kolbitsch, Johannes Bolhar-Nordenkampf, H. Hofbauer","doi":"10.2516/OGST/2010036","DOIUrl":"https://doi.org/10.2516/OGST/2010036","url":null,"abstract":"A chemical looping pilot plant was designed, built and operated with a design fuel power of 120 kW (lower heating value, natural gas). The system consists of two Circulating Fluidized Bed (CFB) reactors. Operating results are presented and evaluated for a highly reactive nickel-based oxygen carrier, total system inventory 65 kg. The performance in fuel conversion achieved is in the range of 99.8% (CH4 conversion) and 92% (CO2 yield). In chemical looping reforming operation, it can be reported that thermodynamic equilibrium is reached in the fuel reactor and that all oxygen is absorbed in the air reactor as soon as the global stoichiometric air/fuel ratio is below 1 and the air reactor temperature is 900°C or more. Even though pure natural gas (98.6 vol.% CH4 ) without steam addition was fed to the fuel reactor, no carbon formation has been found as long as the global stoichiometric air/fuel ratio was larger than 0.4. Based on the experimental findings and on the general state of the art, it is concluded that niche applications such as industrial steam generation from natural gas or CO2 -ready coupled production of H2 and N2 can be interesting pathways for immediate scale-up of the technology.","PeriodicalId":19444,"journal":{"name":"Oil & Gas Science and Technology-revue De L Institut Francais Du Petrole","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80487973","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Eyring, G. Kónya, J. Lighty, Asad H. Sahir, A. Sarofim, K. Whitty
A preliminary analysis has been conducted of the performance of a Chemical Looping system with Oxygen Uncoupling (CLOU) with copper oxide as the oxygen carrier and coal approximated by carbon as the fuel. The advantages of oxygen uncoupling are demonstrated by providing the energy balances, the circulation rate of oxygen carrier, the oxygen carrier mass loadings, the carbon burnout and oxygen partial pressure in the fuel reactor. Experimental data on the cycling of cuprous oxide to cupric oxide and kinetics for the oxidation and decomposition reactions of the oxides were obtained for use in the analysis. For this preliminary study unsupported oxides were utilized. The decomposition temperatures were rapid at the high temperature of 950°C selected for the fuel reactor. The oxidation kinetics peaked at about 800°C with the decrease in rate at higher temperatures, a decrease which is attributed in the literature to the temperature dependence of the diffusional resistance of the CuO layer surrounding the Cu2 O; the diffusion occurs through grain boundaries in the CuO layers and the rate of diffusion decreases as a consequence of growth of CuO grains with increasing temperature. The analysis shows the advantages of CLOU in providing rapid combustion of the carbon with carbon burnout times lower than the decomposition times of the oxygen carrier. For the full potential of CLOU to be established additional data are needed on the kinetics of supported oxides at the high temperatures (>850°C) at which oxygen is released by the CuO in the fuel reactor.
{"title":"Chemical Looping with Copper Oxide as Carrier and Coal as Fuel","authors":"E. Eyring, G. Kónya, J. Lighty, Asad H. Sahir, A. Sarofim, K. Whitty","doi":"10.2516/OGST/2010028","DOIUrl":"https://doi.org/10.2516/OGST/2010028","url":null,"abstract":"A preliminary analysis has been conducted of the performance of a Chemical Looping system with Oxygen Uncoupling (CLOU) with copper oxide as the oxygen carrier and coal approximated by carbon as the fuel. The advantages of oxygen uncoupling are demonstrated by providing the energy balances, the circulation rate of oxygen carrier, the oxygen carrier mass loadings, the carbon burnout and oxygen partial pressure in the fuel reactor. Experimental data on the cycling of cuprous oxide to cupric oxide and kinetics for the oxidation and decomposition reactions of the oxides were obtained for use in the analysis. For this preliminary study unsupported oxides were utilized. The decomposition temperatures were rapid at the high temperature of 950°C selected for the fuel reactor. The oxidation kinetics peaked at about 800°C with the decrease in rate at higher temperatures, a decrease which is attributed in the literature to the temperature dependence of the diffusional resistance of the CuO layer surrounding the Cu2 O; the diffusion occurs through grain boundaries in the CuO layers and the rate of diffusion decreases as a consequence of growth of CuO grains with increasing temperature. The analysis shows the advantages of CLOU in providing rapid combustion of the carbon with carbon burnout times lower than the decomposition times of the oxygen carrier. For the full potential of CLOU to be established additional data are needed on the kinetics of supported oxides at the high temperatures (>850°C) at which oxygen is released by the CuO in the fuel reactor.","PeriodicalId":19444,"journal":{"name":"Oil & Gas Science and Technology-revue De L Institut Francais Du Petrole","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86994746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ilmenite (FeTiO3 ) is being explored as an oxygen carrier in chemical looping processes. Its reduction and oxidation are described by the system Fe-Fe2 O3 -TiO2 -Ti2 O3 . The phase diagram at 1 000°C, presented here, offers a useful tool for predicting reactions and their products. We see that Fe2 TiO5 (pseudobrookite) and TiO2 (rutile) form a stable phase assemblage following the oxidation of FeTiO3 (ilmenite) in air. The subsequent reduction of Fe2 TiO5 at oxygen partial pressures of 10-15.5 atm stabilizes Fe1.02 Ti0.98 O3 , a solid solution of ilmenite. Further reduction will produce metallic iron, which compromises the integrity of the oxygen carrier for chemical looping processes. We speculate that the reduction of Fe-Ti oxides in several practical instances does not reach completion (and equilibrium) under the imposed atmospheres operating in fuel reactors.
{"title":"Oxidation and Reduction of Iron-Titanium Oxides in Chemical Looping Combustion: A Phase-Chemical Description","authors":"P. D. Hoed, A. Luckos","doi":"10.2516/OGST/2011008","DOIUrl":"https://doi.org/10.2516/OGST/2011008","url":null,"abstract":"Ilmenite (FeTiO3 ) is being explored as an oxygen carrier in chemical looping processes. Its reduction and oxidation are described by the system Fe-Fe2 O3 -TiO2 -Ti2 O3 . The phase diagram at 1 000°C, presented here, offers a useful tool for predicting reactions and their products. We see that Fe2 TiO5 (pseudobrookite) and TiO2 (rutile) form a stable phase assemblage following the oxidation of FeTiO3 (ilmenite) in air. The subsequent reduction of Fe2 TiO5 at oxygen partial pressures of 10-15.5 atm stabilizes Fe1.02 Ti0.98 O3 , a solid solution of ilmenite. Further reduction will produce metallic iron, which compromises the integrity of the oxygen carrier for chemical looping processes. We speculate that the reduction of Fe-Ti oxides in several practical instances does not reach completion (and equilibrium) under the imposed atmospheres operating in fuel reactors.","PeriodicalId":19444,"journal":{"name":"Oil & Gas Science and Technology-revue De L Institut Francais Du Petrole","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89193945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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